Engine spuutter under load

[sidecarKev]

Last night I put about 4 miles on the bike and sidecar driving around my driveway. I was having a hard time trying to dial in the idle speed. The bike fires up easy every time. I let it warm up and make sure the enrichener isn't on and then try to set the idle. Set the idle and give it a few revs, now it wants to idle at 800 rpms and it dies. Reset the idle to higher rpm's give the throttle a couple flicks and it revs at 4000. I can't get it where I want it. Okay another thing, I drive the bike around and it seems to have a real problem in the 2-4000 rpm range. If its in that range it it will sputter and cough, twist the throttle and it will slowly come out of it, hit 5000 rpm and you snap your neck. My thought is that these two problems are related.

At these RPM's my guess would be the needle jets/emulsion tubes if its a carb related problem. I don't think they are the culprit though because I took them out and made sure each and every hole was clear. I have done a carb clean twice, haven't hit the triple mark yet. I hate putting those darn carbs back in. New plugs, new gas line with filters, new battery, checked advancer for broken wires. did a static carb synch, and maybe a few other things I'm forgetting.

Any other ideas? Riding season is finally upon us here in the frozen north, well at least for now.

Kevin

[randy]

Sticky advance mechanism?

Randy

[sidecarKev]

I guess thats a possibility. Right now I have the cover off and I can watch it move. It seems like it surges quite a bit at lower rpm's. How would I go about checking this? I have moved it by hand when I was checking the wires. It seemed to move pretty easy through its movement range.

Kevin

[randy]

Make sure the vacuum line is connected to carb#2 vacuum port NOT at the boot vacuum port. That's probably the issue. HTH

Randy

[sidecarKev]

The tube is to #2 carb. The #2 boot tube is going to the left side petcock. I guess I should have said that this is a '79F.

Kevin

[Ken Talbot]

I've heard of something like this in the past when someone was using the cable adjuster to set the idle speed rather than the hard-to-find thumb wheel between carbs #2 and ##. If there is not enough slack in the throttle cable, even just a bit of movement in the handlebars will start pulling the throttle open.

[skids]

Maybe you are getting some popping through that carburator causing the surging?

Originally posted by sidecarKev
The tube is to #2 carb. The #2 boot tube is going to the left side petcock. I guess I should have said that this is a '79F.

Kevin

[nashville_bill]

It sounds like a vacuum leak to me. Try spraying WD-40 in the intake area at idle to see if it makes it rev up.

[MartyA]

Kevin, is your throttle is returning all the way at idle?

[sidecarKev]

Nope no throttle cable problems, checked that last night. Twist the throttle and it alsways returns and has just the tiniest bit of slack in it actually. I'll be looking into the situation more in the morning.

[scalded dog]

My '79 standard was doing the same thing, found out it was the coil that connects to #1 and #4 carb, only #1 was giving trouble. I had an extra set of coils, it straightened up after I swaped them out. Later 'Dog