Small-Doo M

[Merlin]

I've got no firsthand experience with the Pro X 440 fan engines but I've read about HP numbers being in the 60's.

Forum member TRS posted a few years ago about a Pro X 440 fanner in race form producing 88 HP!!!

Even if you had one dialed to the mid / high 60s that would be a game changer for your little machine.


Regardless, I digress. The machine you built is very innovative & considering the terrain you can get it into & through, nothing short of capable!


Cheers!

Thanks!
Making a snowmobile with a cold fan 440 from scratch, I could probably get a weight half way between my very lean MXZ and the Small-Doo M in the best case, I would need a gas tank bigger. As a 440 cold fan a carburetor makes about 40HP, it would take changes to have a good power difference. The pro X 440 was announced how much?

 

[Ben550]

Thanks!

Still a lot of snow for a month of April. There is crust under the fresh snow but it can break down due to the mild temperature.
The camera broke at 5 min on the video. I continued filming from a different angle that transmits the action better but that can be painful.
The Summit with this 3 '' Track passes well in these conditions but requires a lot of work to get it caught between the trees. He can not go from dead stop uphill without sliding the track.
The original Tundra R lacks traction for big slopes.

The Small-Doo X is more pleasant for light towing than the small-Doo M (better driving) It can still climb the slopes with the scraper behind. (end of the video in the dark)


https://www.youtube.com/watch?v=bQneQ1KM6jA

 

[Ben550]

The Freestyle 300 has undergone some modifications, a track of 128 '' x 1.75 '', elongation of the rails with wheels inwards.

Sprockets of 7 teeth instead of 9 teeth, for more strength.

Milling the motor head to increase the compression ratio.

Adjustment of the power block for with the optimum engine speed.

I would have had several ideas to lighten it, but probably too many ideas, because I would have had to build a completely new Ski-Doo around the engine! My blonde likes it like that then. (Love the least square and minimalist style of the Small-Doo even though they perform a lot better) and the 300 have an excellent resale value.



Despite this The Small-Doo M pulls a lot harder on takeoff, the skis lifts over the snow while Freestyle skis remain on the ground. The Small-Doo M expects are small top speed limited after about 5 seconds.

We also see the difference when driving at about 50 km / h with the Small-Doo, the engine runs at about 4200RPM (quarter of the trottle), while with the Freestyle the engine runs at more than 6000RPM (half the trottle)

The configuration of the rear suspension makes sure that the slides do not heat up despite the very hard snow and the 2.6 "profile. My MXZ would not have been long without the ice scratcher.



I think the Small-Doo have been tested enough to trust their reliability, which is not bad for one-off prototypes.


https://www.youtube.com/watch?v=HUvspe_Okwc&t=2s

 

[Ben550]

Another hike with the Yeti and this time the Small-Doo X. There is crust but it breaks quite easily when you go up.


https://www.youtube.com/watch?v=W6vGEr6rSYM&t=445s

 

[Ben550]

Still a lot of snow for the end of April. it only melted on the roadside.

Wet salt snow, the Small-Doo M still surprised me, I could stop and go back in the big slopes without the track slips. The skis lifted just to remove 95% of the weight on the skis but they still touch the snow, the weight is spread evenly on the track. And this weight is too low to sink into the snow with acceleration at the point of clutch.
Traction at this point makes me think of a chain on a sprocket, it does not slip.

it goes back up hill without much problem.


https://www.youtube.com/watch?v=-pHJlRmuBBw&t=120s













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[ezra]

very cool