# Two cycle engine runs but wont rev



## rdsrds123 (Dec 15, 2011)

Got a rather large two cycle engine. It on a Jacobsen "Greens Keeper." It's used to manicure a putting green, baseball infield, tennis lawn, or cricket green.

It starts and runs fine, but will not stay running at the low throttle setting. I have to use full throttle, but when I do , I only get rpms slightly higher than what seems like idle.

Engine is clean on the outside with a NEW carb. it is a low mileage unit. I just got this machine and apparently the previous owner sunk a bundle into the carb and it did not solve the problem. I'm not even sure there is a problem. Should this machine only run at slow engine speed? Two cycles don't like that. \

carbon build up at the exhaust port?

Lose screws? 

Bad crankshaft seal?

What else could be wrong?

Thanks!


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## 30yearTech (Sep 14, 2006)

My first impression would be a restricted exhaust. Either carbon build up at the exhaust ports, or in the muffler or spark arrestor if the muffler is equipped with one. 

Remove the muffler and inspect the exhaust ports, if clear then test run without the muffler and see if there is any improvement.


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## rdsrds123 (Dec 15, 2011)

Thanks! That sounds like good advice. I'll go do it.

I once had a high mileage chain saw, and worn bearings caused the crankshaft to wobble and push the crankshaft seal out of position. It would not run at all. If I have a problem due to crankcase pressure issues, it will probably be lose screws.


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