If you want 100,000 miles or more without a valve job from your GS500 ponder this. If you consider your GS a beginners bike like Suzuki does and plan on replacing it with a real bike as soon as posible just ignore.
Did my 80k mile valve check yesterday and replaced one exhaust valve shim because the clearance had just dropped below the .003" max spec (.001-.003"). First shim change since 40k mile mark on my 02 GS and all shims are still in 250-260 range with many miles to go before the exhaust valves receed into the seats and reach the min 215 shim like one on my old 97 GS did by 80k miles.
After replacing 2 shims on one of my 02 GS exhaust valves at 30-40k miles I decided to set them a bit looser to give more cooling time on the seats and it worked. A stock GS engine reaches peak HP at about 8500 rpm and nothing is to be gained going above 9-9500 rpm so I set them at .003-.005" like they did on my old 82 CB750 shim over bucket valve adjusted engine with a 9500 rpm redline. If your going to the track to redline your modified GS all day long just ignore this all as the opinion of an old man and do it Suzuki's way. :icon_lol:
http://img.photobucket.com/albums/v443/jcp8832/GSvalvelogs.jpg
Actually, I was interested in this. .03mm is an incredibly small gap. I'm used to seeing .20mm-.30mm on my other bikes.
Are the newer ones different? Mine is a 1991 and I thought the proper clearance was .003-.008, which would leave your .003-.005 still on the tighter end of things.
tt: mm vs inch!
Quote from: tt_four on June 07, 2010, 10:53:54 AM
Are the newer ones different? Mine is a 1991 and I thought the proper clearance was .003-.008, which would leave your .003-.005 still on the tighter end of things.
Mixing up units. OEM clearance is .03mm - .08mm, which equates to .001" - .003".
gotcha, I wasn't paying enough attention to see the ", I actually believe I hate SAE measurements that I probably blocked the symbol from my sight. Jack, do you know off the top of your head, so I don't have to break out the paper and pencil to do the math, what clearance you setup in the metric measurement? I'm guessing you're in the .08-.11 range?
I'm running loose, as well.
LE 0.07mm
RE 0.10mm
i love how the mm guys are all "imperial is hilarious nonsense !" until you get small... then they might as well use inchers, just like us.. :-)
at work, tons of prints come in with metric tolerances, surface finishes, etc and there is a BOOK to define each one with charts and such. i honestly don't know how one operates a machine in mm-land without said chart.
that being said, loose exhaust sounds like the way to be for me. :)
Quote from: tt_four on June 07, 2010, 03:24:15 PM
gotcha, I wasn't paying enough attention to see the ", I actually believe I hate SAE measurements that I probably blocked the symbol from my sight. Jack, do you know off the top of your head, so I don't have to break out the paper and pencil to do the math, what clearance you setup in the metric measurement? I'm guessing you're in the .08-.11 range?
.003"x25.4=.076mm and .005"x25.4=.127mm or approx .08-.12 mm for the exhaust valves. I just leave the intakes at the standard specs. They don't run as hot and receed into the seats like the exhust valves do and rarely change at all. I've been using sae measurements all my life and think in inches rather than mm. I can remember back in the 50's we started converting and put both inch and mm dimensions on drawings where I worked thinking metric would soon be in universal usage. Took a long time to catch on in the US.
Quote from: ohgood on June 07, 2010, 04:58:15 PM
i love how the mm guys are all "imperial is hilarious nonsense !" until you get small... then they might as well use inchers, just like us.. :-)
Imperial units are fine, so long as you stay away from fractional inches and any value that requires unit conversion. :icon_razz:
yeah, while I'll admit I think it's dumb that there's 12 inches in 1 foot, and 3 feet in one yard, I can handle that stuff, it's when you start to get into 3/16 and 5/8 and 1/4 and 15/16ths. It wouldn't be as bad if everyone just used decimals, but they don't. I don't understand why anyone would want to try out a wrench, and instead of saying "ooh, this 15mm wrench is one size too small, I better grab the 16mm, they'd rather try to remember that 5/8th is one larger than 9/16ths. Nonsense.
I was depressed for a week when I realized that Buells are half imperial and half metric, but I guess I'll survive.
At work we have some Monarch EE lathes with metric feeds built right into the gearbox. Fun to play with.
Quote from: gsJack on June 07, 2010, 05:34:12 PM
.003"x25.4=.076mm and .005"x25.4=.127mm or approx .08-.13 mm for the exhaust valves. I just leave the intakes at the standard specs. They don't run as hot and receed into the seats like the exhust valves do and rarely change at all. I've been using sae measurements all my life and think in inches rather than mm. I can remember back in the 50's we started converting and put both inch and mm dimensions on drawings where I worked thinking metric would soon be in universal usage. Took a long time to catch on in the US.
[/quote]
Glad to hear your valve seats are wearing nice and slowly, Jack! I intend to do the same thing, that is, find out how many miles I can put on this thing. It's been two years and I like this bike as much as any bike I ever had. It's perfect for everyday use.
As for the metric system not completely catching on, I can explain why. The metric guys haven't won any wars in ages, and the way they're going, never will again. As for the arcane nature of the Imperial system, is it really that hard to remember that 5/8", which is 10/16", is more than 9/16"? If so, that would explain why the metric guys need us to protect them.
Mind you, get back to older inch products like wood auger bits and they were simply marked 4, 5, 6, 7, 8, 9, 10, 11... - the /16 was known but not marked on the tool, and the user was expected to know that an 8 would make a half-inch hole.
If you were goofing off during fractions in grade school and can't figure out that 5/8 is 10/16 and thus bigger than 9/16, that might provide a good deal of insight into the other thread about dealer mechanics buggering carbs... :nono: Then there's the bit about racking all your sockets/wrenches in order of size, and always putting them back, so that you don't even have to look at what size the socket/wrench is, you just try the next bigger/smaller one, and switch form the inch set to the metric set (or vice versa) if that doesn't do it. I suppose the brave could rack by size without keeping inch and metric separate, but I'm not going that route.
Print this out and put in in your toolbox - or you can get nicer ones (with number and letter drill sizes, too) from any machine shop supply: http://www.hamuniverse.com/antfrac.html (http://www.hamuniverse.com/antfrac.html) Or you might find this one better: http://www.labeldotcom.com/CMSFiles/Image/Tips/Fraction-Decimal-Millimeter-Chart/Fraction-Decimal-Chart.jpg (http://www.labeldotcom.com/CMSFiles/Image/Tips/Fraction-Decimal-Millimeter-Chart/Fraction-Decimal-Chart.jpg)
This one actually works both directions and has number/letter sizes: http://www.davehylands.com/Machinist/Charts/Drill-Conversion.pdf (http://www.davehylands.com/Machinist/Charts/Drill-Conversion.pdf)
The one that gets me annoyed is the mixing, where the bolt that's too small for 1/2 and too big for 7/16 is the 12mm in the midst of a bunch of inch fasteners. Then add chinky-Chinese sloppy tolerances, and who knows what wrench would actually fit it correctly. Got the 11.93mm or the 12.13mm in the tool box?
If they ain't tappy, they ain't happpy! lol
Jack, another possible "trick" is something I think Buddha may have mentioned some time ago, using a top end oil in the fuel. Maybe an ounce or so per tankfull of MMO or a good air cooled type of 2 cycle oil or Lucus fuel treatment. The theory being that this somehow "cushions or seals" the exhaust valves as they contact the seats. I dunno.
Have you noticed any performance loss in the low to upper midrange with this mod?
prs
Pigeonroost, I haven't noticed any performance loss at all with exhaust valves set as loose as .004-.005" on my stock 02 GS500 nor have I heard any increased valve tappet noise. Like burning1 said above the .001"/.03mm min Suzuki spec is an incredibly small gap. Difficult to even measure with feeler guages I think. The .002-.005" spec of my old shim over bucket CB750K was a more reasonable one to work with but that bike had a 9500 rpm redline. Had a couple of old early 80's CB/CM400 twins with screw adjusted valves and they were set at .004" intake and .006" exhaust. Living with my first GS500 I came to appreciate why they set the exhaust valves looser.
I have no idea at what increased gap and high rpm combination that throwing a shim might be a serious concern but have seen pics of mc engines that threw a shim and they were a mess. I try to caution not to go wider if you're going to run at 10-11k rpm very often or very long. A well modified GS engine with proper intake, exhaust, and jet mods will carry near max HP well past 10k rpm but the HP of a stock GS will nose dive above 9k rpm. I think a 11k rpm redline for a stock GS500 with it's decades old 2 valve engine design is increadibly high.
I dont think .12 is such a wide gap that you're going to run into problems; the shims sit fairly deep in the valve buckets and the only way they'd get anywhere close to slipping out is if you were experiencing pretty bad valve float.
With that said, I think the GS engine could be pushed a little higher than 12K with the right rods, and bearings. At 11K, there's a lot of stress on the wrist pins, but the bore/stroke figures are actually a little more over-square on our GS than they are on a 09 GSX-R 1K. Valve float could be a problem, but I think it could be resolved with titanium valves, stiffer springs, and a shim under bucket retrofit.
Thanks again for the info, gsJack.
I had a spare set of shims for my exhaust valves handy, and just spent a couple of hours last night adding an extra .05mm of clearance.
I think I will shoot for .1mm on the exhaust when I re-visit the job next (forgive me for saying the "W" word) winter.
prs
Thanks for the post Jack, I'll be going the same way at my next adjustment (due soon).
Quick update on this thread... I opened my valves up to the spec that gsJack posted at the beginning of my last race season. I haven't been in there since, but I can confirm that running the clearance he recommended didn't seem to cause me any obvious problems under the abuse of racing and track riding. And that's with some pretty extended runs at 10K RPM. I'll update again when I inspect the clearance.
Only potential issue is the loss of .001 inch of lift, but to be honest, keeping the engine alive and avoiding spending a lot of time wrenching on it is worth it to me. In my experience, every time you open a bike up, you have a chance of creating an oil leak, or other problem.
FWIW, Megacycles recommends .004 inches of clearance for all of their higher lift cams.
Timely thread update burning1, I just did my annual valve check and changed one shim on an exhaust valve from 250-245 so the minimum shim in this 02 GS with 86k miles on it is a 245 now. It's been set to my greater exhaust valve tolerances since my 40k mile check they have held up well. I put a minimum 215 thick shim in my 97 GS at 76.8k miles and parked it at 80k miles. I expect to run this bike to 100k miles without further valve checks assuming I'm still running that long myself. :thumb:
http://img.photobucket.com/albums/v443/jcp8832/GSvalvelogs.jpg
On the down side it's been an all time low in annual milage for me, just 6100 miles since last June's valve check. I used to go 15-20k miles a year on my 97 GS. :cry:
BTW... I am glad you did this experiment and post this thread. There are two big complaints I see about the GS over and over - Suspension, and Valve Check interval. It's nice to know that both are trivially corrected. :)
Sorry for digging up a zombie thread, but I never had the chance to thank gsJack for coming up with this!
Thanks! :thumb:
FYI,
Yesterday I went to the dealer to get shims, and the mechanic there told me that they use to set clearance at 0.10mm in the intake valves, and 0.15mm in the exhausts! He said that more than running with less stress, the bike would run smoother and provided a better response from the engine! The said mechanic, has 30 years experience, and he have read clearances on the GS500 with engine cool and after a dyno run. Curiously, after the dyno run, when hot, the clearances were tighter! :woohoo:
:cheers:
Good info piresito. Validates what the community here has discovered.
Quote from: piresito on February 22, 2013, 05:07:52 AM
FYI,
Yesterday I went to the dealer to get shims, and the mechanic there told me that they use to set clearance at 0.10mm in the intake valves, and 0.15mm in the exhausts! He said that more than running with less stress, the bike would run smoother and provided a better response from the engine! The said mechanic, has 30 years experience, and he have read clearances on the GS500 with engine cool and after a dyno run. Curiously, after the dyno run, when hot, the clearances were tighter! :woohoo:
:cheers:
All good to hear and I see nothing wrong with the mechanics choice of .10 mm intake and .15 mm exhaust clearances. But that would be approximate since shims come in .05 mm increments and a .05 mm range would be required on a setting spec. I set exhaust valves at .08-.13 mm and leave intake valves at the .03-.08 mm factory setting. My 97 GS went 80k miles and my 02 GS has 97.5k miles on it both with the original factory shims on the intakes, the problem is with exhaust valves.
But I find it hard to believe the mechanic's clearances were tighter when hot after a dyno run. It's been my experience they increase as the engine gets hot, confirmed by:
An exhaust valve went tight twice on my 97 GS requiring a 2 shim smaller change (.1 mm) to get adequate clearance. When tight the engine would start and run rough for a minute and then smooth out as the clearance increased until the engine cooled again.
On my 82 CB750K with shim over bucket valves set at .002-.005" (.06-.13 mm) I actually checked them hot once and they all measured .015" or greater when hot.
I got my 02 GS with 4k miles on it and with a tight exhaust valve bucket and it measured .008" minimum when checked cold with the stuck bucket. The bucket loosened and the engine smoothed out within a minute after cold startup as the engine heated.
On overhead cam engines with aluminum heads the aluminum head expands faster than the steel valves lifting the cams and increasing the valve clearances.
http://img.photobucket.com/albums/v443/jcp8832/GSvalvelogs.jpg
Quote from: gsJack on February 22, 2013, 08:44:16 AM
On overhead cam engines with aluminum heads the aluminum head expands faster than the steel valves lifting the cams and increasing the valve clearances.
This came to my mind first as well. Aluminum expands a little under twice as much as steel (12.3E-6/f in Al vs 7.3E-6/f in steel if I remember right).
And if you don't wait for your bike to cool off all the way before setting your valves they end up way too tight (from others' experiences).
If the GS is an exception, I'd be very curious as to why. The only reason I can think of would be if the bike wasn't fully warm for the dyno run and the heat sank out of the head faster than the valves... but that'd be one quick teardown.
Quote from: gsJack on February 22, 2013, 08:44:16 AM
On overhead cam engines with aluminum heads the aluminum head expands faster than the steel valves lifting the cams and increasing the valve clearances.
http://img.photobucket.com/albums/v443/jcp8832/GSvalvelogs.jpg
I allways tought that way too, but I have never measured the GS500 clearances after "hot". And with my limited experience, I would not argue with the mechanic about that!
You know, I asked me if I was using 0.03-0.08mm of clearance or 0.08-0.013, as I told him I was using the 8-13 in the exhaust, then he told me he used even higher (0.1 intake, 0.15 exhaust)!
So, I think we can say that the 0.08-0.13mm exhaust clearance range is safe, even if a bit larger than the 0.13mm mark, as we now know that there is people driving with even more than that!
Hi all,
I am new here, owner of a 1992 GS500e. This is my first post.
I did my first valve check (79800km) and found the exhaust clearances to be 0,13 mm and 0,15 mm.
A very experienced mechanic (suzuki authorized) who was responsible for its maintenance the past 12 years told me NOT to decrease the exhaust clearances being out of the service manual limits.
He suggested I could keep the in valves in service manual limits but NOt the exhaust valves.
He explained the reason:
If someone drives for some time in low RPM (like me) there is a very small "smoke fog" built up in the exhaust valve seating (small film of smoke). This makes clearnces increase a bit. But he told me that if you open up your GS in a hard ride with high RPM (especially using 100 octane fuel) the smoke fog gets cleared from valves seating and the clearances decrease.
He says he has seen many bikes setting the exhaust valve clearances set on official setting (with fog eveloped) and then after a hard ride the seatings are cleared and clearances get so tight that burn the valves.
I trust him because he held this bike for 12 years with exactly zero problems and high engine performance.
I should also mention that in this bike, whose history I know since previous owner is my closest friend, did about 25000km with valve clearances not changed at all from the previous settings!
I vote for high exhaust valve clearnces ( up to 0,15 mm) and intake clearances above 0,05
The only down side to running them loose (and you're at 3X for exhaust and 2X for intake) is that the valve train noise might prevent you from hearing other noises, like when my alternator rotor was hitting the stator, it took me a long while and only when I had the bike shaking and vibrating more I found the problem. Else its all good.
Cool.
Buddha.
Quote from: manosalx on October 18, 2021, 01:28:35 AM
I vote for high exhaust valve clearnces ( up to 0,15 mm) and intake clearances above 0,05
This seems to be the consensus around here. Different people have different maximum clearances they are comfortable with but generally .13 to .15 maximum. I generally shoot for .05 -.08 on intake and .07 -.13 on exhaust. If I don't have the exact right shim I have also run all the way out to .15 without any noticeable issues.
Thanks for the info!