Topic: Stuck front sprocket

[Kong]

I have been trying to get the front sprocket off my 550K for the last couple of weeks.  I removed the retaining clip and expected it to slip right off, it did not.  I put a puller on it, nothing.  I put a puller and low (propane) heat on it, nothing.  I put the puller, heat, and banged on it, nothing.  I soaked it for a week in the best liquid wrench I know of (Aerokroil), did all of the above again, and still no movement at all.  I have put a lot of pressure on that sprocket.

So in the morning, if and after it gets warm enough to turn a Baboon's butt blue, I'm thinking I'll just go out and take a cut-off wheel to it.  Still, I'd like to know why its stuck and see if anyone has any last suggestions before I cut it off.  Oh, on this engine the PO use an O-ring chain and there is damage to the cases and seal below the forward edge of the sprocket.  I have a new (16 tooth) sprocket for it and planned to give the shaft a very good inspection and clean up if necessary.

Any last minute suggestions before I go break something?

Added on Edit  Is there anything under there I need to make sure I miss with the cutting wheel?

[jakecb420]

maybe try heating where the sprocket slips on with the propane torch and then spray it with penetrating oil. i find that pb blaster works the best for me.  when its hot the oil will suck into where it needs to be.  you probably already know this but i was just throwing it out there.

i would think tapping it with a puller on it would do the trick. everythings a project!

[754]

 Are you sure its not welded on? If so, get ready to split the cases.
 I had a sprocket spin out the centre while shifting at the drags, felt like a neutral, I pulled in the clutch and it welded itself. That held till the next burnout, well shortly after that as the tree turned green..  . So I had to wait till I got home pull engine, split cases, re & re shaft..
 Just mentioning it, cuz if that happened, you either weld it and keep riding, or do the re & re..

[Kong]

Nope, it wasn't welded on by anyone.  I don't know if its the original sprocket or not, the bike did have a replacement chain on it (the damnedable O-ring) but as best I could tell that was all that had been changed.  At first I couldn't get the retainer off, not understanding how it worked.  The works were explained to me and it came right off after a tap.  Then I expected the sprocket to follow easily.  No such luck.

I immagine it got galled somehow.  Once I cut through half of it I expect it will pop right off, if not I'll cut through the other half and either watch it fall off or bang it off with something.  Right now I'm just real interested in seeing what's holding it.

[754]

My guess is it galled due to the o-ring chain.
 If its galled and stuck, heating quicly with a torch, between shaft and outside of sprocket, may let it grwo enough to release it.. good luck..

[scottly]

I'm guessing the edges of the groove in the shaft have raised burrs, which are binding on the inside of the splines in the sprocket. Did the sprocket move outward enough to cover the groove where the retainer sits before binding up? If so, I would push the sprocket back on and carefully smooth out the high spots with a Dremel.

[seaweb11]

I think it may be just #$%*ed.

[scottly]

I think it may be just #$%*ed.

Pessimist!!!! 

[Kong]

Well, she's laying on the floor now, in two pieces.

I cut it off right above the output shaft and the remaining sliver of metal cracked right away, but even that didn't free it.  



With half cut off I had to put the puller back on and then use a cheater bar on the wrench on it to finally pop it loose.  It remained so tight that I had to use the foot long cheater to pull it half way off, and then it freed up.

The problem was corrosion, no burs, no nothing else.  The new sprocket (16-tooth, for you 550 guys) slipped right on easily by hand, just as it should.

In the process if cutting it off I nicked the upper case in two spots, no damage done there.  I also put a nice little cut into the output shaft, but didn't touch either the case or the seal (although I came within a few thousandths of an inch of it) where where output shaft exits the case, still, no damage done and I am happy enough.



I also then hit the area with a squirt of carb cleaner that was close at hand to wipe some crud off of the area.  I was please to see that minimal damage was done by the use of the O-ring chain; there is some cutting but it doesn't appear the seal was compromised.  What do you think?

[Bob Wessner]

If you had had a properly leaking shaft seal, the thing would have been lubricated.  Glad to hear you finally got the sucker off.

[Kong]

Thanks Bob.  I was thinking maybe I should go back out there and make the cut through the seal just a little bit deeper, that way the new sprocket won't get stuck in the future - and my wife could follow my trail to any tree I climbed up; and that my dear friend is a knot in the tail that I would just as soon avoid.   

[madmtnmotors]

Maybe some anti-sieze on the ouput shaft to fend off a repeat performance!

[754]

Never heard of that on a lubed chain bike..  Good luck trying to cut a sprocket off on a 750..

[seaweb11]

I told you