Carb rebuild and other stuff - "Newbie with a pig"

[Barry]

Pretty sure somebody around here knows the proper needle protrusion for stock settings.  

I've got the measurements for each needle position but I'm away from home until tomorrow. I have posted them before so maybe a search would find them.

Here you go

Needle Position vs Measured Needle Length in mm

1      42.37
2      40.57
3      38.79
4      37.10

[DerekM]

Checked the enricher disks, floats, slide needle, and all the passages and idle jet with a copper wire and still no dice. Jets are correct, but I had the idle screw a half a turn too far out, so I tried to start it up again and no go. Only wants to start with my hand over the carb still, so I think it's getting too much air or not enough fuel.
When I rebuilt the carb I didn't take the butterfly valve out or replace the o-ring on the shaft. If that o-ring is bad or the valve isn't seated perfectly that could be the source of air. Other than that I think replacing the idle jet and screw are the other culprits.

[DerekM]

Slide needle on one side was in the wrong position, used a better caliper to measure it and bingo starts up. Choke makes the idle too high and the idle appears to be a but low. Transitions are choppy too. But it runs. And it will run better after tweaking the carbs!

[Luca]

Sweet deal!  It takes a good 15-20 minutes of riding for these engines to really get up to temp before you synch the carbs, though on a fresh start like this you probably want to try synching them a bit just to make it run more nicely while you warm it up.  Poor off idle performance is most likely the throttle cables out of synch--you can get it roughly dialed in by making sure the free play of the cable sheath at the adjustor screw is the same on both sides.

If you still suspect air leaks you can go around with a can of starting fluid and spray it at the boot joints, throttle shaft, etc.  Have a fire extinguisher on hand just in case  [smiley=thumbup.gif]

[montmil]

Insure that valve lash is correct and -since you're experiencing temporary running problems- the timing spot on before beginning a carb synch job.

If you get the carbs before the horse, you'll waste your time chasing your own tail.

[DerekM]

A month later, with the bike all back together after greasing the transmission splines, i got to spend some time tuning last night. it runs a ton better, and i've got a buddy with a sync tool that i'll be borrowing for a final proper tuning.