# Converting KZ550 Motorcycle to Electric



## Padenormous (3 mo ago)

Hey everyone,

I'm working on converting an old Kawasaki KZ550 standard motorcycle to electric. My goal is to do this as cheaply as possible without losing too many features such as speed, reliability, and range.

Here's the motor I'm working with (already bought)
*8' diameter, 70-80lbs *









And here's the drive shaft helical bevel pinion gear I have to work with:
















Turning this pinion gear makes the wheel spin 3/7 of a revolution for every 1 revolution of the pinion gear. My thought is I can design, print, and install a ring gear connected to a shaft connected to the motor that makes the pinion gear rotate 2.33 times for every revolution of the motor shaft. My question is is this going to rank my torque so bad that I can’t even begin moving on this bike? Or is my logic here sound even though I’ll lose some torque?










Also, if I ran this motor at a higher voltage, like 60V, could it handle it or would it degrade too quickly/burn it out?

Another question, if 1KW is equal to 1.337HP, why is this motor only rated at 10.9HP considering it’s a 14KW motor?


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## remy_martian (Feb 4, 2019)

It's not. Horsepower is not given on that nameplate.

The two kW numbers that printed are under "HP" relate to corresponding RPM and voltages printed to the right of them.

I hope you're not thinking you can transmit power with that 3d printed gear...


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## remy_martian (Feb 4, 2019)

Driveshaft gear needs to be bigger than the motor gear...I think you got it backwards


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## Padenormous (3 mo ago)

remy_martian said:


> It's not. Horsepower is not given on that nameplate.
> 
> The two kW numbers that printed are under "HP" relate to corresponding RPM and voltages printed to the right of them.
> 
> I hope you're not thinking you can transmit power with that 3d printed gear...


thank you! I don’t, I plan on casting the gear if my plan here is feasible.


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## Padenormous (3 mo ago)

remy_martian said:


> Driveshaft gear needs to be bigger than the motor gear...I think you got it backwards


Well the motor is 2000rpm which won’t get me over 50mph given the current drive shaft gearing. So I need the motor to turn a larger gear to spin that pinion more times per motor rpm


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## Functional Artist (Aug 8, 2016)

Padenormous said:


> My question is is this going to rank my torque so bad that I can’t even begin moving on this bike? Or is my logic here sound even though I’ll lose some torque?


I would say "yes" for Q #1 & "no" for Q #2

Having a bigger "drive" gear (on the motor) than the "driven" gear (on the wheel) would be basically like always "running" in "overdrive" 
...& would/should overload the motor (sooner or later)

It's very difficult for an electric motor to "get going" with a heavy load (like starting off in OD)
...& IMO this is one of the reasons why using hub motors on a motor vehicle has so many issues. (no gear reduction)

My ElMoto (1980 KZ440 LTD) is motivated by a ME0709 motor, powered by 48V Chevy Volt module(s) & is running at ~3:1 GR
My top speed is ~48MPH & my range is ~25 miles (w/1 48V 50AH module) or ~50 miles with (2) of them


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## Padenormous (3 mo ago)

Functional Artist said:


> I would say "yes" for Q #1 & "no" for Q #2
> 
> Having a bigger "drive" gear (on the motor) than the "driven" gear (on the wheel) would be basically like always "running" in "overdrive"
> ...& would/should overload the motor (sooner or later)
> ...


I found this yesterday, G Series Gearbox – RJ Link International, Inc. which is called a“Speed Increaser”

With 24HP at standstill, wouldn’t that be enough power to get my bike rolling? And then as speed increases it gets easier and easier on the motor?


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## Jordan325ic (Jun 8, 2021)

Shaft drive motorcycles are very difficult to convert., the issue of getting the gear ratio correct aside, I would be pretty impressed if you could successfully cast a gear at home that would be strong/precise enough to survive any length of time. It would be easier to redesign/replace the swingarm to accept a beefy hub motor than it would be to get the shaft-drive setup to work. And you would simplify the packaging immensely... fitting that giant motor, a giant industrial gearbox and enough battery to run that inefficient setup down the road... difficult.


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## Padenormous (3 mo ago)

Jordan325ic said:


> Shaft drive motorcycles are very difficult to convert., the issue of getting the gear ratio correct aside, I would be pretty impressed if you could successfully cast a gear at home that would be strong/precise enough to survive any length of time. It would be easier to redesign/replace the swingarm to accept a beefy hub motor than it would be to get the shaft-drive setup to work. And you would simplify the packaging immensely... fitting that giant motor, a giant industrial gearbox and enough battery to run that inefficient setup down the road... difficult.


I think you're right. What about this idea.

Put this motor inline with the shaft so it's 1:1 rpm. Then overvolt the hell out of the motor so that it's at 96v instead of 48v. If at 36v I get 1500RPM and 48v I get 2000RPM does it stand to reason that I could get 4000RPM at 96v? I could make sure the batteries are volt heavy and just 20Ah which gets my my 20 mile trips (I hope) and gives me time to charge while at work.

As far as weight then, the original motor was at least 150lbs and as long as I keep the batteries under 80lbs I should be at the same or less weight since I don't have to worry about gas or oil.


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## remy_martian (Feb 4, 2019)

Nope.

Current (which makes torque) is your problem, not voltage (which makes speed)

Save 4000rpm at your wheels for the Bonneville Salt Flats. RPM does nothing for you except put you in a wheelchair when the motor grenades.

Where this is going is a non-starter, imo. The machining on your cast ring gear will be half the cost of the project. No, you can't use it as-cast...if you've ever clearanced a ring and pinion set, you'd realize how horrifically nitpicky the setup is.

Buying a hub motor, subsidizing it by selling your GE boat anchor, and wheel as a set (AliExpress...maybe 10kW) was a wise suggestion. That motor and shaft drive is making dumb design constraints for you....say bye to it.

A good build thread on this channel, also giving you an idea of his hub motor sizing. How's your Ukranian?


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## Padenormous (3 mo ago)

remy_martian said:


> Nope.
> 
> Current (which makes torque) is your problem, not voltage (which makes speed)
> 
> ...


I appreciate the info and the video. I'll watch that later today. 

"_Save 4000rpm at your wheels for the Bonneville Salt Flats. RPM does nothing for you except put you in a wheelchair when the motor grenades._"
The wheel won't be spinning 4000rpm, the motor would. The pinion gear there has to spin 2.33 times for a full revolution of the wheel. So the wheel would be something like 1,700rpm and 90mph max.


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## Padenormous (3 mo ago)

remy_martian said:


> It's not. Horsepower is not given on that nameplate.
> 
> The two kW numbers that printed are under "HP" relate to corresponding RPM and voltages printed to the right of them.
> 
> I hope you're not thinking you can transmit power with that 3d printed gear...


After some redesigning and testing I decided to use the original transfer case and make an adapter to motor adapter, I think I can use a 3D printed object to run this.


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## remy_martian (Feb 4, 2019)

Looks nice.

You'll need to run that 3D print design by a machine shop to see if it can be cut the way you modeled it.


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## electro wrks (Mar 5, 2012)

Padenormous said:


> Put this motor inline with the shaft so it's 1:1 rpm. Then overvolt the hell out of the motor so that it's at 96v instead of 48v. If at 36v I get 1500RPM and 48v I get 2000RPM does it stand to reason that I could get 4000RPM at 96v? I could make sure the batteries are volt heavy and just 20Ah which gets my my 20 mile trips (I hope) and gives me time to charge while at work.


It may seem logical that overvolting a motor would be the answer to generating more vehicle speed with a given motor/drive reduction ratio, but it is not the case. It's true the power increases at a linear rate, within limits, as more voltage is applied to the motor. However, the power required to increase your speed increases exponentially. I forget, is it the square or the cube of the increased speed? In practical terms, it means you'll need to increase the drive ratio to take advantage of the increased motor RPM and power. And, as many of us have found, it usually takes some adjusting the ratio to dial in the proper one for a vehicle.

And, this adjusting would be difficult to do with your latest idea with the ICE right angle gearbox. The best solution to this problem I've seen is to use a chain, or better yet, a toothed belt between the motor and the shaft. The drive ratio can be adjusted be varying the teeth on the drive and/or the driven sprockets. Zapyourrideguy did this on his sidecar bike.


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## Padenormous (3 mo ago)

electro wrks said:


> It may seem logical that overvolting a motor would be the answer to generating more vehicle speed with a given motor/drive reduction ratio, but it is not the case. It's true the power increases at a linear rate, within limits, as more voltage is applied to the motor. However, the power required to increase your speed increases exponentially. I forget, is it the square or the cube of the increased speed? In practical terms, it means you'll need to increase the drive ratio to take advantage of the increased motor RPM and power. And, as many of us have found, it usually takes some adjusting the ratio to dial in the proper one for a vehicle.


So I think using the ICE right angle gearbox is going to end up giving me a 1.69:1 motor-to-wheel ratio. If I can get the voltage up to allow for 2,500RPM the bike can go 80MPH. So would that be a simple 16v ontop of my 48v to make it 64v? Is that going to be so much more demand on the motor/batteries that it'll tank me entirely? I read a post where a guy is using a 24v motor and running it at 96v. My idea seems much more conservative.


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## remy_martian (Feb 4, 2019)

The cooling on your air cooled motor is rated at 2010 RPM. If it was my build, I'd try to live with 64MPH at 48V.

80MPH on a bike is unpleasant for any extended period of time, anyway.

You can do whatever you want. It starts becoming a question of reliability and of getting rid of the heat you are adding by putting more kW into the motor.


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## Padenormous (3 mo ago)

remy_martian said:


> The cooling on your air cooled motor is rated at 2010 RPM. If it was my build, I'd try to live with 64MPH at 48V.
> 
> 80MPH on a bike is unpleasant for any extended period of time, anyway.
> 
> You can do whatever you want. It starts becoming a question of reliability and of getting rid of the heat you are adding by putting more kW into the motor.


Since the throttle is basically a potentiometer, couldn't I do a 72v battery and only crank it up that high if need be, like if I need to move out of the way quickly. 

I typically run 80MPH on the highway on my Kawasaki Ninja 250r. If it's bearable on that bicycle of a crotch-rocket, I think this is going to be exceptionally more comfortable. 

Isn't air flow to a forklift motor pretty minimal when on a forklift? My thought was on a motorcycle going 60MPH+ it would be getting saturated with fresh air and allow for some extra kW. 

Thanks for all the back-and-forth on this topic, it's forcing me to consider a lot of items I hadn't yet.


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## piotrsko (Dec 9, 2007)

Just because it's in an airflow, doesn't mean it cools well.. a forward facing scoop would channel the air, what you showed has air flowing around the motor so no real increase in cooling.

Forklifts I ran had protections for overheat, you ran it too hard, you got a red flashing light just before it turned off to cool for a half hour.


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## remy_martian (Feb 4, 2019)

That'd be fun in the rain....flashing red light at the side of the road for 30 minutes.

That's the problem with heat soaking these motors. While it may take a few minutes/seconds to overheat, it can take a half hour or more to cool back down.


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## GL1100EV (3 mo ago)

They are right on the build and gearing being much easier on chain drive but I wouldn't give up on it if you're set on the bike (and understand the additional challenge and possible cost). The motor will be the biggest restriction since you can't play around with gearing as much as chain or belt. There have been a few successful builds with shaft drive motorcycles with varying budget and complexity so it's definitely possible. Main builds I've seen couple the motor directly to the drive shaft so you're kind of stuck with RPM, toque, and gear ratio of the motor and original drive train unless you run it through a gear box. You'll need to spec the motor out for that gear ratio and torque range along with RPM for speed. Going to be extremely difficult to squeeze a consistent 60mph out of that motor. You could build with that motor to get the concept down as a prototype but you will definitely be upgrading if you want 80mph at that weight.

As for the 3D printed parts in a drive train, they'll need to be metal. Those gears/coupler, even in ABS or Nylon, would break just about instantly. It would be like taking lug nuts off with a plastic screwdriver every time you accelerated.

Here are examples of shaft drive conversions at 2 ends of the spectrum in the linked videos. Low budget guy has a few episodes, maybe you can get some reference material from either one:


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## Padenormous (3 mo ago)

piotrsko said:


> Just because it's in an airflow, doesn't mean it cools well.. a forward facing scoop would channel the air, what you showed has air flowing around the motor so no real increase in cooling.
> 
> Forklifts I ran had protections for overheat, you ran it too hard, you got a red flashing light just before it turned off to cool for a half hour.


You think I'd be getting less cooling airflow with there being more area for wind to flow over? I would think if the motor was inline with the tires, I'd be getting considerably less cooling.

Also, as far as the overheating protections, are you sure that wasn't handled by the forklift electronics vs the motor itself? From what I see with this motor it doesn't seem to have a lot of complexity to it when it comes to sensors etc. 

Is the problem you folks have with my motor the horsepower or the RPMs or? It seems like ~20hp is enough to get me moving and given the size of this thing pushing it 25% harder than it's rated for doesn't seem to me like it's going to cause a ton more heat to build up. Am I misunderstanding something here?


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## Padenormous (3 mo ago)

GL1100EV said:


> They are right on the build and gearing being much easier on chain drive but I wouldn't give up on it if you're set on the bike (and understand the additional challenge and possible cost). The motor will be the biggest restriction since you can't play around with gearing as much as chain or belt. There have been a few successful builds with shaft drive motorcycles with varying budget and complexity so it's definitely possible. Main builds I've seen couple the motor directly to the drive shaft so you're kind of stuck with RPM, toque, and gear ratio of the motor and original drive train unless you run it through a gear box. You'll need to spec the motor out for that gear ratio and torque range along with RPM for speed. Going to be extremely difficult to squeeze a consistent 60mph out of that motor. You could build with that motor to get the concept down as a prototype but you will definitely be upgrading if you want 80mph at that weight.
> 
> As for the 3D printed parts in a drive train, they'll need to be metal. Those gears/coupler, even in ABS or Nylon, would break just about instantly. It would be like taking lug nuts off with a plastic screwdriver every time you accelerated.
> 
> Here are examples of shaft drive conversions at 2 ends of the spectrum in the linked videos. Low budget guy has a few episodes, maybe you can get some reference material from either one:


I'm set on the bike and motor as I've got them and find more joy in solving my needs with existing equipment than just buying my way out of it. With the transfer case I have here it creates a clear mounting location and helps my gear ration to 1.69:1 vs 2.33:1. I don't have any way to spec out this motor, I've looked and looked and cannot find any information on it online. Can you tell me why pushing 60mph consistantly out of it is going to be hard? It's got 20HP and is 8" diameter which seems large for a motorcycle motor to me. 

The 3D part in the drive train are just for proof of concept. I tested it last night and it can spin the wheel just fine with only 12V running through it. I imagine I can get my design machined or cast or something when I get to that point.

I've seen both of those videos, but the first cost $11,000 in motor and battery, and the second seems very underpowered. But that doesn't mean there isn't anything to learn from these guys. Thank you for sharing!


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## Functional Artist (Aug 8, 2016)

Padenormous said:


> I'm set on the bike and motor as I've got them and find more joy in solving my needs with existing equipment than just buying my way out of it. With the transfer case I have here it creates a clear mounting location and helps my gear ration to 1.69:1 vs 2.33:1. I don't have any way to spec out this motor, I've looked and looked and cannot find any information on it online. Can you tell me why pushing 60mph consistantly out of it is going to be hard? It's got 20HP and is 8" diameter which seems large for a motorcycle motor to me.
> 
> The 3D part in the drive train are just for proof of concept. I tested it last night and it can spin the wheel just fine with only 12V running through it. I imagine I can get my design machined or cast or something when I get to that point.
> 
> I've seen both of those videos, but the first cost $11,000 in motor and battery, and the second seems very underpowered. But that doesn't mean there isn't anything to learn from these guys. Thank you for sharing!


IMO before you get "set" on anything, you need to think thru 
...& plan the whole project (at least the major components) 

OK, you have a motor 
...& a transfercase 
...& a mounting location 
...& drivetrain connection, "in mind"  

So now, what controller are you going to use, to control "your" motor? 
...& how are you going to choose the proper one?

What battery pack? 
...at what voltage? 
...& what Amp Hour? 
...BMS? 
...& where are you going to put/mount it?

How about the contactor? (it must match "your" systems voltage & amp requirements) 
...& where are you going to put it?

DC to DC convertor (it must also, match "your" systems voltage & also, the 12V systems Amp requirements)

Oh yea, check with your local machine shops, on the cost to create "your" custom gear 
(custom machine work is NOT cheap, NOR should it be)


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## Padenormous (3 mo ago)

Functional Artist said:


> IMO before you get "set" on anything, you need to think thru
> ...& plan the whole project (at least the major components)
> 
> OK, you have a motor
> ...


We're still working through the battery pack needs here, I can't work on the mounting locations until that's picked and I can't pick it until I know what I can do with this motor. I can't image finding the contactor is going to be difficult to find once the battery pack is selected as well as the DC-DC converter. 

I have a CNC machine capable of milling aluminum, so I may go that route if I can't find a more plug-and-play option.


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## electro wrks (Mar 5, 2012)

You seem to have a very naive and stubborn attitude about how gears, bearings, and shafts work. Also, this applies to your concepts of how to match the realistic power available from a motor to the power required for your project. I've wasted far too much time trying to assist people with these kind of attitudes. I suspect there is very little I, or others here can point out as problems, and make suggestions to improve with your project that you will mostly foolishly ignore or reject. 

So, why bother?


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## remy_martian (Feb 4, 2019)

Buy yourself 4 cheap 12V lawn mower lead acids and see what 48V does. It'll be for a minute or two, but close enough for government work.


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## remy_martian (Feb 4, 2019)

That helical gear will likely cost you a couple grand to get cut. 

Even if the motor doesn't work out, if you design it with some forethought it might still be useable on a gearbox or other motor.

But, the approach you're taking is not a cheap one. And shafts suck on a sport bike if that's how you ride, but are OK for street/highway cruisers. I've owned both, done both, but an R6 ICE sport bike and chain is where I wound up. 

It had an insurance-writeoff dead motor after the wheelies-r-us idiot lost it and bounced the engine case off a curb (my own forensics), I had bought it as a dead engined bike for EV conversion, but after the shipper dropped it off I looked at it and managed to reliably repair it 🤦‍♂️.


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## piotrsko (Dec 9, 2007)

Look at the ratings for the motor and see what you can output for hp for a 60 minute hour. I know it aint good enough for 80mph. So you over-volt it to get more hp. About 30 minutes into a run @80 it will zorch, zap, or explode if not sooner. Even H rated windings. Btw: it's the internal stuff that needs to be cooled, and electrical motors suck at cooling those, even liquid cooled car stuff. They still get hot, but they have done super trick cooling efforts you don't have, plus if it gets too hot the electronics shut things down. As proof, I almost cooked my motor climbing a 6% road at 45 mph even at 4000 rpm on a frosty day in 3 rd gear. The field went hot and set a light, then the external to mp set a light, I backed way off when the comm temp light set.


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## Padenormous (3 mo ago)

remy_martian said:


> That helical gear will likely cost you a couple grand to get cut.
> 
> Even if the motor doesn't work out, if you design it with some forethought it might still be useable on a gearbox or other motor.
> 
> ...





piotrsko said:


> Look at the ratings for the motor and see what you can output for hp for a 60 minute hour. I know it aint good enough for 80mph. So you over-volt it to get more hp. About 30 minutes into a run @80 it will zorch, zap, or explode if not sooner. Even H rated windings. Btw: it's the internal stuff that needs to be cooled, and electrical motors suck at cooling those, even liquid cooled car stuff. They still get hot, but they have done super trick cooling efforts you don't have, plus if it gets too hot the electronics shut things down. As proof, I almost cooked my motor climbing a 6% road at 45 mph even at 4000 rpm on a frosty day in 3 rd gear. The field went hot and set a light, then the external to mp set a light, I backed way off when the comm temp light set.


What motor were you using? And what HP was it? 

I cannot find any information on this motor online to see what it can output for 1 hour. At 48v, not over-volted, I can go 64mph, is that less unreasonable?


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## piotrsko (Dec 9, 2007)

Kostov 13" 192 vdc rated for 60 minutes under 300 comm amps @ 5000 rpm
Perhaps 100hp at the time so +400 amps bit overspec.

9" motor 48 volts maybe 20hp continuous so < 310 amps. No sure how fast 20hp will get you but that's in the ballpark.


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## GL1100EV (3 mo ago)

Padenormous said:


> I'm set on the bike and motor as I've got them and find more joy in solving my needs with existing equipment than just buying my way out of it. With the transfer case I have here it creates a clear mounting location and helps my gear ration to 1.69:1 vs 2.33:1. I don't have any way to spec out this motor, I've looked and looked and cannot find any information on it online. Can you tell me why pushing 60mph consistantly out of it is going to be hard? It's got 20HP and is 8" diameter which seems large for a motorcycle motor to me.
> 
> The 3D part in the drive train are just for proof of concept. I tested it last night and it can spin the wheel just fine with only 12V running through it. I imagine I can get my design machined or cast or something when I get to that point.
> 
> I've seen both of those videos, but the first cost $11,000 in motor and battery, and the second seems very underpowered. But that doesn't mean there isn't anything to learn from these guys. Thank you for sharing!


Pushing 60mph will be tough cause it seems like you're only going by HP of the motor then trying to ramp voltage to get more rpm. HP is a function of torque and speed times efficiency of the motor. So, it can be 20HP with over 130ft.lb of torque(at the motor) but max out at 800rpm. If the 1.69:1 gear ratio is motor to final drive, that would get you a max speed under 40mph depending on weight and efficiency but have decent torque to move (roughly over 200 pounds linear force pushing you and your bike). Or it would be 20HP with a max 2500rpm to get the speed you're looking for and 42ft.lb torque (around 66 pounds of linear force pushing when you translate it to the tire). Depending on weight, drag, incline, etc... that may not be enough to get moving at all and if it is, it won't be going anywhere fast. Volts will get you more RPM but Amps get you more Torque. Motors have limits for both. These are just to give you an idea of the mechanical side along with the electrical limits others mentioned about duty cycle, temp, etc...

It's understandable trying to use existing equipment to save budget and add to the challenge. That underpowered build will be very close to the setup you can hope for with that motor. He even overvolts it to 72V. You will definitely end up buying your way out of it to get that motor to do what you think it can. It's the equivalent to putting supercharger and turbo on a lawnmower engine to run a bike 80mph (increase it way past its designed power output). Might work for a little bit but you'll spend way more money on parts than you would for just buying a better fit to your needs in the first place. You're either going to have to sacrifice your expectations if you want to solve your needs with what you have or you will need to upgrade.


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## Padenormous (3 mo ago)

GL1100EV said:


> Pushing 60mph will be tough cause it seems like you're only going by HP of the motor then trying to ramp voltage to get more rpm. HP is a function of torque and speed times efficiency of the motor. So, it can be 20HP with over 130ft.lb of torque(at the motor) but max out at 800rpm. If the 1.69:1 gear ratio is motor to final drive, that would get you a max speed under 40mph depending on weight and efficiency but have decent torque to move (roughly over 200 pounds linear force pushing you and your bike). Or it would be 20HP with a max 2500rpm to get the speed you're looking for and 42ft.lb torque (around 66 pounds of linear force pushing when you translate it to the tire). Depending on weight, drag, incline, etc... that may not be enough to get moving at all and if it is, it won't be going anywhere fast. Volts will get you more RPM but Amps get you more Torque. Motors have limits for both. These are just to give you an idea of the mechanical side along with the electrical limits others mentioned about duty cycle, temp, etc...
> 
> It's understandable trying to use existing equipment to save budget and add to the challenge. That underpowered build will be very close to the setup you can hope for with that motor. He even overvolts it to 72V. You will definitely end up buying your way out of it to get that motor to do what you think it can. It's the equivalent to putting supercharger and turbo on a lawnmower engine to run a bike 80mph (increase it way past its designed power output). Might work for a little bit but you'll spend way more money on parts than you would for just buying a better fit to your needs in the first place. You're either going to have to sacrifice your expectations if you want to solve your needs with what you have or you will need to upgrade.


Thank you for this reply! It may seem like I'm being stubborn about this but it wasn't clear to me why my motor wasn't able to do what I was hoping it would do until your remark. 

I'm blown away that your Kostov 13" 192 vdc @ 5000 rpm couldn't do a 6 degree incline at 45mph??How are people running cars on similar sized forklift motors? I was looking at the big post about using forklift motors and 9" diameter was considered the smallest you could use for a car. What voltage/rpm do I need to work on a motorcycle? I was really thinking that the massive weight reduction from a car to a motorcycle that this wouldn't be near as demanding on power


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## remy_martian (Feb 4, 2019)

It isn't. 

Your problem is you've watered down the torque to the rear wheel with the 1.6:1 ratio, whereas a car does 10:1.

So you've created the same push, assuming tire diameters are close, in your 500lb bike as a 3000lb car. How big is the motor in the car in terms of torque?

Your 80mph is overly ambitious. 

I think you should build it and get what you get by running nameplate ratings vs stopping on the side of the road for 50 minutes every time you run beyond nameplate for 10 minutes.

40-50mph is ok. Tell yourself that.

You still need to get a machining quote for that helical gear - that is your priority, top of the to do list, item right now. 

That cost will kill your project and send you scrambling for a hub motor and wheel for half the money of the gear spend, so all of this is mathturbation, as @kennybobby once put it.

Your problem is that the driveshaft and motor have created a constraint, when they aren't limiting at all. 

You're in love and love makes people do dumb things.


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## GL1100EV (3 mo ago)

Padenormous said:


> Thank you for this reply! It may seem like I'm being stubborn about this but it wasn't clear to me why my motor wasn't able to do what I was hoping it would do until your remark.
> 
> I'm blown away that your Kostov 13" 192 vdc @ 5000 rpm couldn't do a 6 degree incline at 45mph??How are people running cars on similar sized forklift motors? I was looking at the big post about using forklift motors and 9" diameter was considered the smallest you could use for a car. What voltage/rpm do I need to work on a motorcycle? I was really thinking that the massive weight reduction from a car to a motorcycle that this wouldn't be near as demanding on power


I can't speak for his build but I'm guessing it would be the amp rating for the motor. Going up an incline will be asking more amps (toque) for longer and will start dipping into your continuous amp rating or duty cycle. For a simplified example, lets look at a heavy bike (250kg) with a 100kg rider (350kg or 771 pounds total) going up a 6.5 degree incline. Say a coefficient of friction of 0.7. Using the stock KZ550 rear tire(110/90r18) and 2.33 final drive ratio directly to the motor. You would need 671 ft.lbs torque at the wheel or 624 pounds force pushing you and the bike up the incline. That would be at least 288 ft.lbs continuous torque (after efficiency losses) to move up the incline. So, more weight and more speed will require more power. Most fork truck motor builds are going through a gear box and/or build for low speed/flat areas.

Your motor will need to work for the gear ratio you have, the weight you'll be moving(including inclines), the speed you'll move, and the time you spend at a certain torque (depending how long the inclines expected). Torque is also inversely proportional to speed when doing gear ratios. So the more you gear a motor up for speed, you're dropping the torque. Low torque ICE motors usually have really high RPM to gear down to the final drive and amplify torque.


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## Padenormous (3 mo ago)

remy_martian said:


> It isn't.
> 
> Your problem is you've watered down the torque to the rear wheel with the 1.6:1 ratio, whereas a car does 10:1.
> 
> ...


I'm not doing that helical gear at all anymore. I've moved to that connector so I can use the existing helical gear in the transfercase. It shouldn't be hard to find a 10 spline shaft I can weld to the coupler I have from the original ICE. So that won't be killing the project at least. But if this motor can't cut it then it can't cut it. 

I guess I'll save up for a Netgain motor. I should be able to get plenty of speed and torque out of that thing.


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## Functional Artist (Aug 8, 2016)

Your 550 isn't much bigger then my 440LTD
...& I'm scootin' around with a (similar motor to the) ME1003 (~$650.00)
*ME1003 is a Brush-Type, Permanent Magnet DC motor with very high efficiency. Capable of 11.5 KW continuous and 20 KW for 30 seconds (at 72 VDC). For voltages from 12 to 72 VDC input and 200 amps continuous (400 amps for 30 seconds ). Designed for battery operated equipment. Motor weight of 39 pounds.*
ME1003 Brush-Type DC Motor
...a Kelly KDZ72550 controller (~$300.00)
...& a 48V 50AH Chevy Volt module (~$400.00)
&
It will climb an incline, without even thinking about it.  
* I don't think the Amp meter (that I was using) is accurate (at least when it shows them 400A - 500A spikes)
...because the PZEL051 (that I now use) never shows "huge" spikes like that.


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## Functional Artist (Aug 8, 2016)

Same bike
...same set-up
...same bridge
...but, with an analog Amp meter


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## Functional Artist (Aug 8, 2016)

Same bike 
...same set-up
...but, with a PZEM 051 meter  

* This is a full ~25 mile ride (sped up a few times) 
...to see/document the power draw "info" 
...& the range, using (1) 48V 50AH Chevy Volt module





Not trying to "hijack" your thread
...just "spreading the love" (I mean lots of "food for thought")


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## remy_martian (Feb 4, 2019)

Yes, but....you can live with 50mph...he wants 80....


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## Functional Artist (Aug 8, 2016)

I was mainly showing (real world results) what could be done with a ~11kW motor
...running at (only) 48V
...on a mid-size motorcycle
...with a relatively small batt pack (48V 50AH & ~50lbs.)
&
As everyone can see, from the videos
...I ride it all over town
...keep up with traffic 
...& ride up, over bridges & everything  

FYI:
These type motors are "supposed" to produce ~70 RPM's per volt, of input
...& "if" ran at 48V that's ~ 3,400 RPM's (48V x 70 = 3,360 RPM's) = ~50 MPH

So, "if" ran at 60V it should produce ~4,200 RPM's = maybe ~60 MPH?
...or "if" ran at 72V it should produce ~5,040 RPM's = maybe ~70 MPH??


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## remy_martian (Feb 4, 2019)

Add 50% more heat at 70 than you had at 50. 

These kinds of motors aren't really cooled (blowing air really doesn't do a whole lot beyond a certain point) - they soak up heat and rely on 3:1 or 4:1 cooldown periods.

The bike here would be fine if he could accept what he gets. Bent on hitting 80mph will cost money and weight.

One thing we haven't mentioned yet is that a shaft drive has higher drivetrain losses than a chain drive, and a hub motor has none (in theory).


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## Padenormous (3 mo ago)

Alright, I found this absolute unit of a 3 phase AC motor. It's 75hp, 3550RPM for $!,000. If I could figure out the best battery setup for this thing (230v....ay caramba) would this give me what I want? Could I push 1.6:1 gear ratio through that drive shaft? Is it going to heat and melt down on me? Is it far too heavy? This thing looks like it's 200+ lbs.


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## remy_martian (Feb 4, 2019)

Waaay wrong for an EV. Too heavy, cooling nightmare, probably hates inverter harmonics.


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## piotrsko (Dec 9, 2007)

If you're going 3phase monster current, might as well use a motor from a junked EV, preferably with liquid cooling, but you have introduced new annoying $$$$ problems just with batteries and their placement, wont mention inverter or controls.
Go ahead and build it your way, but do report back from time to time.


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## GL1100EV (3 mo ago)

I would look at a Motenergy ME1905(1507) for your build to get the speed and power you're wanting while not having to break the bank on a heavy Netgain motor. They're basically a Zero motor clone and very light for their power output and price point.

Lower budget will be lower output along with having a shaft drive so it does make it challenging as you now see. You can try building something like this to give you the ability to play with Gear ratios while keeping the shaft drive. That'll open the options up for motors,






You could also get creative and add a CVT instead of the fixed gear pulleys. Effectively adding multiple gear ratios depending on speed to your system.


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## GL1100EV (3 mo ago)

Just found what you're looking for! He doesn't have any info after this video but is able to show the CVT mounted in a shaft drive bike using a golf cart motor.


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## electro wrks (Mar 5, 2012)

People have tried and tried to use CVT in EVs and pretty much found them not worth the effort, and very inefficient. A straight reduction that can be adjusted for the proper ratio using different tooth numbers on the sprockets of a chain or belt drive is the way to go.


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## GL1100EV (3 mo ago)

electro wrks said:


> People have tried and tried to use CVT in EVs and pretty much found them not worth the effort, and very inefficient. A straight reduction that can be adjusted for the proper ratio using different tooth numbers on the sprockets of a chain or belt drive is the way to go.


I think that's more to do with the space and weight it takes up. A CVT would be more efficient than running a fixed gear motor slower or faster than what it's geared for. CVT would have to be sized correctly to get any benefit and net gain may not be worth it. You're right, electric motors need a lot less gears with how wide the torque range is so right sized setups can cover any speed you want. But that's not to say it wouldn't benefit from it. You're better off using the space for more batteries using a correctly sized motor with a fixed gear but this would be a possible solution for higher speeds (with overdrive gearing) and better acceleration with an undersized (low budget) motor while sacrificing space, weight, and range.


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## GL1100EV (3 mo ago)

Here you go! Writeup on how someone converted a shaft drive motorcycle with a similar motor and jack shaft to change the gearing where he wanted it. Range is pretty low with his battery setup but that can be upgraded.

How to Build a 96-Volt Electric Motorcycle


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## electro wrks (Mar 5, 2012)

Yep, this is a much better set-up, and with a smaller motor than the OP. The OP's motor and it looks like the motor in this 96V conversion are series motors. One concern with this type of motor in any kind of drive is a broken belt, chain, or coupling might allow the series motor to overspeed(series motors have this unfortunate characteristic) and throw its rotor windings, destroying the motor. Just something to watch out for. Ideally, controllers used with this type of motor should have some kind of RPM limiter built-in.


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