Chain tension

Wbcor

Active Member
#1
Hello all.
I’m really close to finishing my BC1300 restoration. Thanks to all the members here who support me.
My question/problem is that when I rotate the rear wheel the chain that goes from the jack shaft to the rear sprocket gets tight then loose as I rotate the wheel. It’s not the jack shaft or the gear on the jack shaft. It seems to be the 60 tooth sprocket being “out of round.”
I swapped a different sprocket and got the same result. There are three female studs that engage the Go Power wheel.
I suppose I could rotate the sprocket 120 degrees and see how the chain slack reacts. Wheels, bearings and axle are all in good shape.
Suggestions?
Regards,
Bill
 

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desert rat

Well-Known Member
#2
All right lets see if I can keep this one short. If the same bolts that hold the sprocket on hold the rim together you will need to let all the air out of the tire. Do not loosen the axle bolt at anytime during this process. Now slowly rotate the rim until the chain is at its tightest point mark the top of the sprocket so you can get back to the same spot in the rotation,this is you reference mark. Step two mark the center of chain /sprocket contact, if you have 15 teeth in contact mark the sprocket at tooth #7[not the chain]. Now it time to loosen the sprocket just enough that it will move. Find the tooth that you marked and place a peace of card board { from a spark plug box} in between the chain and sprocket covering three teeth and then rotate the assembly back to the tightest spot and keep it there. Now this is important, tighten the sprocket bolt closest to the tooth you marked first then the next closest working away from the card board. Now rotate the wheel and remove the card board and see if that fixed the problem. If so you are done if not you will need to remove the sprocket and file the holes just a little, don't get carried away. Repeat.
 

Wbcor

Active Member
#3
All right lets see if I can keep this one short. If the same bolts that hold the sprocket on hold the rim together you will need to let all the air out of the tire. Do not loosen the axle bolt at anytime during this process. Now slowly rotate the rim until the chain is at its tightest point mark the top of the sprocket so you can get back to the same spot in the rotation,this is you reference mark. Step two mark the center of chain /sprocket contact, if you have 15 teeth in contact mark the sprocket at tooth #7[not the chain]. Now it time to loosen the sprocket just enough that it will move. Find the tooth that you marked and place a peace of card board { from a spark plug box} in between the chain and sprocket covering three teeth and then rotate the assembly back to the tightest spot and keep it there. Now this is important, tighten the sprocket bolt closest to the tooth you marked first then the next closest working away from the card board. Now rotate the wheel and remove the card board and see if that fixed the problem. If so you are done if not you will need to remove the sprocket and file the holes just a little, don't get carried away. Repeat.

Thanks - makes perfect sense. I'll work through it and report back.
Regards,
Bill
 
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