downhiller
XS650 Member
Hi All- first post, would appreciate input on the two items below. The site has been invaluable as I have disassembled and now prepared to reassemble my engine.
Background: Purchased a 75-76 engine in a 1982 frame and ran it for a few months. Replaced really loud mufflers with Mikes XS Commando mufflers. Later noticed a whirring sound as engine revved. Tore down engine this winter thinking maybe worn cam chain guide or spun bearing.
Cam chain guide & tensioner ok, no exposed metal. However one side of the cam chain showed wear to the outer edges. (Sorry, picture makes it look like inner edges) I could find nothing internal that indicated the chain had been rubbing on it. Maybe a PO had replaced a worn cam chain guide, but not the chain? I will replace the cam chain, but wondering if I am missing something. Anyone seen this type of wear on a cam chain? Any other thoughts?
The crankshaft bearings were properly seated on pins and not spun. However, the case locations where the transmission bearings sit seemed to show some wear. The wear appears to be where the bearings contact the case and some areas show the wear the full size of the bearing, while others have "bands" of wear as if the bearing does not make full contact with the case. I could find nothing about spun transmission bearings. Are the pictures capturing normal case wear, or do I have a larger issue?
Thank you for any suggestions you may have, I don't want to make assumptions or overlook something while I am this far into it.
Background: Purchased a 75-76 engine in a 1982 frame and ran it for a few months. Replaced really loud mufflers with Mikes XS Commando mufflers. Later noticed a whirring sound as engine revved. Tore down engine this winter thinking maybe worn cam chain guide or spun bearing.
Cam chain guide & tensioner ok, no exposed metal. However one side of the cam chain showed wear to the outer edges. (Sorry, picture makes it look like inner edges) I could find nothing internal that indicated the chain had been rubbing on it. Maybe a PO had replaced a worn cam chain guide, but not the chain? I will replace the cam chain, but wondering if I am missing something. Anyone seen this type of wear on a cam chain? Any other thoughts?
The crankshaft bearings were properly seated on pins and not spun. However, the case locations where the transmission bearings sit seemed to show some wear. The wear appears to be where the bearings contact the case and some areas show the wear the full size of the bearing, while others have "bands" of wear as if the bearing does not make full contact with the case. I could find nothing about spun transmission bearings. Are the pictures capturing normal case wear, or do I have a larger issue?
Thank you for any suggestions you may have, I don't want to make assumptions or overlook something while I am this far into it.
