# Accelerating a long heavy spcns Harley..



## remy_martian (Feb 4, 2019)

Rich Rebuilds on Youtube is in the middle of a Harley build....

Not an endorsement, merely entertainment


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## piotrsko (Dec 9, 2007)

How much is excellent? 200hp stroker motor was excellent on my shovelhead dresser, but crap on drive train wear.


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## remy_martian (Feb 4, 2019)

My numbers: 5lb per HP is really good. 3 is borderline controllable. 10lb/hp is my boundary of why bother. 15 is ok for a factory rig, commuter, or grocery getter.

That's weight with rider.

I wouldn't mind building a 300mm widebutt hardtail one of these days.


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## MarkDoronin (8 mo ago)

piotrsko said:


> How much is excellent? 200hp stroker motor was excellent on my shovelhead dresser, but crap on drive train wear.


agree with this argument


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## ARNAV (Aug 13, 2021)

You are correct… does 40hp (30kw) sound reasonable to you? 
Can I assume that a motor larger than 30kw will be simply too big for a Harley frame? 
Sorry for the dumb question, but what is the difference between a given power amount (let’s say 30kw) with X Volts (say 72v) , and the same kw with Y volt (say 96v)? Is it a matter of different torque?of different battery size and weight?…
And last question- any recommended manufacturer/supplier for a motor + controller + batteries?… I have experience importing directly from China, if it makes more sense. 
Thank you! Appreciate your help.


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## piotrsko (Dec 9, 2007)

Using obsolete series DC methods, you could use a 9" outside diameter motor, get perhaps 75 hp and still fit in the frame without a Trans. Battery capacity is the next issue because it is dependent on how you arrange the cells into what space. More volts lowers current, increases watts available, but is generally bigger because your voltage is divided by the 3-4volts per cell. I suspect we're in either the golf cart or ZERO motorcycle place for power. Look at those systems for initial planning ideas


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