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Post by karsten on Jan 23, 2015 8:32:00 GMT -5
Hi there.
I´ve had the fortune of inheriting a ´76 xs, from a buddy that didn´t have the time to take proper care of it.
It actually is in a pretty decent shape considering three years of standstill, and got it running last year after doing the basic service stuff (Oil and filter change, carb cleaning etc.)
Sorry if it seems like a noob question, as I´m quite a novice around 4-stroke engines, but I hope you guys can help me with determining the origin of a high-pitched tinging noise from the engine. It´s only audible at idle, which, in my mind, sounds like the camchain grinding against a worn cam-chain guide. But what do you guys think?
Please take a look/listen here:
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Post by richard on Jan 23, 2015 18:35:05 GMT -5
I've listened to it a couple of times and can't really hear anything other than lose valve tappets. You might try adjusting the valves to see if that helps. You could also adjust the cam chain tension on the back of the cylinder. Worn chain guides will show up in your oil filter as flakes of black rubber or as flakes of aluminum from the chain rubbing on the guide. The lower guide down by the crank is rubber on aluminum with metal pins holing it together, when it gets down far enough the chain will rub on the pins which would show up as metal shavings. At that age it could have worn guides, but the best thing is not to assume anything, and just adjust it all to spec and then see how it sounds then. The top end on xs650 is mechanical as opposed to hydraulic lifters, which makes the tappets kind of noisy under normal conditions. Back in the day they use to say it's better to hear the tappets than not hear them at all and burn a valve.
Tappets, Rockers or Cam Followers, take your pick. People use them all in terminology
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Post by karsten on Jan 25, 2015 8:18:15 GMT -5
Seems I might be overly sensitive to metallic sounds from such an analog engine  . What you´re saying makes perfect sense as I haven´t adjusted the valves yet. Just to be sure I´ll check the oil and filters for shavings and plastic bits, and as I need to replace the old leaky gaskets on the top end of the engine anyhow, I´ll check the cam chain and the guides at the same time. When that is done I´ll make proper adjustmens of cam chain tension, valves and carbs - in that order. Thank you so much for listening and helping with advice Richard. |
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Post by grizld1 on Jan 25, 2015 11:08:21 GMT -5
While you're inspecting and adjusting, don't forget the ignition. Here's Rule 1. of carburetor tuning: Everything else first!
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Post by karsten on Jan 29, 2015 7:42:24 GMT -5
Will do! - but as the ignition is electronic, do I need to adjust it? |
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Post by grizld1 on Feb 2, 2015 23:45:07 GMT -5
If you're dealing with a 76, you either have an aftermarket camshaft-driven ignition or a rare situation in which a late ('80 and after) crank triggered ignition, complete with late harness and alternator, have been installed.
If you have an aftermarket cam-driven ignition, yes, you need to inspect timing. But that's not the only thing that needs inspection. Make sure connectors and switches are clean and passing current without creating excessive resistance, make sure plugs, caps, and wires are good, etc.
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Post by coltsguy on Jun 28, 2015 22:29:23 GMT -5
Were the valve tolerances out of adjustment or cam chain need adjusted? I am wondering because I am experiencing the exact same noise
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Post by grizld1 on Jun 29, 2015 8:47:04 GMT -5
Those are periodic adjustments that need to be carried out anyway. Just do it.
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