Ticking Sound Coming From Right Exhaust Valve

[Adam Savage]

I'd like to preemptively apologize for this being about an XS750. I was a member of the Yamaha Triples forum, but after a slight break from the forum my account is no longer active (or something), the account recovery process kicks back with an error message and no admin email is to be found. However, from what I have found my issue seems to be one that XS's share.

Video:

This problem cropped up shortly after I had my engine rebuilt (1978 XS 750). It rode fine, I rode it from the shop back home. At the time I was still dealing with failing O-Rings and replacing them, so the carbs promptly flooded and I went in and replaced the last of the O-Rings that needed fixing. I put the carbs back on, started it up, ran.....just with a nasty tick. I figured it was just a matter of breaking in the new valve seals and everything else that was replaced, so I continued to ride it. Apart from the nasty ticking noise there are no other issues. Power seems fine, the cylinder isn't lean/rich and is tuned more or less the same as the others. I asked the shop and confirmed that it was probably just something to do with the new seals and to adjust the valves after the break in period. I did so, they were tight (which is what i was told to expect), so I replaced the shims to be within spec or slightly loose. No change in the ticking. It has been roughly 1000 miles since the rebuild with no problems other than the ticking.

I posted a similar post on a facebook group and received advice ranging from "don't worry about it" to "some really specific chain somewhere in the lower engine may or may not be a little loose".

I have checked for exhaust leaks, found none. The cam chain seems to be okay, the tensioner is all the way tight, but i hear NO chain slap from the left side of the engine. The only other strange thing is that the right exhaust has a hint of white/grey (I'm colorblind, so not quite sure. It's not black or blue. There's no coolant, and it doesn't smell like oil or gas). It dissipates at the engine warms up, and recent'y it has been cold/wet where I live so I assume it is probably condensation burning off.

I would be happy to change the Cam Chain, it's 40 years old, might as well, but could a loose cam chain ONLY effect one valve?I would think that if the chain was loose all the valves would see a change, or at least all the intake/Exhaust.

My fear is valve/piston slap. But i don't see how that could just appear out of nowhere so quickly.

Any help would be greatly appreciated., Thanks

 

[Christine79xs]

If you find out, let me know lol i have the same noise from the same cylinder on my 79 XS650. I’ve been trying to figure it out since last August.

 

[Adam Savage]

Since the post I swapped out cam chains ( I desperately needed a new one, still ticks), let some oil sit in the cylinder overnight to maybe lube up some stuff, still ticks, and went though the exhaust system, removed the buckets and added lube as well as poured oilnover all the cam shaft bits, still ticks. It's just a tick as far as I know, I give up.

 

[peanut]

well its near impossible to diagnose these noises from a video as we all know but I would swear that that sounds to me like a dry bearing somewhere along with the ticking noise. Theres a slight squeaking / chafing noise so characteristic of a dry bearing or one not receiving oil like the sound an Alternator bearing makes when its dry .

Try using some sort of stethoscope to pinpoint the noise , a long screwdriver will work or a length of wooden dowel. Place it against your skull just in front of your ear and hold the other end on various places around the engine & gearbox. You might be able to pinpoint the source of the tick .

Its a long shot but you could remove the stator and make sure the rotor and stator are not rubbing together somewhere.

 

[grizld1]

Piston slap occurs at the skirt; if you're using a stethescope or similar, you're not likely to mistake it for valve noise. White/light grey smoke indicates oil burning, and when the motor smokes when cold and stops smoking at operating temperature it indicates oil getting past the valve guide. A new seal will fail quickly if a guide is worn past spec. That condition wouldn't make noise, but you may want to look into it. If the shop that rebuilt your motor missed a sloppy guide, they may have missed other things as well. If it were my motor I'd run a leakdown test on the problem cylinder, then pull the head for a look at the clearance between valve stem and guide, installed valve spring height, valve spring free length, valve train installation, etc.

 

[peanut]

how do your spark plugs compare ? keep them in the order they come out and they are a very useful diagnostic tool to tell you what each cylinder is doing.
It wouldn't be a bad idea to do a compression test whilst you have the plugs out.

if a cylinder is burning oil it should show when comparing the plugs .

I re-read your initial post and the ticking seemed to start directly after you changed the carbs .........did you do anything else other than pull and replace the carbs like adjusting the valves or chain tension etc ?