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Adamam

Mcculloch 338 low compression?

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Compression around 110psi.

 

Absolutely no sign of damage to piston or cylinder.

 

Wouldn't usually bother with this sort of saw but interested in the lack of compression; just worn out? I would be surprised if a saw like this would see enough hours to wear the piston/rings out without something else breaking first.

 

Any ideas? Worth fixing for £30 (aftermarket cylinder kit)? Saw cost nothing.

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Check that the decomp valve is seating properly . Whip it out and give it a good clean . Maybe fit a new piston ring ?

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Ok . Maybe the ring is stuck ?

 

Yes! I supposed this might be it!

 

I doubt you can even get replacement rings for that saw.

 

:biggrin:

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This little hobby saw was not that bad for small fire wood cutting, pretty sure it was a chrome bore not silica bore, i would pull it all apart, doesnt take too long, check the main bearing cages, they can lose a part of the bearing cage which can nip the ring in.

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I would say it is a ring issue or collapse of one of the ends - you can usually tell if an end is damaged by rotating the flywheel to and forth with the piston visible through the exhaust port and see if there is just too much play in the crank.

 

I would say the ring is just bonded in the piston with gummed oil or carbon. Had that before and freed mine up with a bit of heat from a plumbers torch and a little GT85.

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