Jumping cam chain

[spooksDJ]

looking for help/advice, I have just finished rebuilding my XS1.1 sport. Started first try, ran for 5 minutes then i shut it down . Next day i went to start it, very slow to crank as the battery is smaller than standard (waiting for correct one from supplier) and the compression is high due to new pistons etc. During cranking for about 3 seconds the motor stopped . when i checked by pulling side cover off and turning the motor gently with a spanner it felt like the timing had moved (cam chain jumped teeth) and the valves were hitting the top of #1 piston. Have i not located the chain in the track? Would a worn chain do this? are the cam chains available in Oz? etc etc etc.

[TADracer]

I would pull the plugs and valve cover and then CAREFULLY rotate the engine to TDC and then check to see if the cam markers are lining up with the arrows on top of the caps. If not, you chain has jumped.

I think thee are a couple of good threads on here about cam chain replacement.

[skids]

I don't know how much time/wear your chain has, but it would seem that replacement would have been easier as the bottom-end was redone. Water under the bridge. If you didn't have the chain on the bottom sprocket, I think it would be so loose that you would know immediately when you were putting the head back on. It would have been difficult turning the cams with the crank also! BTW, having the bike on the centerstand can really help in keeping the chain on the crank's sprocket while doing the job.

Everyone always blames the cam chain wear for the lack of adjustment that is available in the tensioner, but after replacing a cam chain in one of mine, I only gained about 3/16 inch (4.76 mm). I suspect that there was wear on the chain slipper as well.

One nightmare that occurred (different bike) was that while being dilligent on maintenance, I tightened the stopper bolt until it felt like maybe it began to feel like it was beginning to strip. Yup, I caused that problem. I ran the bike and with the weakened tensioner, it allowed slack in the chain and then held it there so that the valves could be bent.

[oldnortonrider]

I've been sooooooooooooo lucky, not to have bent valves in the last 13 years of doing lots of chain maintenance, adjustments and replacements. I hope it never happens to me.

I'm surprised--it worked good the first day--and messed up on you the second day...........(?).............

The following thread is very helpful:>http://www.xs11.com/forum/showthread...threadid=11009 .

A few years ago I actually made my own "manual" chain tension
adjuster--pulled the stem out of the chain tension housing and knocked the plug out on the outside end. I installed a 5 inch bolt, "double spring loaded" the thing--washer on head-bolt end for spring(s) to go up against; the head bolt now going up against the slipper instead of the plastic head piece of the OE piece apparatus. The bolt will have about 1-2 inches of threaded portion sticking out of the forward end of the housing. (The bolt shank thickness being same diameter as the original shaft stem). I put 2 nuts on the end to "finish this up"--the first nut you gently cinch down against whatever jim dandy O-ring seal you've rigged up. The second nut you lock down just in case the 1st one might want to "vibrate" loose. Of course the side bolt is already cinched down. (INCH POUNDS)

It doesn't look good, but it works good.

A.P.E. (American Performance Engineering) in California sells these "manual" adjusters. $40.00 . I made my own at the time, cuz I was trying to "improve" on their method and design.

The "accomplished" XS11 owner eventually would want to go this avenue--probably for a couple reasons. When the OE adjustment mechanism is fairly streched out with a fairly worn chain, the spring is not strong enough after all these years to really push in and do its job in subsequent adjustments. You don't gotta worry about this "tricked version". Actually A.P.E.'s adjuster doesn't have a spring; it's all manual.

Always, always, rotate the crankshaft (slowly), by hand, when you've had the cam chain adjuster--housing and all--off the front of the cylinder, and have reinstalled and adjusted the plunger--a couple rotations--to make sure that something's not going to bind up.

Also, the OE plunger length is too short; it runs out of adjustment length too soon to suit me.

[oldnortonrider]

Folks, this was not me that got this on here multiple times. The site (?) or something (?) was refusing to take my reply for the first few tries; and then finally it told me "OK". I couldn't find the edit section in time to remove 2 of these postings; I think all 3 are the same. How about one of the moderators taking the "first 2". All 3 are repeats.

Editing Done...John

[spooksDJ]

Jumping Cam chain

Thanks everyone for your valuable input. BUT, i must admit to being such a smart guy that i don't need to read all the instructions when fixing something, for instance, after loosening the cam adjuster and hearing the click as it takes up the slack, the next line in the book say's "tighten the 10mm bolt". But i didn't read that part.
Result = 1 bent valve in #3. all i have to do now is dissasemble the head and fit new valve and learn how to read all of a sentence. Very painfull lesson learnt.

Also thanks to Skids. when i held the bike level it was much easier to set the chain on the bottom sprocket.