Doodlebug and Racer Chain Upgrade?

#1
Hi y'all

I am plagued with #35 chain on two of our smaller mini bikes; Doodlebug and Racer (they have stock 212cc Hemi Predator swapped in)

The chain get stretch like crazy. We made the new chain short as possible and adjusted the tensioner all the way forward ("loose") and adjusted the engine to snug up the chain but they get stupid loose FAST and the tensioner get maxed out (all way to rear). I use chain from TSC. I know, not best quality, but come on.

I want to say I have to put new chain on them about every 3-5 tanks of gas. The #45 chain in our Baja warriors last all summer no problem. The #45 chain are from TSC, no issue there.

Are there any direct bolt-on/easy swap #40 sprocket available I can buy to ditch the #35 chain for longer/acceptable service life? I am tired of my friends or myself getting strained somewhere away when the chain either fall off and jammed up bad or snapped.
 

CarPlayLB

Well-Known Member
#8
#10
The top speed increases a lot. Low end suffered though. It's likely doing 50 mph plus after new, larger tires with new clutch and baja warrior's sprocket. I think the torque converter will get the acceleration and torque back nicely.
 
#11
Never buy cheap chain. I sell bearings for electric motors and PT (power transmission) products from couplings and pulleys/sheaves to chain of all sizes. I live/breathe this type of stuff all day every day. Cheap chain will always stretch and you will never get what you want out of it. Good chain will stretch a little,but never enough to cause an issue or notice. I see you found a solution,but for future reference spend the money on the good stuff.
 
#12
Never buy cheap chain. I sell bearings for electric motors and PT (power transmission) products from couplings and pulleys/sheaves to chain of all sizes. I live/breathe this type of stuff all day every day. Cheap chain will always stretch and you will never get what you want out of it. Good chain will stretch a little,but never enough to cause an issue or notice. I see you found a solution,but for future reference spend the money on the good stuff.
What is a power transmission? Something that could be used on a mini bike?


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#14
Update

Update: I installed torque converter on this mini bike and bought the engine swap adapter/mount plate to gain better adjustability. Still running the same chain since day 1. Zero chain-related problem. I LOVE the combo. Hydraulic brake system, snow hog tires, torque converter, upsized chain. It’ll go anywhere as long as I’m not high centered or in deep mud. I even used it to tow a dead Studebaker car up a inclined driveway (yes I had to put a lot of my weight forward lol)

Worth every penny (which hardly any) to step up to the bigger chain.
 

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#15
Personally I'm a fan of JT Sprocket X1R2 chain.

Pros: X-ring, beefy as hell, riveted, hardened enough to outlast my stock sprockets, some type of wonder grease that stays on the chain but doesn't pick up dirt

Cons: Expensive unless you can find a deal (got mine from somebody who ordered the wrong size), physically wide so might not fit behind a TAV, hard to break unless you have a Dremel
 
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