Cause of chattering / clattering sound from 1975 XS650 engine, seems louder recently

[larrynyc]

Stock 1975 XS650 with about 13,000 miles, I'm the 2nd owner. Bought this bike in late spring. Most parts original. Decent shape mostly aside from a few fixed age-related stuff.

I've always noticed a consistent metallic chattering/clacking sound from the top of the engine, which wasn't exactly loud, but it was definitely audible. It was only mildly noticable, so I left it alone. From what I knew, it was the valves.

A few months later, I had some spare time and adjusted the valve clearances to get rid of the sound. The old valve clearances were within spec, so I adjusted the the valves a hair closer based on stuff I saw here on this site.

Some notes when I adjusted the screws:

• When I manually turned the engine counterclockwise at the rotor with a 17mm socket, everything seemed to be okay, no noise or anything odd.
  
• The rear valves I used a 0.075 mm (~0.003 in) feeler, the front valves I used a 0.1 mm (~0.004 in) feeler. The feeler resistance "scraped" through, the next bigger size wouldn't fit, the next lower size went in with no resistance. I made sure to do these adjustments right after the rear intake valve came back up, rotor lined up to top-dead-center.
  
• The tips of the valve adjuster screws (which seem to be original) weren't flat. They seemed to be worn to a slight angle (like a lipstick tip but not as exaggerated), so technically there's slightly more clearance on one side of the screw than the other. Since I adjusted the screws, the worn angles are now pointed at slightly different directions. Clearances were based on the closest side of the tips.
  
• There's evidence of very tiny amounts of oil weeping from all four valve covers. Not gushing, but like a dried-up "runny nose" after a long ride. The gaskets seemed okay but I can't verify their age. The valves and screws were moderately wet with oil, and the inside of the covers had a little oil inside, I assume that's normal?
  

Upon finishing, the chattering sound seemed just as loud, if not a little louder. The sound is always consistent and doesn't matter whether the engine is cold or warm. Oh well, the bike still runs, and at least I knew the valves were on-spec.

Here's a video of the sound:
http://s1159.photobucket.com/user/LarryGoesOnVacation/media/Motorcycle/IMG_2777.mp4.html

But now, after a couple weeks of riding, it seems *even* louder. Like so loud I'm a bit worried. Is this a valve sound or something else? Or is it something as simple as raising the screws higher, or getting new screws?

Thanks in advance.

 

[xskid]

Now im by far no expert, but have u checked the cam chain? I had the same symptoms about a week ago turn out it was my chain tensioner was out of adjustment.

 

[TwoManyXS1Bs]

The adjuster tips should be convex/spherical, not lipstick or flat, that end of the rocker sweeps an arc.

A fun read: http://www.xs650.com/forum/showthread.php?t=28536

 

[ANLAF]

larrynyc, is the the noise you have? If so it is a worn cam chain. This one was very loose - so loose it ran of of adjuster to adjust.

Anlaf

 

[larrynyc]

Thanks everyone.

The seller said he adjusted the cam chain tension, and it wasn't noisy when I first got it, so I never suspected it.

It got noisy about a week after. Now that I'm thinking about it, after reading all of your comments -- perhaps because the bike wasn't run in so long, the cam chain slowly shrank over the 20 years of not being ridden. And now since I've been using the bike a lot, the chain has stretched a bit.

So last night I tried to adjust the cam chain tension, but both the big nut and the little nut is really tight and would not budge at all. So I pulled out the whole rod/spring thing and now I'm soaking it in WD-40 to loosen those nuts. I'll try to see if it successfully loosened again after work and report my findings.

 

[larrynyc]

Yes, ANLAF, it's a similar noise, here's my video: http://s1159.photobucket.com/user/LarryGoesOnVacation/media/Motorcycle/IMG_2777.mp4.html

 

[ANLAF]

Yes, larrynyc, you know what I am going to say - new cam chain! And if you do have any cash, new pistons, rings, re-bore, head gasket, valve guide seals, ThreeBond sealant.

Sounds daunting to do, but the fellers will all agree you should get that sorted. The difference it will be make is phenominal. You heard the same rattle on my video - tomorrow I will do a post top-end rebuild video.

There is plenty of help available.

Anlaf

 

[ANLAF]

I recall you don't have the garage resources, larrynyc, hmmm! If this is going to be your first strip-down you will need some indoor space, so you can take your time.

Anlaf

 

[gggGary]

Sound s a bit more consistent like a valve to me, but finish the cam chain adjustment and check some threads about cam chain adjuster and brass washer. Pics of the valve adjuster tips/valve stem ends?

 

[larrynyc]

Hey guys, thanks for the further info.

Unfortunately there's a bit of a thunderstorm brewing today, so I'll have to put the tensioner dampener thing back on the bike tomorrow. Luckily, I brought the dampener assembly up inside my place so I can try to loosen the nuts tonight (they've been soaking in WD-40 today).

One thing I noticed was when I held the tensioner in my hand, when I pushed the spring-loaded damper rod all the way in, and I mean ALL the way until it firmly stopped (as if to put the least pressure on the chain if it was on the bike), the rod end wasn't flush with the little nut, it was still a few millimeters inside. Shouldn't it stick out a bit, and only be flush when it's actually on the bike? I'm just taking an educated guess.

Also, another question — Is a loose chain a dire situation? I'd like to do one last roadtrip before packing it in for the winter.

The noise isn't so bad when I'm going fast, it's only at lower RPMs (although I can't be sure, the noise from the pipes might be masking any header sounds).

Replacing the cam chain is a daunting task, but I'm willing to do it (there are garages here specifically for winter storage and for working on one's bike for a monthly charge), I'd like to save that as a wintertime repair. BUT I do know a garage space that has a day rate if this really is a matter of safety (I'd hate for something awful to happen on the highway).

 

[larrynyc]

Gary, I happened to shoot a pic of one valve adjuster tip last week right before I adjusted it, here it is:

 

[TwoManyXS1Bs]

Larry, you need to UNSCREW the adjuster completely off the rocker arm, clean it and the valve tip it touches, THEN take pics of the END of the adjuster(s). All 4...

 

[gggGary]

Great picture though, big and sharp.

 

[TwoManyXS1Bs]

Anybody wanna guess what kind of red sealer that is?

 

[gggGary]

The very best kind to plug the oil passages?

Hope it was just on the covers and not in the head rocker cover seam.....

Larry grab a big screwdriver put (the blunt end) in your ear, see if you can narrow down where the sound is coming from.

 

[Brian902]

Okay, let's play the guessing game.

I'm betting it's the right front exhaust valve that's the problem.
.

 

[larrynyc]

Well I ran into a setback. Last night I had the tensioner in my apartment, and found the nut is still seized, bigtime. I let it soak all day yesterday in WD-40 and it had no effect. It's *frozen* solid. There's absolutely no way the previous owner adjusted that nut, unless he was the idiot who tightened it that tight.

If I could just get that nut un-seized, it does seem there's room to adjust the dampener a little bit more outward or a lot more inward, maybe that's a good sign that I can get a little more life out of my current cam chain?

Now my problem is — how to un-seize that nut. I'm going to buy something better than WD-40, like PB Blast or Liquid Wrench. I don't have a blowtorch but I do have a gas stove.

 

[wiggins]

Before you do that, hit the nut a few times with a hammer and punch. Put the whole assembly in a vise if you have one and do a few quick strikes to the nut using the punch. Most of the time that will free up things.

If you don't have a punch, find the nearest sacrificial screwdriver and try it. Or even a stray bolt. Almost anything will work. Just need to get impact on it somehow.

 

[gggGary]

Bolt the tensioner back on the head, use a 6 point socket and perhaps a few loosen and tighten taps from a persuader?

A few passes over gas burner pretty warm not ridiculously hot, use pliers quench under cold tap water. repeat.

 

[TwoManyXS1Bs]

... One thing I noticed was when I held the tensioner in my hand, when I pushed the spring-loaded damper rod all the way in, and I mean ALL the way until it firmly stopped (as if to put the least pressure on the chain if it was on the bike), the rod end wasn't flush with the little nut, it was still a few millimeters inside. Shouldn't it stick out a bit, and only be flush when it's actually on the bike? I'm just taking an educated guess.

Also, another question — Is a loose chain a dire situation? I'd like to do one last roadtrip before packing it in for the winter...

Larry, you've go the `74-`75 type "C" tensioner, unique rod length, someone may have put a shorter rod from a different model in there. I suppose you could make a little tool, like from a nail or piece of clotheshanger, and mark the depth of the rod end in the hole when fully seated, then use as your guage when setting tension.

DO NOT rotate the engine at all with the tensioner out if you suspect a loose/worn/stretched camchain. Rare as it is, another member here had a really stretched one jump 4 teeth.

The best possible torque you can get on that locknut (without damaging the aluminum housing), would be with it installed back in place. Sometimes takes a hammer smack on a long wrench to loosen those...