can i put monster trinity power blend into a K&B .40

Trinity has 12% oil. I wouldn't use anything less than 18% oil in a k&b . You could add some klotz or castor to bring it up to the 18% level. About 2.5 oz per quart.

no it is 20% what i got and i got a 25 years old motor

20% nitro content - 12% oil

Ouch! 20% nitro is on the high side for a 40 sized motor. Could run way too hot and burn the crap out of it!!![X(]

More oil, less nitro....maybe Wm. Robinson will reply to this post. He knows more about K & B's than K & B does. Dave

I run my K&B's on 15% nitro w/o a problem, don't know what effect 20% would have. Definitely needs more oil if only 12%. Bringing oil up would also lower nitro level slightly.

yeah,my motor is 25-30 years old and has been sitin there prolly 20 years

Don't knock the old motor. It will probably run harder than you.

Do up the oil content. The nitro should be fine. The K&B 40 was a gonzo engine in its day. They got run on 60% nitro in control line ratracers and competition freeflights.

Jim