Kids bike gearing and torque question

[projectminibike]

Hello all,
I'm piecing together another mini soon. I have been collecting parts from eBay and locally.
This time I'm using a 3 horse Tec with 11.5" tires. The total gear ratio is 8.33:1 this is intentionally designed to top out at 15mph for my little squirts in the backyard and not burn up clutches.
My only question is whether the multiplied torque with cause the front wheel to lift too easily for the kids.
I am going to continue as planned and make necessary changes after I see for myself.
This is just meant as open conversation among those with similar interest .

 

[jeep2003]

sounds like youve done your homework. iv never geared a bike that low right off the bat so I cant say for sure but it sounds like the best place to start. speed will be low so thats the priority. If they are lifting off it will be just a matter of learning throttle control

 

[Motra]

I don't have the torque specs for the Tecumseh easily available but going by the 3 HP Briggs numbers you'd have 38.33 ft. lbs. of torque to the rear wheel. With the small wheel you'd have 80 lbs. of drive thrust (the power actually applied to the ground taking into account drive wheel size) which is peppy but not enough to get into too much trouble.

 

[projectminibike]

Thanks Jeep & Motra
as I said I am going to continue as planned and make changes if needed.

 

[cxbra]

That sounds like a good gear ratio.. The kids will definitely have plenty of torque, I'm not sure if its enough to lift the front wheel. It might be. My 212cc Predator is putting out probably 7 wheel hp (stock exhaust, modified intake, drilled carb jet) and its more than enough to lift the front wheel easily with a 6:1 ratio gearing and 12.5" tall rear tire (30mph top speed). A 3hp geared for 15mph might be just enough to give the kids a real thrill. If its too much, re-gear it for about 20mph top speed and that should keep the wheel on the ground.

 

[projectminibike]

Thx Bra,
what do you guys know about the cheap Chinese torque converter kits available on Ebay for a little more than a 100 bucks?
You already know I'm building a kids mini so running a Tav seems unnecessary