husqvarna 460 low compression 60psi

[Willoughby]

I picked up a used Husqvarna 460 from a saw shop mechanic, he said it had a new oe piston and needed carb work and a worm gear for oil pump
got it home checked compression , best it would do is 60psi , so I took it apart to look at the cylinder , found clutch cover melted on inside , no I know what happened to the plastic worm gear. but the piston and cylinder walls look great , I expected to find them scored . I am a retired auto mechanic 40 + years ,but im new to 2 stroke - I dont see why the low compression , unless the hole is egg shaped , I dont have inside mikes that small , I did measure piston its 48.93 mm every thing I read says it should be 47 or 50 mm , I dont mind buying piston and jug but am I missing something here ? any help appreciated

 

[Marshy]

Does your co.pression tester have a Schrader valve in the tip of the hose that screws into the cylinder? If not then you are getting a false low reading. What kind of compression tester is it?

 

[Willoughby]

Does your co.pression tester have a Schrader valve in the tip of the hose that screws into the cylinder? If not then you are getting a false low reading. What kind of compression tester is it?

all compression testers should have a Schrader valve unless your using it for cyl leakage test, I've been a mechanic since 1980 , the gauge isn't new but its always served me well , I put a aftermarket piston and cyl on it today and it fired right up , haven't measured compression yet , but judging by the way it pulls its gonna be good

 

[Marshy]

all compression testers should have a Schrader valve unless your using it for cyl leakage test, I've been a mechanic since 1980 , the gauge isn't new but its always served me well , I put a aftermarket piston and cyl on it today and it fired right up , haven't measured compression yet , but judging by the way it pulls its gonna be good

Not all do. It has been the cause of false readings for others in the past.

 

[old guy]

Does yours have a valve at the end of the hose that screws into the sparkplug hole? if not you will get a low reading.

 

[Willoughby]

Does yours have a valve at the end of the hose that screws into the sparkplug hole? if not you will get a low reading.

yes that's the critter

 

[Willoughby]

Not all do. It has been the cause of false readings for others in the past.

how does it work without some sort of valve to capture the pressure?

 

[Willoughby]

thanks for all the help everyone ! much appreciated

 

[Willoughby]

new cylinder kit and its fixed