Purpose built snowbike

Dec 19, 2007
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This is my purpose built. 3 years and I still haven't painted it. (Too busy riding) the front is a stock 380 frame but I cut off everything below the swing arm bolt to move the track forward then attached remaining frame directly to the side panels. The 380 is a vibrating beast and this 3 point attachment to the side panels really helped knock down the vibes. This build works great and I cringe when I have to ride a crappy conversion kit. The conversion market needs to do a 180 and go a totally different direction.
 

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wwillf01

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Heber Ut
I agree with Eric his set up is by far the most fun snowbike I have ridden... it feels like a nimble 85cc bike and like it is a 500cc powerplant...

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fgauvin7

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Oct 14, 2012
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This is my purpose built. 3 years and I still haven't painted it. (Too busy riding) the front is a stock 380 frame but I cut off everything below the swing arm bolt to move the track forward then attached remaining frame directly to the side panels. The 380 is a vibrating beast and this 3 point attachment to the side panels really helped knock down the vibes. This build works great and I cringe when I have to ride a crappy conversion kit. The conversion market needs to do a 180 and go a totally different direction.

Very nice build! Maybe the way to go to, plain simple has a lot of advantage! the need of a CVT vs shifting gear I think vary a lot with the terrain you ride. Around here we don't have may climbs, but we have a lot of very tight terrain. If I had to just pick a power plant for my project and don't worry about any budget I think I would have chosen a 450 4t with electric start and fuel injection... Add to it a Rekluse auto clutch and I think It would make a very capable an forgiving setup.

CVT are nice but very large to stuff in a small build like mine and make it larger was not a desired option. Plus I don't think the inertia of those clutch would help the light feeling that I'm looking for. Even with a Blast 400 engine, I still don't now if I would be able to fit those clutch without having them hanging on the side of the bike... (I would still like to try it trough)

Last point in favour of a 4t, the exhaust is not a problem anymore.... 2t expansion chamber become a problem very soon when you increase the CC's. The YZ250 pipe was manageable but it took many hours to figure out how to make all of this go together in a decent way! The Blast pipe plus the cvt I think would be a nightmare to fit.

All in all the yz250 I got was a good deal that I could not pass and at the end I find many advantage to it like the lowest inertia possible and it's physical size. Plus it should have some decent power with the weighted flywheel and V force3. What scares me the most is the potential lack of torque that could make it hard to ride for a newbie like me.
 

wwillf01

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Heber Ut
The yz is harder to stall than the big bore 4 banger... and personally there is so much rolling inertia with the kit I don't see the reason for a recluse... there is very little slipping of the clutch...normally you just on the gas even cutting through the steep and deep. Much different than with wheels in my opinion... I almost think you loose a lot of power with not having a regular clutch because it starts slipping at bad times...

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Nov 29, 2008
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This is my purpose built. 3 years and I still haven't painted it. (Too busy riding) the front is a stock 380 frame but I cut off everything below the swing arm bolt to move the track forward then attached remaining frame directly to the side panels. The 380 is a vibrating beast and this 3 point attachment to the side panels really helped knock down the vibes. This build works great and I cringe when I have to ride a crappy conversion kit. The conversion market needs to do a 180 and go a totally different direction.
Like the use of the outboard tank!!!

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Epicride

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Oct 6, 2020
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Let me introduce you to a project that I have been working on for the past few years! From the time I saw the first snowbike I knew there was a lot to be done and the design really match the very tight terrain and dense forest that we have here in North Quebec Canada.

So a bit about me, I'm just 26 and I ride snowmobile since I can walk, over the years this sport became a passion. This project started when I was out of town for school, I first saw a picture of a PowerHouse custom propex chassis, this chassis just triggered something. I had a few years to think and draft many idea and concept on how I think something like this should be built and what it should look like. At the origin I wanted more of a lightweight machine more or less like the blast that we just saw last year. Over the years the project just merged to more of a snowbike since it matched more and more to all my expectation. So three years ago, I started working as a mechanical designer, got a house and then started gathering tools to build whatever project I wanted in the futur! As we are, I have around 1.5 years in building and drawing this thing. Sometime it is long to just get the tooling or get the skills to use them.

Finally I fixed some goals to make all of this quite challenging. Many told me that I was not realist and it would not work. But hey, I don't have much to lose here.... time, parts, material... Yes but at the end it would still works if I don't achieve all my goals.

Original goal was to be lighter than the donor bike, in this case a YZ 250 2013 2t that is rated at 227lbs from Yamaha I think. This one was the biggest one, other goals was to have a better weight distribution by being shorter over all, lower seat height since I'm not that tall and I want easy access to the bike and not have to climb that much on it when riding off trail.

Now here is the final product of all this time and effort. A machine that is built to do what I want to do with it, the way I want to! Yes it is probably not the best design for some utilisation, but this is not the point. I just wanted it optimal for what I do. All the main goal was achieved event the most challenging one being the overall weight!

As it sits right now, 99% done minus few panels to cover It up, I'm at 217lbs Dry weight! For me this is quite a achievement and I'm proud of it.

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There is still a lot of little Idea that I want to add or modify but for now It is mostly ready for some testing and I need those test to answer some of the questions. Design and idea also need to be tuned before going further. When this thing will be dialled in I plan on building some fairing to close it up a bit, a few pounds in bodywork will save a lot more in snow accumulation.

All in all, I think this little writeup do a good job telling the story of this project and I hope it won't be the last one! I became a member on this forum quite long time ago mainly because there was some nice writeup like this that was very inspiring, so here is my contribution!

I post this in the Snowbike section, Yes I know there is a modified one, but I think it will have a lot more interest here.

Thanks everyone for reading, and thanks for all the good info your are putting in this forum!
Real nice job there, looking forward to hear the ride reports. Looking forward to the future of snow bikes, especially when seeing builds like this.
 

fgauvin7

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Oct 14, 2012
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First ride report! Last week I took the opportunity to do a little rip on this thing! There was just about 6in of fresh snow. Anyway I have to say that it is more powerful than my expectation! It is very light in the handling and I like the riding position for now. The steering is a bit on the heavy side but I suspect the wide ski and low snow condition doesn't help a lot.

On the suspension side, the front double A arm deal is just working... I can not tell it is there vs any other setup so for the moment this part of the build is up to my expectation. I will follow it to see how it age up and it it wear up to quickly. For the back suspension I'm not as happy as with the front one. There was way to much transfer, I feel the mountain bike shock is way too small to limit any transfer since there could be some high force generated. So I have done my best to lock the MTB shock (acting like a coupled suspension) and it was way better. So for the next time I think I will install a small bushing to lock the transfer and completely couple the rear suspension (that will just allow the rail tip to get up to climb on snow). Even with the MTB shock locked I was still able to get the front ski to lift from the ground since the bike is so short and the CG is over the track. So I think I will have success this way.

Last one was the cooling, just like some have pointed out in previous post the cooling was the major issue. The weather was not very cold and there was not enough snow to have the engine in a bloc of ice so the radiator was the only source of cooling... Well at the end this is the way I want it to be, the radiator do the cooling by itself so when I close everything with panels everything will be happy. But the small cooler and the minimal amount of coolant in the system made it get hot very quickly and the temp was climbing. Well it was not a surprise like pointed by some here! So like Said before the plan was to add a tunnel cooler to do the major part of the cooling. Also this way I will get a lot more coolant volume and better capacity.

So I will probably test it this way and build a thermostat to control the cooling and bypass both radiator. Also I will add a short section of snow flap on the end of the tunnel to provide a surface for the snow to hit and make its way up to the tunnel cooler. Bonus that will keep snow off my back and my helmet haha!

Here is a couple pics of the work done on those modification!

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Here the cooler is just a 22in section of an M8000 long cooler, cut and welded to close it up. It looks good, it is quick and free! Thanks to the local dealer for the scrap part!
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Here we see the bungs for the hose, just two little pice turned on the lathe and welded to the shortened cooler.
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dooman92

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Fgauvin7, did you add that tunnel cooler after the ride or was it in place and you still had cooling issues with it? You mentioned a small cooler with radiator and temp issues.

Thanks for report, nice job on tunnel cooler install..
 

fgauvin7

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Fgauvin7, did you add that tunnel cooler after the ride or was it in place and you still had cooling issues with it? You mentioned a small cooler with radiator and temp issues.

Thanks for report, nice job on tunnel cooler install..
Yes It was not there for the first ride, I just added it yesterday. Before I had just the small air radiator in the front.
 

wwillf01

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Heber Ut
Just saying it again.. such an awesome build. With more snow you ski pressure should get better . 6 inches is thin.

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fgauvin7

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Just saying it again.. such an awesome build. With more snow you ski pressure should get better . 6 inches is thin.

Thanks! Yes we will see if it get better soon. For now allmost all the snow have melted, I'm glad I have tested it and not waited!

Ok, makes sense. Should be good with that cooler. Is there an inline thermostat?

There is no thermostat at the moment but there will be one soon, I just have to fab the housing for it. It is on the to do list with the snow flap/ tunnel extension before the next ride!
 
Jan 18, 2018
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You have done the build I was dreaming of in my head... really strange to then see it in the back of your truck as that is the exact same truck I have (same color and everything).

The world aligns in weird ways sometimes. Build looks great, I think you are definitely on the right track.
 

fgauvin7

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Oct 14, 2012
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You have done the build I was dreaming of in my head... really strange to then see it in the back of your truck as that is the exact same truck I have (same color and everything).

The world aligns in weird ways sometimes. Build looks great, I think you are definitely on the right track.

Well that is a special coincidence! I think it is a sign that you have to start building one haha!
 
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