Yamaha XJ 650 Top End Engine rebuild

Rebuilding the top end of a Yamaha XJ 650 using a donor engine with a few tips along the way. There will be more video to follow.

[@karlvanboxel561]

I had a 1980 xj650H very gd bike a bit of an oversight by mr yamaha tho imo is the lack of tensioner on the alternator/ starter chain which can flap around with higher mileage and cut the oiling nozzle 😮

[@pat2bornot2b]

Thank you I learn something new every day.

[@karlvanboxel561]

From memory u r supposed to position the crankshaft in a certain position via the marks on the ignition trigger plate and crank case b4 you release the camchain tensioner I know this all too well because I failed to do that prior to slackening my tensioner and retensioning the lock nut and there was a rather disturbing noise coming from the cam chain😮

[@pat2bornot2b]

Thank you for making the comment, you need to check position after tensioning best to have the cam cover off when doing this because it can put the cams out by one or more teeth

[@karlvanboxel561]

Just checked my factory manual it says to line up the C Mark on the trigger plate with the crank case mark b4 u do the undo the lock nut and bolt not quite sure why this is could be when all the pistons are all lined up evenly in the centre of their stroke or if there’s a spot in the crank rotation where there is not as much tension on the cam chain? Some people swap to the later model auto tensioner

[@pat2bornot2b]

@@karlvanboxel561 you are correct as this is for adjustment and most likely as you point out that the cylinder are all at the same point and possibly that no tension from the valve springs is on the camshafts themselves. I'm must check this out, thanks for the comment and info.