372 XP BLOWN PISTON

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Flouridated

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So last year I got a used 372xp and it runs like a banshee. I just fixed and modded 3 climbing saws and they run awesome. So I cracked open my 372 to do some quick maintenance and mod the muffler. Now ever since I have had the saw there has been something rattling in the muffler. Pieces of ring. So I looked into the port to sight the piston and it looks haggard. Chipped and broken on the top edge, down almost a quarter of an inch and there is only one ring in tact. And it runs great!? Yeah. But this aint gonna last, barrowed time. So my first question is how is this thing still running so great? No scoring no nothin.

My second question is what should I replace it with when it goes? I have been looking at the ported/bored cylinders and better pistons but this area is a tad bit deeper than my knowledge of saws. Who does good jobs? Do I need to buy the cylinder and piston only to throw the factory piston away? Should I just do it myself? Are there bored kits available as a whole package?
 
I wouldn't wait, get that thing apart and clean up the cylinder first, then change the piston with an OEM or Meteor piston. While you are there....try to figure out what failed. Probably an air leak leaned it out and the piston stuck a bit on the exhaust port side. Air leak or lean condition can be from a lot of things from simple to complex....too nice a saw to run hurt and then replace damaged part without solving the root issue that killed the piston to begin with.

Oh..BTW it might have been running like a "banshee" because it was too lean.
 
You will be lucky if a piece of broken ring didn't damage the cylinder at all! Replace the piston (and cyl. if need be),then give the saw a minor overhaul/tune-up.Buy 2 crank seals and replace them.Rebuild the carb and be sure the high speed jet is set correctly,not TOO lean! With the piston off wash out the bottom end with gas(Spin the crank around lots,then quickly flip it over and dump it out.Oil the bearings and check for smoothness and looseness too.Inspect the bearing cages very closely! Any cages that look a bit bent or twisted are trash. Replace bad bearing with aftermarket versions purchased from local bearing suppliers and specify that your new bearings have the teflon cages.These are far superior!!
 
I bought an 084 once and i took a torq bit out to do the usual check piston ect , it was in that good condition and ran that well i never bothered to pull the muffler , used at work for a few weeks cut a heap of slabs with it one weekend , gave it a bit of a clean and swapped a muffler of a wreck onto it and when i looked inside it there was a massive chunk out the top of the piston and not a lot supporting the ring ... All i could think was the guy must have had a screwdriver jammed in it trying to get the clutch off or something
must of put a hundred litres of fuel through it like that and it went like a train !
 
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