The 300 feels like a lightweight tree dicer compared to the 4 strokes. You have to ride it up on the pipe, but its really fun. It won't climb with the 450's.
Great comments on the 2 vs. 4 topic. We didn't have any issues jetting the 300, but I've never seen a 500 that would run right on snow (only seen 2- one stocker, and an 500AF). Both owners tried and tried, but never got them really running. The stock Berg 650 puts more hp to the tire than the 500.
Turbos... I happen to know a guy that has felt the addiction of boost on a snowbike- and even though he's always messing with it he still keeps it around. There's nothing like feeling 10 pounds of boost on a bike. Drew is right about the loss of 'bark'. On the turbo 450 (we tested from 8 to 16 pounds of boost on a stock motor) it lost its bark. On the bottom, it felt like an XR 250. Once it came up on boost (about 1/2 throttle) it was awesome. 12 psi was my preferred place. Running full c-16, and now Vp-110, mine has never missed a beat.
On the 650, it feels like almost like a stock bike on the bottom. I think it's a combination of massive torque, and the aerocharger (vs. the garret on the 450).
I've been working on a dual stage turbo to solve most of the issues. Last week, a great friend in Canada gave me an idea that will be much easier to implement, and inexpensive to install- and will solve the low end issue on the 450 turbo. He's tested it on several 2-stroke turbo sleds.
Just waiting for parts...
My naturally aspirated bike pick is the 570. Then do as Drew suggested, and go with the TR 610 kit. The only bike that beats this is the 650 Berg with the JBS racing 700 or 750 kit. But the EFI would get my vote.
2nd pick for me is the 5 speed 505. I wrung the snot out of an '08 for 3 seasons (with a 10ah battery) and never had any issues. I was REALLY hard on it.
Blaser
