Gertrude Has Me Scratching My Head

[GrandpaDenny]

Put in a set of Carl Leo rebuilt carbs a couple of months ago. Maaaaaaaannnnn she ran GREAT! Had a couple of minor instances after fueling up where she'd stutter and stumble for a couple of minutes - I chalked that up to something in the gas. Different stations. Well then after about 1000 miles she started acting that way all the time. Pulling the choke helped. Ok, so figured she's running lean, looked for vacuum leaks. Sure enough, found a couple (kronkin' air box boots). Put in new airbox boots. Still the same. Thought it might be a misfire, so trimmed the spark plug wires. That was a pain in the a$$ all its own. Trimming them was easy, getting them to stay well and throughly seated in the spark plug boots wasn't. Fixed that. Replaced new Kaw fuel filter with a NAPA generic. Replaced fuel pump with a cheapo EBay one. Improved, but still acting up at about 1/3-1/2 throttle, regardless of gear or speed. Reconditioned the points on the original fuel pump and put it back in. Improved some more at idle and she no longer barks and snarls quite so much under deceleration, but STILL stumbles at 1/3 to 1/2 throttle. Pulling the choke still seems to help, but not totally. What the heck is going on here? I can't find a vacuum leak, the air cleaner is a K&N and is properly seated. She's not blowing smoke, she idles like a dream and off idle pulls like a, well, Elephant, until 1/3-1/2 throttle.

Any ideas?

[SgtSlag]

You said cleaning the points on the OEM Fuel Pump helped? Wondering if the pump can't keep up as the engine draws more fuel as the throttle opens up? Did the after-market pump have the same/higher flow rate as the OEM's spec's? A weak pump might explain the issue.

Have you checked the float bowls: levels set properly, moving properly; junk plugging/restricting fuel flow? What about the fuel lines: make sure no blockages or leaks?

Is your electrical system supplying enough power upon acceleration? If you don't have a voltmeter installed, it would help cross that off the list, and it would be a great tool to have onboard at all times. It will allow you to keep an eye on the battery and charging system health and function. Cheers!

[triton28]

Your problem to my way of thinking may be carb related. This may help you determine where to look should that be the case.
https://www.motorcyclecruiser.com/motor ... on-basics/
Just a hunch on my part.
Dave

[GrandpaDenny]

Carl Leo provided the rebuilt carbs. So I really doubt the problem is with the carbs. Could be, though. However, the bike ran great (up to 120 mph) for 1000 miles.

[SgtSlag]

You said, yourself, that the rubber air boots were leaking. That could have allowed particulates to get inside the carbs, plugging something up. Nothing is off the table, at this point.



Best of luck. Cheers!