So my idle is set to about 1300.

After I ride around, as soon as I hit about 2500-3000 the rpms jump to 4k and just stick there.  The only way to bring it back down is to slow down and start letting the clutch out to force the rpms to drop, then it returns to the correct rpm
I am wondering if it may be a throttle issue, as I am not sure what else it could be at this point.  As a side not, I have about 1/8-1/4" of play before the throttle cable is engaged when I twist.  Is this normal?

What I have done:
Float heights should be damn near perfect, measured to 14.6mm before installing carbs.
Watched the choke cable move open and closed I as I slide the lever
Covered the air intake and carbs with wd40 to see if there is a vacuum leak, with no effect.
Stoke jets, intake, and exhaust.  Idle air screws are turned to 3 turns out.
Gets spark, new iridium plugs installed.

I am a little lost what to do next, so any advice would be great.

Quote from: ctjacket on June 15, 2013, 09:42:46 AMFloat heights should be damn near perfect, measured to 14.6mm before installing carbs.

Always double check with the clear tube method. Just because you triple checked the measurement doesn't mean the float needle is functioning properly. Also, check your carb diaphragms for small holes or tears.

Quote from: RossLH on June 15, 2013, 09:53:02 AM

Quote from: ctjacket on June 15, 2013, 09:42:46 AMFloat heights should be damn near perfect, measured to 14.6mm before installing carbs.

Always double check with the clear tube method. Just because you triple checked the measurement doesn't mean the float needle is functioning properly. Also, check your carb diaphragms for small holes or tears.

Hm okay.  I'll have to find some clear tubing and go check them.  What I describe is a symptom of running lean right?


Also I checked the diaphragms twice, and looked everywhere for holes and tears and they were okay.

Small update to this:  I haven't been able to find any vinyl tubing at the local mom and pop places, so I'll have to trek further out to HD tomorrow.

In the meantime, I did a half turn (I think) of the mixture screws, and it seems like it helped a little...

So when I rev the engine in neutral, it is totally fine.  If I get rpms above 3/4k in 1st, it is fine.  In 2nd, it sometimes catches then drops a little.  In 3rd, it seems like it always stays pegged at 4k.  Could this really be the cause of just float heights?

Well looks like I have to adjust the float heights....

Could this small difference be causing my hanging idle?

Left carb



Right carb