Chain Tension problem!

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FractaL64

New Member
May 8, 2013
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0
0
Canada
My bike's chain tension likes to go from really loose to really tight about every full revolution of my front sprocket.

I've installed a new 34T sprocket, and the problem is still there, so I've ordered a new clutch kit, a new front sprocket, and a new chain.

Its still rideable but I want to fix the problem obviously.

Ive been meaning to replace my clutch shaft anyways since its flared out on the clutch side.

How much of a pain in the ass is it to remove the entire clutch assembly and to replace the front sprocket? I've only ever opened my clutch open to replace the pads but I'm unsure of how to remove the large clutch gear, and the front sprocket for that matter.
 

bluegoatwoods

Active Member
Jul 29, 2012
1,581
6
38
Central Illinois
Well, to start with, are we talking about a stock china girl 2 stroke with with direct chain drive to the left side of the rear wheel? It sounds like it. But you'll want to confirm this to get the best advice. (That won't come from me because I'm not all that expert. But others'll come along.)

But are you sure that your problem is up there in the clutch assembly or drive sprocket?

The first place I'd look is at the rear sprocket. If that's not centered well on the wheel it'll cause the symptoms you've described. This is the usual cause, in fact, for your troubles.

And if the trouble actually is up in the clutch assembly, then it might not be worth your while to fix. A new engine is pretty cheap.
 

crassius

Well-Known Member
Sep 30, 2012
4,032
158
63
USA
assuming it is an HT, I've seen front sprockets sometimes that have a lip running all the way around just under the teeth - this might cause the chain to lift up a bit

take the cover off & the plug out and watch the chain as it goes around - if it's lifting off the sprocket, you can file/grind it a bit to make a better fit

most likely tho, is that the problem is at the back end
 

FractaL64

New Member
May 8, 2013
55
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Canada
It is a china girl, the thing is that my OLD 48T sprocket was VERY misaligned, but the issue wasnt so prominent.

Is it possible the chain or the front sprocket was worn down because of it which is causing the chain tension to vary? My rear sprocket and rear rim are both aligned well....

EDIT: I checked again, sorry I meant the chain tension changes every 1 revolution of my rear wheel, but again both the rear sprocket and my rear wheel are true.
The chain is rusted, worn and has been running for almost 6 months now with my OLD mis-aligned rear sprocket and my front sprocket likely has some wear aswell.

Doesn't the chain try to seat itself into the sprocket a certain way and with extended use of a misaligned rear sprocket it's worn it down in some places between the links, and less in others?
Maybe the chain is stretched?
 
Last edited:

CTripps

Active Member
Aug 22, 2011
1,310
1
38
Vancouver, B.C.
The only thing I can add would be to get it up off the ground, remove the drive sprocket cover (and plug), and slowly turn the wheel until the slack shows up. Then you'll be better able to see what's happening when it goes slack.
 

rustycase

Gutter Rider
May 26, 2011
2,746
5
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Left coast
Question... are you running the stock rag-joint rear sprocket mounting assembly?
It is most likely the sprocket is running in an eccentric pattern, or will be in a very short time.
Also, the stock chains are not a very good product. They should be replaced with better quality.

Best practice is all the fixes should be done at the same time, so one bad part in the system does not contribute excess wear to the good ones.

Have fun!
rc
 

2door

Moderator
Staff member
Sep 15, 2008
16,302
175
63
Littleton, Colorado
Your rear (driven) sprocket is not centered on the rear hub. Remove the chain, suspend the rear wheel and spin it while watching the sprocket. You'll probably see an eliptical (egg shaped) rotation of the sprocket. That's why the chain loosenes then tightenens.

Also you said your chain is "rusted and worn". Why? Do you not keep the chain lubricated? You should.

Tom
 

FractaL64

New Member
May 8, 2013
55
0
0
Canada
Your rear (driven) sprocket is not centered on the rear hub. Remove the chain, suspend the rear wheel and spin it while watching the sprocket. You'll probably see an eliptical (egg shaped) rotation of the sprocket. That's why the chain loosenes then tightenens.

Also you said your chain is "rusted and worn". Why? Do you not keep the chain lubricated? You should.

Tom
How would I go about fixing it then?

Also, I'm replacing the chain. I rode the bike in the snow a week ago, chain was lubed, but it still rusted. I always keep it lubricated.
 

FractaL64

New Member
May 8, 2013
55
0
0
Canada
Your rear (driven) sprocket is not centered on the rear hub. Remove the chain, suspend the rear wheel and spin it while watching the sprocket. You'll probably see an eliptical (egg shaped) rotation of the sprocket. That's why the chain loosenes then tightenens.

Also you said your chain is "rusted and worn". Why? Do you not keep the chain lubricated? You should.

Tom
How would I go about fixing it then?

Also, I'm replacing the chain. I rode the bike in the snow a week ago, chain was lubed, but it still rusted. I always keep it lubricated.
 

2door

Moderator
Staff member
Sep 15, 2008
16,302
175
63
Littleton, Colorado
Lots of information here on the proper way to install the rear sprocket.
If you're using the kit supplied 'rag joint' you must use a lot of patients and confirm that the sprocket is exactly centered on the rear hub. It also must be aligned precisely with the engine drive sprocket. It can't wobble and must spin true.
Here's some reading for you > http://www.google.com/cse?cx=partne....tab=0&gsc.q=Sprocket installation&gsc.page=1

Tom
 

rustycase

Gutter Rider
May 26, 2011
2,746
5
0
Left coast
HD, I don't know what "2.) Tubrobuick1 kit" is...

Would you post a link for us?

Tnx
rc

Definitely agree, though... IMO, a proper hub/sprocket adapter rates nearly as high as proper brakes for anyone serious about their motor assisted bicycle.
.
 

KCvale

Well-Known Member
Feb 28, 2010
3,966
57
48
Phoenix,AZ
My bike's chain tension likes to go from really loose to really tight about every full revolution of my front sprocket..
The front engine sprocket 1 revolution or the rear?

It sounds to me like a crappy front gear if it is every front gear revolution.

It is easy to diagnose, pull the plug so you have no compression, take the left side cover off and roll the bike around and see what is binding there because the rear sprocket is not likely the cause if every rotation of the front sprocket causes it.

NOTE: check the case metal and inside of that clutch cover for signs of the chain hitting either one as that I have seen and it is easily fixed with a small grinder to make a tad more room for fat chain.
 
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paintgun

New Member
Nov 17, 2013
90
0
0
Illinois
HD, I don't know what "2.) Tubrobuick1 kit" is...

Would you post a link for us?

Tnx
rc

Definitely agree, though... IMO, a proper hub/sprocket adapter rates nearly as high as proper brakes for anyone serious about their motor assisted bicycle.
.
In answer to your question, here is the Turbobuick1 Kit that HD was talking about:



You can get this on EBay or directly from him here on the forum.

http://motorbicycling.com/showthread.php?t=48647

I have one and it's one of the best things you can get if you insist on running a chain tensioner.
 

maniac57

Old, Fat, and still faster than you
Oct 8, 2011
4,484
22
0
memphis Tn
The proper way to deal with this issue is to properly center the rear sprocket on the hub. When the ragjoint is assembled right, you don't need a spring tensioner for high and low spots. Try loosening the bolts up and filling the gap between sprocket and hub with a strip of tin can. Anything to hold it centered while you tighten the bolts.
 

huffypower

New Member
Jan 26, 2014
27
0
0
carrollton, Mo
A little off topic here but about turbobuick1's tensioner...it is fantastic for taking any slack out of your chain. Trouble free and zero maintenance required. When I installed mine I had to get a 1/2 link for proper tension. With that installed I didn't even need a tensioner but like it so much and like the looks of it that I put it on anyway. Get one and get rid of that ugly troublesome POS tensioner that comes with the kit. After u get ur sprocket trued u should be good to go
 

maniac57

Old, Fat, and still faster than you
Oct 8, 2011
4,484
22
0
memphis Tn
I've bought over 20-25 kits from rose/zminglu/mingsinternational (all same vendor)
and had very good results and service.
Just remember to BE POLITE if you have any issues.
Screaming demands for replacement parts will get you blocked quick.