Please confirm this carb notion...

[corey]

Alright then. I adjusted the floats on my carbs (which appear to be 80sf carbs) to 23mm height. Even though I have a 79SF, I figure since the carbs are later, use the later setting. That's where the problems begin, however.

When trying to synch my carbs I can't get my idle lower that 1100 rpm, even with the trottle set screw out all the way (i.e. butterflies completely closed). Also, it seems my pilot screws are best set at only 1/2 turn out from lightly seated.

To me, this is all saying the floats are set way too low, thus I'm tempted to go with the earlier higher setting (25.7mm). I believe my floats are in good shape, as they stop the flow of fuel.

Does this seem right to everyone else? I'm mostly trying to save taking the carbs off and on six more times!

P.S.: Just to clarify, if my carbs only have one fuel T per each carb pair, they are 80s carbs, right? Also, I don't have adjustable needles.

[TopCatGr58]

Hey Corey,

Yep, it does sound like you have the later model/styled carbs. Another check is 4 holes in the intake bell instead of 3, the extra one is for the float bowl vent, that's why it only has the 1 "T" fitting for fuel, but not one for AIR!

Some bikes like leaner settings, and so you might try adjusting the floats to 24 instead of going all the way to 25.7. As has been stated by the PRO's, float height affects pilot and mains performance. More fuel sitting higher can make it easier to draw up the straw to richen the mixture. You're able to set the pilot screws at 1/2 turn out, so that's a good thing. Another member recently posted that they were able to screw them all the way in to the gentle seat position and it still idled and too high!

Sounds like you're close, so that's why I wouldn't change the float height too drastically!
T.C.

[John]

Any chance that the cable needs adjusting at the handlebar? It may be holding the throttle open.

[corey]

I wondered about the cable. I think its not that, though, cuz once I seat the pilot screws it won't idle. That would be a valid test for a short/bound/sticky cable, no?

I think I'll try adjusting the floats to 24mm erring on the leaner side. Thanks TC and John, I'll let you know how it goes!

[mro]

Throttle cable adjusted properly will have a small amount of free play.
Throttle closed, check cable at the carbs.
Not sure what the "book" says, but you should have close to 1/4 inch of slack.


mro

[jwoell]

If I am understanding this right, you're saying that the problem is that you can't get your idle to drop below 1100 RPM when you're trying to sync it, even if you turn the center idle set screw all the way out?

My understanding is that if your carbs are not synced, you could have one of the 4 butterflies completely closed while the rest are open a substantial amount, therefore keeping the engine at higher RPM. Did you pre sync the carbs using the bread tie trick?

http://www.xs11.com/tips/maintenance/maint35.shtml

I dunno, just another thought to consider. It may not be a mixture problem at this point.

[corey]

GOOD POINT!

I briefly considered this, and then instantly forgot about it. I did do the bread tie trick, but I fiddled with them so much trying to get the idle down I'm not sure where they are set in relation to each other. I'll definitely check it out before I try adjusting the floats.

Also thanks to mro, I'll check out the cable for play!

Thanks for the reminder, jwoell!

[prometheus578]

"Just a tip."

A too tight throttle cable will also rev the engine when you turn the handle bars.

[corey]

I had a buddy with a Suzuki dirtbike that would rev the motor every time he turned the bars all the way to the right. It was like clockwork... hilarious clockwork.