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OS 91 Surpass Pumper

Old 09-06-2009, 02:03 PM
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Default OS 91 Surpass Pumper

This 4-stroke 91 Pumper has been running perfect. I tried starting it today and it backfires (pop) through the exhaust and will not run. Has very good compression. Checked the vales and they both were OK. Put new plug change. Also tries to run backwards.
Engine has about six gallons of 15% synthetic fuel through it.
It sounds like it is out of time to me??
Old 09-06-2009, 05:01 PM
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Default RE: OS 91 Surpass Pumper

i think it is time for the cam shaft setting
in the manual u should have the full procedure and what filler gauge to use
Old 09-08-2009, 09:26 AM
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Default RE: OS 91 Surpass Pumper

The engine cannot get out of timing unless you've taken it apart and re-inserted the camshaft incorrectly. It could only change timing that way, or if the gear, itself, was broken. If it was broken, then the engine would be difficult to turn over because of the metal that would have gotten caught in the crankshaft/case areas.

Very likely, you may need to reset the valves, and possibly check your glow plug. Use an O.S. Type F plug. Also, please check to make sure your fuel is absolutely fresh. Old fuel can give running problems.

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