Gear ratio - looking for better take-off power

[Jamie P]

I've seen threads on here before where some of you guys are really good at figuring out gear ratios. I've been test-riding my homemade creation, and I would like it to have more take-off power, and I would be happy to lose top-end speed. I haven't had the throttle fully open, but when I get close it gets pretty scary. What I need is more punch when I take off.

The centrifugal clutch has 12 teeth, the sprocket has 72 teeth, and the rear tires are 14.25" tall. I'm using a Predator 212.

At GoPowerSports they have an 80-tooth sprocket and hub for $50. Would I even notice a difference with that setup? What is the best bang-for-the-buck change I could make?

 

[Hellion]

That sounds like a job for a...

Spoiler

Torque Converter

 

[Sparkwizard]

A simple torque converter will make that creation have about three times the gear on takeoff and not lose any top end speed. They can be found for about 50 to 70 bucks.

 

[Hellion]

I've been test-riding my homemade creation

...

 

[Whitetrashrocker]

...
View attachment 162680

Is she available for test rides?

You could drop to a 10 tooth on your CC.

But I'll 3rd 4th and 5th vote for a CVT.

CCs are for full throttle, small street karts.

Keep your 72 rear and with a cvt you'll have wheel spinng torque and still will keep your butt puckered at the top end.

 

[panchothedog]

Post #3 and #5 are your answer. A brand new Amazon 30 series torque converter won't cost a whole lot more than the 80 tooth sprocket you are considering. The difference in dead stop acceleration will amaze you. GET ONE.

 

[Hellion]

I've been test-riding my homemade creation…

Disregard, I forgot who you were. I have trouble remembering the non-avatar people.

You must mean the Mini 1933 Ford P’up…unless it is something new. But photos would help readers to see what kind of room you have for a TC, Torq-A-Verter, CVT, Torque Converter.

 

[Jamie P]

Thanks guys. I will look into a torque converter. Pancho is right that they are very affordable on Amazon - same price as a bigger sprocket setup.

I think there will be room for a torque converter. The good thing about Amazon is I can return it if it doesn't work out.

Here are some recent pics. It's a work in progress.

 

[Sparkwizard]

That thing looks amazing!

 

[Denny]

Remember to get a GENUINE COMET BELT ALSO!!!!

 

[Jamie P]

That thing looks amazing!

Thank you

 

[panchothedog]

Looking at your picture, you probably will have enough room.
Your little truck is really cool.

 

[Sparkwizard]

Is there a build thread on here about that truck? I have so many questions...

 

[Jamie P]

Looking at your picture, you probably will have enough room.
Your little truck is really cool.

Thanks

 

[Jamie P]

Is there a build thread on here about that truck? I have so many questions...

Yes. The title is something like "mini '33 Ford pickup". I'm not sure how to link the thread.

I need to update the thread and add some progress photos. The process of creating a rolling sculpture from a pile of junk is a messy one. It's all trial-and-error.... lots of error.

Ask away.

 

[Sparkwizard]

Thanks! I found it.

Mini '33 Ford Pickup

I figured I'd start my first build thread. I've been watching you guys post stuff for years, and I've been messing with this project off and on for a while. Years ago I had a real 1933 Ford pickup that I started to turn into a hot rod, with the help of my father. I didn't get far and sold the...

www.diygokarts.com

Very interseting project and a good read.

 

[EdwardWare]

Going from a 72T to an 80T rear sprocket will help, but it’s not a massive change. Your ratio would increase by about 11%, so you should feel a better launch. If you want a bigger difference, look at reducing tire size or going with a larger rear sprocket, but make sure you don’t overdo it and make the clutch run too hot.

 

[Jamie P]

Going from a 72T to an 80T rear sprocket will help, but it’s not a massive change. Your ratio would increase by about 11%, so you should feel a better launch. If you want a bigger difference, look at reducing tire size or going with a larger rear sprocket, but make sure you don’t overdo it and make the clutch run too hot.

Thanks. I went with the advice of the guys on here and installed a torque converter (I still need to buy a Comet belt). The kart takes off better and doesn't get bogged down if it goes off the pavement. It will plow right over soft ground now.

I hadn't planned on the TC when I built the seat support and boxed my engine in pretty tight. The TC fits, but to clear the sprocket I added a spacer under the engine, which lifted it up and impacted the air cleaner. The Predator 212 air cleaner has an abundance of "head room" above the foam filter, so my best solution at this time is to make a little sheetmetal replacement that sits lower than the tall, round air cleaner cover. Maybe such a product already exists.

One change can have a snowball effect...