Need help with gearing

[Threeelectric]

I bought an old beat up yerf dog scout
No engine and all kinds of parts removed
Trying to fix it up for the kids but I want to haul stuff with it as well
I installed a predator 13hp, 40 series tc and a reverse gearbox transmission. It doesn’t want to move lol and tc belt smokes
So I know I have a gearing problem
I’m pretty sure someone changed the axel sprocket before I got it
As it’s a 42 tooth and welded on. The originals were bolted on.
They also put some old atv 22 inch tires on there

So 10 tooth drive 42 tooth axel 22 inch tires
Changing the axel sprocket is a no go but I could install a jack shaft
But what gears do I use to give this thing power not worried about speed

 

[frostyflammable]

That is a very high gear ratio (1:4) with 22in tires. If my calculations are right with governor in tact 3600 RPM that is somewhere in the 55mph area. With 22in tires and a 40 series I would do at least a 1:6 ratio maybe even a tad more.

I am sure more knowledgeable people will chime in, but I believe that had a GY6 (or clone of it) so the variator and reverse gearbox had reductions.

Daniel

 

[JTSpeedDemon]

I'd do ~8/1 gear ratio with those huge tires. The Predator 420 helps, of course.

 

[Threeelectric]

When you say 8:1 how would I achieve this?
I have to use the 42t axel sprocket
Where can I find formulas for gearing when more than two gears are used?

 

[mckutzy]

Here is a calc...
Its pretty good for what you need now...
https://affordablegokarts.com/pages/gear-ratio-calculator

Something about 10-20-10-42= 8.4:1

Let see some pic as to what you have and for space....

 

[JTSpeedDemon]

Why do you have to use the 42T sprocket?

 

[Threeelectric]

It’s welded to the axel. Pretty hefty weld. I could grind it off but would rather not

 

[JTSpeedDemon]

It's either that or install a complicated jackshaft setup.
So you can pay something like ~$50 or more plus a lot of effort installing it.
I would definitely grind off the sprocket and pay ~$20 for a new sprocket.

 

[landuse]

Here is a calc...
Its pretty good for what you need now...
https://affordablegokarts.com/pages/gear-ratio-calculator

Something about 10-20-10-42= 8.4:1

Let see some pic as to what you have and for space....

This is probably the way to go. If you have enough space for it all that is.

Post some pics

 

[anderkart]

If you didn't want to install a jackshaft; another possible option would be to bolt an 80-tooth Split Sprocket to your 42-tooth axle sprocket.

You'd need to perfectly center the split sprockets before drilling the mounting holes in your old sprocket. This would effect your chain alignment, so you'd need to address that issue too.

80-tooth Split Sprockets are available in serveral different chain pitch sizes at this site:
http://gokartgalaxy.com/sprockets-and-sprocket-hubs.html

 

[Jhoppe]

I'm with anderkart. One solution to the offset would be to weld another plate to the sprocket and then bolt a split sprocket to the new plate. Significantly more complicated, but probably not as much as a jackshaft setup.

 

[mckutzy]

Be easier to use the existing sprocket as a hub for the next one....

 

[JTSpeedDemon]

...I'm anderkart....

Mmm hmmmmmmm.......

 

[Jhoppe]

Mmm hmmmmmmm.......

I fixed it. Stupid phone lol

 

[JTSpeedDemon]

autocorrect!