Problem with front cylinder misfiring

[Copytech]

I have had this problem since I have had the bike, its been in storage so I forgot about it.
I start it with the choke and let it warm up till the temp gauge is halfway then turn the choke off and it will idle without a problem. So I suit up take her out and after a couple of miles it will start to backfire then barley runs on one cylinder (always the rear) the temp gauge is now at the "C". If I stop it will die, I can get it restarted and let the temp gauge come back to half, the front cylinder will start to fire, and I am on my way. A couple miles later same thing again.
This seems to do this when the weather is cool( less than 75 degrees).
It has new plugs the carbs have been cleaned I recently installed a stage one jet kit but the problem still persist.

before ride:


and after 2 miles:


P.S. I pulled the thermostat yesterday and checked it seems fine.

[MrDude_1]

my first thought was to replace the thermostat.
you can try covering half the radiator with cardboard, then riding and see if that solves it. if it does, then that means the motor is overcooling itself, and since its the thermostat that determines the minimum temp of the system, its most likely that.

if you cover it that much and it still happens, then its something else that i dont know.

how did you check the thermostat?

[Copytech]

I think you are right. When I took the above pictures the temp was about 55F, I got home from work today and it was 75F so I took the hawk out and it ran perfect. (14 miles)
I let the bike cool down for a couple of hours then started it but this time I held the lower radiator outlet with my hand. After about 2 minutes I could fell it heating up. SOO I'm going to stop by the dealership tomorrow to get a new thermostat.

[Hordpower]

Check/clean the wire harness ground under the seat, also the battery cables. When they get corroded/loose it causes symptoms just like you are having. Runs on 1 and the tach/temp goes goofy.

[Copytech]

That was it J.D.. Mine was loose, runs great now and I don't even need to let it warm up before I can ride.

[Hordpower]

Proof that I am not crazy.