Moto Grand Prix
Main Motorcycle: 03 TBird
Join Date: Apr 2004
Location: Nutmeg State
Other Motorcycle: '76 Bonnie
T140 Cold Misfire
Can't seem to nail this one down.
Bike has developed a misfire on all cold starts, in all types of weather, that lasts for a couple of miles then it runs fine. Restarting a warm engine shows no issues.
It seems like it might be from just the left cylinder.
There are new coils, points, condensers, voltage regulator and main wiring harness (but that's another story). Carbs looked clean but were shot with cleaner anyways, set the floats (repeatedly), new O rings on the manifolds, etc, as well as a fresh dose of high octane fuel.
There is ample compression, perhaps a bit much and there is possibly some carbon buildup on the pistons. From what I can wee in the ports, there is a bit of buildup on the backs of the valves, but as far as I can tell not on the seating edges. The engine has never been open, but there are only about 12,000 miles on the clock.
I might add that it fires right up, cold or warm and has never needed choking, but shots from the tickler while running seems to help.
So, any ideas what could cause a cold miss?
Last edited by Beemie; 11-22-2012 at 08:58 PM.