High Pitched Mystery Sound

this thread is better than a TV detective drama lol:D

I guess if the extra washer and /or the dissassembly /reassembly has reduced the rotational friction somewhere on your crank/clutch then yes it would feel easier to turn the engine over.

the only other reason I could think of for easier engine turnover is if you had changed your timing in any way ?

Regarding the rubbing noise.... I'm beginning to wonder if the rubbing is only occurring during high engine load because a bearing or a thrust washer has gone somewhere in the transmission.?

The heavier load is obviously causing something in the transmission to move out of normal rotational alignment.

Have you checked to see if there is any crankshaft float ?
 
I know right? It's like CSI except instead of an x-ray spectrometer, I'm using a $3 screwdriver. It's under any sort of load, not just high load. I have not checked for crankshaft float, mostly because I don't know what it is lol. What is it and how would I check for it? I did a search here for it but couldn't find anything.
 
well its basically axial movement along the axis of a shaft due to worn or missing thrust washers or damaged bearings.

I was just thinking out loud here as I have no experience of crank float on a XS650 engine.
I think as long as you have fitted the half-moon rings/clips to the crank bearings there should be no float in the crank .

if the crank or output shaft had any movement axially or rotationally then something would rub somewhere .
 
Gotcha. Hmm, suppose I'll have to open it up again and look at the crankshaft :) This is great, I'm learning about all the parts of the engine I didn't before! Also, thanks on the kickstart thing, maybe that's it that with the thrust washer there there's lest rotational resistance. I'm hoping it took a few kicks to start the other day just because I hadn't ran it in a couple of months.

D
 
don't take it apart yet :eek:

Its got to be something obvious we are overlooking . Any chance of another video ? maybe about 1x minute long so we can really hear the sound . perhaps move the camera around the engine so that the mic can pick up sound from different angles.

Have you tried putting a long wooden dowel on your ear and listening to various parts of the engine casing ? try to narrow it down a bit
 
I can't say much about your noise but if you worked on the clutch, that maybe why your kickstart isn't right.
The kickstart engages with gears in the transmission to turn the input shaft. The input shaft is what the clutch hub bolts to. When the kickstart turns the input shaft, the hub turns, as the hub turns the plates are pressed together and turn the clutch basket that is geared to the crank.
If you have your clutch adjusted a bit to tight the plates are not pressed together and the clutch slips.
So to fix your kickstart adjust your clutch.
Leo
 
I hope by now that you've figured out your high pitched noise but if not ...it may sound silly but I had one and it would sound like everything from everywhere. It ended up being my speedometer cable and was resonating through the forks and the tank and I also thought from the engine. I put the bike on center stand and propped it up so could spin the front wheel and there it was that noise!! Hope it's an easy fix like mine,grease the sleeve and keep riding. GOOD LUCK!!
 
Ok so I'm about to get back into the engine now that work has cooled down and the weather is beginning to get nicer. I'm thinking I may get a stethoscope and find the location exactly. I figure I'll remove the drive chain so I can run it under load and have it not crash through the wall of my garage :) Here's my question: Let's assume for a moment that the high pitched sound comes from worn bearings/washers in the transmission (which may be the case as it only squeals under load). If that is the case, is it possible to remove and replace the bearings/washers without removing the engine and tearing it down? It seems like the bearings are all located on the sides of the engine, can I just remove and replace them through the side engine covers? Any insight is appreciated. Thanks :)

Dave
 
No,the only way to change the tranny bearings is to pull the engine, flip it upside down, spilt the cases. Swap out the new parts for old. Put the lower case back on. Install the engine.
If you can think of a way to split the cases with the engine inplace then more power to you.
Leo
 
Ok, so there's more in the saga of the high pitched noise. Today I started to work by lifting the back wheel off the ground. I figured I could run it in gear and have the wheel spin and with my stethoscope figure where the noise was coming from. Only thing was, when I ran it with the wheel off the ground (no real load) there was NO NOISE!
So I think we can eliminate the entire top end and even the clutch, right? Someone had mentioned some sort of axial drift, could that be it? Could it be that when the rear wheel is under real load it pushes something to the side which rubs on something? I'm seriously perplexed. I'd rather not break down the entire engine and completely rebuild the bottom end. Anyone have a thought?
 
Is your chain aliegnment straight? Also while the rear is off the ground, spin your tire and look for any abnormal tread movement. I've had car tires with tread problems that make high pitched sounds like you are discribing.
 
I can't see how it would be the wheel or the tire since the bike makes the squealing noise in proportion to RPM when under load, NOT tire rotation. It can squeal when the clutch is even a little engaged but slipping and the bike is not moving at all. I'm thinking that maybe there's a missing washer or some sort of something worn in the transmission so that when the transmission is under tension from the load it moves a little and rubs against something. Does this sound feasible to anyone?
 
Hi Dave -

Just found this thread and it's been a fascinating 20 minute read :)

You mentioned earlier that you rebuilt the engine. Did it make this noise prior to the rebuild? And did you rebuild the transmission along with the engine? If not, my thinking is that it wouldn't be anything in the gearbox that's missing - or even worn - as it would be quite the coincidence if wear noise were to start immediately after the rebuild. If you did rebuild the transmission, maybe something was installed incorrectly. Odds are this noise is the result of something that was done during the rebuild.

I'm not sure that the lack of noise with the wheel off the ground eliminates the clutch - as you mentioned, there's virtually no load under those circumstances and the clutch internals would move around a fraction with a higher load. There's a red flag waving over the difference in the kickstarter feel, in my opinion, as that started at the same time as the noise, right?. If the clutch is slipping very slightly on my BSA, I get that same feeling of reduced resistance in the kickstarter. I'm new to the XS650 but I understand from earlier in the thread that the kickstarter drives the crankshaft through the clutch and that as soon as you begin to engage the clutch with a running engine, you hear the noise. So what's between the kickstarter and the crankshaft? The clutch and the primary drive. My two cents worth is that's where you'll find something.:twocents: Man! It's tough diagnosing something from a distance, isn't it?:umm:

Good luck!
 
Hi, Dave.
Man, I love/hate a mystery...
Looks like you've got it isolated to between the clutch basket and the primary gear.
Cheap test (I love cheap):
Closely observe your shift lever, note position. Grap it and yank outward. If it moves, then the shift shaft restraining circlip may be displaced or missing.
Here's the thinking:
You say it makes noise not rolling, but by releasing the clutch and applying load?
The clutch basket is free wheeling until clutch release. During clutch release and under load, the basket will displace to the left, and may rub the shifter mechanism (It is close in there).
It may rub other things behind there, too. The frequency of the 'whirr' on your video sure sounds like primary drive sound to me.
Good luck!
 
Continuing,
Lets do a little math (*gasp*).
In your video, lets assume the whirring sound is at about 1 khz (find a musician).
Also, lets assume the engine was going about 3000rpm. That's 50rps. (divide by 60).
1000hz sound at 50 rps means 20 events per revolution.
What occurs 20 times per engine revolution?
What's the number of teeth on the crank primary gear?
What is the ball roll rate on the crank primary bearing?
What am I doing here? (been up all night, going to bed)
Good night...
 
Heya Twomany!
Thanks for the interest and the insight. It's funny you should mention that, the shift mechanism DOES in fact have a bunch of freeplay side to side. I've also had a few instances in the short time since I've rebuilt the engine (top end and clutch only) where the screw that holds the little five-pointed star retaining wheel that the shifter arm pulls (on the left side of the engine kinda behind the clutch and to the left) has come out. I've had to red-locktite it. So maybe it is the shiftshaft restraining circlip! Wouldn't that be awesome! Shit man, I'd have to send you some beer. From what I understand that circlip is on the left side of the bike in front of the oil seal for the shift shaft. Can't wait to look!
 
Yes, with a flat washer (#8) under it to keep it from digging into the seal (#7) .....

ShiftShaftReduced.jpg
 

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