pressure testing results

[spudulike]

cheers spud, thought it was a bit low,just ordered one from arb Ireland ,saws quite tidy,too good to be confined to the bottom of the shed anyway lol

 

Enjoy fitting that - it is a clam engine so not that easy a job, you will need some liquid gasket for sealing the clam to the upper crankcase/cylinder plus if you remove the oil adjuster, when you screw it back in, push the oiler shaft well in so it doesn't bend the oiler shaft - common error!

[adw]

The 338XPT has an auto deco valve, you need to blank this off before an compression test

[forest tink]

Enjoy fitting that - it is a clam engine so not that easy a job, you will need some liquid gasket for sealing the clam to the upper crankcase/cylinder plus if you remove the oil adjuster, when you screw it back in, push the oiler shaft well in so it doesn't bend the oiler shaft - common error!

 

jeezo,cheers spud,sounds like fun

[spudulike]

jeezo,cheers spud,sounds like fun

 

Thats a good point ADW has just made, I forgot the 338 had an auto decomp valve - bloody horrible things but he is right that it would drop the compression down. Don't know why you need one on a small saw like this but measuring compression on one of these saws is a PITA as the deomp needs blanking off before testing!

[forest tink]

ahh ok cheers,will check that out,never noticed his post,will it make much odds do you think when the psi is that low ?

[adw]

The 338xpt had to have an auto deco valve because the engine unit is held to the tank unit via av springs, but the starter is screwed to the tank unit, so the engne can move away from the starter and slip if the compression is too high, it works really well on this saw, unfortunatley it did not work too well on the 357xp

[spudulike]

The 338xpt had to have an auto deco valve because the engine unit is held to the tank unit via av springs, but the starter is screwed to the tank unit, so the engne can move away from the starter and slip if the compression is too high, it works really well on this saw, unfortunatley it did not work too well on the 357xp

 

Yup, that's where my not liking of this device comes from, usually it kills the piston with time.

 

It would be a good reason why the saw is only making 100 psi.

 

You can pull the muffler off to take a look at the piston, any deeper scoring is bad.

[forest tink]

looks like todays job due to that white crap that falls from the sky

[spudulike]

looks like todays job due to that white crap that falls from the sky

 

The muffler bolts can be a bit tricky to shift sometimes but once off, you will be able to see the piston and look at its condition.

 

If it is OK, the running issue is probably fuel/carb related!

[Eddy_t]

If it is OK, the running issue is probably fuel/carb related!

 

 

And if it is the carb and lines, get a swear box to save for a new saw