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I did a rings and valve grind on my 89 TW. I honed the cylinder, assembled everything carefully with anti-seize compound or coated with oil, torqued to specs, put it in and filled with oil, bled the air out till it was pumping oil out, and as far as I know, all to the book. I started it and let it idle a bit on the stand, then took it for a gentle ride around the country block at about 40 miles an hour. I never made it home. At 12 miles it clattered and quit. I pulled the cylinder, and the piston is fried, as if it had no oil, but the oil is up. The little holes that let oil through from the inside of the piston to the cylinder wall were open, the oil filter seemed fine, and had collected some filings. I just can't wrap my head around it. TW brain pool, what do you think?
 

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Did you have any side covers off during the work? Is the oil still registering as full?
 

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Side covers off and new gaskets, new oil and still up with no leaks.
The reason I asked, and most members know this already, you lose some oil when you pull the cover off, then when the work is all done and everything is buttoned up again, folks tend to check and top off the oil and then start the bike and go for a ride. They fail to remember that the oil has to recirculate through the passages, tailshaft, etc to fill up again that which was lost. You can be several ounces low when you get back from your ride not knowing that the engine should have been started briefly, allowing the oil to reach those areas, and then re-checked before an actual ride. A 40 mile ride might not be good with only a half a quart in a bike that only holds 1.3 quarts in the first place...
 

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Is the connecting rod fried too?

Oil is filtered going from the outside of the filter to the center. Once inside it goes two way -- out the 4 little holes to the top of the head and camshaft and out other way to the center of the crankshaft to the lower rod bearing. The upper rod bearing, piston, rings, etc. are all lubricated by splash which is oil being flung around everywhere. So check the oil passage way out the side opposite the 4 little holes -- out of the filter into the block. A blockage going to the crankshaft can cause the problem you say you have.

oiol flow 2.jpg
 

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I did a rings and valve grind on my 89 TW. I honed the cylinder, assembled everything carefully with anti-seize compound or coated with oil, torqued to specs, put it in and filled with oil, bled the air out till it was pumping oil out, and as far as I know, all to the book. I started it and let it idle a bit on the stand, then took it for a gentle ride around the country block at about 40 miles an hour. I never made it home. At 12 miles it clattered and quit. I pulled the cylinder, and the piston is fried, as if it had no oil, but the oil is up. The little holes that let oil through from the inside of the piston to the cylinder wall were open, the oil filter seemed fine, and had collected some filings. I just can't wrap my head around it. TW brain pool, what do you think?
Why did you take the engine apart to put in new rings and grind the valves?
 

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This sounds more like a piston fitting too tight in the cylinder. All air cooled engines require more clearance between piston and cylinder. This is the exact symptom of that, not loss of lubricant.
Mel
If the little end of the con rod is OK I will agree with you. If it is fried I am betting on lack of oil.

Clearance for piston ranges from .001 min to .004 max according to the shop manual. Think they got it less than .001"?

Piston.jpg

Or maybe they used a Wiseco forged piston and the clearance should be at least .002" minimum.
 

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Post some pictures of the piston and cylinder and the connecting rod. I think there will be some interest in them.

What elime said. I'd like to compare your situation to the one I had, which was caused by the lack of earl.
 
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Did you check the ring-end gap before assembling it all? Who did the hone? Does the big-end look like its been hot? I don't think it will be a clearance problem between cylinder-piston due to you honing a cylinder that has been run on OK.

What exactly did you use anti-seize on?
Boy that ring gap will kill you! A pain to remove the rings if they are already on the piston.. ugggg! But it is absolutely a requirement...

Finding out if the rod bearing is still ok is an important clue.

Jim
 

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Discussion Starter #14
To respond to all: The oil was halfway between the 2 marks, and it was only 12 miles. I rebuilt it because the motor was beginning to smoke. I didn't change the piston, it looked good. It was the same one fitted with new rings into the honed cylinder. The upper (piston) end was very stiff, and the bottom end reasonably loose. I tried to drive the pin out, but decided to leave it in, as it wasn't willing without force. It looks totally oil starved, but I know for a fact the pump worked. I am suspecting it wasn't putting out enough-- I hadn't run it in a while. Since the piston is splash fed, and has 4 little holes to lube the cylinder, I just can't put it together. In fact, with no pump at all the the piston should be okay. The cam turns over well, which indicates the pump worked. I checked all clearances before I ordered parts, and it met specs. The oil filter is the one that had been in before, I planned to change it after a 100 miles or so to capture the breaking in filings. I checked it first. After the fact, the first place I went was there, and it had caught a lot of metal from the issue.
 

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The 4 little holes lubes only the camshaft. Oil to the crank and rod goes out the other end of the filter -- the one big hole. Check that passageway for a blockage.
 

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Discussion Starter #18
I would sent a picture, but somehow I can't figure it out. I have done in the past, but the cues fail me. Guide me, please. I have a iPad.
 

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Discussion Starter #20
Valve stems and cams. Permatex anti- seize compound, as per shop manual, carefully so no globs would clog oil passages. Maybe a small amount in cylinder and piston pin, but I really don't remember, but definitely a lot of oil.
 
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