Chain popping

#1
I have finally completed the rebuild of my son's Doodle Bug. Upgraded the 2.5(?) HP for a 6.5 Predator. Everything looks to be lined up, and when we rode it in the back yard on grass, it worked fine. As soon as my son took it out on the paved road, the chain started popping off. I put spacers between the rear axle and sprocket to square the front sprocket with the rear and keep the motor centered in the frame, and the chain looks to be square. The teeth don't appear to be overly worn on the sprocket. I am at a loss. Any ideas will be helpful!!!
 

desert rat

Well-Known Member
#2
What is your slack #1 and have you pulled a string down the side of the sprockets or used a strait edge on them. Do you have pictures of your chain set up as it is right now.
 
#6
What is your slack #1 and have you pulled a string down the side of the sprockets or used a strait edge on them. Do you have pictures of your chain set up as it is right now.
I have about a half inch of slack. I have tried to put a straight edge between the front and rear sprocket, never thought of a string. When I look down the chain from the rear and from the top, it looks almost arrow straight. Was starting to think it's the rear sprocket as the teeth are a little rounded on the outside edge. I'll see if I can snap a few pics and post them. Thanks!!
 

MKW

Active Member
#7
Are you still running the tensioner?? The one bike that I had that would loose the chain was from flex in the frame and mostly the engine mounting plate. A spring tensioner fixed it. Those DB30 engine plates are kinda thin. Just re-enforcing the plate by putting another piece of plate steel under the engine might help.
Then again...maybe none of this will help, but I'm trying. LOL
 
#8
Are you still running the tensioner?? The one bike that I had that would loose the chain was from flex in the frame and mostly the engine mounting plate. A spring tensioner fixed it. Those DB30 engine plates are kinda thin. Just re-enforcing the plate by putting another piece of plate steel under the engine might help.
Then again...maybe none of this will help, but I'm trying. LOL
I appreciate the thought. Yes, I'm running the old screw tensioner, adjusted all the back, putting as much tension as possible. Never saw a spring tensioner. I'll look into that!!! Thanks
 

I74

Well-Known Member
#9
I appreciate the thought. Yes, I'm running the old screw tensioner, adjusted all the back, putting as much tension as possible. Never saw a spring tensioner. I'll look into that!!! Thanks
I make different size tensioner rollers out of ''Urethane'' skate board wheels.
They are ''way'' better & smoother than the hard plastic ''P.O.S.'' rollers.
The different size O.D.'s, ''as needed'',, also help in keeping from having to potentially ad & subtract links & 1/2 links ect., when you run out of adjustment. ;)
Send me a PM if you might be interested in one.

I
 
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#10
you cant align the sprockets with the chain on. Take it off and look from the rear end across the widest part of the sprocket by the axle inside and out comparing it to the front sprocket
 
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