Why not one more. Snowmobile engine board track "replica"

Kanticoy

Mad Science!
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Re: Why not one more. Snowmobile engine deadtail

Hurco550 said:
Well, I guess ill be getting back on this project since all my friends are building bobbers and choppers, and I feel left out. (Looking at you Eric, John and kiley)..

I opened up the old cad files to try and finalize some designs and clean it up a bit. If all goes well I'll be bending tube for the frame before to long and finish collecting parts for the Springer front end I'm building as well.


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Hurco550

Keep er' Between the ditches
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Re: Why not one more. Snowmobile engine deadtail

Did a little more reading and a little less "winging it" while getting closer to the final design. I added 5 degrees of rake which will take me out to 30 degrees from 25 degrees as drawn before. A little less sportbike and a little more Cruiser. Also Drew up some rear axle plates instead of the Springer. The design is getting closer and I'm about to put an order in for some more dom tubing.


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Hurco550

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Re: Why not one more. Snowmobile engine deadtail

Well, imagine that, ol hurco had a change of plans. I've always thought that one of these old hirth engines had about the ideal crank case shape for a curved cradle board track type frame. After spending some time last night drawing up a dimensionally true cad rendering of the engine, I'm thinking that it would be a waste of the shape of the engine to put it in a regular old bobber frame. I started sketching around, and I think that this thing NEEDS to be more of a board track inspired build than a bobber. Here are a few renderings. The engine alone on top, the engine in the bobber frame in the middle and my new favorite, the board tracker rough layout on the bottom...



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bvander

Gold Coast, Queensland
Re: Why not one more. Snowmobile engine board track "replica"

Yep. Everyone is building choppers at the moment. Break the mould. Build a stupidly fast boardtracker.
 

Hurco550

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Re: Why not one more. Snowmobile engine deadtail

irk miller said:
Do you want that GT380 hub I somehow ended up with?
I appreciate it, but I ended up with a pile of titan front drum hubs at mid ohio from brad a few years ago. I'm going to run one of those out front and a Yamaha R5 hub out back. The 19" rims will lace to both with stock titan front spokes.
 

Hurco550

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irk miller said:
I got this fukin thing from Brad, too. :-\
you may just decide that good brakes aren't important someday, and keep it for then ;)

I know disk would be better, but I'm thinking the big 2LS titan drum will stop a 200lb motorcycle that makes 17 h.p. just fine.
 

Hurco550

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Re: Why not one more. Snowmobile engine board track "replica"

I am still tweaking away on AutoCAD and trying to come up with some finalized designs. In this picture what I'm thinking right now is the backbone and the cradle will be made out of waterjet cut plates, the Cradle itself being a pair of 3/8 thick aluminum plates and the backbone being a pair of 3/16 thick steel plates. There will be other bracing in between the plates as well. The rest of the frame will be made out of 1 .25 O.D. d.o.m. tubing with.120" wall, less the tubes for the V, which will be 1.625 O.D. tubing.

 

irk miller

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Just curious- if you go the board track route, does it need to be a hardtail? That rear down tubes will take a shock pretty nicely on bother sides and not interrupt the lines at all they way you have it drawn up.
 

Hurco550

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irk miller said:
Just curious- if you go the board track route, does it need to be a hardtail? That rear down tubes will take a shock pretty nicely on bother sides and not interrupt the lines at all they way you have it drawn up.
I guess mostly for simplicity sake, and the fact that most board track racers didn't have a rear suspension. I'm trying to stay at least marginally true to form, or as far as I can while using a 1970's hirth engine haha
 

irk miller

You've been mostly-dead all day.
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Make it a chopper, lame-o. That's really what you should be doing, even though this is way cooler than a chopper.
 

Hurco550

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Re: Why not one more. Snowmobile engine board track "replica"

trek97 said:
Gotcha bookmarked bro
glad to have you man. Your talk about board track racers is part of what got me going on this again lol

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