1985 atc 125M help!!!!!

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Feb 14, 2011 | 12:10 PM

#11

Doctorturbo

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Quote:

Originally Posted by sclark

i have a hand pump leak down tester i would have to make a adpter for it to fit but been awhile sense i have done engine repair if i recall i have to block off exhaust and intake? and by doing a leak down test what will that show? or how will that help me narrow the problem done? been a long time sense i have play with engines so refreash my memory please

You don't have to block anything for a leakdown. Screw your tool into the sparkplug hole and bring the engine to TDC and pressure up. I like to bring it up to 100 PSI because you can really hear where the air is coming from.

Pin the throttle open, take the oil fill cap off. Listen for air coming out of the carb, pipe or crank case.

If it's coming out of the pipe you have an exhaust valve problem.

Hear it coming out of the carb and you have an intake valve problem.

Hear it coming out of the crank case and you have ring problems.

I don't think you will get the volume of air you need with a hand pump. A bad leak will go through a LOT of air. Yor going to need an aircompressor to do the job.