Odd exhaust temp difference

[Road_Clam]

Hey guys, maybe you can shed some input on my strange issue. On my GSXR I am observing cyl's 1,2,3 typically measuring about 270F at idle measuring the exhaust pipe header at the cylinder. Cyl #4 is always about 50 dergrees cooler than the rest. Compression on all 4 cylinders is right to spec at 130 psi. If one cylinder is running "cooler" than the rest is it a rich fuel condition or possibly a lack of fuel delivery issue to that one cylinder ? The engine seems to run perfect. I've had the carbs apart many times over the past year for jetting tweaks, so i highly doubt there is debris clogging a jet. I'm stumped.

[Nessism]

Maybe spark is weak on that cylinder and it's misfiring at idle sporadically? If that bike has screw-on type plug caps it might be worth a look at it.

[OldVet66]

Mine never did read close until I switched to the Dyna green coils and new Dyna wires. The old coils and wires were new stock replacements, with the Dyna S triggers. Never did figure it out, but am glad to be entirely rid of any of the stock ignition.

[Road_Clam]

Thanks for some input guys, I do have another set of coils, and I think I might swap the #1-4 coil to see if I can observe a difference. If all of a sudden after a coil swap my #4 temp comes up, now I know I had a suspect coil.

[Darin Jordan]

My GS850GT is doing exactly the same thing... after a hard ride, I measured the header temps and found that 1,2, and 3 were all around 330... but #4 was only 270 or so...