Number 2 cyl. not firing? Plug is good and wire is hot....

[Anonymous]

Hoping some one could help me work out a problem I am having. What initally thought was a ignition problem turned out to be something else. When started my 79 gs425e cold it would run with full power with both cyls. firing, then after the bike got a little warmer ( 15 - 30 secs.) no 2 would stop fireing and the pipe would get cold. I had the wires and plugs tested and both were in great shape. The coil was delivering the power for the spark. Any reason the cyl. would just stop fuctioning after warming up?
Any suggestions?
Thanks in advance.

[Dink]

Most often this sort of problem is related to wiring, in particular loose or corroded connections, go over all your wiring clean all connections. If that does not help it is time to trace each wire and resistance test them.
Dink

[Anonymous]

Could this be a valve problem? Maybe clearance is getting too big after warming up? From what you say, I cannot see if you still get a spark after its warmed up.

[Anonymous]

It could also be a coil that is breaking down under load when hot. (I imagine you have two coils.)

Try changing over the coils, both "in" and "out" leads on each. See if the same coil fails when it is firing the other cylinder. Then try swapping your plugs. Do each thing one at a time so you can isolate any changes.

Kim

[Anonymous]

Yes, check your coil!

I agree, check your coil(s) I had a similar problem with my 1100GZ. It would run and then I would lose one or two cylinders. i thought it to be a fuel/tank corrosion problem and added a filter to the line and cleaned the carbs. Carbs were very clean... I checked the coils and found one was working but would be intermitent when it got hot...
FWIW.
GY

[blkhk1up]

Number 2 cyl. not firing? Plug is good and wire is hot....

i had the same issue and it was the carbs. one shut down to the point were the fuel flow was so small it did fire but so week it was like a dead cyl.

i would check your Carb on that side for blocked ports. if it's a blocked main jet or something like that. the other jets still have a week send of mixture. just enough to burn but not enough for an explosion at the cycle

i hope that made sense.

[headsbikesmopars]

Does the fuel tap vacuum line run to that carb. I had a similiar problem with the number two carb, and it turned out to be the fuel tap was bad and was flooding that cylinder with fuel and it wouldn't fire the plug. That cylinder was gas fouled. Good luck Terry.

[dietcokeking]

Does the fuel tap vacuum line run to that carb. I had a similiar problem with the number two carb, and it turned out to be the fuel tap was bad and was flooding that cylinder with fuel and it wouldn't fire the plug. That cylinder was gas fouled. Good luck Terry.

Me, too. It may be too gassy to fire. Do a search for "petcock" in the forum archives for more info on that problem. Good luck.

[tfb]

Or it may be that the vacuum line going from the manifold to the fuel tap has a crack/leak and is sucking air... that will get it misfiring on #2 as well.

Whenever it's #2 cylinder that's stuffing up, the first thing to do is check the fuel tap, its diaphragm, and the vacuum line to the manifold. Coz it's often something wrong there that's doing it.

Mike.