2.5 HP oily spark plug

[dmontgomery]

Hello
I have a 2.5 hp 4 cycle
compression is good no bleed down
valves clearance good
new impeller and thermostat
spark plug is black
engine runs weak

any comments

[robert graham]

Maybe the choke/enrichening device is in the "on" position causing a rich mixture?....maybe your fuel is old and degraded so not firing well?.....

[TownsendsFJR1300]

The compression rings will help keep the leak down #'s high BUT leaky oil rings won't. If worn, they can allow oil past them, thus an oily top end..

What is the actual compression and what percentage is the leakdown?

Are you burning any oil? (not just visably but the actual oil level)

If the (oil rings) are gooed up, a strong dose of Yamaha's "Ring Free" can't hurt.

ANY other recent mods to the engine, (carb rebuild, carb cleaning, re-jetting, etc?)

[saltydognegril]

oily plug...if your oil rings are bad or your valve seals that could well be ur probl

Check your oil rings and valve seals