Oil & Fuel John Deere - ONE exhaust glows orange on full throttle

[KubotainNH]

Ok- I just ran the compression test according to the above latest instructions.
1st time: (after running engine for 45-60 seconds on med throttle)
Left side: compression gauge fluxed from 145-180
Right side: compression gauge fluxes from 140-170

2nd time: (after letting sit for 5 minutes)
Left side : 150-180
Right side 150-180

What does that tell us!?

Looks like they're pretty well matched. While running, you can try spraying some carb cleaner where the carb and intake should be sealed well. Do it with the engine cold for obvious reasons and stay sway from the exhaust. Change in engine speed will show an intake leak.

 

[tcartwri]

Those are very good numbers, in fact the 180 tells me you are right on the threshold of having to use premium fuel.

 

[tcartwri]

You know, after more consideration I would bet that the fuel is the problem. You are getting into pre-ignition under load, which is overheating the chamber and the exhaust.

Just for comparison, rule of thumb is that anything over 200 psi cranking compression is getting into race fuel territory...

 

[JiminGa]

something I've not seen mentioned, some of those 425's were built with a plastic cam gear, not sure what years, but I know it was an issue.

 

[SPYDERLK]

Ok- I just ran the compression test according to the above latest instructions.
1st time: (after running engine for 45-60 seconds on med throttle)
Left side: compression gauge fluxed from 145-180
Right side: compression gauge fluxes from 140-170

2nd time: (after letting sit for 5 minutes)
Left side : 150-180
Right side 150-180

What does that tell us!?

The numbers are good. It tells us your engine is in good shape and is not the cause of the problem. By alternately removing spark wires [not plugs] could you tell us which cylinder will run the engine best? Were talking throttle response in the low to mid RPM range. ... I know you said something about this earlier. But Im not sure the exact situation then.
larry