Engine Swap and Gearing Combo Questions

[BrandonF260Rem]

I have a go kart that is fairly big. Two adults can sit in it with a little squeeze. I'm replacing the power plant in it, was a 150cc motor and integral gear reduction and torque convertor.

Lets say the kart with a rider(s) weighs 800 lbs to be safe.

Power plant will be a tuned up GX390. No governor, mild cam, a little head work maybe.

Question is will this gearing below have good take off (in your opinions) with a decent top end speed?

So engine to 40 series converter
with a 10 tooth
feeding a 36 tooth
36 tooth is tied on a shaft to a 16 tooth
that's feeding a 31 tooth on the axle

On the ground is 22inch tires.

 

[itsid]

what's with your font size?

'sid

 

[mckutzy]

WOW the font is super huge. could you tone it down a bit.

 

[BrandonF260Rem]

Just making it where you can see! Sometimes you post things and its tiny letters. This isn't one of those times

 

[mckutzy]

well you can edit your post.

 

[danssoslow]

You're looking at a 5.54:1 ratio. Shoot for something higher if you're looking to pull a bunch of weight. 31 tooth on the axle is pretty small, is it on a live axle? What size axle is it?

 

[itsid]

You're looking at a 5.54:1 ratio. Shoot for something higher if you're looking to pull a bunch of weight. 31 tooth on the axle is pretty small, is it on a live axle? What size axle is it?

5.5?

10-36-16-31 would end up being 1:6.98 almost seven;

A nice number for small wheels, for 22" wheels it's different (I'd say double that to 1:14)
Then again, there's a series 40 in this equation that would add another 1:2.43 for the lowest gear.

But a 800lbs kart/passenger *shrugs*
Nope, I don't think it'll be very useful at all for a good take off.

I'd increase to at least 1:10 on the jackshaft part

so let's say
10-36-10-31 (would end up in 1:11.16)
or
10-32-10-32 (would be 1:10.24)

with the TC that would provide a take off ratio of 1:25 at least, which I think should be a good ratio for a kart this heavy (with wheels this large)

'sid

 

[danssoslow]

5.5?

10-36-16-31 would end up being 1:6.98 almost seven;

A nice number for small wheels, for 22" wheels it's different (I'd say double that to 1:14)
Then again, there's a series 40 in this equation that would add another 1:2.43 for the lowest gear.

But a 800lbs kart/passenger *shrugs*
Nope, I don't think it'll be very useful at all for a good take off.

I'd increase to at least 1:10 on the jackshaft part

so let's say
10-36-10-31 (would end up in 1:11.16)
or
10-32-10-32 (would be 1:10.24)

with the TC that would provide a take off ratio of 1:25 at least, which I think should be a good ratio for a kart this heavy (with wheels this large)

'sid

My bad. I was using a formula found on eBay, and the math is wrong. The writer stated the two sets of gears as additive. That would explain the 8 people that gave the write up a "thumbs down".

Thanks for learnin' me something!

 

[KartFab]

These guys have already answered your question, but I just want to add that I actually have a large kart with a gx390 (stock), a comet 40 series TAV, 9 tooth jackshaft, 54 tooth axle sprocket, and 22" tires. Its got enough torque to pull me and my son up steep hills, and goes 40 mph.

 

[landuse]

My bad. I was using a formula found on eBay, and the math is wrong. The writer stated the two sets of gears as additive. That would explain the 8 people that gave the write up a "thumbs down".

Thanks for learnin' me something!

Nope. You multiply

 

[OzFab]

My bad. I was using a formula found on eBay, and the math is wrong.

Quite obviously

Next time, use this calculator

 

[danssoslow]

Quite obviously

Next time, use this calculator

Bookmarked it shortly after I was corrected. :bigthumb: