372 question

[Big_Wood]

I suspect "some" is an understatement, based on the North American loggers shown on TV!

it's reality, 2 of my best friends are fallers and they are very good with saw maintenance and rebuilding. i swear 1 out of every 30 actually know something about taking care of their equipment. that something usually consists of tapping out the air filter and making sure bolts stay tight LOL

 

[Full Chisel]

The OP may just be a woodtick (casual cutter), so instead of infecting him with CAD at this stage, maybe we should see how much time he can get out said hoof rasped cylinder. Lol

Nahhhhhh, let's just toss him in the deep end!

 

[Jules083]

OK, I'm doing something stupid and don't know what.

Put the compression tester on, got 60. Hmm, that's not right. Put it on my 55 Rancher, that I was just cutting with yesterday, and got 55.

Something's missing here, can they even run that low? Is there a small engine specific compression tester? Because this thing works fine on cars and motorcycles. It's Harbor Freight but I tested it along side a different one and it got the same readings....

 

[Jules083]

Got it. Hose was too long for the tester, used my old one and got a much better reading.


120 PSI cold.

 

[cus_deluxe]

which is still quite low for that saw. pull the muffler and take a look at the piston and what you can see of the cylinder. as @SawTroll mentioned, the saw probly scorched the original top end, and it was replaced without fixing whatever caused it, probly a torn intake boot or leaky crank seals.

 

[cus_deluxe]

that saw with a "ported" top end should be well above 150 psi i should think, even if it was a hack job. did you pull until it quit going up or just a few pulls?

 

[Jules083]

that saw with a "ported" top end should be well above 150 psi i should think, even if it was a hack job. did you pull until it quit going up or just a few pulls?

Just a few pulls. The picture is my compression tester, it was hard to hold on while cranking saw over without the saw.

 

[cus_deluxe]

ahhhh, ur really gonna have a hard time getting a good reading with that im guessing. still gotta pull that muffler.
you dont wanna see anything like this

 

[mt.stalker]

I suspect "some" is an understatement, based on the North American loggers shown on TV!

Those "Reality" TV shows are mostly drama and ******** .

 

[Jules083]

Ok, got the muffler off and saw some light scratches. Kind of borderline in my opinion, so I decided to pull the cylinder to have a better look. They're not that bad, but I'm still thinking of replacing the top end.

However, I don't believe this is my issue. I'll have a closer look at the carb next. Either way I have to order stuff at this point, I tore the exhaust gasket pulling the muffler.

You can feel the black marks with your fingernail. Cylinder looks good. It's a Mahle, and I'm not sure what size it is.

 

[SawTroll]

Those "Reality" TV shows are mostly drama and ******** .

I don't doubt that at all!

 

[SawTroll]

If it is Mahle, it is not Aftermarket. Are there any numbers in ink on the top of the cylinder? Pictures?

 

[Onan18]

If it's a Mahle top end and it is a "Big Bore" then it is a XPW 51.4mm top end. VERY nice find, they will run a 32" bar (the limits of the 372 oiling capacity) with authority.

Joe

 

[decableguy2000]

That doesn't look real bad.Looks more like carbon streaks than a gouge. Maybe hit with a scotchbite and re-ring. You will never get a good reading with that compression tester. You need one that screws in and has a scharder valve in it.

Jeremy

 

[Jules083]

Ok, measured stuff and ordered some parts. And called the original saw owner while I was at it.

This saw wasn't the big bore saw after all. He couldn't remember for sure either, so I did some measuring. It is the original cylinder that was ported and polished. Original piston, he says he re-ringed it a few times probably but can't remember for sure.

I figured it wouldn't hurt freshening the motor up, so I ordered a piston/ring kit, a carb rebuild kit, spark plug, and all needed gaskets. The porting looks great to me, I see no reason to not run this cylinder. All he did was smooth out the intake and exhaust tracts, no material removed from the cylinder wall itself.

I also ordered a better compression tester, and a Tachometer while I was at it. The Tach is on back-order.

Once everything gets here I'll put it together, along with all new fuel lines. From there I'll see where I'm at, but I see no reason why it shouldn't be fine. I doubt there's an air leak, because the piston seems fine but worn. Wouldn't an air leak cause a lean condition, leading to more scoring?

 

[TimberWolf530]

Before you tear the saw down and put the new parts on, you should pressure test it. If it has an air leak (the way you describe how it runs, it very well may), and you put the new parts on without fixing it, it won't be long until your new piston looks just like the old one.

 

[Jules083]

I'll have to get tools to pressure test it, I don't have anything right now.

Any suggestions?


Sent from my iPhone using Tapatalk

 

[Jules083]

http://www.ebay.com/ulk/itm/181925760868


Is this a decent one? $129, seems high?

 

[blsnelling]

What brand of piston? I would only consider OEM or Meteor.

Any compression gauge you use MUST have a Schrader valve at the very tip of the hose.

 

[RIDE-RED 350r]

While you are wrenching on your 372, pull the fuel pickup/filter (inside the fuel tank on the end of the fuel line accessible through the fuel fill hole with whatever you can reach inside and grab it with)) and make sure it's not clogged and in need of replacement. Some folks aren't too concerned with brushing away the sawdust and other debris that can accumulate around the fuel cap area before unscrewing the fuel cap to re-fuel. Wouldn't hurt to verify the tank vent is clear as well.