got a couple of pics
Some of the photos are washed-out by the flash, reducing the detail, but clearly there is an oil control issue; although the detail in the photos isn’t clear enough to point at anything specific.
If hd-dude has a couple of low mileage, standard size 110 “take off” pistons laying around, they could be used to help gauge the condition of Van’s front cylinder piston.
Van writes that that there is .0045” piston to cylinder clearance. This is exceptionally high and may be the result of a collapsed skirt resulting from extreme heat. In my experience, issues with excessive clearance are usually the result of inconsistent bore dimension, rather than a broad variance between pistons. I would expect standard size pistons to have less than .001” of variance; significantly more than that and I would suspect a skirt collapse related to overheating.
As a piston overheats the contact patch with the cylinder will increase in width. If the pattern on Van’s front piston is significantly wider than a known good used piston, that is a good indication of higher than normal operating temps.
After cleaning the piston, preferably in a vat, if there is any evidence of material missing from the top of the piston, that would be clear evidence of unstable combustion and extreme heat. Cracked ring lands would also be clear evidence of unstable combustion.
Gauge the top compression ring’s tension in the cylinder by hand, and compare it with a known good top piston ring. If the ring has little or no tension, that is clear evidence of extreme overheating.
The compression rings do not run flat against the bore, so if the wear pattern on either ring, typically the top ring, runs the full depth of the ring in any spot, that is compelling evidence of a lubricant issue, considering the low mileage.
Good luck Van.
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Topic: last Saturday my bike bleed out (Read 12967 times)