Primary Chain

[Teach]

Hey Guys, I recently purchased a 1981 XS1100 27 000 kms. After about 1000kms it picked up an knock that seemed to orginate somewhere in the drive train. The Knock is only present if the bike is engaged in gear, not there in idle. Have striped the engine and can see nothing wrong, no gears chipped, no marks on engine housing , all bearings seem to look good. The only thing I can see that looks a little outta place is the primary drive chain looked a little slack. but not knowing how tight it should be cause concern. Really like to know if someone out there has any pointers for me.

Teach

[trbig]

The primaries do have a little slack in them. If all the bearings looked good and don't have any copper color showing on them, I would look at the piston/wrist pin/top of connecting rod area. Check over the cylinders well to and look for any areas of piston slapping. Besides that...??? Possibly timing related and just detonation problems?


Tod

[79XS11F]

Yeah look somewhere else for the source of the noise. From what I have read the primary chain is good for more then the life of the engine.
Rob

[AlanB]

Hi Teach,

Does the noise get less if you pull the clutch in? If so, it is probably nothing to worry about.

Clutch and drive-train noises usually get much better (or go away entirely!) when carbs are properly balanced (synched?)

Best of luck!

AlanB

[mro]

Since you have the engine apart would plasti-gauge the bearings just to be sure.

Knock Knock...
have found one with piston slap
found one with a crack in the clutch basket (no continious noise, mostly starting off in first or when twisting the grip XSively)
80G has a most annoing knock, beleave it is inherent to some XSes and is related to pre-ignition/timing which Yamaha had known about and was recently talked about here on the forum.


mro