850 Cylinder wear

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MS850

MS850

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Any ideas why both cylinders look like this, the vertical marks. Has Emgo pistons and Hastings rings, about 2000 miles on motor. Head was removed because of stud pulled on re-torque, (has inserts now).

850 Cylinder wear
 
Hi,

you need to remove the cylinder barrel to have a look at the pistons. The play between pistons and cylinder could be to low. May be resolved with honing and new rings.

Ralf
 
Have a very close look at how the oil ring sits on the piston when it comes out of the cylinder,
before disturbing anything else.
Those vertical marks seem to be only related to the oil ring, judging by the wear limits. (?).
 
Rohan said:
Have a very close look at how the oil ring sits on the piston when it comes out of the cylinder,
before disturbing anything else.
Those vertical marks seem to be only related to the oil ring, judging by the wear limits. (?).
Click to expand...
+1
One piece oil ring? Or 3 piece?
 
The oil rings are 3 piece,
Im on it :) in the garage and pulling the barrel. Ill report back soon.
Im rtetired, nothing else to do. :D
 
Did you clip and shorten the oil ring expander upon initial install of the Pistons and rings? The butting of the expander ends does not look right and could be binding the rails, thus causing scuffing.
 
Dances with Shrapnel said:
Did you clip and shorten the oil ring expander upon initial install of the Pistons and rings? The butting of the expander ends does not look right and could be binding the rails, thus causing scuffing.
Click to expand...


There butted against each other, not over lapped. look close at pic
 
MS850 said:
Dances with Shrapnel said:
Did you clip and shorten the oil ring expander upon initial install of the Pistons and rings? The butting of the expander ends does not look right and could be binding the rails, thus causing scuffing.
Click to expand...


There butted against each other, not over lapped. look close at pic
Click to expand...

It looks pretty normal to me. I would wash it up and put it back together. Jim
 
comnoz said:
MS850 said:
Dances with Shrapnel said:
Did you clip and shorten the oil ring expander upon initial install of the Pistons and rings? The butting of the expander ends does not look right and could be binding the rails, thus causing scuffing.
Click to expand...


There butted against each other, not over lapped. look close at pic
Click to expand...

It looks pretty normal to me. I would wash it up and put it back together. Jim
Click to expand...

Ok,

Now for the million dollar question.
Base gasket, To-Be or Not-To-Be
 
MS850 said:
Ok,

Now for the million dollar question.
Base gasket, To-Be or Not-To-Be
Click to expand...

One thing I do not see is the end of the lower oil ring rail.

To get the correct rail pressure you should have one end gap 1 inch to the side of the expander end and the other rail end gap 1 inch the other side of the tensioner end.

I would re-assemble it using the same method as it was before so you don't change the ring travel.
I usually prefer a base gasket with an 850 with a bit of red anaerobic sealant to lock it in place. Jim
 
comnoz said:
MS850 said:
Ok,

Now for the million dollar question.
Base gasket, To-Be or Not-To-Be
Click to expand...

One thing I do not see is the end of the lower oil ring rail.

To get the correct rail pressure you should have one end gap 1 inch to the side of the expander end and the other rail end gap 1 inch the other side of the tensioner end.

I would re-assemble it using the same method as it was before so you don't change the ring travel.
I usually prefer a base gasket with an 850 with a bit of red anaerobic sealant to lock it in place. Jim
Click to expand...

Actually one of the piston expanders where they meet were at the same spot as the ring.
 
MS850 said:
Dances with Shrapnel said:
Did you clip and shorten the oil ring expander upon initial install of the Pistons and rings? The butting of the expander ends does not look right and could be binding the rails, thus causing scuffing.
Click to expand...


There butted against each other, not over lapped. look close at pic
Click to expand...

I was not referring to overlap as I don't see any. I was referring to the ends of the expander which do not look correct to me. Zooming in very close on the picture where you have the red arrow you see two non-parallel ends of the expander butting together. I don't recall expander ends looking like that. Usually, there are two parallel butting ends. Furthermore, the RH end appears to be riding over the top of the LH side and neither the left or right ends seem to be firmly against the top rail; especially the LH end. Given the high accelerations, forces could be significant, even with something as lightweight as an expander ring.

If this is a typical expander ring end butt, then move on to other things.
 
Dances with Shrapnel said:
MS850 said:
Dances with Shrapnel said:
Did you clip and shorten the oil ring expander upon initial install of the Pistons and rings? The butting of the expander ends does not look right and could be binding the rails, thus causing scuffing.
Click to expand...


There butted against each other, not over lapped. look close at pic
Click to expand...

I was not referring to overlap as I don't see any. I was referring to the ends of the expander which do not look correct to me. Zooming in very close on the picture where you have the red arrow you see two non-parallel ends of the expander butting together. I don't recall expander ends looking like that. Usually, there are two parallel butting ends. Furthermore, the RH end appears to be riding over the top of the LH side and neither the left or right ends seem to be firmly against the top rail; especially the LH end. Given the high accelerations, forces could be significant, even with something as lightweight as an expander ring.

If this is a typical expander ring end butt, then move on to other things.
Click to expand...

heres the expander

850 Cylinder wear
 
Does the piston top look like it's seen detonation?

Some of the scratches on the piston skirt could be from honing grit.
 
Triton Thrasher said:
Does the piston top look like it's seen detonation?

Some of the scratches on the piston skirt could be from honing grit.
Click to expand...

Not at all, looked normal, layer of carbon
 
Like always, thanks for great info.

Cooking my freshly painted barrel..........Probably should have cooked the ribs first. :oops: hehehe

850 Cylinder wear

850 Cylinder wear
 
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