After 2 years of deep contemplation I decided to Buy a 4 stroke engine. I bought a Magnum XL .61 RFS. I need to know if I can run my Byron 15 percent nitromethane, 20 percent synthetic/castor blend fuel on it.

The document that came with this engine says that for break in I should use fuel with no more than 10 percnt nitro, and no less than 20 pcnt libricant. BUt, after break in I should use fuel w/no more than 15 prcnt nitro and no less than 16 prcnt castor blend.

P.S. What is a 4 stroke .61 equal to in 2 stroke terms?
Thnx in advance.

I would break it in with the Byron fuel you mentioned, just run it real rich for the first couple/few tanks. It will be fine.

I would say a 61 4-stroke is roughly equivalent to a 46-50 2-stroke.

Enjoy your new engine!

You should be fine with that fuel. As with any engine, don't run it lean.

Yup, run it a little sloppy for 3 or 4 tanks, and then have a ball!

I run the same fuel in just about everything now days. Seems like its 19% oil and 15% nitro.

We run 2 Stroke fuel in every thing here saves takeing two fuels to sight . I run 15 % Red Max in my 52s and 91s have had no problems.

Like RC Outlaw, I run only one type of fuel in all my engines, typically 15% Cool Power Heli fuel. I like the heli fuel for its 20% oil content.