Strange carb issue

[tuna boy]

I have a 1980 1100 and have a problem that comes and goes. When I leave the house the bike coughs and misses under load that surfaces @ 3500 rpm. Once I get out on the hi way the bike kicks in and pulls real hard throughout the rpm range. Then I go through a small town with low speed and traffic lights. When I clear the town the same carb stumble is back. This pattern repeats as I ride, small town and stumble returns. During the entire time the bike idles nice. I have run some ATF and Seafoam in the bike with no results. The bike starts, idles and is well behaved except for the above and when the stumble is gone it pulls real hard. Any ideas or thoughts?

 

[slabghost]

Check your vacuum advance. Might be a leak.

 

[mcgovern61]

I had the same type of issue with my '81 carbs. It was several things; O-rings leaking at the carb intakes, the floats were not adjusted correctly and the needle and seats were not sealing letting gas through.

 

[zman]

A high float or float that isn't sealing will cause that too, when your on the highway your fuel consumption makes up for the excess fuel but slow the bike down and your not burning fuel as fast so it loads up the engine.

 

[tuna boy]

I was hoping that the atf or seafoam would fix this. I will check the vacuum line first. I am really not excited about pulling the carbs an if it comes to that I will probably put up with the stumble until spring. When the carbs are spot on they are beautiful, crisp, reactive and powerful. And when they are off they can be frustrating.