Two headers very hot

[George R. Young]

Trying to help a fellow Ottawa Concours owner over the phone. Bike sat for 2 years, carb cleaning brought it back to life, jets and passages, float height, yielding good idle and throttle response. Valve clearances have been checked.

He has a temp gauge and, after idling a bit, headers on cyl 1 and 2 are at 450 deg F while 3 and 4 are cruising at 175 deg F.

I can't think of anything that would cause this and not screw up throttle response.

Any ideas?

[redzgrider]

First thing on my agenda would be to push the plug caps down on all four. Obviously the coils are split across the cooler pipes, so shouldn't be there. If the plugs are getting good spark, and the carb circuits are clean, I'd say it's time for a compression check.

[George R. Young]

Ah rats, 2 things he's done I forgot to mention, compression check and carb synch.

[T Cro ®]

Ah rats, 2 things he's done I forgot to mention, compression check and carb synch.

Then I'd look into a fuel delivery problem; perhaps right where the T branches out to left & right banks. Really lean running carbs can cause high cylinder temps.

I'd try pulling the spark plug caps one at a time while the engine is at idle; the cylinders doing all the work once pulled will cause the engine to stumble badly as the lazy cylinders will not affect the idle much when the caps are pulled.

[T Cro ®]

Ah rats, 2 things he's done I forgot to mention, compression check and carb synch.

BTW Carb Synch has everything to do with how evenly the engine pulls air through the carbs and could really care less if the cylinder is even firing.... (think of the engine as nothing more than an air pump)