372xp rebuild issue

[Dave0846]

Hi

Have recently rebuilt my 327xp xt
Fitting meteor p & c and pulled it down after less than 5 hours and theres scoring on the piston and cylinder. New bearing and seals.
Any help diagnosing the issue would be greatly appreciated

 

[cuinrearview]

It looks like you either didn't clean things sufficiently or you still have a lean running condition. What did your pressure and vacuum test tell you after you assembled it? What was the original cause to re-build it? You look like you caught it early enough that you can probably save that piston and cylinder.

 

[Dave0846]

It looks like you either didn't clean things sufficiently or you still have a lean running condition. What did your pressure and vacuum test tell you after you assembled it? What was the original cause to re-build it? You look like you caught it early enough that you can probably save that piston and cylinder.

I brought the saw a a straight gassed saw,
Was thinking the cylinder was ok, but thought about replacing the piston and rings.
Thoughts?


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[cuinrearview]

A new meteor and cabers are cheap enough, but a little light sanding and that piston should give plenty of hours on a personal saw. Why the damage occurred is of larger concern.

 

[Dave0846]

Yeah it's got me, possible it was a bit lean as I modded the muffler and had an issue tuning it.

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[cuinrearview]

I would not run it anymore without making sure I didn't have an air leak. Funny things happen assembling those strato saws...

 

[Huskybill]

Must know the reason why it seezed first? I’d assemble the saw and pressure test it first? Straight gassed could of burned up the seals?

 

[Dave0846]

Must know the reason why it seezed first? I’d assemble the saw and pressure test it first? Straight gassed could of burned up the seals?

Was split and bearings and seals were replaced


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[Brent Nowell]

Dirt coming through filter will show signs of that too, the 372 filter could have came loose allowing particulates through.

I use a film of rtv on the base of the filter in order to make a better seal myself.

Straight gassed usually base scoring on the whole circumference of the cylinder

 

[Brent Nowell]

Also could to small a ring gap cause this? Just throwing ideas out there trying to help

 

[ken morgan]

could have turned the lip of one of those dog gunned seals while reassembling as well... but lets not talk about my trials and tribulations...

 

[grizz55chev]

Also could to small a ring gap cause this? Just throwing ideas out there trying to help

Pressure vac test, then go from there.

 

[Ronie]

Was split and bearings and seals were replaced


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Did the o ring on the clutch side get replaced? If someone didn't know one went there it could easily be missed. Also did it get a vac/pressure test after rebuild? Just because it has new seals doesn't mean you can't have a leak. Sorry if you already know all that, just trying to help.

 

[Huskybill]

I purchased the husky oem seal installer cams. It’s so easy to cut the seal lip or pop the seal spring off on the inside. The pressure check should show up if something is wrong.

I’m at that age where I hate to do things twice my time is limited. It’s a learning process. I put three pistons in a Honda 125cr, then i was taught to pressure test, the PO hit the cylinder base with a big screwdriver and hammer to knock off the cylinder leaving a big burr. I found the airleak. My first Honda engine, we all learn.

 

[Andyshine77]

As everyone has mentioned vacuum pressure test is always required after new seals are installed, or rebuild do to a failure of that type.[emoji106]

 

[Dave0846]

Did the o ring on the clutch side get replaced? If someone didn't know one went there it could easily be missed. Also did it get a vac/pressure test after rebuild? Just because it has new seals doesn't mean you can't have a leak. Sorry if you already know all that, just trying to help.

Yeah was replaced coz I pissed and moaned about the price of it, $14 for a bloody oring

 

[Ronie]

Yeah was replaced coz I pissed and moaned about the price of it, $14 for a bloody oring

That's crazy high! I think the last ones I got I paid $3 or $4 a piece. I have use one from the auto parts store before, It was a little thicker but worked fine and the saw hasn't had any problems.