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Author Topic: Broken Rear Sprocket Teeth  (Read 637 times)

Superchuck

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Broken Rear Sprocket Teeth
« on: August 08, 2014, 01:45:26 PM »
Greetings all.  I'm compulsively inconsistent on the forum, and last night I came across something that needs guidance.  My bike was parked outside, covered for about 7 months with very little use.  Only started it a handful of times.  This week I got it going and it ran like a charm.  Got it all cleaned up and took it for a spin yesterday after work.

It ran great... has some great acceleration due to the free-flow mods and jetting I did last summer.  Unfortunately I realized that when accelerating quickly, I started shearing off a few teeth from the rear sprocket.  Only did it twice then stopped and realized what the noise was.  When starting gradually, it's doesn't slip at all.  Regardless, I want to replace this. 

My AVL has 8000 miles on it, so the chain is in need of replacement anyway.  I assume a loose chain is what caused the tooth loss in the first place... chain slipping up high on the teeth combined with my throttle hand while accelerating.

Tonight I will tighten the chain to hopefully prevent this from getting worse, and I'll just accelerate gradually until I fix the sprocket.  A few questions though:

I hear the rear sprocket is attached to the rear drum brake.  How elaborate is this fix, and do I need to replace the drum as well?

I will be replacing my chain too.  Is it necessary to replace the front sprocket as well when replacing the rear one and the chain?  I know in non-motorized bikes that they 'wear together'.  particularly the rear gear and chain though.  Not necessarily the front sprocket.

Any advice from the masters?  Looking to get it into shape again and get some serious riding under my belt.  It's been way too long!

Thanks in advance,

Chuck

ace.cafe

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Re: Broken Rear Sprocket Teeth
« Reply #1 on: August 08, 2014, 01:57:21 PM »
The rear sprocket is an integral casting as part of the rear brake drum. They are not separable. You will buy a new drum and it will have the sprocket teeth on the rim, just like the one you have now.

You won't be riding long with those teeth broken off. The rest of them will come off in just short amount of miles, regardless of how you adjust the chain, or how you ride. The sprocket and chain are finished.

Check the front sprocket for wear or broken teeth. If it is okay, then it doesn't need to be replaced, but it doesn't hurt to replace it if you want to. It's probably okay. It's the rear one that shears all the teeth off with a worn chain.

You may need a new cush drive rubber. This is the rubber cushions that are between the drum and the hub in the rear wheel. If it doesn't look perfect, get a new cush drive. They are cheap. The cush drive will save your gearbox from ruination. If the cush drive goes bad, it will kill the gearbox.
« Last Edit: August 08, 2014, 01:59:54 PM by ace.cafe »
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Superchuck

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Re: Broken Rear Sprocket Teeth
« Reply #2 on: August 08, 2014, 02:54:33 PM »
Thanks for the info- do I simply want the chain and sprocket overhaul kit from our hosts, or am I better off getting an aftermarket chain?  I like my gear ratio where it is now, so not looking to go up or down a tooth on the front.

http://nfieldgear.com/enfield-store/chain-and-sprocket-overhaul-kit.html

ace.cafe

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Re: Broken Rear Sprocket Teeth
« Reply #3 on: August 08, 2014, 03:26:40 PM »
I have no experience with that kit.
The sprockets are what you would need to get anyway, but I don't know anything about what chain is in that kit.
I'm sure it would get you back on the road for a time.

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Superchuck

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Re: Broken Rear Sprocket Teeth
« Reply #4 on: August 08, 2014, 05:30:33 PM »
Agreed.  The stock chain has lasted me 8000 miles thus far.  No reason a stock chain won't be good enough for the next 8000. 

I'll check out my front sprocket and if it needs replaced too I'll just get this package deal.  If it's fine then I'll start looking into aftermarket chains as a possibility.

I want to replace the cush drive rubber too, just to be safe.

Thanks again- I'm sure I'll have a few more questions when I get into rear wheel removal, etc.

Cheers,

Chuck

Arizoni

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Re: Broken Rear Sprocket Teeth
« Reply #5 on: August 09, 2014, 04:35:06 AM »
As Ace says, the front sprocket is probably all right but it doesn't hurt to check it.

I'm assuming Royal Enfield makes its front sprocket like most other makers so it is made out of steel and it is heat treated to make it hard.  That keeps even a funky chain from messing it up.

The rear brake drum and sprocket are made out of a iron casting so the teeth are not hardened or strong.  A loose or worn out chain can play havoc with it.

That's why I replaced my OEM chain at 3000 miles and I check the chain adjustment every 500-700 miles. :)
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Superchuck

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Re: Broken Rear Sprocket Teeth
« Reply #6 on: August 11, 2014, 12:52:05 AM »
Good call on the frequent adjustment- I'll be sure to do so in the future.

Checked the front sprocket and it seems to be perfectly fine.  Going to search old threads now for recommended aftermarket chains.  Hoping this doesn't leave me off the road for too long.

Thanks again!
Chuck

barenekd

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Re: Broken Rear Sprocket Teeth
« Reply #7 on: August 11, 2014, 10:01:26 PM »
Rhe stock chain is crap. That is what tore your sprocket up. Get new sprockets from CMW. Get a new chain from Tsubaki, DID or some other reputable chain dealer. If you use the Indian one, you'll maybe get another 8000 out of it, then have to replace everything again. If you use a good chain, you should be able to get well over 20,000 out of it and might even still have good sprockets!  And you wont have to adjust you chain every 3-400 miles!
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REpozer

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Re: Broken Rear Sprocket Teeth
« Reply #8 on: August 11, 2014, 11:04:16 PM »
Super Chuck, you must have up jetted your carb too much. Please use only half throttle as not to snap off any more sprocket teeth. Yes, let your jets cool.
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Superchuck

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Re: Broken Rear Sprocket Teeth
« Reply #9 on: August 12, 2014, 01:19:40 AM »
Haha yes the new machine is a monster compared to how it ran stock.  Ordered the sprocket and cush drive rubbers today from CMW, and a DID 530 roller chain, 100 links from amazon.

I counted my stock chain today and it seems to have 95 links.  I've heard to get an odd number you need a half-link?  Didn't buy one of those... is it needed? 

Is it bad to just cut down the 100 to 94 or 96?  Advice? 

Thanks!

Chuck

REpozer

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Re: Broken Rear Sprocket Teeth
« Reply #10 on: August 12, 2014, 01:48:43 AM »
I did not buy a half link. I think I am one link over now. I used a grinder and hammer and punch to get rid of a few links.
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Superchuck

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Re: Broken Rear Sprocket Teeth
« Reply #11 on: August 12, 2014, 12:30:17 PM »
I'm assuming that number of links isn't that important since you adjust out the excess slack with the rear wheel cam adjusters anyway. Safer to do 96 links then I'm assuming?

REpozer

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Re: Broken Rear Sprocket Teeth
« Reply #12 on: August 12, 2014, 04:24:52 PM »
Yes, I have 96 links on a DID 530 chain.
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ERC

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Re: Broken Rear Sprocket Teeth
« Reply #13 on: August 12, 2014, 09:37:49 PM »
Just hope when you install it you have enough to adjust it without being to tight or loose. 95 is just right.  ERC
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Superchuck

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Re: Broken Rear Sprocket Teeth
« Reply #14 on: August 14, 2014, 01:34:37 PM »
Cool yeah I think it'll be fine. My 95 link stock chain is super stretched out and there's still room to tighten.

Any pointers for the sprocket and cush rubber replacement? The parts should be here today or tomorrow.