My Homemade Mini Chopper

[jeff091796]

I took my schwinn stingray occ bicycle and cut up the frame, rewelded box steel to it and put a honda gx200 clone on it, i've had this bike for a while, and i just bought a torque converter for it, i used to have a centrifugal clutch on it, but it would break all the time. the engine's governor has been bypassed, and it now has a K&N style air filter with a red foam prefilter. when i had a centrifugal clutch, i had a 35 pitch chain drive train, i always had problems with the chain being too small to handle the power from the engine, so when i bought the torque converter, i upgraded to 41 pitch chain and a 54 tooth sprocket. i am also doing a hydraulic disc brake conversion on the rear tire, before i had a crappy mechanical disc brake from a pocket bike. in the pictures you will see a stone between the engine and the frame, i put that there to judge the distance that i have to raise the engine for the torque converter to fit. after i took these pics, i bought some more box steel and started to make the spacer, i am using 1in by 1in box steel with 4 1/2in thick bolts, i am placing 1 bolt between the engine and steel, the mounting bolts will go through the engine, bolts, and the steel before bolting the the frame. i am only 16, and ive done almost all this work by myself. dont pay attetion to the camera date, my camera got messed up the oldest pics are from 2011, not 2007.

 

[landuse]

And a few more for the OP .....

 

[OzFab]

I'm a little confused: The pics landuse posted have a 2012 date; are they the lastest pics, after the engine was raised? Did you raise the whole mounting box or just the engine? It appears to be very low (the engine, that is)

Other than that, keep up the good work

 

[mckutzy]

Wow looking good, light weight too, maybe a little too light looks like.
One thing I would suggest is a chain guard and tensioner aswell as moving the exhaust outside from the rear tire.

The pipe is cool looking, I got something similar on my bike, but the space where the tire is is a really hot area, within a foot of the port. The motor is of a design that dosent have many options for a typical chopper straight pipe. I had the same issues on my bike build.

All in all, cool ride.

 

[beansdaddy78]

thats sweet man

have you gps'd your speed on it before the torque converter and upgrades?

 

[jeff091796]

I'm a little confused: The pics landuse posted have a 2012 date; are they the lastest pics, after the engine was raised? Did you raise the whole mounting box or just the engine? It appears to be very low (the engine, that is)

Other than that, keep up the good work

yes, the latest pics are from 2012, my camera got messed up, and i forget to reset the date on it.

 

[jeff091796]

thats sweet man

have you gps'd your speed on it before the torque converter and upgrades?

no i didn't, but if i had to guess, my mini chopper went about 30 to 40mph. the drive train had a lot of issues, the sprocket caused a lot of issues.

 

[minichoper]

Good job on this.

 

[chain]

I bet thats a blast to ride. There are upgraded parts for the forks and trees out there if you wanted to widen them. Ive got a stingray on the back burner. I have to keep pedal system to drive on roads. So still trying to figure that out with the high chainline.

 

[jeff091796]

here is a little update, i made the spacers for the solid motor mount, and i welded a piece of steel on on the frame over the old steel. I started to make the slots for the motor mount, but my cutting wheels for my grinder have gotten a lot smaller from being used, so, i have to buy a new one tomorrow to finish.

 

[mckutzy]

Well thats a start. Gota work on the welding. A lot of people forget that with fluxcore, after you stop welding(after the trigger is released) you have to chip and brush the weld area clean, even for a tack. Its the only way to avoid slag inclusion that makes bad welds.
So with a little more practice it will look much better.

I will say we would like you to continue posting here, so please put that guard back on that grinder. I understand you might need a bit more room with that blade, but should it blow it will with a vengeance. Rotate the position of the guard in a different manner for more access.

So looking good, good to see another project, and stay safe.

 

[minichoper]

Mc is right about the grinder. i have pics and a nasty scar on my face as a constant reminder of safty with angle grinders

 

[smgs92]

just curious on a project like this why are you going to a torque converter instead of a race clutch? I don't see you taking this off road so the benefits of a torque converter aren't necessary. Instead you should upgrade to a racing clutch because with a torque converter you are losing 20% of your power. A race clutch is adjustable and rebuildable.

 

[mckutzy]

A price point maybe. How much for a cent race clutch/CVT. When it gets to that level, isnt the cvt going to be cheaper?

Edit: I did look for the race clutch(typically) and it is more expensive than a cvt.

 

[smgs92]

you can get a cheetah race clutch for $140 it's not any cheaper to run a cvt and for the application i'd rather not lose 20% of my power for a few bucks.

 

[minichoper]

When i built my chopper "same frame as this one" i had a hard time with chain alignment and chain whip when using a centrifical-clutch. I belive it was due to such a long run of chain. I installed a tav, which shortened the chain quiet a bit. Never had a problem again. Power was never a problem on mine. Had it up to 60mph with some throttle to spare, and tons of takeoff. I would try to locate a little more robust rear tire. Those spokes wont take too much abuse

 

[mckutzy]

Wow, that cheetah it pretty cool. I didnt see that one. A good price too. I stand corrected.

As for chain length, needs a tensioner. A skateboard wheel with bearings and a bracket. mount in a good spot, it will work.

 

[smgs92]

Wow, that cheetah it pretty cool. I didnt see that one. A good price too. I stand corrected.

As for chain length, needs a tensioner. A skateboard wheel with bearings and a bracket. mount in a good spot, it will work.

that is actually a really cool idea i'd put that on my mini bike but since i regeared the tension has been fine.

 

[tundrabeagle3]

I did the skateboard wheel before and it is not a permanent fix. after a while the chain will cut into the skateboard wheel. As it does this it becomes loose, cuts through the rubber layer of the skateboard wheel and eventually becomes obsolete. i like the torque converter idea better since the bike has tires over 20 inches and it also fixes the need for a chain tensioner since it allows you to make the distance between the two sprockets shorter.

 

[smgs92]

Curious did you use a walmart board wheel or a legitimate skate brand wheel and what hardness? I could see this happening to a cheaper wheel or softer wheel but anything 99a should hold up i'd think.