Baja doodlebug gear ratio

[2005hondacivicex]

I have a baja doodlebug and I plan on swapping a predator 212 with a torque converter and removed governer. Would a 60 tooth rear sprocket and 12 tooth front sprocket have a good gear ratio? I plan on riding it on small hills, and I'm a heavier rider so would it need a lower gearing? Is a top speed somewhere around 30 obtainable. I am new to modding minibikes so any help is appreciated.

 

[River Rat Ron]

I have a baja doodlebug and I plan on swapping a predator 212 with a torque converter and removed governer. Would a 60 tooth rear sprocket and 12 tooth front sprocket have a good gear ratio? I plan on riding it on small hills, and I'm a heavier rider so would it need a lower gearing? Is a top speed somewhere around 30 obtainable. I am new to modding minibikes so any help is appreciated.

Hello and welcome. Here is a link I refer to. It will at the least get you in the ball park

https://www.bmikarts.com/Go-Kart-Gear-Ratio-Speed-Calculator

 

[creia]

For the riding you will be doing and your "heavier rider" size you describe I would recommend keeping the original rear sprocket (72 tooth?) and use the 12 T clutch for a 6:1 gear ratio. Down the road, and if the budget permits, I would recommend eventually upgrading to a torque converter for even better performance.
Michael

 

[Strigoi]

With the torque converter you will want a smaller sprocket for sure. Look into the sprocket adapters and split sprockets for karts. The split sprockets are relatively cheap so you can try out some different combos. The biggest hassle is adding/removing links from the chain each time. I'd get a 60t and a 65t sprocket and see which works best. You might want to go even smaller. 53t is the smallest you can run with the adapters.

Speaking of chain, get yourself some quality chain like RLV. It's much better than the cheap Chinese shit that's out there.

Sprocket adapter: https://www.studzracing.com/product-p/universalsprocketadapter.htm

Split sprockets: https://www.studzracing.com/product-p/35splitchainsprocket-asterisk--asterisk-.htm

Chain: https://www.gopowersports.com/rlv-gold-on-black-35-chain-5ft-roll-xtreme-performance/

For chain, be sure to measure . You can buy 120 links, 5' or 10' sections of it.

Get a chain tool too. They're 100% worth the money and make removing or adding links easy. It's a must have tool if you plan on playing around with minibikes.

https://www.studzracing.com/product-p/kmctm.htm

 

[2005hondacivicex]

Thanks everybody for your knowledge. I think I'll be starting with a 60 tooth rear sprocket, and I'll probably try a few sizes to see how it accelerates with different gear ratios to find what I like the most.

 

[SAS289]

With 12/60 and a torque converter you should get at least 30 governed to 3600 RPM.

Depending on how and where you ride governor removal may have been a waste of time. Governor removal should come after the decision is made to gear for higher than stock RPM and build the engine to support the RPM you intend to run at.

 

[Outlaw Ace]

I have a baja doodlebug and I plan on swapping a predator 212 with a torque converter and removed governer. Would a 60 tooth rear sprocket and 12 tooth front sprocket have a good gear ratio? I plan on riding it on small hills, and I'm a heavier rider so would it need a lower gearing? Is a top speed somewhere around 30 obtainable. I am new to modding minibikes so any help is appreciated.

I have an old sprocket from one of the original Doodlebugs with 64 teeth on mine currently with a 12 tooth clutch and at 200 lb I can go up any Hill I aim it at with enough approach speed and my top speed is north of 40 mph ungoverned. I plan on adding suspension Forks that I already have and then I'll be done with it. I have a few vintage mini bikes that need my attention.