78 XS650 Whirring sound

[xjwmx]

Bent crank? How does that happen in routine operation?

In my case at least, the starter apparently somehow caught funny and there was a bang! and that was that. Now I always keep my thumb on the button until after the engine starts and the relay turns the starter off. In 4G's case, maybe his 750 kit was too much for it. They're pressed together, not welded.

If it is the crank, the good news is they're fairly cheap on ebay, and occasionally even cheaper here in the classifieds. The rods will be attached and you connect them to your pistons using new wrist pin clips. I've also heard of pitted bottom end bearings making noise

 

[thuban]

Woof! Sounds like more than a couple of beers job!

 

[Jan_P]

Sorry
I was listening to the wrong video ---the one from Machine
Not this one Sorry about that .
Never heard this Sound Before
A longer video with sound from both sides.
Up and down
I get the impression engine has problems turning not running even.
Bearing ? But go for others advice Since I have not heard this. before.

With at steel rod or a screwdriver to your ear and holding against the engine one might better localize it

https://www.quora.com/Why-did-old-s...-long-screwdriver-to-a-motor-and-listen-to-it

 

[Raymond]

Agree with Jan - I've successfully used a long screwdriver as a stethoscope to locate source of engine noises. Opens your ears to all the noises going on in there.

 

[clegg]

The bike actually runs fine

 

[thuban]

Well, if it runs fine, idles good and there were no rubber bits in the sump. I think I would ride it and keep an eye on it. But it has to be something. My bike sounds like Machine's and Jim's, which I think, Is normal for the XS. There is literally hundreds of years experience with XS's on this site. Jim and xjwmx are two of the top many Big Kahunas when it comes to the XS. If they are the only ones chiming in, it's a rare problem. I'm gona say, all things being equal, it may be a gear mesh problem. If the crank is not bent, maybe a worn gear or support bushing? If so, expect for the whine to get louder. With only 5k miles..? I would try to isolate the noise as best I could. Also with a gear mesh problem, when the oil is thick and cold, the noise should be less, I think. Sorry I can't be of more help. I know if bothers me when my bike is not just right.

 

[clegg]

Thank you to everyone that has responded.

I have the carbs off right now (BS38's) to check my sketchy idle. The left carb had a bleed type pilot and the rh one had the non bleed. Luckily I had some non bleed type at hand.

I have not checked the right side of the crank yet. If that all looks fine. I will then pull the sump and check for pieces of whatever. I may also swap to 20/50 oil.

It's crazy that it runs fine, but my daughter even commented on the sound!

 

[member28833]

but possible chain tension or guides..

I'm betting you answered your own question suspecting the front cam chain guide.
Hope it all goes well for you

 

[Jim]

If that all looks fine. I will then pull the sump and check for pieces of whatever.

Just thinkin' out loud here... It might be possible to check the crank from the sump. Watch the outer cheeks as you rotate it and see if there's any wobble. Maybe attach a piece of safety wire as a reference pointer. Might want to try that before you pull the right cover.

 

[clegg]

All good stuff here. I will try that. Thanks.

 

[clegg]

Got the sump off. Not too bad inside, besides that piece that I am assuming would be part of the cam chain guide

 

[thuban]

..on one of the edges I think.

 

[member28833]

Very interesting sump screen there. That is not a "virgin" its been patched like so many apparently. And yes, the black strand is almost certainly a piece of the guide

 

[xjwmx]

The right cover is just another half hour. Take the peg and the kicker and the brake pedal off, one bolt each. Take the tach cable out. Get a 5MM allen for your ratchet to do the cover bolts. 3/16" will work too. With one of the screws the frame is in the way but a 1/4" extension will get through. Pop the cover off without prying too much. If it has the factory gasket, it's reusable many times. As the Allens come out, lay them in order to make it easier getting the lengths right when you put them back. Don't let the cover pull the kicker shaft out.

P.S. the pic definitely looks like a rubber piece from the guide. When I had my engine apart with the "bent" crank, one end of the crank was sitting up out of the case like 1/4" or more -- that's got to be some bad stress on the case to run it that way.

 

[Rasputin]

Just watched your video, I’m not an expert but I would say the cam chain may be too tight. Just out of interest try slackening the adjuster off.

 

[clegg]

Here's the rh crank side. Does anyone see anything out of the ordinary?

 

[clegg]

@Rasputen- I have adjusted the timing chain to spec and tried loosening to no avail.

 

[Jim]

Here's the rh crank side. Does anyone see anything out of the ordinary?

You're gonna have to mount the camera to something to be able to see any runout. It's too jerky.

 

[xjwmx]

Yes, hard to tell with the camera moving. You've got the plugs out; when you turn the crank slowly by hand do you feel roughness or clicking or binding anywhere?

 

[gggGary]

Looking at that sump filter, is that orange RTV on the top right?
Open an exhaust valve cover, if you look in you can see some of the cam faces, how do they look?