Well, I've been cooking up this project for a while, and I guess it makes sense to start a thread here in the projects section of GSTwins. As a few of you may know, I campaigned a GS500 in 500 twins with the AFM last year. Took 4th place overall in my class, collected a few top novice awards, and a 3rd place trophy. Unfortunately, the GS500 isn't super competitive in that class, especially against the 70+ horsepower SV-500 that sometimes runs there.
However, there is a rules exception in the AFM that permits a 450CC twin to run in the 250 superbike class - the rule exception permits unlimited mods. Toughest competition is a 2 stroke yamaha pulling high 2:04s around T-Hill; that's about 7 seconds better than my best pace. The good news is that a more or less stock GS500 should be powerful enough to consistently podium in the class.
The class it's self is pretty diverse, made up of 2-strokes, 450cc singles, one or two 450 twins, and a lot of production legal Ninja 250s. Broad range of lap times, and excellent competition. Because the GS can be made competitive there, it starts to make sense to put some real money into the bike, rather than running it just for fun.
Goal of the project is to drop 2-3 seconds based on riding skils, and pull down a few more seconds through mods. Thread will document my research, as well as mods.
I already have a bunch of parts, including my crashed out GS race bike.
- 06 GSX-R front end
- Race wheels
- RGV 250 swingarm, wheel, brakes, etc
- Yoshimura Pipe
- GS450 block/Pistons
Planning to add some go-fast parts as well.
Knowing that the GS450 & GS500 share the same crankshaft, stroke, and similar bore was the starting point for this project. I'm in the process of measuring up the various parts to ensure that they can fit together, but I have made the following initial assumptions;
- GS450 block shares the same oil passageways & stud spacing as the GS500.
- GS500 head can bolt to the GS450 block
- Clearances are okay with everything bolted together.
The assumptions seem pretty safe, but need to be confirmed.
GS450 & GS500 are similar, but the GS500 piston isn't simply a scaled up GS450 piston. Even without comparing the two pistons side by side, it's obvious that the GS450 piston has different valve relief. I will compare the two parts with a vernier calliper to see if the relief are due a taller piston crown, or if they are actually deeper, offering more lift. Both would be ideal; since a taller crown will increase compression, and a deeper relief will provide opportunities to machine down the cylinder block, and or install high lift cams. My eventual plan includes a set of Megacycle race cams, which I've read work best on a high compression engine. Crown diameter seems similar between the two pistons, which is a good sign that everything will fit.
If the GS450 piston isn't suitable for use, it's also possible that a 71mm KZ1000 piston will work. It features a high dome, and deep relief for compression, but uses a 17mm wrist pin, rather than the 18 I need to bolt to the GS rods. Ape Performance will machine out the wrist pin hole for $49 per piston. I'll probably buy a stock 70mm KZ piston to confirm that the dimensions are similar to the GS; I'd rather not waste $150/piston until I due diligence.
I have found that the GS450 uses a different style CCT than the GS500. I've confirmed through parts fiche that the GS450 CCT is the same part used on the GS1000. APE Part number is ST1100, and the gasket is #EC062.
On the bottom end, I'm planning to remove the balance shaft and send the crank to APE for a rebalance/lighten. I'm also considering removing the alternator, and possible the starter for weight and power savings. If I remove the starter, I might have a bolt welded to the counter-shaft sprocket, permitting possible use of an electric ratchet to start the bike on cold mornings.
Suspension work:
I already have a GSX-R 600 front end I've been running at local trackdays. Been very happy there, thanks to the amazing machine work of Bob Brussard.
I also have a R6 shock, that's been running like a champ since it was installed.
At the tail end I've been working on a conversion to a RGV250 swingarm. Bad news is that I started with the double braced swingarm, which uses an atypical wishbone linkage rather than the more common dogbones. The good news is that a GSX-R 600 linkage can probably be made to fit. Will post photos as I complete that project.
It's not a huge priority though; stock rear end is working okay for the time being.
You sir, have my attention.
If you haven't already, check around on the GSResources. There is a LOT of info for abusin........I mean "modding" a GS450 engine. Off the top of my head there was a mention of keeping the counter balancer (for ride-ability) and somebody was fitting an 8 valve head to a GS450 (or maybe a GS400?)
Thanks for the heads up. Can't believe I hadn't checked out that website before. :)
Yeah, they have an extensive knowledge of the pre '89 GS's over there. I highly recommend checking it out.
I just measured out the old and new pistons. All measurements were done with a vernier calliper, and are probably only accurate to within half a MM or so. Although there are some clear similarities between the two pistons, there are also some very obvious differences.
To start with, the height of the piston pin to the bottom of the skirt is pretty much identical between the two pistons, and the general construction and casting is very similar.
However, the deck height is quite different - the GS450 piston had about a 0.5 mm lower deck height. Since the two pistons shared the same skirt to pin distance, the measurement for deck height is pretty easy.
Skirt to deck height:
GS500: 56mm
GS450: 55.4mm
The next, and probably most obvious difference is in the size of the crown on both pistons; the GS450 has a much larger dome:
Dome circumference:
GS500: 57mm
GS450: 62mm
Dome height:
GS500: 8.5mm
GS450: 10mm
Valve relief are deeper, and not just due to the increased size of the dome:
Relief depth from deck:
GS500 Exhaust: 2.3mm
GS450 Intake: ~.8mm from deck (1.2mm from crown.)
GS450 Exhaust: 3.22mm
Only big concern is the spacing of the valve relief. Measured from the outside edges of the exhaust relief to the outside edge of the intake relief:
GS500 Estimated at about 59mm
GS450 measured at 57mm (bottom of relief, not top.)
A visual inspections suggests that the valve diameter hasn't increased noticeably on the GS500.
So... Conclusions...
There are some remaining questions about whether the shape of the GS500 combustion chamber will work with the GS450 pistons. Wider, taller dome could potentially cause interference issues with the GS500 head; especially if I deck the cylinders. I am however optimistic, especially based on the wide spacing of the GS500 valves.
Lower deck height means that it's potentially possible to machine down the GS500 cylinder block and/or head for increased compression, and in order to optimize the squish band.
1mm deeper valve reliefs on both intake and exhaust side may help ensure clearance for a race profile cam... I'll have to measure everything out to ensure. According to megacycle, the Race profile add 2.845mm and 2.362mm to intake and exhaust lift respectively, as well as 12-15 degrees of duration. Might be a tall order to find that much clearance without sacrificing compression.
One other good news is that there is plenty of material in the GS450 pistons around the outside edge of the valve relief. If necessary, I could probably machine out the relief a little, if their spacing turns out to be too narrow. If things work out that way, I'll effectively end up adding a little depth to the reliefs as well.
Next stage:
I have a spare GS500 engine that's currently got the bottom end off. I'm thinking I'll start bolting things together to see how everything fits. Plan is to remove the valve springs on one of the cylinders, and actually see how much lift is available on the valves with the GS pistons stock deck height. I'll probably coat the pistons with clay or something to see where the valves end up when they make contact. Will probably also try bolting the engine together without the base and head gaskets to see what happens when the cylinder block is 'decked.'
In the process, I'll fill the combustion chambers with oil, to measure the effective chamber size; should tell me how much I'm raising up the compression. I think a target of 12:1 or so would be good combined with the race cams.
Thoughts?
Best of lucks, I am keeping tabs on this thread.
Compression ratio...
According to David J. over on the racers page on the main GSTwins website, It's safe to remove about 1.27mm from the GS500 engine. Since the circumference of the cylinder head combustion chamber isn't quite as big as the circumference of the piston, we can easily conclude that all the material being removed subtracts space from the combustion chamber at cylinder level... If we assume that there is 1.5mm of combustion chamber in the cylinder/head gasket, and that the rest is in the head, along with the known compression ratio of the GS500 engine and the measurements listed above, we can calculate the following bits of information.
GS450 displacement per cylinder: 224.0cc
GS500 displacement per cylinder: 243.4cc
Total GS500 combustion chamber volume (with piston @ 9:1 compression): 24.98cc
GS500 cylinder combustion chamber space: 6.45cc
GS450 cylinder combustion chamber space (no decking): 8.31cc
GS450 cylinder combustion chamber space (decked so that piston deck is at same height as GS500 piston deck at TDC): 5.94cc
GS500 head combustion chamber space with GS500 piston crown (total, minus cylinder space): 18.53cc
GS500 piston crown volume (ignoring valve relief): 11.16cc
GS450 piston crown volume (ignoring valve relief): 15.61cc
GS500 head combustion chamber space without piston crown (head space + crown volume): 29.69cc
GS500 head combustion chamber space with GS450 piston crown (GS500 head, minus 450 crown): 14.08cc
In conclusion:
GS450 total combustion chamber volume (no decking): 22.39cc
GS450 total combustion chamber volume (cylinder decked so that GS450 piston deck is the same as GS500): 20.02cc
Resulting compression ratio, GS450 cylinders w/ GS500 head: 10:1 (no decking)
Resulting compression ratio, GS450 cylinders w/ GS500 head: 11:1 (decked so pistons are at same deck height as stock GS500)
Potential compression ratio, 1mm decking: 12.1:1
Potential compression ratio, maximum decking* (1.85mm): 14.9:1
* Maximum decking assumes that we can deck the 1.25mm that David J suggests is safe, plus the extra 1mm the GS450 pistons give us. In practice, this is probably not a reasonable assumption, due to issues of valve to piston clearance with GS450 pistons, dome to cylinder head height, spark plug clearance, etc. Beyond that 14.9:1 is probably more compression than I'd want to run on the stock GS500 pistons and bottom end.
All of these numbers are *very* rough of course; they are based on semi-accurate vernier calliper measurements, make quite a few assumptions, and don't take into account the displacement of the valve reliefs. As the resulting compression ratios increase, they are compounded by all inaccuracies. Ultimately, the best way to proceed is through empirical testing. Will be interesting to see how close I got... :)
Sounds like it'll be a great thread to keep reading. But don't forget the most important thing.
(http://nicubunu.ro/moods/pics-or-it-didnt-happen.png)
Will have pictures of the pistons soon, and will continue to post pictures and specifications as I proceed. :thumb:
Quote from: missk8t on October 04, 2011, 04:35:07 PM
Sounds like it'll be a great thread to keep reading. But don't forget the most important thing.
(http://nicubunu.ro/moods/pics-or-it-didnt-happen.png)
Comparison of GS500 piston (left) and GS450 piston (right.) Differences in valve relief are obvious.
(http://i261.photobucket.com/albums/ii63/ctbarbour/GS450%20Pistons/PA050219.jpg)
Side by side:
(http://i261.photobucket.com/albums/ii63/ctbarbour/GS450%20Pistons/PA050218.jpg)
(http://i261.photobucket.com/albums/ii63/ctbarbour/GS450%20Pistons/PA050234.jpg)
Pin height:
(http://i261.photobucket.com/albums/ii63/ctbarbour/GS450%20Pistons/PA050226.jpg)
GS450 piston detail:
(http://i261.photobucket.com/albums/ii63/ctbarbour/GS450%20Pistons/PA050221.jpg)
(http://i261.photobucket.com/albums/ii63/ctbarbour/GS450%20Pistons/PA050230.jpg)
(http://i261.photobucket.com/albums/ii63/ctbarbour/GS450%20Pistons/PA050231.jpg)
GS500 Piston detail:
(http://i261.photobucket.com/albums/ii63/ctbarbour/GS450%20Pistons/PA050224.jpg)
(http://i261.photobucket.com/albums/ii63/ctbarbour/GS450%20Pistons/PA050238.jpg)
(http://i261.photobucket.com/albums/ii63/ctbarbour/GS450%20Pistons/PA050229.jpg)
When I did the initial measurements, I also weighed each piston...
GS500 piston came in at 10.5oz
GS450 piston came in at 9.9oz
Curious what the maximum RPM is for the GS bottom end. I've heard that a spring swap alone is good for an additional 2000RPM or so. With the stock GS power curve, the extra revs would be meaningless... But with a good race cam, they might provide a huge increase in available horsepower, if combined with the right gearing.
http://cgi.ebay.com/ebaymotors/1983-Suzuki-GS400E-cylinder-head-/300589603517?pt=Motorcycles_Parts_Accessories&hash=item45fc895abd#ht_760wt_939
get a GS400 head! if they will fit, 4 valve head!
Would love to. They bolt on, but the exhaust ports are pointed directly at the GS500 engine cradle; can't be made to work without extensive modifications. If I'm going to go to the trouble, I'd rather use a GSX-R head.
I'd like to do a shim-under-tappet conversion on the race GS. Doing some research, I found that the GS500 and GS1000 share the same tappet. A little research on the web camshafts website gives me a measurement of 33.5 OD for the GS500/1000 tappets. I'm hoping to find another bike that uses shim-under with the same size tappets, but it might be a long shot. Good news is that one GS1000 kit provides enough tappets to do 2 GS500s.
Quote from: burning1 on October 06, 2011, 12:21:19 PM
Would love to. They bolt on, but the exhaust ports are pointed directly at the GS500 engine cradle; can't be made to work without extensive modifications. If I'm going to go to the trouble, I'd rather use a GSX-R head.
waitwhut? its possible to convert a gs500 to a 4valve-per-cyl jobbie?
Inoramuses like me would very much like to know how this would even be vaguely possible
(you'd have to get a whole new set of carbs at minimum, presumably?)
and what the likely side effects would be
(possibly more HP, and correspondingly suck-butt mileage? and probably failing any EPA tests?)
Possible, yes.
A few of the old GSX-R 750 oil-cooled heads use the came cylinder spacing, oil passageways, and bolt patterns as the GS top end. In order to use them though, you have to lop off two of the cylinders, modify the cams, and somehow seal the valve cover. It does require different fuelling, though my guess is that it would run well enough with the stock fueling to get the bike on a dyno for tuning.
Again, the 8 valve GS400 head is probably a no-go in the GS500 frame; the GS400 exhaust ports point directly at the GS500 frame spars. Compare:
http://www.motorcyclespecs.co.za/Gallery%20C/Suzuki%20GS400%2077.jpg
http://www.mcnews.com.au/NewBikeCatalogue/2001/Suzuki/Images/SuzukiGS500_lhf_600p.jpg
Keep in mind that there are also two different versions of the GS400 heads; a common 4 valve model, and a less common 8 valve model.
Either approach would require new pistons, extensive machine work, and would get in the way of finishing this project in time for the 2012 race season. If I stay on a GS for years into the future, I might look into running an oil cooled GSX-R 750 head.
Just re-checked the rulebook, and it looks like AFM permits me to bore the engine 1mm above the class limit of 450cc. Good news, since that would permit use of MTC 72mm KZ1000 pistons; they are available in 2 different compression ratios, and officially support a 1mm overbore on the wrist pin, necessary to run the GS's 18mm pins.
Going this route would bump my overall displacement up to 460.8cc, but the main reason I'm interested is the increase in comp ratio, and the fact that the deeper KZ valve reliefs may be necessary for use with high lift cams.
http://www.mtceng.com/piston/mtc-products/pistons/kawasaki/kz-900-1000
Other benefit is that I wouldn't have to re-sleeve to restore the GS450 blocks to factory tolerances; I could simply bore them out by 1mm if it turns out that there is too much wear on the cylinder.
Looks like some of the early model GSX-R 750 and 1150 bikes came equipped with Mikuni Flatslide pumper carbs, but only in the UK. Would be a great performance mod for the GS. I'll probably import a set and comment on how it works out when I have a chance to fit them.
i don't know your rules....
are you building a gs 450 chassis or installing a 450 engine in a GS500 chassis?
if the second....
why not re-sleeve the GS to make it a 450+1mm
a thicker sleeve will make a stronger cylinder.
look at the different kat600/750/1100 and oil cooled gsxrs and build a set of big bore carbs they came as 36,38, and a canadian edition had 41's if i remember
if you are spending stupid amounts of cash..... 450cc dirtbike engine into a 125 GP chassis or 250 GP chassis is a better way to spend cash....about 100-150 # lighter and more HP look at barebones racing site sick bikes there
I'm actually planning to install a GS450 cylinder block between a GS500 top and bottom end. Really cheap, simple solution. Not super expensive either, until I start springing for race oriented parts.
Rules for the class permit pretty much any build that meets the safety specifications, so long as it's 2 cylinders, and 450cc+1mm overbore or less.
I've never been terribly happy with the petcock solution I have for the GS. The Motion Pro inline shut-off valve works fine, but the stock dual pickup is clunky, and makes simplifying the fuel system for maintenance, performance, and reliability rather difficult. Also not satisfied by the Pingle solution; I don't care to spend $130 on a piece of bling that's going to sit behind the frame and fail to add much performance to the bike.
Doing some research, it looks like the Yamaha YZ250 petcock is a direct, bolt on fit for the tank. Good deal, since it's a mechanical 3 way petcock, with a downward facing nipple. Not confirmed, but the fuel spigot does appear to be about the same as stock, which seems fine for race use on the GS. Gasket cross references to be the same as the R1. Cross referencing the R1 petcock against Pingle's adaptors indicates that the bolt spacing is the same as for our GS500. Gasket is very very similar, pretty much the same. Cost for the full kit is ~$15.
Planning to buy one, experiment. Will post a new thread if it works out.
And hey, if someone still wants a bling petcock, we can still buy the Pingle YZ250 valve. ;)
Piston tools arrived. When I have some time, I'll start bolting things together to see how it's all going to fit.
Lots and lots of Hi-Res pictures, yes?
Thanks.
:D
Quote from: Mauricio on October 12, 2011, 03:06:56 AM
Lots and lots of Hi-Res pictures, yes?
Thanks.
:D
+1
(http://i12.photobucket.com/albums/a223/angeltattoo/smilies/drool.gif)
Hi burning 1,
Interested in your post, my project is very similar with the gs500/ gr650 engine. I know you saw my post on balance shafts, and a couple of points.
I am of the firm opinion that removing balance shafts is the wrong way to go. I have modified and rebalanced cranks before and I am aware of the effects. It works very well if done right.
Removing the balance shafts will drastically increase crank and bearing loads, which you are going to do in spades anyway with the mods as is.
Lighter reciprocating parts pay dividends, but require the crank to be rebalanced, which requires the balance shafts modified to suit. Partial assembly of the engine and someone with a balance table, in a perfect world.
Also I have a couple of 425 4valve/cyl heads. I was hoping there would be some advantage in valve area, to be had, but Not much. Works out about the same as the 500 head I have, I can dig it out if you would like to know. I have not flowed them yet but will be happy to let you know what I find, if you are interested. I am still working on the crank #'s if you are interested in my findings I am happy to share info.
Regards Ian
valve diameters on the 425 head?
lift of the cam?
CC of the combustion chamber?
as compared to a gs500???
a set of FJ1200 /kz1000 pistons.....compression ratio compared to a stock GS500? with a smaller combustion chamber of the 425 head....
still cheaper to install a 450 single into a 125 or 250GP chassis (sub 275#) but we all are farquin crazy and do what we do
Hi Harlton,
Yeah, the small valves on the 8 valve heads is something I've seen mentioned elsewhere. I'd be interested in playing around with a 4 valve head, but as mentioned above the exhaust routing issue is something I don't want to deal with right now. I've been idly thinking about cutting down and swapping in a GS1100 16 valve head, but I have too many 'unknowns' as it stands with this project. A GPZ head might also be an interesting option if it could be made to work.
Took a look at the balancer shaft again... It's a heavy sucker - 5-10lbs, and lots of inertia. I kind of figured that pulling it would do bad things to the crank bearings, but the weight savings seems to be worth it, and I've known a lot of other racers to successfully perform the mod. One other aspect of the removal is that I have an otherwise good engine with a seized balance shaft.
Would not just pull the shaft though... If I do the mod, it'll be going to the guys at APE for a pro rebalance/lightening job.
BTW... Did anyone notice that the latest GS500F models get updated rods in the parts fich? I'm very very curious what's changed.
BTW: Just ordered a rack of 4 GSX-R 750 smooth-bore flat slides from the UK. Will document the process of fitting them to the GS. The carbs were stock on GSX-R 750 models, and can be had for less than 200GBP. Should be good for improved throttle response and a little power on our bikes...
Yeeeeah. Dibs on the two left over.
But only if it works... :icon_mrgreen:
Hi Guys,
I agree that a unbalanced regards Lanchester shaft style, 180deg twin can be made to work not to badly.
The first bike I ever tuned way back in 1979 was a Honda 500 twin 180deg crank, I put it thru police speed trap equip of the time at just under 125mph. It was quick, vibration wise I didn't find it unbearable, but it was designed to take the vibration. I love my Nortons, and after carefull balancing and lightening their quite nice and bearable.
My point is, the next step is to smooth things out further and make more power, with less waste. There is also a fair amount of conversation on this forum about how bad the bike shook after removing balance shafts and sad tales of broken cranks and failed bearings.
Sure the balance shaft is a chunk, but its moment is not so bad, especially after it would be lightened to suit the other lightened parts as it has to be.
I'm not knocking a costs basis decision, and serious racing requirements are different to mine, I'm just extending the discussion.
I am sure that ape will do an excellent job, my dynamic balancer guy is also really good, I only static balance to ball park it. But he still cannot get me to the next place.
I am aware of a place in the UK that dynamically balances partially assembled engines, as assemblies, so the moments balance each other out correctly, done on a balancing table.
I felt sure with all the high level racing going on in the states, this service should be available somewhere. (hoping) If anybody reading this knows where, can you please let me know.
That's all I have on the crank subject, sorry if I've gone on about it, I find it really interesting. So I will not post any more on this unless contacted.
As to the cylinder head, and the other comment that was posted. My point is if the potential valve size is limited as compared to the other head, your stuck, all it can offer is maybe more rpm due to the lightness of the parts, if it can be made to breathe. Cam lift and duration can be changed reasonably cheaply and easily, not so with valve sizes past a certain point. Compression ratio's are also fairly easy to adjust, so the valves have it, also important when it comes to porting. I am also building a 650+ bike, but could be great on a 450 with higher rpm potential. After they gave a good boost in an apples to apples, 425 twin UK comparison.
I've seen the cut down GSXR head thing done, still have the article. However then you have to deal with oil cooling the head and the extra demands on the oil pump.
I Much prefer keeping it a simple air cooled if possible, and slightly larger sizes will go in. The compression ratio works out to about 11+ :1 when fitting it to the 500 with good squish, and if the breathing problems are overcome, there's good potential. I can supply any details you wish if you are interested.
The parts are all pretty much the same so cams, heads, barrels can all be swapped around with ease. I don't know of another Jap bike offering that, and it handles great, what more can anyone ask for, Oh it's really cheap to, I got the 8 valve heads with cams for $40 each, $20 without cams, whole 650 motor $100.
Regards Ian
Ian, your imput is very much appreciated. Just describing my thought process, and not taking it as an argument at all. Really looking forward to hearing how the 4 valve thing turns out... Are you doing this with a GS500 frame, BTW?
Hi Burning,
Thanks for the comment, I didn't mean argument in anyway, just that it is my position, sorry I'm originally from the UK so sometimes I use the wrong terminology.
Yes to the second question I have a 99 gs500 frame, I've fitted conventional gsxr 600 forks, 2002 I believe and revalved them, and I'm re-valving an R6 shock as I got it free.
If I can help in anyway with info I am glad to, I have a copy of Engine pro software and can run an engine for you if you wish, I already have quite a few done, but I am still working on finalising some flow #'s, but a good indicators, before spending money.
As to the 8 valve heads, I am fitting one at some point to the 500 engine to see what it does. A straight swap would be nice, but the stock 8v cams would be to mild to be meaning full for the 500. So I think a webcam regrind, but I'm looking at #'s, the fingers look a little frail.
Thinking and figuring on the other, originally I was hoping for 650, if I can move the valves to get a larger size in, but it does not look easy.
A local scrap yard had a few of these heads last time I was there,(late summer) from a now defunct school and cannot sell them,due to lack of interest.
Your 450 project is very interesting what kind of RPM are you thinking of, I've been following your posts.
best Regards Ian
Mikuni RS Flatslides are here. Need a thorough cleaning, but seem to be in good condition otherwise. It'll probably be a while before I can play with them; I don't have a running engine to test with. :(
(http://i261.photobucket.com/albums/ii63/ctbarbour/IMAG0013.jpg)
(http://i261.photobucket.com/albums/ii63/ctbarbour/IMAG0012.jpg)
http://www.motorcyclespecs.co.za/model/suzu/suzuki_gs400s%2085.htm
i don't think these came to the us...... anybody up nort ever seen one?
I thought the 400X was the 8 V engine
have you considered using the early GS400 bottom end(ex: 77 gs400XB) it is showing having a roller crank....
http://www.bikebandit.com/1977-suzuki-gs400xb/o/m6023#sch270649
it should be able to take much more abuse. then big bore it....
Longer stroke though, which could limit peak RPM.
Although I'm throwing a lot of money on this bike, I'm hoping that I can encourage a few other people to campaign GS450s in the AFM. It's nice to build a monster 50+HP machine, but being able to get one on the track for less than $2000 is also a project goal.
and that affects RPM by how much?
69mm bore with a 60mm stroke will yield 448.7cc at a loss of 500rpm....
with a bulletproof bottom end.....you can still wring it to 10.5-11k
that 84-86 GS400S..... read the specs.....56.6mm stroke.... and TSCC now who got that bike.... other than NZ?
Actually, if the stroke is 56.6mm, it's the same as the GS500. So, might be interesting. I think that swap might complicate the project a little more than I'd like right now, though. :)
Measured out the flat-slides... Looks like they are 34mm, so 2mm larger than stock, and also smooth-bore, pumpers. Perfect. :)
I have to figure out a mounting bracket, throttle linkage, choke lever, clean them up, and tune. Kind of excited to try them out.
For future reference, would you mind posting all the dimensions? Input side, output side, spacing, etc?
have you tried racking them on the GS rails yet?
all the kanatunas have 34or 36mm carbs if ya just want the CV's
and the have the same outside dimensions as the GS carbs
Quote from: Big Rich on October 25, 2011, 03:12:03 PM
For future reference, would you mind posting all the dimensions? Input side, output side, spacing, etc?
Sure. Measurements are a little rough, but should be relatively accurate.
Engine side:
Engine side ID = 34mm (33.89mm ) <-- These are 34mm carbs
Engine side OD = 40mm (39.96mm)
Engine side racket screw spacing (L shaped bracket) = 30mm (29.95)
Center to center spacing, middle carbs = 90mm (30.15 - 39.96 = 90.19)
Airbox side:
Airbox side Intake OD = 50mm (50.14mm)
Airbox side bracket screw spacing (flat bracket) = 51mm (51.24mm)*
* Not entirely confident in this measurement. I suspect the actual spacing may be 50mm.
I will update this post with the measurements from the GS500 carbs.
Quote from: werase643 on October 25, 2011, 03:20:38 PM
have you tried racking them on the GS rails yet?
all the kanatunas have 34or 36mm carbs if ya just want the CV's
and the have the same outside dimensions as the GS carbs
I was thinking the same thing. The rails look very similar, and if the hole spacing isn't an exact match, I could probably drill and machine as necessary to make things fit. Throttle linkage and choke lever are an entirely different matter though. Choke is easy, since it's more or less a straight, lightly machined rod that I could just cut down. Not at all sure about the throttle; it's completely different than the GS linkage, and certain parts must be retained for the accelerator pump to function. I'll understand the problem when I start disassembling the carbs to clean them up.
I'm interested in these particular carbs because they are smoothbore flatslide pumpers. Should be good for some extra power on the GS compared to pretty much any CV carb on the market; less restrictive, and much more responsive. A rack of 4 usually costs $600+, but since they were stock on early GSX-R750 and GSX-R1100 models in the UK, they can be imported for ~$250 or less.
The only bolt on carbs I've seen advertised for the GS are ~$600 for a set of Keihin roundslide pumpers. Not quite as good, and much more expensive.
might trade ya if you don't tear them up..... i got a set of roundslides for a gs...sitting in a box for 7-8 yrs after my last little superman impersonation..... guess, i can't fly 35's if i member...
i think i have a rack-o-four...34-36 flatslides...off of a 92 GSXR1100 had a crack on one body up high where it didn't matter same place...in a box I HAVE WAY TOO MUCH S*IT
Stock GS500 carb measurements, taken from an older (~1993) era carb.
Center to center spacing: 108mm (150mm-41.95mm)
Carb throat diameter (inside, engine side): 32.5mm
Engine side outside diameter: 41.95mm
Airbox side outside diamater: 58.26 w x 63 h
Bracket spacing:
Engine side, L shaped bracket: 40mm (48.7-8.7mm)
Airbox side, flat bracket = 51.09mm (59.72-8.63)
So, the easy to reproduce flat bracket will work, but the harder to produce L bracket won't. Because of the way the L bracket is cut, it can't be easily modified to fit the FCR carbs.
More good news on the Flatslides; the throttle shaft is actually just a straight tube with some holes drilled in it; so worst case, I should be able to build something comparable. I'll also need to find a way to cap off and clean up a number of the hoses and tubes coming out of the carbs, and will need to confirm that the accelerator pumps still work as setup.
Can probably produce 2 complete sets for the GS from the rack I have, but each set will be a little different - each of the 4 carbs in the rack have subtle distinctions...
- Outer carbs have plugged fuel and vacuum tubes on outside, rather than caps. Will need to cap the lines, or somehow plug the carbs when I split the set.
- 2 carbs have acclerator pumps, 2 do not.
- Linkage is between the first and 2nd carb. Looks like the carbs are already drilled to accept another linkage, and springs though... So can probably buy some from sudco.
Quote from: burning1 on October 06, 2011, 12:21:19 PM
Would love to. They bolt on, but the exhaust ports are pointed directly at the GS500 engine cradle; can't be made to work without extensive modifications. If I'm going to go to the trouble, I'd rather use a GSX-R head.
that was done here by a former gs'er here. took a gsxr head, shaved off the outer two cyls. buddha or some of hte longer timers here, can fill you in. for life of me, i cannot remember hte guys name. but it IS within hte realm of doability
Was it Cedric?
Yeah... You can't race a GS in the AFM without hearing about that guy. :)
Now that I pulled apart my old engine and seen the carnage, I'm looking at ways to beef up the bottom end. One thing I noticed is that Suzuki has updated every major component down there. I'm curious what the changes are, and if I can get my hands on some of the updated parts I'd like to do a side by side comparison, looking at strength and oiling design.
Digging through the Fiche and making notes. It looks like the 1998+ GS500s get the latest crank shaft, part 12220-01D02. Previous models list 2 other cranks; (12220-01D00, & 12220-01D01) both of which are superseded by 12220-01D02. Negative here; the latest part costs $500 new, vs $250 for the older parts.
The latest connecting rod is part # 12160-44101, and is fitted from the factory on 07+ model year bikes. It's ~$79 each. Previous models get older rods (Part 12160-44100, $50.)
No updates to rings or pins in entire run of bikes. Nor do there appear to be updates to the crank bearing shells.
The latest piston is part # 12111-01D01-0F0 and is fitted to 98+ model year bikes. It replaces (12111-01D00-0F0.)
.5mm overbore pistons are available, part # 12100-01D00-050 $90. 1mm overbore kits appear to be discontinued.
The only direct parts number match between the Suzuki GS500 rods is with the GS450... Which is expected, to be honest. Might make it difficult to source an after-market rod.
After blowing up my stock motor, I'm thinking about adding after-market connecting rods to the build. Took some rough measurements of the stockers today...
Big end diameter is 37mm.
Little end is 18mm (wrist pin)
Length is 114mm
All numbers are very approximate; taken with a vernier caliper, not a set of mics.
There is some flexibility here... Combine adjustable sprockets and some milling, and it *may* be possible to run slightly shorter than stock rods. Conversely, the aftermarket KZ1000 pistons I've been eyeing are going to have a shorter compression height than the stock pistons (by 1-2mm, or greater depending on the year), allowing for slightly longer rods.
I finally had a chance to start test fitting parts together. First observation:
My ring compressor sucks. Not sure if I want to shell out $75 for a better tool, but it may be worth the price.
As expected, the GS450 head and pistons will drop right onto the GS500 bottom end. GS500 heads line up and bolt on. All the oil passages are correct (GS500 is really simple in this regard; 4 outside studs are used to carry oil from the crank journals up into the heads.
Bad news is that the GS500 heads are shaped for the slightly smaller dome of the GS500 piston. There's a slight clearance issue with the wider GS450 dome. It looks like the problem should be pretty easy to fix using my handy dremmel, though. :)
Have not had a chance to see how the GS500 valves line up with the GS450 valve reliefs. Expecting no issues there, but the alignment will affect how much I can trim the cylinders before the valves start hitting the edges of the pockets.
Boy! A guy doesn't log in for awhile and all sorts of neat stuff comes along!
This is one of the coolest projects I've seen in awhile. Good on you! I'd never paid attention to the 450 class rules. Nice!
Any updates?
Glad you like it. I'm going to post a bunch more pictures as I dig deeper.
I believe I mentioned that I'm planning to install KZ1000 pistons. I have one on order to compare, to get a general idea if it's worth pursuing. Major build work is on hold for the time being - just started a new job, funds and time is limited. Planning to bring my last spare engine home to see what the damage looks like.
Just remembered and don't know if it's any interest to you - but a guy on the GSR worked on an electronic ignition or ignitor for his 450. I believe he ended up going with a Dyna from another model and retro-fitting it to his motor.
Either way, his name is Pete on the GSResources if you want to look into it.
Just bought a clean 05 GS500F bottom end off of ebay. Should be here in a week. I'm going to grind one of my heads down a little, fit a APE CCT, and fire it up. Hoping to have something running within a month or so.
Note to self:
RGV250 Model year 91 & 92 (M&N) get the banana swingarm. 93+ is double braced, with the U link linkage.
Quote from: burning1 on October 11, 2011, 07:53:32 PM
Doing some research, it looks like the Yamaha YZ250 petcock is a direct, bolt on fit for the tank. Good deal, since it's a mechanical 3 way petcock, with a downward facing nipple. Not confirmed, but the fuel spigot does appear to be about the same as stock, which seems fine for race use on the GS. Gasket cross references to be the same as the R1. Cross referencing the R1 petcock against Pingle's adaptors indicates that the bolt spacing is the same as for our GS500. Gasket is very very similar, pretty much the same. Cost for the full kit is ~$15.
Planning to buy one, experiment. Will post a new thread if it works out.
Didn't work out eh? ? Any updates? :dunno_black:
Sorry for lack of updates.
The short version is that I have the part and the tank, and I'm confident it'll bolt on perfectly. The long version is that it'll be a long time before I'm ready to install the tank and fill it, and we won't know till then. Would like to confirm that there are no leaks or unexpected issues.
The yamaha petcock looks like it'll flow well. It's a simple on/off petcock, and may not be perfect for street use. But great for racing.
I took some measurements of the GS450 rings, to see if I could save some money on after-market options. Here's what I found:
Top ring
Thickness: 1.18mm (manual says 1.17-1.19)
Width: ~2.8mm
Type: Rectangular (Barrel face?)
Middle ring
Width: ~2.82mm
Thickness: ~1.2mm (Manual says 1.17-1.19)
Type: Tapered
Oil rings:
Stack thickness: 2.90mm total
2.22 Ring width
0.46 Ring thickness
2.55 spring width
2.25 spring thickness
Measurements have some margin of error - I didn't have a ball anvil for my micrometer, so the curve of the ring introduces a little error. And there was some surface rust, so again, margin of error for thickness readings.
However, I included manual spec where I could, from the GS500.
Short version, is that there don't appear to be many readily available aftermarket rings for the GS450.
Running into another snag... It looks like the largest dome the stock GS500 head will accept is 60mm, and unfortunately, both the KZ1000 and GS450 use larger domes than that stock. KZ1000J dome is 65mm on a 69.5mm bore. So, looks like this project will never be a trivial 'drop in' project for anyone who tries it.
It's really annoying how often this thread shows up when I do google searches for KZ and GS parts. :)
Wait til other people find it with Google searches and then bombard you with questions........
Burning, I know a guy that worked on a lot of Suzuki's for a couple decades. I'll ask him if he knows of any good drop in pistons for the gs450.
Thanks! Problem is really with GS500 head at this point, so what might work with the GS450 may not with the 500.
I sent the link for this thread to my friend, and here's the reply I received:
I would skim GS 500 head as far as possible, about 1mm above valve seat, and probably on a 1.5 degree angle towards exhaust to get an asymmetric chamber.
Use GS500 pistons, modify crown for 0.038" clearance
Dowel holes will need re-sizing and made vertical in relation to block to block
The 8 valve heads are GSX in Europe
I know there is an 80bhp 'GS500' running around with modified SACS 4 cyl head (outer ends cut off)
Take from it what you will - hope it helps out somehow!
Please thank your friend for me. I appreciate that he took the time to look at this thread. :)
I will have to digest what he said a little.
Our own Bob Broussard built an 8 valve GS500 head... I have been thinking more and more about it, as there are lots of options for 72mm 4 valve pistons... And the 8 valve heads make for nicer combustion chambers and better breathing.
also consider the FJ1100-1200+ pistons....and machine for your use..... you can get them from legends car builders cheap....for the old ones.... just another option.... and if i remember they are same wrist pin diameter
I am totally subscribing to this. Awesomeness will ensue.
Quote from: werase643 on February 27, 2012, 03:34:46 PM
also consider the FJ1100-1200+ pistons....and machine for your use..... you can get them from legends car builders cheap....for the old ones.... just another option.... and if i remember they are same wrist pin diameter
Looks like the FJ1100 is 4 valve?
Quote from: burning1 on December 30, 2011, 01:39:35 AM
I took some measurements of the GS450 rings, to see if I could save some money on after-market options. Here's what I found:
Top ring
Thickness: 1.18mm (manual says 1.17-1.19)
Width: ~2.8mm
Type: Rectangular (Barrel face?)
Middle ring
Width: ~2.82mm
Thickness: ~1.2mm (Manual says 1.17-1.19)
Type: Tapered
Oil rings:
Stack thickness: 2.90mm total
2.22 Ring width
0.46 Ring thickness
2.55 spring width
2.25 spring thickness
Measurements have some margin of error - I didn't have a ball anvil for my micrometer, so the curve of the ring introduces a little error. And there was some surface rust, so again, margin of error for thickness readings.
However, I included manual spec where I could, from the GS500.
Short version, is that there don't appear to be many readily available aftermarket rings for the GS450.
I know this is a totally Heath Robinson approach but it did work on my old CB1100R. Get car rings that are the same diameter and either surface grind the rings or open up the ring grooves on your pistons. Just an idea if you get really desperate.
Just purchased a 1/3HP Flex Shaft machine. I'm going to take a shot at machining the head for clearance.
http://www.wecheer.com/show_prd.php?id=330&lang=en
Quote from: werase643 on October 24, 2011, 05:43:41 PM
http://www.motorcyclespecs.co.za/model/suzu/suzuki_gs400s%2085.htm
i don't think these came to the us...... anybody up nort ever seen one?
I thought the 400X was the 8 V engine
Nah. I don't think I have ever seen one up here. Can't say for certain they weren't imported but I doubt it.
Quote from: burning1 on March 09, 2012, 11:04:33 AM
Just purchased a 1/3HP Flex Shaft machine. I'm going to take a shot at machining the head for clearance.
http://www.wecheer.com/show_prd.php?id=330&lang=en
Please do report your experience with carving out the head. I've over-bored the GS500 cylinders to accept Wiseco 78mm pistons as was done by Dgyver and others. However the piston crown design has changed over the years and is tremendously larger that the pistons that other riders had used in the past. [Actually, I'm starting to wonder if their pistons were not Wiseco but another make??]
So I'm looking into machining down the pistons AND enlarging the combustion chamber in the head. It appears the valve pockets are fine as-is. I really don't know how much material is too much when it comes to carving up the head however, and I'm a little afraid of really mangling the combustion chamber shape.
Short version: I'll be watching your experience with interest. ;)
Ahem :cool:
(http://farm8.staticflickr.com/7118/7033749521_2aaa60f6a6_b.jpg)
(http://farm8.staticflickr.com/7080/6913529316_e77d096a51_b.jpg)
(http://farm6.staticflickr.com/5149/5626276972_16cb9a6784_b.jpg)
http://www.thegsresources.com/_forum/showthread.php?t=172422 (http://www.thegsresources.com/_forum/showthread.php?t=172422)
1981 GS400LX 8 valve Canadian model.
Stock cylinder block
GR650 sleeves set in
Half of a 78mm JE 1260 piston kit
Custom 355 cam's in the works
Increased combustion chamber
10.5:1
80% done.
I like this thread.
Any updates on this?
dont mean to bring the thread off track but could you provide part numbers or year ranges for the yamaha petcock?
Never mind.
id love a 8 valve head, anyone in south africa have one for me?