I want to set the gap in my butterfly valves correctly.
2000 GS500e. Lunchbox and full Vance and Hines exhaust. 40/150 jets.
How wide a gap should there be in the butterfly valve at idle? Is there any standard?
IDK the Mikuni technical +/- tolerance answer, but my gut says it should idle with the throttles completely closed. There's an air hole in the throat of the carb that's the bypass for idle air, should be metered to let it idle. Opening the throttles at all will lean it on idle a lot. You can set the pilot way too rich and then open the throttles a little and get an erratic, but fast, idle. If you have bad compression or other issues then you might have to do this to get it to idle or avoid hart starting.
Mark my words, the lunchbox is going to cause you trouble.
It really seems to be.
I hate getting that stock box in and out.
There are NO ENTRIES in the jetting matrix for V&H full exhaust plus stock airbox with K&N drop in.
But I have that. I can try it.
For jets, I have 40 pilot. 140, 150 and unknown (what was in the bike when I got it) mains.
I don't mind ripping the lunchbox off and fiddling with the tuning with stock.
Anyone have recommendations for a starting place? I read what you said about the butterflies being closed. Since there are those pilot air holes I follow what you are saying. Makes me wonder though. Why the idle screw at all then? If it's supposed to idle at dead closed, and that screw changes the opening size?
Quote from: struckjm on February 23, 2021, 06:18:07 PM
I hate getting that stock box in and out.
Don't we all. But you won't have to do it often if you get the jetting right to start with, which is much easier to do with the airbox.
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There are NO ENTRIES in the jetting matrix for V&H full exhaust plus stock airbox with K&N drop in.
Do you own K&N stock or something? Just put a stock paper filter in. The K&N filter technology, if you call it that, the so-called "cotton and oil" filtering method, is known to be very poor at actually filtering dirt. If you MUST put a not-paper filter in, use a UNI drop in (which is what I have, in both of my bikes). At least it filters as well as stock and flows air like a K&N. But in the case of the GS, flowing more air is not necessarily a good thing, because the stock filter is not an impediment. If you make it rev to 20K rpm or increase the displacement 50% then you will need to think about moving more air. But with a stock engine bore/stroke/crank you don't need more air than the stock filter will provide.
And ignore the jetting matrix. with the V&H full exhaust with stock airbox and any air filter you need 40/125. The air filter choice will affect needle shimming and idle mixture more than anything since you are screwing up low-rpm/low-throttle vacuum and air velocity. The exhaust is going to affect WOT/high-rpm more than anything so that's main jet and needle doesn't matter.
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For jets, I have 40 pilot. 140, 150 and unknown (what was in the bike when I got it) mains.
I have a box full of a bunch of jets plus pod filters I never installed because I also wanted to get rid of the airbox. Stock jets were probably 122.5. That will work close enough with what you have, might be a touch lean at WOT and high revs. might take a washer or two shimming the needle. But I'd get a stock air filter and some known 125 jets, then take everything off ONE MORE TIME and put the 125s, one washer, stock air filter (or a UNI if you're really stubborn), and be happy.
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I don't mind ripping the lunchbox off and fiddling with the tuning with stock.
It won't take much fiddling if you leave it stock. The fiddling happens when you switch from stock.
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Anyone have recommendations for a starting place? I read what you said about the butterflies being closed. Since there are those pilot air holes I follow what you are saying. Makes me wonder though. Why the idle screw at all then? If it's supposed to idle at dead closed, and that screw changes the opening size?
The idle air holes (whatever they call them) are not immune from getting clogged, especially if you put an oiled air filter in there (HA!). So then you have no choice to get the bike to start and idle but to add some air through the main venturi. And as the entire system wears, air you can't control might leak into the carb through things like the throttle shaft, hardened o-rings, vacuum leaks, etc., but those air leaks are not consistent or adjustable obviously. So opening the pilot jet some to enrichen the idle mixture and then adding some (more) controlled air through the throttle via the throttle stop can smooth it out and make it run, even if it's at a fast idle, and even if it happens to wind up with hanging idle, at least it'll idle without stalling. Hanging idle is preferable to dying at stop lights.
This is an imperfect system so this is just a way to work around expected wear conditions when a full carb rebuild is not quite warranted. But a freshly serviced carburetor set with correct airbox, air filter, jets, etc. should idle at close to 1100 rpm with the throttles completely closed. That is my practical experience, not from a service manual.
Quote from: mr72 on February 24, 2021, 05:37:49 AM
Quote from: struckjm on February 23, 2021, 06:18:07 PM
I hate getting that stock box in and out.
Don't we all. But you won't have to do it often if you get the jetting right to start with, which is much easier to do with the airbox.
Quote
There are NO ENTRIES in the jetting matrix for V&H full exhaust plus stock airbox with K&N drop in.
Do you own K&N stock or something? Just put a stock paper filter in. The K&N filter technology, if you call it that, the so-called "cotton and oil" filtering method, is known to be very poor at actually filtering dirt. If you MUST put a not-paper filter in, use a UNI drop in (which is what I have, in both of my bikes). At least it filters as well as stock and flows air like a K&N. But in the case of the GS, flowing more air is not necessarily a good thing, because the stock filter is not an impediment. If you make it rev to 20K rpm or increase the displacement 50% then you will need to think about moving more air. But with a stock engine bore/stroke/crank you don't need more air than the stock filter will provide.
And ignore the jetting matrix. with the V&H full exhaust with stock airbox and any air filter you need 40/125. The air filter choice will affect needle shimming and idle mixture more than anything since you are screwing up low-rpm/low-throttle vacuum and air velocity. The exhaust is going to affect WOT/high-rpm more than anything so that's main jet and needle doesn't matter.
Quote
For jets, I have 40 pilot. 140, 150 and unknown (what was in the bike when I got it) mains.
I have a box full of a bunch of jets plus pod filters I never installed because I also wanted to get rid of the airbox. Stock jets were probably 122.5. That will work close enough with what you have, might be a touch lean at WOT and high revs. might take a washer or two shimming the needle. But I'd get a stock air filter and some known 125 jets, then take everything off ONE MORE TIME and put the 125s, one washer, stock air filter (or a UNI if you're really stubborn), and be happy.
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I don't mind ripping the lunchbox off and fiddling with the tuning with stock.
It won't take much fiddling if you leave it stock. The fiddling happens when you switch from stock.
Quote
Anyone have recommendations for a starting place? I read what you said about the butterflies being closed. Since there are those pilot air holes I follow what you are saying. Makes me wonder though. Why the idle screw at all then? If it's supposed to idle at dead closed, and that screw changes the opening size?
The idle air holes (whatever they call them) are not immune from getting clogged, especially if you put an oiled air filter in there (HA!). So then you have no choice to get the bike to start and idle but to add some air through the main venturi. And as the entire system wears, air you can't control might leak into the carb through things like the throttle shaft, hardened o-rings, vacuum leaks, etc., but those air leaks are not consistent or adjustable obviously. So opening the pilot jet some to enrichen the idle mixture and then adding some (more) controlled air through the throttle via the throttle stop can smooth it out and make it run, even if it's at a fast idle, and even if it happens to wind up with hanging idle, at least it'll idle without stalling. Hanging idle is preferable to dying at stop lights.
This is an imperfect system so this is just a way to work around expected wear conditions when a full carb rebuild is not quite warranted. But a freshly serviced carburetor set with correct airbox, air filter, jets, etc. should idle at close to 1100 rpm with the throttles completely closed. That is my practical experience, not from a service manual.
Ok. So let me tell a backstory again. I got this bike NOT running for $750. It had the exhaust and NO airbox or filters installed. None of the installed jets were labeled, but the pilots were stripped and other little details were changed/missing on the carb, so I am confident it has been rebuilt and probably jets changed a few times. But I have no idea to what.
It already has the V&H installed, and I don't have a stock to replace it with (and that seems a bit of shame) so I am stuck with that. I bought a stock airbox FIRST (it came with K&N drop in installed, saving me cash, so I took it). I installed that airbox first (without rebuilding carbs) and could not make the bike run. Gave up on the bike all together and bought a Monster. Had fun with that for a while. But for some reason, decided to re-test the Suzuki, and got some better results, so decided to go full ham on it.
I stripped the carbs down to the core (except choke circuit, which I realized later) and ultrasonic cleaned them a bunch of times. Night and day difference. By the way, I have a compressor and blew out everything too. I bought a K&L rebuild kit (they were mislabled and for the 2002+ models with 3 jets) and some extra jets. I chose to go with lunchbox because ALL the listings in the carbs threads EVERYONE is using a lunchbox. I got 40 bleed pilots, and 150 main jets.
So I can rebuild the bike as close to stock as possible by:
installing OEM airbox with K&N drop in
Keeping V&H full exhaust
Using 40 solids or 40 bleeds for pilots
Using 130, 140 or 150 main jets (i have already bought these. If a majority of folks INSIST that I buy 125s, I will buy those).
I have the c-clip style needle jets, and they have a washer on them, so I can adjust up or down 5 positions and/or plus/minus one washer.
If I can get some suggestions on how to rebuild as close to stock at 500ft above sea level in central Virginia, I am all ears and I will go for it.
Thank you and god bless.
And I will even put street sport tires on it instead of knobbies FFS.
130 jet will be way too big with an airbox regardless of air filter. 127.5 was way too big in mine with the Uni. 125 is almost too big. 122.5 is just a hair lean.
The exhaust makes very little difference in jetting. Maybe one jet size. A drop in air filter makes less than one jet size difference, mostly at idle. Changing the exhaust and fiddling with the air filter with a stock airbox will require some tuning but no big changes. 40/125 should work fine with some dialing in of needle position.
Just to be clear, I have no intention of taking the Vance and Hines exhaust off and replacing with stock.
Of course not. That's why I mentioned that it doesn't affect jetting (much). Biggest thing is the airbox.
The K&L rebuild kit I received 'probably' includes 122.5 main jets. It's a mess, because it was labeled as 1989-2000 and receipt says I got 37.5 and 122.5, but actual kit was clearly for 2001+ as it came with a pilot, mid and main. Funny thing is the main was still the 604 mikuni size for the old carbs... Like I said, that kit was a mess. But anyways, it could 122.5, or it could be 'stock' for later gens... so when I ask below, I don't know if I have a set of 122.5, 17.5 or possibly even 130's. :D (FFS)
If I use the stock airbox with KN drop in, should I try to retune with 122.5* or 130? I understand neither is ideal, but wanna see if I can get one close to right and diagnose other problems (is there a vacuum leak? starter clutch? Oil leak?) I am leaning towards the 122.5* because how bad could stock really be, right?
Quote from: mr72 on February 24, 2021, 01:40:44 PM
130 jet will be way too big with an airbox regardless of air filter. 127.5 was way too big in mine with the Uni. 125 is almost too big. 122.5 is just a hair lean.
The exhaust makes very little difference in jetting. Maybe one jet size. A drop in air filter makes less than one jet size difference, mostly at idle. Changing the exhaust and fiddling with the air filter with a stock airbox will require some tuning but no big changes. 40/125 should work fine with some dialing in of needle position.
So this is from the Wiki. I know it's for the later carb, but it gives me pause: Do I trust mr72, or the wiki? Go somewhere inbetween? Give up and buy a new Yamaha?
QuoteTo what degree
A conservative Starting Point for upgraded Jetting (Pilots/Mid Main/Main) for a:
Stock GS500 = 20/60/135
Drop in K&N Air Filter Only = 20/62.5/140
Jetting on the later carb is completely different.
Look, I'm tired of trying to help. Do what you want. I'm not trying to talk you into anything. But you might keep in mind that you are new to this.
Quote from: struckjm on February 21, 2021, 07:41:10 PM
I want to set the gap in my butterfly valves correctly.
2000 GS500e. Lunchbox and full Vance and Hines exhaust. 40/150 jets.
How wide a gap should there be in the butterfly valve at idle? Is there any standard?
That is the correct jets for your setup. Non bleed 40 pilots, 1 washer and 3 turns if you have the stock needle.
The butterflies are synched by looking at the sun and adjusting the synch screws till the daylight you see under each - the crescent you see is equal.
Then you put it on the bike and open the idle screw as needed to keep 1200 cold and 1300 warm idle. Personally I like a higher idle but that's not the recomended number. So no exact amount it is open, you synch it by eyeball and open idle screw to set idle.
Cool.
Buddha.
Are we talking about jetting or syncing?
Because they are two different things FFS!!!! :dunno_black:
Quote from: sledge on February 26, 2021, 03:29:05 PM
Are we talking about jetting or syncing?
Because they are two different things FFS!!!! :dunno_black:
For what its worth, I think the syncing issue was resolved pretty early and easily.
Just seems now folks can't decide what my real problem is. Vacuum leak? misfiring cylinder? Airbox? Jets?
I am getting pretty confused at this point to be honest. Seems like Buddha and a lot of other people think you can run 40/150 with my altered set up. Seems like some people think I will never get it running unless I restore it to stock.
:dunno_black:
If a 2000 GS with 2000 carbs with K&N and slip on or full pipe doesn't run spot on with 40 non bleed, 150 large mikuni's, 1-2 washers under needle, 3-5 turns on mixture screws, and you dont have a leak in your mainfold/carb/butterflies (believe me butterflies leak is very very very rare, I found 1 case, had the guy sent it to me, concluded it was a leak in the body at the butterflies ... and turned out even I had misdiagnosed it, the rest can leak pretty routinely)
And, then my order of diagnosis would be
1. cyl vs cyl (Synch plays a part here true - that is my first stop). So you're not cookoo ...
A close close close second -
2. Float level. Make sure with U tube method it is at the top of the bowl exactly. Not one 3mm higher and other 1/2" down.
3. Air vent plugged up in 1 carb or heck check both.
4. Electrical - Aux ground screws up 1 cyl over the other.
5. Valve adjustment etc. Cant have that hanging open in 1 chamber anyway.
6. Motor itself non related to valves. One cyl vs other ... if you got 100 psi in 1 and 150 in the other you're always gonna run weird. It would run, in fact I may have run one that way for a bit.
PS: Lunchbox K&N is a open element filter that goes on both carbs. K&N RU2970 is the part number. If you have K&N in airbox SU5589, then you need 127.5 mains. Stock paper filter is 125 mains. Make sure your airbox has all the hoses intact and not ripped/missing.
Cool.
Buddha.
Thank you Buddha. That really does clear a lot up.
I have the lunchbox RU2970. Vance and Hines full (different headers, and can). I was trying to use 40 bleeders. I have 40 non bleeds ready to put in today. I also have unknown (probably 122.5 or 127.5), 130, 140 and 150 mains I can put in.
I discovered there are vacuum caps on each carb. Only the left was sealed. The right was wide open. I couldn't find an OEM replacement at partzilla, so I have sealed it with electrical tape for the time being.
I also bought new rings for the intake boots, and the exhausts just in case those were sources of vacuum leaks. Finally, I got some new OEM bolts to make sure the V&H exhaust headers are probably attached.
Final known issue: I didn't have all the perfect shims for re-doing the valve clearances. So ONE EXHAUST VALVE is at about .012 clearance. The other is at about .010, and the intake valves are in spec perfectly.
0. I have a 'c clip' style needle, it's at 3rd position, with one washer under it. The mixscrews are turned out about 3 turns.
1. I think timing is correct vis a vis valve clearance work and manually turning the engine. I think ignition coils and spark strength is cool too
2. I don't really understand float height tuning. BUT, I followed my Clymer and used a micrometer and they both measured at middle of spec after some adjustments
3. I used an ultrasonic cleaning machine, a lot of time, and compressed air to clean and blow out everything. I sorely hope it's not mechanical grime in any spot clogging anything.
4. Don't really understand that one
5. Intakes are about .005, exhausts are little over about .01 and .013
6. Left cylinder measures 147 when 'kinda warm' (since it runs like shaZam!, not really road riding it for 20 minutes to fully warm), and right 152PSI.
I am willing to try either the stock airbox with a K&N drop in at 40/130 (or 122.5 or 127.5 or whatever main came in my K&L kit (unknown)) or the lunchbox at 40/150 (which I have exactly).
Any consensus on what route is the easiest to get it idling correctly would be much appreciated. With the 150 mains plus lunchbox and V&H, to my inexperienced ears, it sound like it revs pretty nicely at 50% WOT. It was just shambolic below 2500rpm.
Quote from: struckjm on March 02, 2021, 09:37:23 AM
I am willing to try either the stock airbox with a K&N drop in at 40/130 (or 122.5 or 127.5 or whatever main came in my K&L kit (unknown)) or the lunchbox at 40/150 (which I have exactly).
Any consensus on what route is the easiest to get it idling correctly would be much appreciated.
It'll be easier to get it to idle right with the stock airbox.
But it'll be way too rich at revs/open throttle with 130 jets and stock airbox. It'll run better with the 150s and the lunchbox. But it will be harder to get the idle dialed right in with this setup since you have much more turbulent low speed air.
Listen. I got NINE miles per gallon on the test run I did with mine with 132.5 jets and a Yoshimura and UNI drop in filter. NINE. AND I got a crankcase full of gas. That's what I mean by WAY TOO RICH. With 127.5 it ran kind of OK but would flat out stop revving at 9K, too rich. 125 it is perfect.
Actually its easier to tune idle with K&N. However if you suffer in any 1 spot in the K&N setup, its likely at 1/4 throttle where it seems to rev through instead of stay and pull. Its almost like you're running out of gears in traffic there and shuffling between 2 and 3 or 3 and 4 with K&N while you row that gearbox less with airbox unless you want to get down the street at walking speed with a motor screaming at 7k.
Anyway my thoughts - 3 and washer seems a bit too much. try just 3. No washer.
40 bleeds are not right. 40 non bleeds. 150 is fine. Your setup is perfectly tunable all across, with the caveat above, lower gears under 1/2 throttle you'd rev through so fast you're shifting up, then its too high and its back down ...
40/150/3 turns and neelde @ 3 float level at the top of bowl. Set that up and report back. Almost there.
Cool.
Buddha.
I just finished replacing the o rings and intake manifolds.
also the gasket/ring for the exhaust. The exhaust ring was totally shot. The intake rings seemed ok, but I had a new manifold and new o rings, so why not?
I am going to try it with the stock airbox and the known 130. The only thing I have that (MAY BE) smaller is unknown. Is it 122.5? 127.5? 130? Not sure, K&L rebuild kit kinda sucks. It's half and half the right parts for Pre 2001 and post 2001.
If it runs ok at idle, I can play with it a little and tune the needle and the main jet. I want to try SOMETHING and I don't want to wait another week or two for parts in the mail. I know it's less than perfect, but I kinda just want to see if I can get it close enough to fine tune. Right now, it still behaves like a barn bike not quite back from the dead yet.
try it with the rebuild part. Certainly a 122.5, that's stock. It might be a hair lean but not bad.
IDK what needles you have, normal stock USA needles are alloy and don't have multiple e-clip grooves.
130 is going to be too rich.
I regret to say that with the stock airbox installed, it wouldn't start at all.
Not a single catch, with starter fluid or anything. Killed the battery after 10-15 different attempts.
https://imgur.com/gallery/3kNCWBH
I broke that. Trying to get the vacuum tube from the petcock on.
that's going to be a problem.
Not starting is not the airbox's fault. I said it before, but I mean it now. Good luck, but I think I am done trying to help. Follow the link in my signature for a walk thru, I don't have anything more to add.
Thanks.
I will read it again.
The 122.5 is a hair lean if you have 40 pilots in. If you have 37.5's its well about 1 size lean.
How in the freeeeking heck does the rebuild kit have 1/2 pre 00 and 1/2 post parts ??? Those 2 carbs dont have a single common part save for an O ring here or there. As usual, Suzuki fixed what wasn't broken except by design, making an even worse broken part and ignored all the broke crap with carbs.
Cool.
Buddha.
Buddha. Put the lunchbox back on. 40 no bleed pilot jets. 150 (small head) mains.
When it was cold, I pulled the choke out and gave it a squirt of starter fluid. Fired right up.
I had to give it 'a blip' to get the rpms over 4K. Then they dropped to 4000 and stayed there. Let it run like that for a minute and then tried playing with it. Lowered the choke to 50% and the rpms dropped fast. Revved the throttle. Sounded good.
Tried to replicate for a video and it won't hold rpm at choke. Started smoking.
It seems like maybe some oil or gas is somehow getting out the exhaust valves.
Here's where I see smoke or oil: https://imgur.com/gallery/dtHRqmT
Once the bike is warm (warm only) I start getting more and more white smoke out the exhaust.
You likely have an overflowing float (white smoke is gas, greyish is water and gas, blue is oil - LOL I know depends on your eyesight) and, put the right large slotted round mikuni mains. ot that its a huge deal at this point but better to eliminate that issue too.
Why starter fluid - wont it start without that ? Then plugged up air and fuel passages and pilot circuit are the culprit.
Choke when cold is normal, full choke till fully warm, I know all that 1/2 choke BS, but really 1/2 or not, till up to temp choke is acceptable.
Next step, smell your white smoke. Put your hand in it. If its gas obviously you'd smell it and it gets your hand nice and ... well combustible, so dont light up a cigarette. Water will smell like nothing, and oil will send you running for cover.
Cool.
Buddha.