my mini chopper

[mckutzy]

well i finally have made a post of my build.
I made it out of 1.5 square pipe, some bike parts, a doughnut, some shaft parts, pillow blocks, and a bunch of bits of steel. I mostly got all of this for free, except the motor and the drive train parts.

This is the bike as of just recently.

It had all started on the rear end. Sadly I didnt take any pics of these in the building process but I will take it all apart later to show what i was doing then.
I had to make a hub for the tire and another hub for the disc brake, these hubs comprised of an weld-on hub for a sprocket that I bought at princess auto and a plate of steel.
The tire hub was a bit of a ***** to make. I didnt have a wide enough piece of steel to make a full disc that was 6" in dia.
and the steel shop was not open just yet, so i made a plate out of 4" and a piece of 2" welded together. I found the center and then drilled a pilot hole for a mandrel to fit. I had also cut most of the excess material off with the bandsaw and belt sander to make a rough circle. then I turned the rough disc on the lathe, to make it round, then the inside to fit the weld hub.
The brake hub was about the same except I had the right piece of metal, then of course the lug holes and drill and tap the brake hub.

The axle I had also milled the keyway, but on the jackshaft I milled to deep, luckily this was the excess to the axle and I decided it would be best to mill this first encase I messed it up, and I did but I had some extended key for these mistakes so it worked out well after I adjusted the depth and carried on.

This was the first couple of days on making it, I didn't think to get the camera out after the first day and by the end of the first week i figured out what i was going to do and took some pics,


I had a tough time on the rear end, these ends hold onto the pilowblock bearings,

I made one side then i had to mirror it, the second one was originally off by .25", but after some thinking and tweaking it was good.

After the first wile I had gotten this far...



theres more.. but ill fill u guys in later....

 

[mckutzy]

sorry i was busy, been a few day since i posted. mmmm no replies???

any way, after i had got the over all frame welded up, i thought on how to get the motor mounted and jackshaft hooked up.

i had thought up of using a plate with the jackshaft and the motor conected on one unit, the using that to tension the rear chain drive.

The plate has holes with a spacers for the motor to bolt down and a pair of angle iron hangers "clamps", that ride on top of the bottom rails of the frame, and a clamp plate underneath the frame that when bolted tighten against the frame to hold it firm. The front of the plate has another hanger, but instead there will be a bolt that will pass through the frame to the front to move the motor plate forward.
When the chain is on, the front chain will tension with the jackshaft and clutch. The rear chain from the jackshaft to the rear sprocket will tension with the motor plate moving forward.

here is the setup at the front.

 

[mckutzy]

The next week after that i started the forks. once again i got to enthusiastic working, but i did take some pics.

I had used the steering from a scrap bike that i had, took the headset tube and steer tube from the fork and frame, made up the tripple tree plates, fork tubes. i made a couple of caps with a split pipe, to hold the top plate to the forks. this was a bit of thinking as to what was i going to do but i figured something out.

heres the head set tube and welded.

later i built a stand for the frame and then mounted the forks to the frame. i have to make a few gussets for the neck but its pretty solid.

heres me on the bike, on the welding bench to show what i was doing.

when i was last at the shop, i had made a riser for the bars. there was a bar from the junk pile with a 1" hole drilled through, i cut off a bit i needed and set up for drilling for bolts through.
i tacked the halves together with shims then centerdrilled the start of the bolt holes.

After drilling holes.. i also had drilled the relief holes for the bolts to pass through on the top part as well as the mounting bolt underneath to the top plate of the fork tree.

thats what i got so far, mostly done, except for better handle bars, throttle/grips, seat and the brakes.
oh ya i had originaly had the rear tire with the brake on the right, but that was when i was mocking up the frame i didnt want to flip it.

 

[bigfootrules31]

i thought jackshafts had to have different sprockets on them to make it lower geared?

 

[brendonv]

i thought jackshafts had to have different sprockets on them to make it lower geared?

Jackshafts arent always used for gear reduction purposes. In this case it is to make the drive go from the left hand side to the right as u cant just turn the engine around or u will do 30mph in reverse.

 

[brendonv]

Sorry for double posting.
Yes, you definitely need a gusset where the steering joints the frame or it will just snap.

 

[modelengineer]

Gusset the red areas in this pic, at the very least. That frame is........... well, it needs gussets. If you can put some bars where the blue lines are it would be even better.

It does look well fabricated though. Very nice!

 

[mckutzy]

thanks for the reply guys. the neck ya.. definatly need some gussets, i had not gotten there yet, i built most to just get the frame and the basic idea, for both myself and others.
i have added some straps to the backbone and the underside of the frame where the rear trailing ends are.
Im still undecided as to the final look, I still need a brake caliper and grip, aswell as a throttle grip assembly. im trying not to have to make these things, though im not opposed to i just want a better safety margin.. especially to stop.

 

[mike75925]

you can take a spanner wrench and remove the gear pack off the mountain bike wheel, that is unless you are making her a 2wd. yes, i've seen it done, a long time ago. didn't quite understand how it was steerable. maybe like a helicopters swash plate.

 

[brendonv]

that is unless you are making her a 2wd. yes, i've seen it done, a long time ago. didn't quite understand how it was steerable. maybe like a helicopters swash plate.

2 engines, mount 2nd engine on top of front wheel and run chain down to wheel. U can get front mounted motorized bike engines. Like so: http://tinypic.com/view.php?pic=9sz12e&s=4
and http://www.fiveflagsmotorbikes.com/BicycleEngineMotorizedBicycles/tbfeThumb.jpg

 

[mckutzy]

it took me a moment for what u were saying. the front (and the rear tire) i had found just walking home from work one day. i was going to try to remove the gears, but i hadn't gone to a bike shop yet to do so. So ya this was what i had on hand. it doesnt bother me now, but later i will get it removed.

 

[acg23]

can you post some pictures of ur hub on the doughnut tire? i am looking for some ideas so i can make the best custom hub i can.

 

[porsche930dude]

its easy to remove the bicycle gear set. on the hub youll see some holes where the bearing is. just tap it with a screwdriver in the off direction. The frame is such big tubing that you wont need any gussets except for the neck

 

[Blazkowiez]

Looks really good so far something done from scratch. Aside from structural integrity, the thing that concerns me most is the bike wheel in the front. It gives a great look but I've seen it done on several different bikes, and even ridden a few when they came in for repairs, it makes it hard to steer and very dangerous.

 

[khank1995]

NICE, you need a smaller gear going from the jackshaft to rear tire though. What you have on it now will give it torque but not to much speed. Good luck!!!!!!!

 

[tykenfitz]

looking good, cant wait to see it finished!

 

[mckutzy]

oh ya, i have been busy for the last little wile, soon i plan to finish the job. i got a brake and going to put on a better looking bar, as well as a simple throttle. I also plan on left/right brake peddles to stop.

acg23-
The hub is just a 6" square piece of 1/4 hot rolled. bored to fit a shaft hub like the ones i welded up for the jackshaft sprockets. then i cut most of the square off to make a round piece, turned it round, mounted, trued....very important, then welded. after welding any thing like this, the heat can distort is like hell, so going evenly and allow for good cooling helped me, i also checked with an indicator and straightened more with a lead hammer in the lathe. i think im less than .005 out. drilled all my holes for good size bolts, that about it i think..

 

[rgvkid]

looking good, Any pics of the hubs would be cool to see. I wish i had a lathe.

 

[acg23]

thanks man

 

[Blazkowiez]

Well, I said I'd throw a pic up of the customer's mini-bike with the bike wheel on front. This is Robert on the bike not me, it had a 6.5hp Tecumseh and very large rear sprocket on this... I think he totaled it in two weeks. Just figured I would show you just how scary I think those front wheels are.