Drive sprocket too large?

[frostic]

Hello, I recently got an 80cc engine kit and put it on my cruiser bike.
when i tryed to put the chain on i noticed that the drive sprocket DON'T fit the chain. it is a 415 chain and works on another motorized bike without issues. do i have to buy a new drive sprocket? why don't the chain fit? i can measure the tooth spacing with a measuring tape if someone needs to know the spacing and size of the teeth if needed. it seems like the 4th tooth the chain goes on it causes the 5th one to fall about 2mm shy and goes up over the sprocket and causes the chain to get stuck and jammed in the drive sprocket housing. any help would be appreciated.

 

[crassius]

often the drive sprocket is one that was stamped out flat rather than machined with pointy teeth - with a 415H chain, the rollers are a bit wider than regular 415 chain so one needs to file or grind the tips of the teeth a bit

I've seen folks get away with putting chain on REALLY tight and riding carefully until the chain stretches some, but I always grind the teeth when I get one of those sprockets.

 

[frostic]

Thankyou for the reply Crassius. yea i started hand fileing the sprocket. this takes forever but its almost accepting the chain now. i took a break to reply lolol

 

[bigkev81]

I seem to be having the same issue. A 415 bike chain, purchased from my local motorized bike dealer.

I have a dremel and can grind the teeth down.

Do I grind them flat so it's shorter. Or at an angle to make it pointy.

And do I grind all teeth. Or just the one I'm having problems with?

Also how can I get the sprocket out so I can work on it?

Cheers
Kevin

 

[frostic]

i wouldnt make them shorter... and dont grind into a point. just follow the shape that is already there on the inside between the teeth. worked for me...

 

[frostic]

the red in this image is where you will want to dremel out all the way to the tip. you wont take off but a very small amount then all chain links will fit. just work slow till you can run the whole chain around on the sprocket
this is the tip i used.

 

[agrmodz]

the red in this image is where you will want to dremel out all the way to the tip. you wont take off but a very small amount then all chain links will fit. just work slow till you can run the whole chain around on the sprocket
this is the tip i used.
View attachment 73319

View attachment 73318

If you can get it on, pedal it for a bit and it will wear-in, Happend to my santa fe 66cc motor..

 

[frostic]

you should have a sprocket puller in your engine kit. its black and there are tutorials but i dont suggest it. i did it with the sprocket still attached.

 

[frostic]

If you can get it on, pedal it for a bit and it will wear-in, Happend to my santa fe 66cc motor..

if you like breaking chains yes. however mine was really bad and needed alot of grinding down. if it is just a small bit sure but i wouldn't make the bike force the chain on as you can 1 break a chain, and 2 you can cause your sprocket to go out of alignment when it jams up the chain inside. i had both happen on seperate bike builds. he should dremel out the teeth to be safe...

 

[agrmodz]

if you like breaking chains yes. however mine was really bad and needed alot of grinding down. if it is just a small bit sure but i wouldn't make the bike force the chain on as you can 1 break a chain, and 2 you can cause your sprocket to go out of alignment when it jams up the chain inside. i had both happen on seperate bike builds. he should dremel out the teeth to be safe...

Your probably right, but i couldn't be stuffed with my build it was about as bad as the chain in that picture... I just stuck it on and went for a pedal.. lol about about 300m it was alot better, it still clicked on and off for the next few km but it did work out in the end..