[Thunder Chicken]

I recently acquired an older OS 1.20 surpass pumped engine. After a long google session I found the correct manual for the engine. This is the first pumped surpass with a 'C12' carb on it.
It has been sitting for some time I think, and i'm unsure of how much run time is on it. Initial running of it I could not get to run consistent at all. Words can'r describe how many different ways it was running!
Does anyone have one of these engines? Any advise on things to check? I've read that parts are very hard to get, and to not take the pump apart or the magic will be let out.
I disassembled the engine and cleaned all the old gunk from it, checked the valve clearance, cleaned the carb, put in a new OS F plug so time will tell tomorrow if it can be brought back to life.
Has anyone converted this engine to a 'non pumped' engine? would it be as simple as replacing the back plate?
Thanks for any ideas

[Thunder Chicken]

Well it appears the fuel pump is leaking fuel from somewhere, can't really tell with the engine running. I tried to run it without the pump but it will just not tune up, seems to lean on the low end. So I'm looking for a 120 sized carb and we'll turn this into a non pumped version! Anyone got one, or an OS 120 engine for parts?

[Ken Currell]

Originally Posted by Thunder Chicken

Well it appears the fuel pump is leaking fuel from somewhere, can't really tell with the engine running. I tried to run it without the pump but it will just not tune up, seems to lean on the low end. So I'm looking for a 120 sized carb and we'll turn this into a non pumped version! Anyone got one, or an OS 120 engine for parts?

I have one NIB but if I decided to fly it the carb would be the first thing to replace. I think you are doing the right thing as parts for the pump or carb are probably not available.

[Jim Tennant]

I have one of those engines that did the same thing
I installed large dia fuel tubing and a clamp on the fitting on the engine and it runs like a charm now.
just a thought

[Raymac]

I have an OS120FS for parts....I have the pump and carb but they are broken in a number of places (see arrows) The PD07 pump unit may still be good as well as the regulator....Are these any use??

Ray

[Thunder Chicken]

Hi Raymac, that looks like a different version than I have.
I've since broke down and bought a new carb for an OS 120 (non pumped) had an adapter made to mount it to the existing intake (thanks andrew!) and she ran like new. I put a bit of A/T fluid in the pump and just plugged the all the fuel pump fittings off. She's just a normal ole' 120FS.