2 stroke compression

da.bees · Nov 15, 2015

I'm about to conclude weed eaters and chain saws die in the same sense that dogs and cats die. Never had much luck with 2 strokes anyhow but this one realy top's them all. 40cc chainsaw started just fine for 3 years and two dozen times last week until primer bulb cracked. Ran to store for bulb and changed it. Now it will not even pop,much less attempt to start. Changed plug,let it sit over night,tried starting fluid,switched mufflers and its got plenty blue spark but still nothing. It feels the same as ever and I feel each compression as rope is pulled slowly. Can compression be tested?

AzPeapicker · Nov 15, 2015

Goog Morning D bees
Yes they can be . They should have at least 120 lbs . I would also check the exhaust port
And. Muffler for carbon .

John. Az . Speaker. [email protected]

RogerinIowa · Nov 15, 2015

If primer bulb failed, the fuel lines may have also.

da.bees · Nov 15, 2015

Thanks Roger,I looked and primer is squirting gas each push on bulb. Just for my information bank,if fuel related problem causes a no start condition will ether or couple of drops of gas make a motor hit once or twice or at lesat result in a little smoke?

da.bees · Nov 15, 2015

Thanks pea picker,I'll get a plug hole adapter for my gauge and test it.

RN · Nov 16, 2015

One other compression check if practical- the Crankcase compression. At a low turn start compression check through spark plug hole , you may get a good reading--BUT the crankcase seal on open bearing units especially may have 'popped' or finally worn out, the now effective compression in crankcase means no real fluid(fuel/air) transfer into cylinder. Other low crankcase compression problem- the reed valve assembly/block used on many small 2 stroke engine in place of the piston port timing. Harley golf Cart motors up to a certain year were known to have a crankshaft seal fail fairly often after a few years of intermittent use- then design for seals changed late/mid 1970s? The single seal design is still used in some chainsaws, some are external easy access to replace, others need case splits for inside replacement. Have fun, may need a aircompressor to do a crank pressure test. RN

Jiles · Nov 17, 2015

I would go back and check the work you did. Make sure carb is receiving impulse and is not drawing air around gasket.

2 stroke compression

da.bees

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AzPeapicker

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RogerinIowa

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da.bees

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da.bees

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RN

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Jiles

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