Hello everyone! I am back with my 1978 Yamaha SR-500 which has been running without incident for about 200 miles at this point. One thing that happened, however, is that I was riding it on the highway and I experienced an unusual noise at high speed / high load / high RPM (around 70mph). The best way I can describe it is the sound of someone rattling a chain against my gas tank, if that makes sense. Here's a video of the sound that I took while riding.

photos.app.goo.gl/TyyHjzDWyQdZoxbJA
(it starts with no noise and then the noise comes in a few seconds into the video)

When I stopped, I noticed the engine ticking. Here's that video.
photos.app.goo.gl/sCoRD4byhLspXM1V8

I shut it off right away and checked my oil and to my horror the dipstick was dry. I went and bought two quarts of oil and put about 1 3/4 in the bike to fill it back up, and the ticking stopped to my relief. I rode it back home but now I have noticed that even despite having totally full oil, the bike seems still to be making this "chain slapping" sound at any speed above 70mph, which is making me nervous.

So guys, did I nuke my top end? Does this sound familiar to you guys? Please let me know if you have any input at all because my worst fear is that my engine is destroyed and I could really use some input from you guys if you have any.

Thanks!
Daniel

P.S. Please read the whole thing, its not even that long this time. Yeah I know you guys skimmed it.

After the fact, but it would have been good to have drained the oil and check it and the filter for metal debris. I'd pop out the cam and check for wear/damage. The noise could be from a number of sources, maybe something as simple as camchain tensioner. Good luck, hope it's nothing terrible.

#21 will be a rubber & steel bonded washer to damp out any noise. It's possible it's spat the rubber out & now has excess movement. But that is pretty unlikely. The noise is at valve gear speed & really sounds like "one" tappet so check then by removing the tappet screw & see if the end broke of. In which case it'd have bulk clearance.. I've had similar on suzuki quads where the exhaust valve would recess until the rocker arm tapped against the valve lifter "decomp thingy" but unlikely once again. I hate to say it but my first thought the way you described, was that the pesky crank key had got damaged again & "Way" over-advanced the ignition. But she sounds ok idling away there so far as timing goes. So back to the tappets & cam chain. Chain should be adjusted running until the pin just stops chattering. If the rubber washer is shot then the pin might stick through that much extra but still adjust until it is stable. Does sound more in the valve tappet or cam-rocker area though. Might have lost a pad off one rocker arm face if they're somehow bonded on--i can't remember now. Hope it's not too serious.
www.partzilla.com/catalog/yamaha/motorcy...r500g/camshaft-chain

Which cam do you mean exactly? The camshaft?

A couple clearance. First of all where is the tappet screw and does it require removal of the valve cover? Would you recommend removing the engine from the frame for this? You mean if the end of the tappet broke off, right? What is bulk clearance?

When you say the chain should be tensioned until the pin stops chattering, which pin do you mean? If there's a number on the part sheet please let me know.

I may try to take more videos, I will keep you all posted. Thanks for the input as always!
 

Camshaft yes although in my opinion something like severe wear isn't going to happen on the spot. The reason i initialy though ignition was severe overadvancing causing detonation. But think were past that litening to the tapping sound but then again i'm not sure extra tappet clearance would resonate up through the tank but steel or alloy tank so ok maybe.
Sorry i think your question was to pahiker question #2

Tappet screws #11below
www.partzilla.com/catalog/yamaha/motorcycle/1980/sr500g/valve
Under cover #22
www.partzilla.com/catalog/yamaha/motorcy...sr500g/cylinder-head

With cap #25 off & motor running pin #19 could be pulsating 'moving' in & out. If it 'is' moving plenty then loosen locknuit #23 then adjust in #22 until pulsing stops 'just', then lock up the big nut & put the cap on. Cap might be plastic so be careful tightening.
www.partzilla.com/catalog/yamaha/motorcy...r500g/camshaft-chain
Sounds like you need a good service manual to reffer to.
To check the tappet clearance probably the easiest way for you would be with the covers off, kick it over to compression then feel it through 'just' untill you feel a bump on the kick lever--by hand might be best--so then you're on the back of the cam & can set the valve clearance.
If you stop between bumps then you're ok but a little too far & you'll need to go around again untill compression.
Or i guess find TDC mark on the flywheel on the compression stroke now it's secured & accurate. I was just trying to make it easy at this point as there's a bit of leeway where you're on the back of the cam & everything stays neutral for checking tappet clearance "in your case".
First feel how much clearance you have as remember you're looking for a reasoin for the tappety noise.
Only have a few thou clearance.
If you can feel lots of clearance than that's your noise but question remains as to why it came on quickly.
Sorry if i'm over-complicating it but not easy to explain if you've not been there!!.
Maybe get advice from a shop familiar with these oldies although its pretty standard procedure for all similar motors. Cheers.

Here's a video but i'll see if i can find a better one although this guy know what he's doing but ill see if i can find one with more detail.

There's endless videos out there, heres another.

Lots of videos on cam chain tensioner adjusting too. Here's a short one showing how it should be. I see some where the adjuster big thread is in about flush with the locknut which means the cam chain is worn to the limit but this one has plenty to go, as good as new.

No need to take the motor out of the frame to do the tappets but is a fiddly job.

Videos i'm finding aren't that good to see right in there.