Carburetor adjustment

[jgsfancy]

My bike idles irratically and is hesitant in lower RPMS, so I read through pages and pages on this site and everyone seems to say that cleaning the carbs and synching them will fix this issue. Although the problem is more pronounced when it gets warmed up real good. I have a 4 into 1 Yoshi pipe if that matters at all. Anyway, I got my carbs off now, and they are (and already were) clean as a whistle and all mechanical parts move soundly. No cracked rubber or anything either. So, the question is the a/f screws before I put them back. I have adjusted them all to 2 turns out from the stop, but I don't know for sure if thats right. Can someone tell me what to do here? Also, would turning it out make it run leaner or richer? Any reply would be appreciated. I really want to get this beauty of a bike running properly, or else its gonna drive me CRAZY!!

Its a 1993 GSX600, if that makes a difference.

[arsenic]

The A/F screws should be 2.5 turns out. Turning it out makes it richer. If it gets worse as it warms up, it's likely a vacuum leak. It gets worse as the rubber warms. I need more info to tell you what the A/F screws should be at for sure. Like do you have a jet kit? Which one Dynojet or Factory Pro? What air filter do you have? What are the main jets? Let me tell you what will work the best. Factory Pro jet kit, 115 main jets, 2.5 turns out on the A/F screws. You can tell if you have a jet kit by the needles. FP needles have 5 grooves for the e-clip. DJ has 6. Stock is non adjustable and it will be marked 5F104.

[jgsfancy]

Its all stock...

Everything is stock, I checked the measurements on the jets, they all matched stock figures. ALL is stock. Except for the 4-1 Yoshi (please say thats not the issue??) Also, I've read that 2.5 is the best, but why is the stock suggested number 1.5 turns if 2.5 is unanimously better? I appreciate you taking an interest in my issue here.

Also, how come carbs 101 states that "more turns= more air" if turning it out makes it richer? Doesn't more air mean its going to be running leaner??

[arsenic]

You SHOULD have a jet kit with a full exhaust. The factory makes the mix extremely lean to appease the EPA. To use the stock jetting with a full exhaust, shim the needles with two half step washers on each needle and turn the A/F screws to 3 turns out. If you want a set of carbs with a FP jet kit, I can help you out there. Why does carbs 101 say to set the A/F screws to 1.75 turns out? Cause it's wrong.

[jgsfancy]

Strange problems....

I really appreciate this. But, how about if money is low right now and I have to make due with what I have? Will I ever get this bike to run half sensibly with the carbs and jets I have if I follow what you said (i.e with the 3 turns, etc.) The bike starts up first and works ok, revs up well and that. The revs drop back down a little slower than usual, but at this point its tolerable. So I go out for a ride. At stop signs most times it will manage to stay alive at about 1000 RPM or 900... a bit low it seems, but even this is semi-tolerable. The more the bike reaches full running temp, now when I get to stop signs the idle hangs betweenm 2-3000 for a bit, which sounds ridiculous. Also, at this point, the bike is hesitant at RPMS of 3000-3500 but pulls with full force once I get it up past 4000. This is such a nuisance. Starting the bike off with the hesitation takes away every bit of "cool factor" completely. I'm so stressed !!

[arsenic]

Yes, you can make it run just fine. However, your high idle issue isn't jetting, it's a vacuum leak. Find it and fix it. Have you synced the carbs recently? If not, do that.

[jgsfancy]

No vaccuum leak...

Already checked for vaccuum leak, and there is none to be found. Non-existent. I thought that was the problem too. But no. Also, the carbs, as far as my eye could see, seemed to be synced up perfectly when I pulled the throttle open and looked at the 'butterflies' or whatever. HOWEVER, I don't trust naked eye, and yes, tomorrow morning we're going to use the actual tool to sync them before I put them back in the bike (carbs are still on work bench right now). I have the screws tentatively set to 2 turns out for now, but if you are adamant and strongly believe that 2.5 will help me , then....... I'm inclined to think you know alot more about this than we do !!! Again, thanks so much

I meant WHEN we put them back in the bike.

[Wild-Bill]

I had a '96 750 with stock jetting and a Yoshi exhaust. Once I'd chased down every last vacuum leak including the o-rings between the intake boots and the head the bike ran great with the A/F screws set at 2.5 turns out. It did take a thorough cleaning (including tearing the carbs all the way down and soaking the bodies), all new o-rings and some very careful re-installation but when all was said and done the hesitation was gone and she pulled hard from any rpm.

Oh, and I also re-packed the exhaust can, too. Worn out baffling will make the bike run lean. I discovered that years ago with a VF700F Interceptor and a V&H exhaust.

Edit: When I was looking for vacuum leaks I never had any luck with squirting stuff around in there. I've heard that an unlit propane torch works but what worked for me was just looking for anything that might cause a leak and fixing it. Glue the intake boots to the airbox, install the airbox to the carbs before putting the carbs on the bike, make good and sure those sync ports are capped off with spring clips in place and when all else fails, replace those o-rings between the intake boots and the head.

[djdaredevil]

I would be very inclined to think he knows alot more than not just you
about these carbs.
Set the screws to 2.5 and get the vacuum sync done and she how she does

[jgsfancy]

Immaculately clean.

The carburetors are absolutely clean. So clean that I think the guy who owned her before me recently gave them a good cleaning trying to figure out what the heck was going on with his bike.... but he never did figure it out, so therefore he sold it to me. I really like the look of the bike, and heard they were reliable and fairly quick, so I fell in love with it and bought it. And now I'm suffering trying to get it to run sensible, because I like to ride, ride, and ride some more and so therefore its performance must be at MINIMUM semi-tolerable. The guy who checked for vaccuum leaks works on about 25% of motorcycles here on the west coast of Newfoundland, and he tells me with confidence that I do NOT have a vaccuum leak. What do you think? Isn't this weird?

[arsenic]

You can't say a vacuum leak is non-existent. Sometimes you just can't find them. Have you replaced the intake boot o-rings? Does the air have a drain hose on it? Is the air box drain hose capped at the end? Those would all be vacuum leaks. Do your carbs look like [ame="http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=190674715982&ssPageNam e=STRK:MESE:IT"]THIS[/ame]? Because that is immaculately clean.

[jgsfancy]

Guys, your input is extremely helpful. I guess I'll put it all back on tomorrow carefully and properly with the screws set to 2.5 turns and get em synced up with the vaccuum guages before I think too negatively about my new (awesome I thought) bike. I really, really hope she works out for me.... ironically, I bought it partly on its solid reputation for reliability (because I am such a high-miler, reliability is key to my happiness!)

[Wild-Bill]

Once you get her right she'll be incredibly reliable. The key is to stick pretty close to stock and keep running her. The carbs don't like it when you don't run the bike and they don't like for the intake to be messed with.

[jgsfancy]

Yep, clean.

Those are beautiful carbs you have there, and yes, mine are so clean that the guy I mentioned helping me (who works on about 25% of bikes on the west coast here) told me that they look as good as brand new carbs, and I agree, because they REALLY do! Like I said, the guy who owned her before me probably did everything trying to figure out what the HECK was going on.....

Oh trust me I WILL be running her! Our bike season here is short (i.e 3 months, 4 or 5 max if you're hardcore like me) and I put on at least 10 K a Summer just in joy rides alone, in between kids and a full time job. So. The carbs won't lack running!!!

[Wild-Bill]

Bet you're going to have to change out the intake boot o-rings. My 750 was almost but not quite exactly right for quite a while until I thought of them. I did them at the same time as I removed and re-glued the airbox boots and all of a sudden... (Angels singing, big guy dressed like a jug saying "Oh, yeah", whatever. It worked and it worked right.)