Lets discuss why the chain keeps derailing, on my Rupp Bandit

#1
HELP! I have my Rupp Bandit, from when I was 10, and now restored it so my grand kids can learn to ride. All is working well until the chain pops off the large rear sprocket ever 5 mins or so, and becomes wedged between the sprocket and the rear frame 'bar', there is maybe 12 inch clearance between the sprocket and the bar, the chain always drops down in that 12 space, every time it comes off! Getting the chain out of there requires great effort , strength, and also contorting of both the chain, and my hands!
Keep in mind, as you read t is and picture this mini bike, that The Bandit has no suspension system, it is a ridged frame.

I have viewed the chain from the rear tire position, sighted down to the centrifugal clutch sprocket, and chain looks to be straight in line. I used a straight edge and lined up the sprockets, still the chain will pop off after a 5 mins of riding. So, after I reinstall the chain to the sprockets, I sight down the chain again, I rotate the rear tire through full revolutions.
The only problem I can see is there is one place where the chain may be 'kinked', or 'bent', for it appears to wobble left to right, at one place in the chain, as the chain travels to the small engine sprocket. Could this cause the frequent derailments? Can you tell me a means to straighten out this section of chain?....aka... would it be ok to bang it with a hammer against a anvil, or something?

Also know, I rigged up a pivoting chain tension-er, that has a small sprocket, the pivoting point comes from the only mounting bolt, and that I also suspended this tension-er from the frame, by means of a med duty spring. This pulls the chain up slightly, near the rear sprocket, and has helped to prolong the time between derailments, to maybe 10 mins..maybe.
DO I need a new chain to correct this? trouble is, that as soon as that new chain comes off, and wedges itself between the sprocket and the frame, I am back to probably having yet another chain with a bend or wobble.

I'm running a No#35 chain, so is this the correct size? It appears to fit the sprockets well. but then again it could be wrong size?
What brand of replacement chain links do you guys use for Rupp bikes?
I'm fresh out of ideas and solutions and thus why I am posting these Qs. to all of you. Help!
 
#2
I'm pretty sure the Rupps do not use 35 chain. The bandit could be different but the roadster and Scrambler do not use 35 chain. The chain is probably bent from getting wedged in the sprocket. Check the web site blackwidowmotor sports. They might show the sprocket and chain size in their diagram.
 

SAT

Active Member
#6
You can check your sprockets with a standard end wrench set. Sprocket width and pitch is all you need to start with. It either 35 or 4XXX. Call up a chain chart and have at it. We buy RLV gold on gold in #35, and DID racing #420. We use the RLV type chain breakers as well, they work great for us.
Hope this helps,
Steve
 
#7
Now I'm not sure about the chain after looking at another photo. Do you have a photo of the chain sitting on the sprocket.? The chain should sit all the way down in the teeth.
Thank you for all your research and answers! greatly appreciated. I will get a picture soon. May I ask of you to post to this post of mine, a picture of the Rupp tensioner you found. or send me a picture. I would sure like to see what was originally designed as a tensioner, to compare to my 'home made' one. There is the possibility mine is not designed correctly. Maybe we could find one that would work better?
 
#8
You can check your sprockets with a standard end wrench set. Sprocket width and pitch is all you need to start with. It either 35 or 4XXX. Call up a chain chart and have at it. We buy RLV gold on gold in #35, and DID racing #420. We use the RLV type chain breakers as well, they work great for us.
Hope this helps,
Steve
I will do that, thank you!!
If your chain has a loose or tight spot or is bent, it is time to replace your chain.
Rupp did offer a chain tensioner for the Bandit, so you are already on the right track
with your added tensioner.
May I ask of you to post to this post of mine, a picture of the Rupp tensioner you found. or send me a picture. I would sure like to see what was originally designed as a tensioner, to compare to my 'home made' one. There is the possibility mine is not designed correctly. Maybe we could find one that would work better? Thanks!
 

ruppking

Active Member
#9
#12
Can any one tell me why the Bandit, did not have the jack shaft set up, like the Digger, or Continental? Or the TC-1? For years I so wished my Bandit had one of those set ups!
 
#13
WHile Im here, is it possible to place a suspension on my Bandit? it needs one! My 10 year old grand son complains that the bike bouncies him around, shaking him really good. I recall as a kid, wishing mine had a suspension. I drewled over the suspensions of large street bikes! For, Until this web site, I never saw another Rupp bike of any kind. No one in my neighborhood had a mini bike. just me, and being on a farm, there were no many other kids close by.
 
#14
If your chain has a loose or tight spot or is bent, it is time to replace your chain.
Rupp did offer a chain tensioner for the Bandit, so you are already on the right track
with your added tensioner.
I just discovered who you are, and that you are! cool! I just know you can answer my chain questions, and suspension Question! This is great!
 
#17
WHile Im here, is it possible to place a suspension on my Bandit? it needs one! My 10 year old grand son complains that the bike bouncies him around, shaking him really good. I recall as a kid, wishing mine had a suspension. I drewled over the suspensions of large street bikes! For, Until this web site, I never saw another Rupp bike of any kind. No one in my neighborhood had a mini bike. just me, and being on a farm, there were no many other kids close by.
You can replace the rear struts with shocks.
You can also install a jackshaft with sprockets, just flip the rear wheel so sprocket is on the right hand side of bike.
You will need to spend some time aligning the sprockets on the jackshaft to match the drive clutch and then the rear wheel sprocket, but it will handle better with less chain issues.
 

jeep2003

Well-Known Member
#18
You cant align the sprockets with the chain on the bike. Take the chain off and look from the back of the bike to the clutch across the wide part of the sprocket near the axle both on the top and bottom. Sometimes the axle and engine plate are not parallel and you need to account for that or split the difference. #35 can be a real pain because of the small teeth it jumps off easy. It has to be a good chain and sprockets.
 

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