engine lost power


Old 07-20-04, 04:15 PM
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engine lost power

Hello, i recently took the head off a tecumseh H50 go-kart engine to clean the carbon deposits and lap the valves in hopes of "freshing" it up a bit. Anyway i got it back together and now the engine feels like its lost power, it has a dogged feel to it. Im guessing ii've done something which has made it lose compression. any suggestions? thanks
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Old 07-20-04, 05:44 PM
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Location: southern louisiana
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The little bit of metal you removed by lapping the valves might have been just enough to decrease the clearance between the valve stem and the tappet to the point that the valves are not completely down 100%. Did you check the valve clearance?
Old 07-22-04, 08:06 AM
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I didn't check the clearance, what would be the proper way to go about troubleshooting this? How would i check that? Also what is the correct technique for valve lapping in your opinion. Thanks
Old 07-22-04, 08:55 AM
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HI Matt,
I found this for another thread but should help you as well. This manual covers tecumseh engines 3 to 11 HP, includes theory and operation as well as teardown and rebuild.
Old 07-22-04, 11:25 AM
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thanks a lot!
Old 07-22-04, 02:11 PM
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Have you ever done a valve job? You will have to remove the head again as well as the valves in order to grind the stems. The proper clearance for each valve will be .008-.012". You will need a square faced grinding wheel and feeler gauges to do the job right. To be sure the compression release cam doesn't come into play (if so equipped), rotate the crankshaft until the piston is 1/4" past top dead center on the power stroke and then go ahead with the valve grinding.

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