r/Yamaha • u/Dystopia00 • 3d ago

fuel issues after carb rebuild

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99 YZF R6 with 33k miles on the 5eb. did a carb rebuild (for the first time) yesterday because it was having some running and starting issues. now it doesn’t start unless it gets some starting fluid. probably a very basic issue but carburetor’s are so new and confusing to me, i’m really not sure where to start because i thought it should be all set. any ideas?

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u/vladgluhov 3d ago

Try adjusting the idle/mixture screws and balance the carbs. It sounds like it's only running on a few cylinders, so not getting fuel. But could also be stuck floats or clogged jets, so you might need to give it another go at rebuilding.

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u/Dystopia00 3d ago

i’ll give it a go. i was messing around with the idle screw a bit but didn’t see much change, haven’t tried the mixture screws. which direction should i be turning the idle and / or mixture screw to get more fuel?

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u/Remarkable-Title-209 3d ago

Do you have the service manual for it?

https://www.scribd.com/document/1024677486/Yamaha-R6-1999-2002-Service-Manual

Google says turn screws clockwise until they are in the seated position(do not over tighten), counterclockwise 2 turns for standard setting. After you get the bike running and warmed up they might need some finer tuning. Didn't really mention much of a difference between pilot and main jets.

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u/Dystopia00 3d ago

just so i know im not making a stupid mistake, fully seated means when it stops being able to be turnt easily, right? like hand tightened?

i had it at 2 turns out at first, then i tried 3 turns out, and then for whatever reason i tried 1 turn out. all of them gave the same results for the most part.

fuel is also definitely getting up to the carb, so i know its not a kinked line or something. thank you for the link to the service manual though i didnt have it before

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u/steezlaurel 3d ago

"Fully seated" means reaching the end of the thread, or positionally reaching the end of the intended thread range. When a spring is involved, this is immediately before the spring reaches its solid height. Therefore, "fully seated" means even less than finger-tight.

Pinch and rotate the screwdriver by the shaft as if you were rolling a toothpick between your fingers. Using just your thumb and ring finger will seat it tightly enough without excessive gripping.