91 OS head
 

Hi guys, Ihave a older 91 surpass engine thats says surpass on one side and FSon the other, The pushrods tubes are in front and the glowplug is in the rear. I think the man said the engine was about 10 years old. A fellow brought it to me for repairs and its in need of a new head ,I was looking at the 91 Magnum head and from the pics it appears to be the same head ,can anyone tell me is this a for sure thing. OS has disscontinued the 91 suprass head and going to there older engine site didn't help out much either.Thanks for any help</p>

RE: 91 OS head
 

The OSSurpass II head will not work for the intake manifold bolts on differently

If all is wrong is that the glow plug or the exhaust is stripped out, there is a guy or two that can fix that?

The Magnum sure looks like a Surpass I, but you are on your own as to whether it will work or not?

I know the valve covers will interchange if that makes you feel any better

RE: 91 OS head
 

I can fix stripped out threads myself,  I wished it was that simple. The guy hit a rock or something on landing and tore the valve cover off the engine, which in turn removed some of the head and all of the places where the valve cover once bolted to. Its really a shame to I just rebuilt the engine and it was running great for him.
Thanks for the info I may go ahead and get a head for the mag I can always send it back if its wrong. 

Let me ask this also does anyone have a used head they want to get rid of? if so PM me.

RE: 91 OS head
 

I had a nice used one but sold it last year to a needy person.

If you get inspired by Surpass II parts, it wil require:

The head - The valves, springs, etc are the same
intake manifold
carb
backplate

The Surpass II is about 300 rpm faster than a Surpass I or a Magnum

The secret is the glow plug is recessed down into the Surpass II head about two milimeters

RE: 91 OS head
 

Thanks for the info, I called hobby people and they told me that the mag 91 parts would interchange with the OS, but as a person would know there out of stock, so it will be next month for I get any parts, but at least its not a lost cause. I think it will run again. Thank you for your help
Richard.