R1 and RX1 Motors

[hovermn]

Can anyone tell me the differences between the Yamaha R1 and RX1 engines? I believe that before '05 they were carbed and after '05 they went to EFI, at least on the sleds. I'm not sure about the bikes.

I have the option of buying either motor for use in a boat and I'm not sure what differentiates one from the other.

Thanks!

[CraigM]

I'm not sure what all the diff. are, but the RX-1 motor is a dry sump. There is a seperate oil reservoir and you wouldn't have to deal with the transmission issue. The sled motor went EFI in 06'. I also believe the sled motor is tuned to run a lower rpm. 10,200 to 10,500 being optimum.

[hovermn]

Craig,

Good info, thanks! I had no idea that the engine revs up that high. That might be a tad too much for my applicatoin. They are nice engines, though...

[CraigM]

I don't know what kind of drive system you would be using, but the RX-1 has a gear reduction on the drive shaft to spin the primary clutch closer to 8500 rpm as 10,000 is too fast for a snowmobile cvt also.

[hovermn]

The engine would drive a hovercraft with a completely different reduction drive using a belt and 2 multigroved sheaves. The tranny on the R1 would just add weight.

The problem with running extremely high RPM engines is that you either run a large upper pulley or have a supersonic prop tip speed. Large pulleys add weight. Supersonic tip speeds do quiete a few things, like extreme noise and prop errosion.

I haven't ruled out the engine as it's nearly 1 lb per HP, but it creates problems I hadn't counted on.