Should i raise my jet needles??

[Guest]

I'm cleaning/rebuilding my Mikuni 2-barrel CV type carbs for my '85 GS550L. (yes, I've completelly disassembled & dipped everything, new o-rings and the like...)

Everything is stock: OEM jets sizes (1,4 - 90 ; 2,3 - 97.5) , exhaust, airbox & filter. No mods of any kind.

I will now need to reassemble & set it back up (idle, air mix, vac sync...)

My question is: Should I raise my stock jet needles now (before I've put everything back), and if so, how high?? These are the type that have no notches, so I would have to put washers in as shims.

Would there be any advantage to raising them, or should i leave them alone??

Thanks

Mike

[Dave8338]

Leave them alone for now...when you get the thing back together, if everything is right, you shouldn't need to raise them..........this comming from a guy that had to raise his, but I had exhausted every option first.

Without running the bike through the paces, you won't know if it is needed.

[Guest]

If you're all stock I'd say no.

[80GS750]

what does this do when you raise the needle? i want to guess and say it allows more fuel through the jet?

[Guest]

If these are CV carbs the slide diaphragm starts to raise the slide and jet needle out of the main jet at about 1/8 throttle which allows fuel to flow out of the main jet gradually untill full throttle where it is completely out of the main and all fuel flows from the main. Raising the needle will richen the needle circuit because it raises the needle out of the main jet sooner than before. If you experience a stumble at 1/8 - 1/4 throttle than you might need to mess with the jet needle. If not don't mess with it.

[80GS750]

ok, that makes sense....