372xp restoration

[parrisw]

I definately see the lines but cannot feel anything if I rub the piston or bore, I think the pic shows the harshness of the light and makes the lines "pop" if you will. They are very faint but the light really makes them stand out.

Or I could be totally wrong and it needs a jug and piston.

This one has two rings so this would be the EPA version correct?

I see them too, but wouldn't worry about it, if it pulls good compression, I'd leave it alone.

 

[Evan]

i havent tore one done yet with vertical lines like that. that cylinder has vertical lines all the way around it.

also looks like maybe a slight amount of aluminum transfer but the piston doesnt look that bad at all.

id slightly hone it and run it.

i was assumeing all 372s were 2 ring pistons

 

[fredmc]

i havent tore one done yet with vertical lines like that. that cylinder has vertical lines all the way around it.

also looks like maybe a slight amount of aluminum transfer but the piston doesnt look that bad at all.

id slightly hone it and run it.

i was assumeing all 372s were 2 ring pistons

Nope. I have a 372 top end with a 50mm bore and one ring. I've seen 51mm bores with both single and double ring. I think it depends on year of manufacture.

 

[gmcman]

I measured the best I could and I have what appears to be a 50mm bore but with two rings. My caliper reads 49.98, given possible error I still don't think it's a 51.

The parts manual from Husky based on my serial# shows 1 ring for non-EPA and 2 for EPA version.

Despite all that...is .030 too much gap?

Another possibility is these are 50mm rings for a 51mm bore, rings are very sharp on the edges if that says anything.

 

[SawTroll]

.....

i was assumeing all 372s were 2 ring pistons

No, but maybe in the US, because of EPA.

 

[gmcman]

In the process of de-carbonizing using the new Stihl de-carbonizer....works pretty good but needed a small amount of elbow. Upon further examination, I didn't see the pins in the piston grooves which explain the large ring gap

I cleaned the piston skirt up and there are a few deep scratches on the narrow area of the skirt. The intake tube was fastened by a small zip-tie but when I removed it the intake was clean but obviously it injested something along the way.

So there are a few deep lines, the bore doesn't have nearly the damage the piston does...apparently the skirt lost the battle of the grit which is fine right now.

 

[gmcman]

How much side to side play can I have with the rod? The movement left to right when looking at the case lengthwise moving against the roller bearings on the crank. Before I put this back together I wanna make sure I don't need to replace something else.

 

[gmcman]

Wanted to add..

If I move the piston all the way to one side, I get 2mm movement measured at the top of the piston to the other side. Doesn't seem like much but figured I would ask.

 

[gmcman]

Just a bump for my last post...need to know before I start bolting it back together, thanks.

 

[Evan]

from thos last pics posted ill suspect there is aluminum transfer in the cylinder. a few of those lines in the piston look pretty deep.

it sounds like your lower end play is plenty tight

 

[gmcman]

Thanks...small sigh of relief.

I went over the bore as carefully as I could, there is one scratch that just barely, and I mean barely, catches my nail....I need to press in pretty good to feel it.

I went over the bore with some fine emory....didn't faze the surface, 400 grit just barely only to put a haze on the surface but not damage the coating. Could not notice any aluminum transfer....hopefully it's all gone if there was any.

Worst case...I get to tear it down again and maybe go for some more cc's

 

[blsnelling]

That piston should be fine with a set of rings, provided it's not worn undersized too far. The piston will always have room so slide side to side on the wrist pin.

 

[Gypo Logger]

The miniscual scratches on the piston don't matter one iota. With new rings nothing could possibly enter or escape through the scoring except residual oil.
I bet you'll end up with a good runner.
YSM

 

[gmcman]

Being I have 160 PSI, do I really need new rings yet? I will replace if needed but figure if compression is good......

Surely I don't want to mess anything up and my chainsaw engine rebuilds are very few so i'm not the say-all in this area.

 

[parrisw]

Being I have 160 PSI, do I really need new rings yet? I will replace if needed but figure if compression is good......

Surely I don't want to mess anything up and my chainsaw engine rebuilds are very few so i'm not the say-all in this area.

If its 160, you don't need rings.

 

[blsnelling]

if its 160, you don't need rings.

+1

 

[Gypo Logger]

If its 160, you don't need rings.

Very true, I thought I had read there was an end gap issue. My Bad
YSM

 

[gmcman]

Time to get this thing back together, need a few minor odds and ends.

Seems another piece is missing from my teardown.....is this an AV piece that goes in here...just forward of the handle bolt hole? Could not find in the IPL.

 

[blsnelling]

Probably just a stop bolt goes in there with no AV. It's like a travel limiter. Sometimes they us an AV, sometimes they don't.

 

[rupedoggy]

Look in your bolt pile from the dis-assembly. Find one that has no threads on the end of the bolt. That is the one that goes into that space.