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PostPosted: October 25, 2021, 9:22 pm 
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I know its not a car.

But could a R1 or other motor be used to drive a Mini jet boat pump ?
Could you crank drive the pump and do away with the tran's ?

Thanks Randy

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PostPosted: October 26, 2021, 9:48 am 
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That's pretty much what a jetski/waverunner is nowadays, bike engine on a jet drive.

If you use a bike engine, you'll need to go directly off the crank, the impellers spin around 7K at the top end.
Alignment of the pump shaft with the engine is a critical issue, the pumps do not like radial misalignment.

If you're thinking berk/panther/jacuzzi, those need torque above all else, and a nice rising curve.
HP at 10,000RPM means nothing if there's not enough torque at 4,000RPM to push through the water and get to that speed.


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PostPosted: October 27, 2021, 11:11 pm 
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You may be able to do away with the transmission but keep the primary reduction that a lot of bikes have. That will decrease the maximum output RPM to more closely align with the pump and also supply more torque.

An easier option, if you don't mind the extra weight, is to just leave the bike gearbox in 4th or whatever gear matches the pump best :)

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PostPosted: October 28, 2021, 6:15 am 
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To add to Beelzeboss’ comment, an R1 cannot turn the output shaft faster than 7000 rpm in any gear.
Every gear provides more torque than at the crank or primary output.

The trans is integral. The benefit of removing it for the weight and parasitic loss is insignificant compared to the work involved and offset by the loss of flexibility in having a range of gears you can select.

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PostPosted: October 31, 2021, 9:47 am 
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The Rx1, Apex snowmobiles uses the technology gained from the R1 motorcycle.
Rx1 is internally reduced 1.19:1
Apex is approximately 1.27:1


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PostPosted: December 16, 2021, 12:58 am 
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Thanks All ! Great info.

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