Running rough off the line

[benjammin]

Ok friends. My stock 1980 has been running rough, and it has been progressively getting worse. I've cleaned the carbs good and changed the spark plugs and it's still doing the same thing. Most of the time it will run pretty good and then after 20 minutes it starts sputtering real bad in first gear off the line, and then a few minutes after that it does it in every gear. I have to twist the throttle hard until it sputters and jumps to life. I've tried riding it like this just to see what it does and after a while it bogs down, shuts off, and farts out the carbs. Then it won't start right away. After I let it sit for 5 minutes it will fire right up like normal and only do it in first again until I get down the road a little and it gets worse eventually bogging down and shutting off again. I've noticed that the longer I sit at a red light the worse it is off the line, and if I sit at several red lights in a row it's so bad I almost can't move until it sputters really bad, farting out the carbs, and then takes off and runs normal at high rpms. Sounds like dirty carbs I know, but I have cleaned them well and it still runs the same. Any ideas?

 

[figure8]

If the carbs are really clean you might want to check the peacock. Another thing to try is open the gas cap and see if that makes a difference. Sounds like it's a fuel issue maybe, just a guess.

 

[benjammin]

The petcock did cross my mind. Should it be removed and cleaned? I ran a can of b-12 fuel system cleaner through it to try and deal with any issues like that but that never seems to do anything for me.

 

[figure8]

It wouldn't hurt to remove and inspect it. Swapping a new fuel filter may help to. If you have access get some clear fuel line so you won't be guessing the whole time.

 

[5twins]

It might be electrical too. When a coil goes bad, many times it only acts up when hot, works OK when cold or cooled down. The way the bike eventually dies when it gets really warmed up, then won't re-start until allowed to cool off some, could indicate a coil problem.

 

[figure8]

I had thought about that too, could the same be said for the TCI box?

 

[benjammin]

Petcock is working properly. 5twins you may be on to something. It runs better at higher speeds when the engine is getting some air, and it runs like shit sitting in traffic while the engine gets hot.