372xp rings

[outdoorsman0490]

Hey All,

I have a 2000 372xp I picked up a couple years ago and use from time to time, the only completely stock saw I have. On this rainy day I figured I would check the compression and see where it is. It is about 130psi. Well, I had planned on modding the muffler, deleting the base gasket and installing new rings. I have a set of 50mm by 1.5mm rings for this saw I bought a while back when I got the saw (I guess I must have checked the comp then too). These rings do not fit, they are too thick to fit in the grooves of the piston. I checked the original rings with my micrometer, they are about .147" and the new rings are about .158", the new ones don't fit.

Anyone have any ideas on this? Are these new rings abnormally thick, if I get a new set of cabers, will they fit?
And does will putting new rings on make a big/noticeable diff anyway?

Thanks for your help.

 

[AVB]

Uuh. 1.5mm is only 0.059" and 1.2 is 0.047" but your posted .147" is 3.7338mm.

According the IPLs the 372 (371) uses the (50mm x 1.5mm) 503289042 but the 372 XPW used the (51.4 X 1.2Mm) 503289039 but there is also a 372 that used (50mm X 1.2mm) 503 28 90-36.

As far putting new will make a difference or not just depends on how wear is the current PNC.

 

[outdoorsman0490]

I may have misread the gauge, you are prob right with the thicknesses. I guess my saw is the 1.2 because these rings are for sure smaller than 1.5. Thanks

 

[Chainsaw Jim]

Your compression should be ok for that saw. You will likely be disappointed after re ringing it because you'll probably get the same compression reading when you're done.

 

[outdoorsman0490]

I figured I would just put it back together, but now it is super difficult to get the cylinder back down over the piston. When I get it down, and tightened up, it won't turn over, like something is getting hung up. Take is back apart, there doesn't seem anything wrong. Did this a couple times; frustrating. I have done this type of work before, I don't know what the problem is with this saw.

 

[AVB]

Didn't re-install the ring upside down did you? Most have notch ends for the locator pin.

Also found a measurement for the ring end gap when install the cylinder which is 1mm or approx .004" max. This is per the service manual

 

[outdoorsman0490]

I got it eventually, thanks for the help. Just sticking with the rings that were on it.