problem :/

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maximillian

New Member
Jan 17, 2010
30
0
0
seattle
I need help! I had a grubee skyhawk and it all worked fine but I chipped the cylinder so i bought a new, slant head engine. It has a bigger, heavier duty chain. I installed it, put the new sprocket on and when i tried it out, the chain just jumped off. I assumed it was too long, shortened it. Then i tried it out and started to work and then all of a sudden, The chain jumped off and tore apart. Im not sure what is wrong...maybe my tire is hitting the new chain and then causing it to jump off the back sprocket? could i solve that by buying a smaller drive gear and putting my old grubee chain on? :-||

thanks -max

:-||
 
M

maximillian

New Member
Jan 17, 2010
30
0
0
seattle
I just checked and it wobbles a ton! also the chain was tight but i wassnt using a tensioner...mine is broken. How do i make it so the back sprocket doesn't wobble?
 
Bikeguy Joe

Bikeguy Joe

Godfather of Motorized Bicycles
Jan 8, 2008
11,837
252
63
up north now
Loosen all the bolts and cross tighten them slowly while checking for straightness. Don't over tighten the chain (3/4") play is about right.
 
Mac

Mac

New Member
Dec 3, 2009
486
1
0
Maine
Max,
Sometimes in addition to the wobble thing, the new sprockets need to be dressed a bit, the teeth are not tapered enough, dremel or I used a 7" 80 grit grinder with the sprocket spinning, carefully, held at an angle of 30 deg to the plane of rotation, make a taper on both sodes, just a bit, don't go overboard, both sides of the teeth tips. As far as the wobble, if your using a rag joint to mount the sprocket, you can get rid of the side to side wobble by finding the high track and torque the 3 bolts more (there is 9 ususally) where the sprocket is high or farthest from the spokes, uf you have a low or close spot, loosen a bit, not too much, don't forget Blue Loctight on all threads. Hope that helped.

Mac
 
M

maximillian

New Member
Jan 17, 2010
30
0
0
seattle
I looked at it again and im sure the chain is hitting the tire. I never had problems with my old grubee chain and I still have my old grubee chain. Is there a way to replace my drive gear that fits with my 415 chain with one that fits woth my grubee chain? and where can i buy a drive sprocket that fits with my grubee chain?
 
Z

zaviii

New Member
Oct 17, 2008
65
0
0
Chico, Ca
Yes, MAC is right tapering the sprocket teeth on both sides is very wise. This works somewhat as a self guide to the chain which makes it much much less likely to jump off. If you can get your rag joint sprocket alignment within a few mm wobble that's fine, but taper the teeth, its insurance. Good Luck...

https://savegasmoney17.com/gtmdecals.htm
 
chopperjoe

chopperjoe

New Member
Nov 15, 2009
130
0
0
bourbonnais il
Try turning your spocket around, it has a concave shape and by flipping it you can gain 1/4 inch of clearance. When I install the spockets I have an adapter for a 1/4 drive socket that I put in my drill its about 6 inchs long, and set torque on the drill to almost max that way all your bolts should be the same torque just make sure drill is fully charged before you start, and man that 6 inch drive adapter makes that job twice as fast, I now can install a sprocket in about 10 mins.as long as I dont keep dropping the damn parts, remember se the drill to almost max torque not the drill mode, or you might strip them cheapo bolts.
 

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