scarab63

I bought a OPS .90 used and know very little about it. What plug to use, What % nitro is recommended and having problems with the engine having a mind of it's own with low to very high throttle without hitting the radio trigger. Even with the radio off and the servo not moving. It did replace the needle valve with a Perry = to the size of the engine.Thanks

WATER_BUGG

HEY....lol your in gas boats...you posted in one forum below nitro!

jetpack

My Feedback: (1)

I don't have an OPS 90 or have run one, but from I have gathered, the larger nitro's need warmer plugs because they stay hotter longer after the powerstroke and help accelerate the flame front. Some aftermarket companies in the past have offered twin-glowplug conversion heads to help combat this "cold" condition as you get big in displacement.

OPS typically is a high compression / low nitro motor, and looking at their tuned pipe charts pretty much confirms that due to there not being very many high-nitro pipes being offered (50% nitro)

As far as the glitching is concerned, I think the 90 has needle bearings which means lots of metal moving around that could cause it.

stempak

Those are near bullet proof motor's!. But a few things need to be addressed to make them run correctly. I've been told, First the carb recommended is a O.S 9b. Taking the gaskette out between rotor cover and crankcase helps quite a bit and a (must) get zimmer intake rotor down to .005 or less clearance which can be done by surfacing the rear case. They also respond with huge gains when modding.

You could find someone to do this on intnl waters if you are not able.