Snowbike build

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Boz Mon

Member
#1
#1
Ive seen 1 or 2 people build snowbikes around the internet, but I could never find a proper build thread. I'm going to start a thread here to document what I'm doing to modify this bike to make a snowbike. I have never messed with any mini bikes of any kind. I'v been riding gopeds since I was about 12 or 13 and I'm a die hard 2 stroke guy, so this is a huge learning experience for me. Also, I am learning how to weld on this project.

I started off with this weird blue frame with an angled motor mount, looks like it was set up for a jack shaft. Cut that angled part off and welded a flat 1/8inch piece of steel for a proper motor mount. I found a 5hp briggs engine in my crawl space from who knows when. Threw some gas in it, and it started right up. I picked up a 16mm china carb, and made an intake for it. I will be running the chinese torque converter from ebay as well. Tracks came from a craftsman showblower. These are different than most that I've seen since the track is driven by the wheel attached to the shaft and theres no chain.

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I got some tubing that is exactly 1 inch ID and welded that to the forks and the ski will attach to that. The tracks are held together by 2 pieces of steel that I cut using the snowblower parts as a template for length. The wheels and bearings for the track are riding on a 3/4inch shaft and I will be welding coupler nuts to the shaft that will engage the wheel because the centers are hex cut.

The project is ongoing and not even close to finished. I will post more updates as they come along. I'm open to hearing constructive criticism or just ideas on how to make my life easier with this project.
 
I74

I74

Well-Known Member
#3
#3
Very cool, but I think you need some thicker plate for your shaft/ bearing carriers.
I can see that bowing between the carriers,, unless you have some kind of frame work that's attached to it.
 
B

Boz Mon

Member
#4
#4
I74 said:
Very cool, but I think you need some thicker plate for your shaft/ bearing carriers.
I can see that bowing between the carriers,, unless you have some kind of frame work that's attached to it.
Click to expand...
The edges of the plates are bent to add strength. There are plans for additional strengthening in the tubes too
 
B

Boz Mon

Member
#7
#7
Finally worked on this thing again. Picked up some bars, and a new bolt for the forks so thats all tight now. Got the track mount tacked this afternoon and basically made it a roller. I will be making additional supports from the back of the track to the back of the frame.

Still need to cut the axles to length, and I will be welding nuts to the axles so they can be driven via the sprocket. I need to grab some chain, so if anyone has any opinions on good chain, I'd love to hear it. I also need a fuel tank, and I think I will be ordering the 22mm carb instead of the 16 that I had originally purchased.

Other than that, opinions? Just kinda flying by the seat of my pants on this one, and I'm learning how to weld on the way.


 
PatrickCraik

PatrickCraik

Well-Known Member
#8
#8
Looks great but I would definitely use a heavier gauge steel for the bearing brackets, 3/16" or weld some gussets in between the flanges close as you can get to the bearings.
 
delray

delray

Well-Known Member
#9
#9
project looking good, couple things I have seen that guys had problems with in the pass building these type of machine. single ski up front might be to unstable and you may have to resort with two smaller ski's spread apart a little from each other. also you may have to build a small tin cover over the intake and extended it over the exhaust pipe little. this will help keep the intake from frosting up inside it and outside or try to wrap the two together with some header wrap material. that may allow the heat from the exhaust to travel over to the intake and gear it down a lot. you will need a lot of torque try to move it at all. last one I seen built he had to go with a big block Tecumseh H block motor.
 
Rapidrob

Rapidrob

#10
#10
When you build the track suspension it is very important that the front of the track cannot drop down more than 45 degrees. The track can try to do a 360 and jamb on the frame and bad things will happen.
You want as much "controlled" movement of the track to stay in contact with the snow/ground but be able to flex/move and absorb shock to prevent shattering the plastic wheels. The track must be dead in line with the ski or you will get some very powerful Torque Steer....been there,cussed that.
There are several vids/photos on the web showing some very interesting and practical suspensions on tracked mini's that work.
 
B

Boz Mon

Member
#11
#11
I was afraid that the hearing was gonna be too tall. I bought the biggest rear sprocket I could fit on there without being bigger than the track. What’s the smallest size I can run on the front of the converter?
 
Rapidrob

Rapidrob

#12
#12
There are several members here that are wizes on figuring out gear ratios. Using a four-stroke engine it would be very easy to gear the track so low that the bike maxes out at 10 MPH.
I'd measure the track wheels diameter, the sprocket diameter, number of teeth, chain size and the drive sprocket teeth and size and post your question over in the TECH section. you'll have your answer real quick.
 
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Boz Mon

Member
#14
#14
Got some more work done on the snowbike today. Welded bars on top of the track area for reinforcement, as well as I made an H piece that will bold into the bottom to support the bottom of the plates.

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I will be getting a keyway cut into the front axle today to hold my sprocket in place, and I have a plan for keeping the wheels centered on the shaft. Theres a 22mm chikuni carb in the mail, as well as #35 chain, and a fuel tank. Its starting to come together now, and I really hope it works when all is said and done.
 
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Boz Mon

Member
#15
#15
It was over 50 degrees out today, so I got to work with the garage door open which was a nice change. First pic is the H piece that I made installed. The H piece makes the whole thing much much stronger. I must stay, getting this whole back end together and taking it apart is a huge pain, but its possible. Right now, everything is held together with regular bolts, but I will be replacing all of the nuts with nylock and lock washers once everything is finalized.

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These are the axles that I designed. The wheel slips over the hex, and the washer holds it in place, the other side is held on by another washer, and a shaft collar to keep it together. The front shaft has a keyway cut into it for the sprocket.
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This is just another mock up. I picked up the header from my friend who used to race flathead briggs karts back in the day. Still waiting on the 22mm carb, and a fuel tank. If anyone has tips on how to drill the holes to mount the motor, I'd love to hear them.
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Boz Mon

Member
#16
#16
Got to the point today that I got to test ride. The 16mm carb was lean upon first startup. Drilled the jet to around 1mm and it ran better, but still lean and not a lot of power. I have a 22mm on the way. Seems like everything will work mechanically, just need to get the engine dialed in. It didnt go very fast at all, and im not sure if that is due to the carb being too lean, and/or being geared too tall.

I still want to get a rear fender, make a plate for the frame in front of the engine to block snow, need to finish the welds on the bearing plates, get my actual fuel tank mounted, and I need foot pegs.

The governor arm is still in the engine. Will it still somehow bog the engine down even though its not connected to the carb?

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Kmanator

Kmanator

#17
#17
Thats a sharp looking machine..Nice job! When you say it's slow, how slow is slow? Like you can walk faster than it?I don't think the Gov. flap on the engine would affect it much- if at all if there is no attachment to carb?
 
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