HOW-TO Help: Mini Chopper Parts List

[RobertD]

So I get this email today. Often people email me direct but I always suggest they ask questions in our forums so everyone gets to see the answer.

Anyhoo, email reads:
-----------
Hello
my name is Hayden and as a school project i have decided to build a mini chopper i was wondering if you had a list of parts i will need ?

i would greatly appreciate it if this is possible
thankyou
-----------

And I think that it's probably overdue. Now, if you've spent time working on these projects you already know that you need the handlegrip throttle kit (plus the cable!) and what not..

But Hayden's right, we could use a few more good "lists" to help out the how-to / tutorial idea suggested back here

So I'll go first, this shouldn't take too long I think.


Engine System:
Engine 3-6.5 HP
Centrifugal clutch or Torque convertor
Chain (sized at #35 or #40-#42 pitch)
Rear sprocket 60 or 72 tooth sized same as chain.


Controls:
Handle grip throttle control
Throttle cable
Wire stops
Method to hook throttle cable to engine (may need a kit)
Brake lever or foot pedal
Brake cable
Brake (possibilities are many, elaborate on this below)


Wheels and Tires:
Choices are many. Maybe have some discussion about the choices .... 4 pattern bolt hole vs 2 13/16"
Axle choices
Hubs plus bearings / Live axle with pillow block

FRAME!
Build or buy discussion


OK so clearly it's not perfectly straight-forward. Maybe from here we can flesh out that starter list, and discuss why you'd choose certain choices vs. another choice (live axle vs fixed) etc. If the threads get too off track we'll just create new ones and keep going.

Thanks!

 

[I like karts]

Ok, based on the stuff he gave me, here's my mini tutorial thing:


Engine: I would suggest using a harbor freight 6.5 because they're good quality and come really cheap. You don't really need anything more than about 6.5hp, but It's up to you

Drive system: This is where it gets tricky. You need to know what kind of riding you'll be doing to figure out what type of clutch to use.
If you're doing lots of hilly or off road riding, you're probably going to want a tourque converter. these make it a lot easier on the engine for rough riding.
If you're going to ride mostly flat areas or on road a lot, you can use a centrifugal clutch. These don't do as well as torque converters for high demand applications, and they burn up quickly when put under lots of strain. The good thing about these is that they are cheap (~$30) compared to torque converters (~$150+).

Chain: For a minibike or mini chopper, you probably won't need any more strength than #35 chain, so 35 will be fine.

Gear ratios: Here is another thing that depends on how and where you ride. If you have a TC (torque converter) you can probably get away with low ratios like 3:1 without a problem, but I wouldnt go much lower than that (i.e. 20 tooth on jackshaft 60 tooth on wheel). However if you have a centrifugal clutch, don't go lower than about 4.2:1. Remember a higher gear ratio with a centrifugal clutch means longer clutch life.


Controls: you can buy a twist grip throttle with the cable attatched at lots of stores online. You can find how to hook it to the harbor freight engine here: Clicky (Thanks to Ironman for showing how to do this)


Brakes:I would recommend using a brake handle instead of a foot lever, however, this is up to you. There are a few different kinds of brakes:

Scrub brakes: This system uses a paddle to push against the rear tire activated by a foot lever, and wears down the tire pretty fast. This is my least favorite kind of brake, and I really reccomend not getting these. My rating: 3/10

Band brakes: These use a band with brake pads on the inside to sqeeze on a drum attatched to the wheel. These dont do very good in wet conditions, but they're decent.
My rating: 5/10

Drum brakes: These are basically the opposite of band brakes, because the pads are on the inside of the drum and push out on it. These do good in wet conditions because they are self contained, and offer good stopping power. My rating: 8/10

Disc brakes: These rely on a caliper with brake pads to squeeze on a disc. These offer the best stopping power. There are two types of these, hydraulic, and mechanical. Hydraulics have more power, but are expensive. mechanicals will do fine.



Wheels: I use 4 bolt hole pattern wheels, but that's just me. It doesn't matter which ones you use.

Axles: For a minibike, I would put the rear wheel on bearings instead of the whole axle. It is unnescessary for a mini bike to have pillow block bearings and stuff, and the wheel-bearing setup is much easier.



Frame: If you want to weld a frame, you can't go wrong with a mig welder, however these are more expensive than flux welders. I use round tubing (1" .125 wall or something like that)
But you can use square tubing if you want, it's easier to work with. If you can't or don't want to weld though, you can find many cheap frames on craiglist or ebay.

Hope this helped

-Jon

 

[RobertD]

More than I expected -- sweet work!

For everyone else, what other parts or ideas is this missing? How did you choose your brakes, etc?

Just shout it out!

 

[gyawo]

I am thinking about using a belt driven clutch, is there anything that wouldn't make it as good of an idea as I am thinking it will be? I just bought a honda 6.5 hp power sport motor, going to essentially use the same frame layout as the DIY chopper, just wider and longer as well to accommodate myself and the engine.

 

[oscaryu1]

Not as efficient? Have to eventually replace belts (versus a long lasting chain)... and most belt clutches are more expensive, and parts are harder to find.

 

[gyawo]

Yea belt clutches are about 30 bucks more than a chain clutch but thats not too much more. Are they really less efficient? With a chain I would probably have to put a jack shaft on it, im looking to make a bit of a longer bike so I don't want a huge chain.

How are they harder to find, at the store I bought my motor at they had about 6-7 belt clutches and a huge variety of sizes of the belt "sprockets".

 

[truesprocket]

lots of good advice, nice to see for a power plant what about an old 2stroke snow blower or a 2stroke gocart motor, chain driven direct drive, my go cart started easy enough & lots of power & lighter by quite a bit, I`d like to ask a question,if I make a mount for the carb can I use a LawnBoy 2stroke as a side shaft mini bike/gocart motor or will it not oil it self properly & burn out quick?

 

[r97]

i was bored and found this sticky, im more of a go kart person but i like mini bikes too. just thought i would mension for gear rateos you should talk about tire size and clutches you should include belt tensioner setups and two speed jack shafts

 

[Bison]

I have the perfect frame DIY kit for your school project. Check out the frame and what you can do with it in this forum. Look for me under the post "Maxi-Frame minibike build". It will give you some idea of the very bare bones you will need to start your project with. You'll will ace your project if you create something new and not copy what is already out there (I'm not saying that you are mind you), along with quality workmanship, of course.

My frames and finished minibikes have both a hand rear brake and an adjustable scrub brake as well. The scrub brake is for us old timers who are used to just a scrub and have a habit of reaching for it when we want to apply the brakes. It's also for nostalgia as well. What's a tube frame minibike without a scrub brake!!

 

[devino246]

I have the perfect frame DIY kit for your school project. Check out the frame and what you can do with it in this forum. Look for me under the post "Maxi-Frame minibike build". It will give you some idea of the very bare bones you will need to start your project with. You'll will ace your project if you create something new and not copy what is already out there (I'm not saying that you are mind you), along with quality workmanship, of course.

My frames and finished minibikes have both a hand rear brake and an adjustable scrub brake as well. The scrub brake is for us old timers who are used to just a scrub and have a habit of reaching for it when we want to apply the brakes. It's also for nostalgia as well. What's a tube frame minibike without a scrub brake!!

You do realize this thread was started 3 years ago and has been dead since 2010, right?

 

[Bluethunder3320]

i believe threads like this, or "stickies" can be bumped

 

[devino246]

i believe threads like this, or "stickies" can be bumped

except that he bumped it to market his product.

 

[Bison]

Sorry about that guys. I didn't see that the thread was closed. I should have looked closer. I'm new the forum thing.

 

[Gokartguy04]

You can just buy a cheap frame at gokartparts.com. The also sell hole kits.

 

[souperman000]

Quote:
Originally Posted by Bison
I have the perfect frame DIY kit for your school project. Check out the frame and what you can do with it in this forum. Look for me under the post "Maxi-Frame minibike build". It will give you some idea of the very bare bones you will need to start your project with. You'll will ace your project if you create something new and not copy what is already out there (I'm not saying that you are mind you), along with quality workmanship, of course.

My frames and finished minibikes have both a hand rear brake and an adjustable scrub brake as well. The scrub brake is for us old timers who are used to just a scrub and have a habit of reaching for it when we want to apply the brakes. It's also for nostalgia as well. What's a tube frame minibike without a scrub brake!!

You do realize this thread was started 3 years ago and has been dead since 2010, right?

lol

 

[hellary]

Ok, based on the stuff he gave me, here's my mini tutorial thing:


Engine: I would suggest using a harbor freight 6.5 because they're good quality and come really cheap. You don't really need anything more than about 6.5hp, but It's up to you

Drive system: This is where it gets tricky. You need to know what kind of riding you'll be doing to figure out what type of clutch to use.
If you're doing lots of hilly or off road riding, you're probably going to want a tourque converter. these make it a lot easier on the engine for rough riding.
If you're going to ride mostly flat areas or on road a lot, you can use a centrifugal clutch. These don't do as well as torque converters for high demand applications, and they burn up quickly when put under lots of strain. The good thing about these is that they are cheap (~$30) compared to torque converters (~$150+).

Chain: For a minibike or mini chopper, you probably won't need any more strength than #35 chain, so 35 will be fine.

Gear ratios: Here is another led lights that depends on how and where you ride. If you have a TC (torque converter) you can probably get away with low ratios like 3:1 without a problem, but I wouldnt go much lower than that (i.e. 20 tooth on jackshaft 60 tooth on wheel). However if you have a centrifugal clutch, don't go lower than about 4.2:1. Remember a higher gear ratio with a centrifugal clutch means longer clutch life.


Controls: you can buy a twist grip throttle with the cable attatched at lots of stores online. You can find how to hook it to the harbor freight engine here: Clicky (Thanks to Ironman for showing how to do this)


Brakes:I would recommend using a brake handle instead of a foot lever, however, this is up to you. There are a few different kinds of brakes:

Scrub brakes: This system uses a paddle to push against the rear tire activated by a foot lever, and wears down the tire pretty fast. This is my least favorite kind of brake, and I really reccomend not getting these. My rating: 3/10

Band brakes: These use a band with brake pads on the inside to sqeeze on a drum attatched to the wheel. These dont do very good in wet conditions, but they're decent.
My rating: 5/10

Drum brakes: These are basically the opposite of band brakes, because the pads are on the inside of the drum and push out on it. These do good in wet conditions because they are self contained, and offer good stopping power. My rating: 8/10

Disc brakes: These rely on a caliper with brake pads to squeeze on a disc. These offer the best stopping power. There are two types of these, hydraulic, and mechanical. Hydraulics have more power, but are expensive. mechanicals will do fine.



Wheels: I use 4 bolt hole pattern wheels, but that's just me. It doesn't matter which ones you use.

Axles: For a minibike, I would put the rear wheel on bearings instead of the whole axle. It is unnescessary for a mini bike to have pillow block bearings and stuff, and the wheel-bearing setup is much easier.



Frame: If you want to weld a frame, you can't go wrong with a mig welder, however these are more expensive than flux welders. I use round tubing (1" .125 wall or something like that)
But you can use square tubing if you want, it's easier to work with. If you can't or don't want to weld though, you can find many cheap frames on craiglist or ebay.

Hope this helped

-Jon

Wow.. I think this car is awesome.. Contrast to what most of people here are saying. Got to agree with metal shapes. This is a very good innovation. I'm just wondering if what other fiat accessories and parts will be put on this baby to run awesome.. I'm new here by the way.. Cheers..
nice! thank u, is the light for the cubby good?