New Chain and Sprocket--Now got a problem!!

02yz125

Member
Sep 25, 2001
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Ok here's my story! Went out and purchased a new 51 tooth sprocket for my bike. Figured out the stock chain was too short so then I ventured out and bought a new o-ring chain. I installed the sprocket (Sunstar Aluminum), put the chain on and cut it to length. I set the chain to the spec tightness and tightened everything up. I spun the rear wheel with my hand and noticed that it was "dragging" somehow. Well I chocked it up to the chain being new and "stiff". I then compressed the brake piston on the rear brake and it spun more freely. Then I began to wonder. I double checked the alignment of the tire. It was good according to the marks, but I have heard they can be off. I rode at Muenster yesterday and noticed with throttle closed the bike would slow down faster than normal. Also the bikes rear brake would lock up with the slightest pedal movement. So now to my questions. First of all the bike is really new with no damage to the rear wheel, brake caliper, or swingarm. Rear wheel bearings are in good shape. What is a sure fire way to align the rear wheel in the swing arm? Is the rear disc so fragile (side load) that I could of bent it changing the sprocket? Is an O-ring chain really that stiff? I'm a pretty mechanically inclined person (aircraft mechanic) and have looked at everything visually. I guess I need to pull everything off and start with just the wheel and no brake. Then add brake with no chain. Maybe chain with no brake and try to isolate the problem. Also check disk run-out. Are these expensive? I need all input and method for wheel alignment, moral support, etc....
 

MX-727

LIFETIME SPONSOR
Aug 4, 2000
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Measure the distance from the swingarm mounting bolt to the rear axle. Measure on both sides of the bike. The distance should be the same.

Make sure that both pads didn't end up on the same side of the rotor, it can happen and you might not notice at first.

Make sure the chain isn't too tight, and make sure you went through the rear guide instead of under it. (don't ask :confused: )
 

JTT

~SPONSOR~
Aug 25, 2000
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I agree, check the runout on the disk, but I would be surprised if you were forcefull enough to bend it changing a sprocket. For future consideration, get yourself a 5 gallon plastic oil pail, or paint pail, and use this to support the wheel while doing any type of wheel maintenance (tire change, bearings, sprocket, etc.). It not only protects disk, but puts the wheel up at a level that is not so rough on the back.

As for the alignment, do check it, the factory marks are often off a little.
 

thorman75

"Team Army"
Member
Dec 9, 1999
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i just had a 01 yz 125 over here with what sounds like could be your problem,the owner changed a rear tire in his case,on reassembly he didnt install the caliper carrier into the swingarm correctly.
 

02yz125

Member
Sep 25, 2001
162
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well I took my chain off and it doesn't seem to be the brake. Maybe a little, but it seems like the chain is really stiff. New DID o-ring. Sucker is like a wedding penis!
 

thorman75

"Team Army"
Member
Dec 9, 1999
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wheel spins easy without the chain.good. remember a o ring chain is wider than a regular chain so it drags in the chain guide too
 

RM_guy

Moderator
Damn Yankees
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Nov 21, 2000
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An o-ring chain will have more drag than a non o-ring. Once they warm up it is suppose to be negligent but I don't believe it. If the wheel turns freely with out the chain, don't worry about it. And like Thorman said, it is wider and may be rubbing on the chain guides but that will wear in after a while.
 

Camstyn

LIFETIME SPONSOR
Oct 3, 1999
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Definitely.. If you went from a non-oring chain to an o-ring it would definitely be rubbing in the chain guide block.. Plus, if you put a bigger rear sprocket, it would be rubbing even more. This sounds like it is likely the case. After 3 or 4 rides it should be normal, or at least close to normal.
 

02yz125

Member
Sep 25, 2001
162
0
I found the problem!!! But now I need to know how to correct it. The chain has been rubbing the case next to the sprocket and the gear lever. Maybe the bike cant use and o-ring chain. If thats the case I got one for sale. Can the sprocket be shimmed out away from the motor? This sucks a big one!! Help me out fellas!!
 

Jaybird

Apprentice Goon
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Mar 16, 2001
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Charlestown, IN
Make 100% certain that your sprockets are lined up perfectly straight with one another. A quick eyeball from the back with the chain off is where to start.
 

Camstyn

LIFETIME SPONSOR
Oct 3, 1999
2,247
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What kind of chain is it? Some o-rings are wider than others.
I had a Regina O-ring on my '00 KX250 and it scuffed the cases a bit around the front sprocket but nothing really worth being concerned over. The DID X-ring chain seems a wee bit narrower, when I put them up against each other.
Some front sprockets are thicker than others, too. Can you wiggle the front sprocket when there is no chain on it? How hard was it to get the snap-ring on the shaft to hold the sprocket on?
You shouldn't case any problems if you put a thin washer behind the front sprocket, as long as you can get the snap ring back into its groove on the shaft to hold the sprocket in place.
 

MX145

Member
Dec 29, 2001
131
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Spacing Out

I would take the o-ring chain off and sell it for what you can get. It's not worth the hassle and replacement of countershaft lock washer (no snap-ring like the KX) Your YZ has a collar that the sprocket rests against and then the lock washer and nut, I wouldn't suggest putting a spacer between the collar and sprocket, It may change the load on the transmissions drive/axle and bearing. As soon as I purchased my '02 - I put on a DID 520 ERT Gold Chain and Renthal 51t rear sprocket - Haven't had a single problem. Just got done putting together another identical setup on my Bro's '02 YZ125 as well. Good Luck To Ya ! :)
 

MXP1MP

Member
Nov 14, 2000
1,845
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This was exactly what stopped me putting the o-ring on my bike cause it was rubbing the casing. The problem is cause the o-ring chain is wider than a non-o-ring. Non o-ring's are 19mms across from one side of the pin to the other side of the pin. I run DID o-rings cause they are one of the smaller ones in width they are 19.5mm across so are tsubaki's. Most fall into the 20 mm wide across like regina's pretty much everyone else. There was a 1 or 2 brands/style of chains that were 20.5mm's across. (I got this info long ago after a huge debate about it so don't ask me if the actual measurements are totally spot on)

On the yz when you line up the chain on the inside of counter shaft sprocket the pins on my did chain knock against it. Fearful of braking the case I opted not to run it. The clearance that was lost by the o-ring chain which happens to be the 5mm's it lost cause of the width.

I have yet to install the chain, running the oem'er still (can't believe its lasted since august) but I have two more teeth in the rear (hence new chain) and its running really tight I got like inch and half maybe in slack. The chain is still tight i'm shocked/amazed the honda had the same chain and it was toast after two rides.

I still don't trust the chain, someone suggested I run one of those washers behind the sprocket but i'm not so sure now. I don't think it will line up properly quite right. I need suggestions on how to get around this? Would a case gaurd be enough? Am I destined to run non-orings forever? :uh:

MX154: hey do you race the arenacross series?? I race 125 beg & bth beg/jr

my #439
 
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