i just bought a 1990 gs500 with 7k miles on it and the previous original owner had the carbs rebuilt and the tank lined at the dealer last season. There was some gas leaking into the airbox so i adjusted the float valves to the 14.6 mm spec because they were only at 9mm. i don't understand how that could happen in such a short time since rebuild. anyways the carbs don't seem to be leaking into the airbox anymore but the running issue hasn't changed. the bike starts really easy and idles great but when i take off just about the time i finish releasing the clutch all the way it bogs down for a second or 2 pretty bad but then it runs perfect the rest of the way through the throttle. hopefully I'm explaining this clearly. I also found the more i run it hard up and down my street it gets to be less of a sputter but never goes away completely. Anybody have ideas what to look for?

did you sync the carbs?  Did you make sure the jets were clear? 


To sync the carbs, there is a tutorial in the wiki.  Sounds to me like its still a fuel delivery issue at low rpm


Check the float needle as well and see if its moving.



HTH!

You may be rich on the pilot. The right size for pilots is 40, stock is 37.5 (causes idle to hover not a sputter @ take off) and some people may over do it and put in a 42.5, thinking that if a little richer is good much richer should be great ... not.
Anyway check that, and check the float level again, and the mix screws. These should be equal for both carbs.
Cool.
Buddha.

i just checked with a clear tube on the bowl drains and the gas level or the right carb is dead on and on the left carb its about 1/8-1/4" high. im gonna go pull the carbs off again in a minute anyways but is that enough to cause the problem?

Quote from: sluginxlt on March 14, 2012, 10:32:12 AM
i just checked with a clear tube on the bowl drains and the gas level or the right carb is dead on and on the left carb its about 1/8-1/4" high. im gonna go pull the carbs off again in a minute anyways but is that enough to cause the problem?

1/4" ... 6+ mm WTF, 1mm is too high. Set it same as other one.
Cool.
Buddha.

i measured over and over again with calipers so i dont know how it ended up that way. also the Orings on the tubes in the bowl seem a little loose but ive never messed with carbs before so i dont know what im looking for. heres a little video to show what im saying

well while i was trying to clean the jets today the screwdriver slot on one of the pilots was all chewed up and would not come out so i had to use a small easy out. after all that all jets look clean as a whistle but since i need to replace the pilot jet now anyways i ordered the #40 instead of the stock 37.5

well i put the new pilot jets "went with the number 40 jets as suggested" and got the float height right by confirming with the clear tube method. i read somewhere to run the mixture screws 3 turns out from seated but i still have the same problem just not nearly as bad. it just seems like when you "gun it" from low rpms its hesitates a bit and also i noticed if i do a wide open throttle run up to higher speeds when i come back down to about 50 its feels as if im running out of gas for a while and then eventually gets better. also around 90 mph  :police:it feels like its running out of gas.

The hesitation on 1/8 throttle is caused by the needle. The stock cut on the needle is too square. You can use some additional shims(washers) under your stock needle clip to work around the issue. The only real way to fix it is to replace your needle. Some jet kits come with replacements but are pricey. I am currently testing an alternative which you can read in my build thread. But I dont have enough testing time to recommend anything yet.

Start with the washers they are cheap and will get you closer. But if you're like me you wont be happy with the weak midrange.

Sent from my Android World using tapatalk

but for a stock bike shouldn't it all work together, should i have stuck with the stock size pilot?

The stock pilot jets are leaned out to meet EPA regulations.

And that hesitation off low rpm's can also be attributed to the stock CV carbs. When the throttle is opened quickly, the butterfly valves open up, but the slide can't raise that fast.

i know im having more problem then a factory hesitation though.

Quote from: sluginxlt on May 31, 2012, 02:34:03 AM
i know im having more problem then a factory hesitation though.

Maybe the previous user has changed the needles/needle position in the vaccuum chamber. If you haven't done so, you can check them, be carefull, that black covers have a jumpy spring under them and a very small oring at the vaccuum port. check the needle position and adjust to stock.

the previous owner was the original owner and he was lucky to figure out how to get the seat off lol. but then again i dont trust the dealer because he had the carbs rebuilt at the end of last season and when i checked the floats were set way high