Hello, I em looking to purchase a .61 os 2 stroke with a Bisson in cowl muffler from the local hobbie shop and the owner of the shop said he could give a great deal on a 4-stroke XL .91RFS engine for my plane. (GP 300s extra) Its a new one right out of the box never been run. He said it's been sitting there for a while an that he would like to sell it, because this one isn't a popular seller. I can get it for $120.00. I never owned a 4-stroked . My question is , is this engine a good runner , easy starter, easy maintenance, and is it a good choice to purchase. Also if it is, what muffler do I use for mounting inside of the cowling . I Have 2 planes with OS 2-strokes .40 &.61. I would like to hear from people that has had experience with this engine good or bad . Thanks for any replies

Hello Sorry didn't mention that the make of this engine is Magnum.

My brother had one in his GP 300, it was a great combo. The Magnum 4's are good engines. If you do not want to try it, buy it for me. I will give you an extra $10.00 plus shipping to Mi. They really are good engines and you should buy it for yourself for that price.
Tim

Mine is a great engine. It does take a while to break in a ringed 4-stroke engine, but the Mag .91 will get better and better for a couple of gallons. $120 is a super price.

Break it in on a castor fuel, then try some 20-20 or heli fuel.

A 14-6 is the normal prop, but try a 15-4W or a 16-4W for a fun fly/3D plane.

You can angle the muffler out the bottom easily.

I have one too. I only ran 2 gallons in it, and it ws going btter and better. they say true, 14X6 or 15X4. I used 15X6 once, but rp was low, thrust was the same, that on 14X6.
get this engine. u'll be happy. it starts wonderfully. I newer used el starter, but maximum 3 flicks with finger,(but it shoots propeller heavely. use something heavy lether or something like it) and it runs.

I have one also. Very good engine.

You can use the existing muffler and just angle it out the cowl as Ed said.

Enjoy,

Jim

I had one in the GP Extra... Beautiful combination... This is a great engine... I originaly had a .46fx in the plane and it flew it but that was about it... The .91 really brought the plane to life...

Ihave one in a perfection. It is a great running engine and Magnum has super product support.

I just bought another one and was glad to only pay $149.95 for it. I say go for it. They are really great engines.

Ed Cregger