Engine Compression for Stock '08 KTM 250XC
Hey E..
176psi is fine... I have been a factory trained Yamaha for 43 years...I have seen engines run fine with 90psi..(not racing engines).. Compression is a good indicator of overall top condition of an engine. Compression Ratio is different than compression psi. Now that you have established your baseline.. you want to maintain it!!
....If you want the engine to last.. run at least a 28:1 OIL/FUEL ratio.. even a 24:1 or 20:1 is better *... settle on a ratio and RUN this ratio at ALL times... if you are fouling plugs.. get a PROFESSIONAL that KNOWS how to "jet" an engine.. you should be able to drop the main jet one size..and maybe raise the needle jet clip UP one groove..this will lean out the mixture to the correct FUEL/AIR ratio and you won't foul spark plugs and the engine will LAST a LOT longer.. >> ... *Remember..the two-cycle oil you mix with the gas ALSO lubricates the main crankshaft bearings and the rod bearings.. (replacing those are $$$$$!!)
.. If you have more questions, reply to me on here...
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