Apex RPM

[SledFreak]

What is the reason why Yamaha needs to run the reduction gear box on these 4 strokes, especially the genesis motor? If they removed the gear box what RPM can they run them at? I heard the clutching is the only issue, because they can't keep a clutch on it at the high of RPM? These motors actaully spin at 14,000?????

 

[Mighty]

Clutch would explode :shock:

 

[Dano]

Yeah I wouldn’t spin clutches past 9000 rpm without having them better balanced and trued. Even then that would only be for a short distance. I wouldn’t run an Apex without the gear reduction without steel toe boots and a bullet proof vest. :shock: Not sure where the rev limiter is set on the apex, but I’m guessing 11,000 rpm.

Dan

 

[Tork]

Yeah, clutching does not live much past 9000. This motor is designed to max out at 11,000 at the most. It is not the higher reving bike motor. Just a guess but the probably have it limited in another way, port or valve sizes, cams something like that.
They have some reason they dont want the bike motor in there. It would require a bigger reduction unit, or cost. Higher reving internals cost more.

 

[MR.HAPPY]

I've spun two sleds at 9000 for about 6000 miles total & never had any problems!

I wouldn't go over that for any amount of time, for sure!!!

"WOW" THAT COULD HURT!!!

BR

 

[Smokey]

Maybe it's just me but I think your missing Rotax's point. The RPM your reading is the motor RPM not the clutch RPM. Clutch RPM is much slower. So the motor RPM is accurate it is not turning 14,000. 10,220 for the RX1. Not sure what the reduction is but the Clutch RPM is probably down around 9,000.

 

[TT670]

Its not really clutch integrity thats the issue, the technology is there to make a clutch that'll easily withstand the high RPMs. Fact is CVT clutches become increasingly inefficient as RPMs exceed 8500, and thats why theres a gear reduction. Now I realize that theres plenty of sleds out there making peak HP at over 9000rpm without a gear reduction, but the clutches would transmit the power more effectively if that same power could be made at a lower RPM.

 

[Bakemono]

They need the gear reducer also because there isnt a drive belt that could withstand 12,000 rpm.
Also, as was said, CVT clutches really lose efficiency once you go past 9,000 rpm.
Even the motor in the R1 doesnt like to be revved much past 10,500 rpm. It CAN be revved well beyond that, but it actually makes LESS power once you wind it up past 11,000.
You also cant just expect Yamaha to use the R1 motor because the needs of a sled and a bike are vastly different.
Cap'n

 

[rxrider]

Not sure what the reduction is but the Clutch RPM is probably down around 9,000.

The reduction on '03-'05 RX-1 is 37/31 or about approx 1.19 reduction. So spinning the motor at 10300 rpms spins the clutch at apprx 8630 rpms.

I was told by my dealer that the gear reduction is slightly lower at the '06 Apex to keep clutch rpm at the same level as the '05s when the engine spins at 10600 rpms on the '06 Apex.