2-cyl 900ccm 4-stroke?

[birkebeiner]

I just read this article @ snowmobile.com about Ski-Doo's all new 600ccm 2-cyl 4-stroke.

http://www.snowmobile.com/products/inside-skidoos-new-600-ace-4stroke-1280.html

Reading it, the engine doesn't look to be a racer with a 60 bhp output. However, in the lightweight (but probably fragile) XP chassis it can be a fun sled. I have to add, I have never tried the newer Ski-Doo's so know nothing about their handling! Nor their reliability, or lack of it

Which made me start thinking, and dreaming, again. The current Phazer has an engine based on the YZ250F, but put two together to make it a 500ccm power plant.

But why doesn't Yamaha come up with a snowmobile purpose-built engine based on the YZ450F engine, but again put two of them together to make it a 900ccm. The power output of a 450ccm 4-stroke motocross racer is about 50 bhp with max power at around 8-8500 rpm. Not sure that you get 100 bhp when putting two engines together, but pretty sure you would get something fun if put into the correct chassis. The 2010 YZ450F engine also have electronic fuel injection, and this engine is one of the smoothest and torque'st engines of all the 450ccm 4-stroke engines out there (but not the most powerful), according to tests I have read online.

Of course it would need a chassis to match, being both lightweight, but still Yamaha build quality, and handle better then any of the current Yamaha chassis. It should have very rider forward style ergonomics, ala Rev XP. I could see two versions, one short 121" version for serious snocross type driving and a long 153" version for deep powder fun.


Anyway, as I said, I'm dreaming...

 

[grader]

yamaha talked about your idea a few years back and said by the time you added in the counter balancers there was little weight difference to the 3 cyl. think about the phazer that puts out 80hp with 500cc compared to the doo with 60hp and 600cc.

 

[birkebeiner]

That might be true, but a 2-cyl would always be lighter than a 3-cyl, with everything else being the same. You would of course get less power, but not sure the power to weight ratio would speak in too much disadvantage of the 2-cyl, if any. For some, weight is more important then just power.

Given that the Phazer has 80 bhp out of it's 500ccm engine, a 900ccm with electronic fuel injection should be able to produce something like 100-110 bhp, I'm sure with the weight advantage over a 3-cyl it should be good enough for most people, incl me.

If you're doing lake running most of your time then of course a turboed Apex is the thing to have, but eg over here in Norway where we don't have groomed trails, light weight is essential. Our trails looks like supercross dirt tracks most of the time.


Yamaha was doing 4-cyl 2-strokes when everyone else was doing 3-cyl. And by the time big bore 2-cyl became the norm 8-900ccm) Yamaha went for the 700ccm triple, claiming it had almost the same weight as a comparable twin. However, the 700 triple had to compete with a 8-900 twins as Yamaha didn't have anything bigger at the time.

It might not be big of a difference between a twin 900ccm 4-stroke over a 1050ccm triple (FX Nytro) weight wise, but Yamaha is for sure losing the weight game. Whether that is to better/stronger build quality or not, I don't know. Of course, a 4-stroke will always weigh more then a 2-stroke, but I'm sure fewer cyl will help on the scale.


Anyway, looking forward to the winter and can barely wait!! And can't wait to start up my RS Vector Mountain

 

[Alatalo]

The current Phazer has an engine based on the YZ250F, but put two together to make it a 500ccm power plant.

Not really. The current Phazer is very similar to half an YZF-R1 engine, but not very similar to two YZ250F engines. The marketing dept. probably liked "two engines put together" better than "half an engine"...

 

[bottlerocket]

Is the glass half full or half empty?