Slipped crank issue and that loud Wrrrrr noise !

Howdy all , I think I may have come upon an idea to fix my bike to get rid of that loud Wrrr sound that it has....which is the primary gear pushing on the clutch gear and making that noise
I Know the Proper method of repair is to pull the crank and replace it with a known good one....
however I don't have the finances available to do that .
the next possibility would be to pull the crank and tap the lobe of the crank that has slipped back into position and weld the pin so it can't move again....
however both scenarios require removal of the crank, something I'ed rather not do.
However , I got to thinking that sense the noise is the primary drive gear pushing against the clutch gear quite hard, why not just take a few thousandths off of the teeth on the primary drive gear to restore proper clearance ?
this definitely will not cure the problem with the slipping crank ,....I realise that... but it should stop the noise completely..... and it would only require the removal of the side plate and drive gear.....
shaving off say .005" off the gear would not be enough to weaken the gear at all , but getting rid of that sound is important to me...it drives me nuts, the bike itself runs fine like a brand new machine
and for my use I think it would last me the rest of my life the way it is without slipping more....
but I could be wrong there... and it could slip in a major way the next time it's ran. it's a gamble I'm willing to take....
Your thoughts and opinions on this idea ? Rants if you feel it completely necessary are also welcome
......
thanks !
Bob............

Ahh the Baron of Baraboo does it again ! the Road runner cartoons are my most favorite of all time ! a perfect example of
things do not go as planned !
LOL......
Bob........

I'm confused..........don't have the money to buy a second hand. crank........cost nothing to remove, crank alighn and tack weld ...........have the money to get the primaries re cut????????????

There is an oval in there somewhere..............just have to remember which side of the primaries had to be shaved to make the round, and then reinstall them to the crank shaft oval..................mmmmmm.............

I have my own small lathe I can cut the primary gear myself.... it won't cost me a cent to do that...
yes just removing the high spots of the Oval is a good place to start ...no doubt,.... finding and marking
the primary gear can be done while on the machine and that could be duplicated on the lathe so only the highspots are trimmed off
...is that what you suggest ?
Bob.......

If the crank slipped its no longer running true. You may be able to get the gears meshing OK, but the bearings will take a good bit of extra wear as things wobble. And if you ever fix the crank you'll have the same problem but in reverse.

Its honestly not that difficult to pull and true the crank. Worst case is it leads to the "while I'm here" syndrome.

Fix the crank

Bob, shaving down the OD of the crank's primary gear won't do it. You're dealing with the lash of the involute gear faces.



By now, the rightside crank ball bearing is shot, and it'll continue to make noise...

Ahhh.... I was hoping that the tips of the gears were touching in the trough between the teeth themselves.....
when I had it apart last time I put a slip of paper between the teeth and kicked it through and it tore the paper to shreds so there is no clearance there ..... fooie ! i bet your right too ! thanks 2M !
.....Bob........

I have an idea. A no-holds-barred, "what have I got to lose" idea. Mentioned it in your other thread. But, this is probably one of those "I hafta be there" kinda things, since it involves hammers, a lotta arm waving, and holding yer tongue just the right way...

let'er Rip 2M ! I'm good with a hammer ! LOL

Ok, re-read these posts.

http://www.xs650.com/threads/that-wrrrr-noise.50290/page-7#post-520729

http://www.xs650.com/threads/ggggarys-latest-xs-project-madness.28289/page-5#post-540541

Digest, let it stew, or ferment.
Questions?

The idea would be to remove the sump cover, rightside clutch cover, and the round leftside rotor cover. Leaving the engine in the frame. Lay the bike on its left side, propped up enuff to allow you to get to the rotor nut (to turn the crank). This also allows you to access the right flywheel.

Then, rotate the engine until you get max primary gear interference. This'll be either at TDC or BDC. Now, rotate the engine backwards 90°. The crank must be set EXACTLY at the 90° halfway point between TDC and BDC.

We're dealing with a flywheel twist on the crankpin.
All straightening forces have to follow these arrors.


At this position, the rightside (driving) flywheel needs to be *smacked* upward (toward the head), since it's displaced downward (to the ground).

The left flywheel in this pic.



Big hammer and brass punch.

Start at medium grunt. Rotate engine forward and see if the gear lash has lessened. Continue, harder if necessary, as needed. Use yer well-honed hammer-smacking skills. It can't move very far. After all, the crank is still in the engine.

Note to others: This is STRICTLY a Bob Kelly thing...

AHH Yes ! I remember that well 2M ! but here is the rub..... the entire problem as I see it, is it is only a very tiny amount of twist to it...
smacking with a hammer may well fix that or may well put it that much further out.... i think for the small amount it is off i would need to dig out the dial indicator just to see what is the high side and which is the low side...the difference is that small easier to see when it's turning fast but turning by hand you can't see it at all.... it could be at factory specks for all I know LOL....( i seam to recall +-.005 for the tolerance and I doubt it is that close so it's out some .... how much I do not know....
... I really didn't want to tear down the entire engine..... i've been putting it off trying to think of any method that would keep me from having to do that.... but.... if that's the only method then I have no choice if I want to ride it ! then again I could just sell it and buy a dirt bike ! HAHAHAH
thanks for the help 2M I believe I can indeed make your idea work.... and it is a good viable option..... THANK YOU !
Bob......


....

Hammer/drift tricks.

If the drift is held in direct contact with the flywheel, the *smack* has to move both the drift and flywheel, good for light movements.

If the drift is held about 1/8" away from the flywheel, then the *smack* will accelerate the drift, and BOTH hammer and drift will deliver their blow to the flywheel. Good for major movements...

Bob Kelly III said:

...it is only a very tiny amount of twist to it...
...i would need to dig out the dial indicator just to see what is the high side and which is the low side...

Click to expand...

That would be better. Pull the crank primary gear, and take readings directly on the shaft...

if I do that 2M I'll remove the crank as I don't want to take the chance of splitting a case.....
not having a flat stone surface to work from or the dial indicators to go along with it, getting something like that back to dead nuts ON is not going to be an easy task..... I know my limitations and i think this would push them to the max ! LOL....
but ... if I did take it out and true it and then zap the pin with the stick welder a short weld it should stay for eternity.
but there would be no future rebuilding of the engine after welding the pins, and if ya don't weld the pins it will slip again...
....I dunno...i'm still thinking it over ! LOL
thanks guys !
Bob.........
Seriously, any sane human wouldn't do this, but I don't have much choice so just because you saw it here on this site doesn't mean it's a smart thing to do ok ? don't do as I do ! <GRIN>

If this works, and you end up with a reasonably true crank, then you could followup by replacing the rightside ball bearing. That's an engine-pull task, but can be done without complete teardown.

Follow Davem222's saga:

http://www.xs650.com/threads/high-pitched-mystery-sound.23162/

I replaced my rotor a couple of weeks ago and took the opportunity to put a dial gauge on the taper. I got bang on 2/1000 which is the maximum of specification. I will check the other side next time I change the oil. Is there any consensus as to what the the typical value should be on bikes considered to be "Good"?

Changing the right bearing: Is this easily done by raising the crank an inch or two with the pistons still in the bores? I recall changing one in about 86 on a 1B and I had the crank right out on a bench. The bearing was very tight and I had to wedge a screwdriver behind it and slowly lever it off the crank. Is it really a pulley puller job??

Edit: Just realised that the cam chain will prevent raising the crank. So is changing the bearing and straightening the crank best done with the crank fully removed?

Bob you seem to know what the symptom is, the practical solution is a different engine. You just haven't devoted enough of your resources to finding one nearby. Have you run a craigslist ad begging for one? Trust me you can have your engine out and on the bench in a couple hours TOPS. Most report it taking about 45 minutes barring the rusted in bolt or two. Cleaning, painting parts only seen during an engine swap will slow things down a bit.