Carb Problem...Perhaps?

[cshumway]

So I installed my Pamco (14-0911) correctly and my 78 special fired up first kick! I set the timing. But for some reason I cannot get the bike to stay running for very long? Before putting the pamco on I adjusted my valves, cam chain, full battery, and cleaned my BS38 carbs. Just today I started her up, she went to about 3000 rpms, rpms started to drop to 2grand and then it just stalled. I can't start it back up immediately, I have to wait a few minutes and she will start again, and then the same thing. I have tried adjusting the mixture screw on the left carb but that doesn't seem to help. I have the throttle stop screw a couple turns from bottoming out (Is that a normal place for it?). So basically it hangs at high rpms for a few minutes then just rapidly dies. My battery voltage is up over 12v after it dies. New brushes on the ALT, Factory jetting. One time when the RPMs were up I put it into gear and it died as soon as I did. My advance pops back like that video floating around. I'm at wits end here. Oh and I also have the Radio Shack retifier. I've tried leaving the gas cap open, same results. I cannot get the Idle to just hang out at 1200 rpms. It only backfired one time through the carb and one time through the exhaust (left side only) but that was when I was really messing with the idle mix screws. Is this a sync issue? Please some insight on what to do next...I know that the weather is sh*t here in Ohio ONLY because my bike isn't running.

Thanks all

 

[Classic]

Sounds like timing is too advanced. What do your plugs look like?

 

[cshumway]

light gray

 

[retiredgentleman]

With carbs, the float bowl level is fundamental to how the engine runs.................have you set it correctly??

Everyone says they cleaned the carbs, but most don't really understand the circuit paths inside the carbs. The pilot circuit is what must work to have low speed idle operation. I think you need to spray carb cleaner and compressed air through the pilot circuits.

Have you removed the pilot jet and main jet and confirmed they are clear?? Pilot circuit includes the pilot jet, air path to the pilot jet, mixture screw opening, single passageway from the mixture screw and the 3 by-pass passageways.

Could be air leakage around carb intake as well.

Check out the Carbs section in the "Tech" at top of page................diagrams of carbs etc.

 

[cshumway]

I did do the compressed air and carb cleaner through the pilot circuits, but perhaps I missed something, I removed the pilot jet main jet, they were clear. I tore those puppies apart, cleaned/soaked everything, except gaskets. I followed that pdf write up on the carbs pretty well! I've also read the "Tech" so many times, but I think I'll give it one more go. Carbs are clamped down to where the flaps on the clap are touching. I also measured the floats as per the amckayltd carb guide...is that the correct way?

Well Tomorrow I'll drop the carbs again and start the cleaning process all over hopefully I just over looked something!
Thanks for the help

 

[retiredgentleman]

My preferred way to set the float level is to use a clear plastic tube as a level gauge. I had to drill a hole through a bolt that threads into the drain plug at the bowl bottom. Plastic tube goes onto the bolt with the hole.

Tie the plastic tube to the side of the carb. Correct level is at the bottom of the float bowl flange. I do this with the carbs on the bench, and a temporary "fuel tank".

Most guys have success using the upside down measuring method shown in manuals.

 

[cshumway]

Problem solved! Thanks for the help..floats ended up being off! Runs like a dream!

 

[retiredgentleman]

Great feedback to the forum!