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Chain Dragging Sound Behind Rotor

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ZillahBill
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Posts: 48
Joined: Sat Sep 16, 2023 8:56 am

Chain Dragging Sound Behind Rotor

Post by ZillahBill » Sun Dec 31, 2023 11:21 pm

Got everything put back together enough to see if I could get a bang out of the engine. Poured a little gas in it, turned the key on and hit the starter button. The starter turned over but there was a terrible chain dragging sound coming from behind the rotor. The rotor seemed to halt and then start to turn. I stopped immediately and started checking the forum. Based on my description do any of you have ideas and/or advice before I start tearing into it? The kick starter spline is so thrashed I dare not use it. Thanks in advance.

deuce_7
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Joined: Sun Mar 18, 2018 10:36 pm
Location: California Central Coast

Re: Chain Dragging Sound Behind Rotor

Post by deuce_7 » Mon Jan 01, 2024 11:14 am

After pulling all right-side engine covers, briefly bump the starter to inspect why the starter chain can be hanging up behind the rotor. Or if you don't want to risk damaging the starter, turn the engine over by hand with the rotor setting bolt.

Regarding the kick starter; 1) the splines on the kick starter spindle are damaged; or 2) the splines on the kick starter arm or damaged?
Attachments
starter chain.jpg
1967 CL77 305 Scrambler

ZillahBill
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Posts: 48
Joined: Sat Sep 16, 2023 8:56 am

Re: Chain Dragging Sound Behind Rotor

Post by ZillahBill » Mon Jan 01, 2024 4:04 pm

Well, I pulled the rotor. Required a little nudge with an impact wrench but it slid right off. It looks nasty. I didn't see anything that looked like springs or caps as provided in the rebuild kits. This unit spinning would have emitted a terrible racket so I think I have found at least part of the problem. I wonder what would have generated the torque to shear these machine screws? Is it repairable? Looking inside this starter clutch I see three rollers inside the starter clutch. Where are the caps and springs located? Do I need to take off the sprocket and chain or is taking it apart this far enough? Re kickstarter - splines on shaft are damaged. Starter motor will turn the chain and sprocket smoothly with no clatter after taking off the rotor and starter clutch. Pics attached
Attachments
starter clutch 2.jpg
starter clutch 1.jpg

deuce_7
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Posts: 130
Joined: Sun Mar 18, 2018 10:36 pm
Location: California Central Coast

Re: Chain Dragging Sound Behind Rotor

Post by deuce_7 » Wed Jan 03, 2024 1:04 pm

Like the immovable object colliding with the unstoppable force - something had to give. At some point, corrosion or mechanical damage froze the mechanism as the starter kept cranking. The good news is that the starter still operates (?).

Clean up the mess, closely inspect the parts, extract the sheared bolts if possible, and size up the situation. Parts (used and maybe new?) can be had to rebuild/reassemble the clutch.

Make sure the rotor keyway and woodruff key aren’t damaged.
1967 CL77 305 Scrambler

ZillahBill
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Posts: 48
Joined: Sat Sep 16, 2023 8:56 am

Re: Chain Dragging Sound Behind Rotor

Post by ZillahBill » Thu Jan 11, 2024 7:20 pm

Found a rotor/starter clutch setup on Ebay. Installed it and it is all good. I've got the bike running but have yet to try and ride it. I'm waiting on a clutch cable from Ebay. At every step of this project I've been a little apprehensive of the next step, in this case the clutch and transmission. The clutch was definitely stuck during teardown. Cleaned and burnished everything and put it back together. Wish me luck because I have zero experience working on a motorcycle transmission and would prefer to get experience at a later date.

deuce_7
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Location: California Central Coast

Re: Chain Dragging Sound Behind Rotor

Post by deuce_7 » Thu Jan 11, 2024 8:31 pm

Good to hear the engine is running while in Neutral on center stand and the rotor and starter/clutch are buttoned up with usable parts.

After you've completed all safety checks, clutch and brakes are correctly adjusted and you've determined the bike is ready, take it for a slow neighborhood check ride. You'll know quickly if there are transmission or clutch issues; e.g., balky or no shifting, skipping out of gear, won't go into gear, internal noises or vibrations, oil seal leaks.

Very encouraging progress!
1967 CL77 305 Scrambler

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Tim Allman
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Location: Guelph, Ontario, Canada

Re: Chain Dragging Sound Behind Rotor

Post by Tim Allman » Fri Jan 12, 2024 10:19 am

ZillahBill wrote:
Mon Jan 01, 2024 4:04 pm
I wonder what would have generated the torque to shear these machine screws? Is it repairable? Looking inside this starter clutch I see three rollers inside the starter clutch. Where are the caps and springs located? Do I need to take off the sprocket and chain or is taking it apart this far enough? Re kickstarter - splines on shaft are damaged. Starter motor will turn the chain and sprocket smoothly with no clatter after taking off the rotor and starter clutch. Pics attached
Don't underestimate the torque of a starter motor! It also looks like the rust weakened the screws.

Yes, it's repairable. First, be kind to the magnets. If you hit the rotor or drop it, the shock can diminish the strength of the magnets and good replacements are hard to find. David Silver Spares has some parts for sale although they aren't cheap. You may find some on Ebay too.

I would degrease all of the parts and remove the rust with something like Metal Rescue or Evaporust. Look carefully for cracks in the clutch piece. A crack will allow the clutch to expand when used and the rollers will not jam between the crankshaft and the clutch piece.

Your problem could have made the loose chain sounds. You can check for wear marks on the insides of the covers to see what the chain has been up to but I've never heard of anyone replacing this chain. Give it a good lubrication before installing the covers.

Have fun!

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