So, what engine would you use?

[Norma Stitz]

If you were going to try your hand at a full custom machine built around any engine you wanted? Would it be a snowmobile engine? Streetbike?

The checklist I'm thinking involves variables relating to the following, with some positives possibly being negatives for others due to cost to complexity:

Power. Ideally around 100hp at sea level seems to be a good sweet spot.

Light weight. Must weight nothing, regardless of power.

Reliability. Bombproof is always a bonus.

EFi. Makes flipping it upside down less problematic

CVT. This one I don't know if can be considered a plus or a minus. Sure shifting is tricky with big boots and etc, but the rotating mass of a CVT might negate the benefits? I don't know much about CVT technology to know the answer on this one.

Big 12v supply. Not necessary but nice.


I know CR500 can make decent reliable power. Down sides being carbs, and tuning. And kick start.
I've read about some maico 700's that seem intruiging. But maybe too exotic.

How about wankel power?

What's the best smaller snowmobile power plant? The snowhawks went through many iterations of power increase but with them came more weight which some users regretted and went back to the lighter rotax engines.

 

[Norma Stitz]

Some neat modern Wankel engines here. Seems low for our power needs but not bad output considering 300cc

http://www.aixro.co.uk/product/aixro-xr-50-rotary-wankel-sports-engine/

They claim 1.17 hp/lb

 

[Grr]

Contact J&l snow hawk on here and he can have you one built for next year. It is a huge mess the first time so you are better off buying a complete one as he has done like 4-5 already and has everything figured out. Engine is a 800R skidoo and you can even use your existing mototrax suspension just change the spring.
Trust me, it's worth spending the money

 

[Grr]

To add to that, if you want to spend a bit more you can do an etec and a 600etec donor sled can be had pretty cheap. The 800 isn't NEEDED, and the 600 is much more reliable. I will probably do a 600etec myself when the time comes.

 

[GlennRMK]

Engine selection is really limited and IMO holding back the OEMs from coming out with something.

IMO, you really need a V-twin to keep the bike chassis narrow yet improve power output.

CVT would be nice sometimes, but the problem is a CVT system is as wide as entire motor/trans assembly on a current dirt bike.

I would rather shift gears then have the width between your feet double.

2 stroke would be nice to limit weight, but someone else mentioned that v-twin 2 stoke would be difficult to make work.

So that basically leaves a liquid cooled v-twin street bike engine of some kind? How about a KTM Super Duke 1290 in a 450 chassis? I'm not sure what else would be lighter and keep you above 100 hp?

 

[up-high]

Yammie vtwin. Its been done. 180ish hp. narrow.

 

[Norma Stitz]

Yeah Les is a huge inspiration on a project like this.
Just spit balling right now, I'm quite happy with my snowbike and I picked up a 503 snowhawk too to play with. Just looking at how the snowhawk was designed is an interesting lesson in engineering. I can see a lot of weight that could be removed, as well as their limitation with the sled engines, however they have a lot going for them too. It's much more compact than my snowbike, and they seem to do okay with the width and even use it to their advantage with sliding the belly pan in tight turns.

I have a full shop and I'm a stunt welder, with many fancy structures built over the years out of chromoly and aircraft aluminum so a project like this is very appealing to me. Not that I need another project! But a great engine that hits all the high points and still fits in ones pocket would be really cool.

 

[dirtybeacher]

I believe I saw dyno numbers at 105 ish. Not a cheap motor though.

https://www.pantheramotorsports.com/panthera-liger

 

[Grr]

ill give you a good pointer after I try to buy this thing next week, don't want anyone stealing it! Its exactly what we are looking for and fairly unexpected

 

[CATSLEDMAN1]

build a bike with either the kaw or Honda 500 motor rubber mounted like a sled engine, engine would live, vibration reduced to rideable, then the kit has to be lighter to make sense, hard to do. requires good design. likely need to junk the heavy forks, ski on A arm type front.

Go for it.

 

[Keystone]

So I have seen the sled motors and a few strung out croch rocket motors. Put into snow bikes. What about a harley sportster motor with some upgrades to handle higher rpms. It would have serious torc and look good. Not to mention sound bad ***. Ive seen a few high hp. Harleys in the hill climbing world.

 

[Norma Stitz]

ill give you a good pointer after I try to buy this thing next week, don't want anyone stealing it! Its exactly what we are looking for and fairly unexpected

Interest is piqued!

 

[Norma Stitz]

So I have seen the sled motors and a few strung out croch rocket motors. Put into snow bikes. What about a harley sportster motor with some upgrades to handle higher rpms. It would have serious torc and look good. Not to mention sound bad ***. Ive seen a few high hp. Harleys in the hill climbing world.

Aren't they heavy though? I found the weight/hp number on the rotary engines website interesting in that it was just a hare over 1hp/lb. now my snowbike has maybe 70lbs of engine and like 50 hp? So, less than that number. It also gets a transmission for that too though. So, it might be roughly 1hp/lb also if you took the gears out. So we are looking for an engine that makes 1.5 hp/lb. would a v twin bike engine be able to claim that? We must not gain weight!

 

[Grr]

Gaining weight isn't so bad if the tradeoff is worth it. Like if you could get a nice v-twin and CVT you want, maybe 80hp, if it added 50# to your standard bike that would be totally worth it. Assuming it had stuff going for it like electric start EFI and stuff I would take 75#!
move the fuel tank to the rear for balance, there are a few FZ-07s out there and they are pretty sweet even at 420#. That is actually a nice bike and you can get them wrecked for cheap.

 

[Grr]

Look into the aprilia 850 mana
75hp 850 v twin
CVT
EFI
electric start.

Make a dedicated bike out of it and strip absolutely everything off, could get it around 420#, heavy but I don't thingk you can really get much under 400 with EFI and a decent motor

 

[Keystone]

Just looking around on the Web it doesn't look like 130 to 150 hp is out of the question with a harley motor. Also see they make a rekluse clutch for one. They are efi, and electric start also. Someone who is educated with the harley v twin mod world should build one. Iron Mountain horse!

 

[Norma Stitz]

HD would be a torque monster but I'm not sure how they would be better than a Ducati or other v2 engine. Heck Suzuki and Honda made some nice liter bikes with v2.

My old Ducati 900 was an interesting engine. Oil cooled and made about 75hp. Maybe more with carbs. Not having a water cooling system surely saves weight. At the cost of hp though. It was a fairly durable engine too.

 

[Apiaguy]

Rs250 tz250 or similar 90 degree two stroke twin.. they prodiced anywhere from 65-110 hp thru the years... incredibly small and lightweight... and if it was fuel injected it would be a snowbike dream!

 

[chumbilly1]

I heard rumor of a husky acquisition by Polaris, and a new twin adventure bike motor being the culprit. Bet we see a dedicated snowbike with close to a 100hp being sold as a husky in the US and as a ktm in Europe. Polaris and ktm have partnered before.

 

[lundracing]

Just supercharge a Ktm 500. Don't overthink it


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