# 92 Kawasaki KX 250 e-bike project



## Little Rhody (Jun 17, 2008)

I think your on the right track. The voltage will be determined by the size of the batteries, and space available on the frame. I'm a firm believer in more volts the better. But thats just me. If you can figure out how to fit 72V in there with some 20 or 30 AH lifepo4 batts, I think you could be fairly happy with the performance. A pancake motor such as the items you listed above will probably be the only type of motor you can fit in that frame.

Good luck, and keep us posted. 
LR


----------



## 85bmw528edude (Oct 17, 2008)

One other thing I have seen on some of the ev bikes is a belt or chain driven sprocket that goes from 1 side to the other, and some that don,t change sides but look gear reduction setups to me. What are they trying to achieve? speed reduction? or trying to increase speed? or?


----------



## frodus (Apr 12, 2008)

Well, I've got an ADC motor for sale, its an A89-4001 series motor....the controller I'm selling to go with it is 48V, but the motor can definately handle 72V. Controller is ~300A, made by GE for golf carts, very simple to setup. I've got a couple of contactors as well. Let me know, I just want to see more bikes on the road  See my add in classifieds. A pancake motor might fit in there better though, but my motor is a smaller diameter.


For your bike:
You'll likely have to change the rear sprocket to get the right gear ratio. Lots of ratios on stock bikes is below 3:1, and for an Electric motorcycle, you will probably need more like 4-5 or even 6:1 to get the performance you need.

For 25 miles, you'll need 2500-3000Wh in your battery pack. 50mph top speed is doable (mine does over 65, keeps hitting battery sag limit though, which is why I'm upgrading bats). Range and speed seems doable, but you'll likely have trouble getting 25 miles @ 50mph. 

The biggest question is, do you have enough room on that frame for that size of pack? Maybe you could do 4 12V 50Ah batteries (600Wh each, times 4 = 2400Wh) and get about 20 miles. It'd get you to 45 (50 maybe depending on gearing). It looks like it'd fit in that frame too.


----------



## 85bmw528edude (Oct 17, 2008)

Thanks for the imput. I like your vfr, its very good looking and well thought out. Your prices are very good for your stuff you have for sale but I am just in the planning stages right now. I am sure you will sell your stuff before then. I am not purchasing anything probably till next February or March. I am just seeking imput now, so I don't make a big costly mistake or have a poor result. I would like to do a streetbike like yours but my streetbike days are over because of a bad car wreck, not my fault, a couple of years ago. I have a 30 mile 1 way commute and a boss who would not be supportive of at work re charging. The Kawasaki will be a neighborhood plaything. I would still like imput on my unanswered questions about the sprocket/belt set up on the Quantya's. whats the purpose and do I need it on my bike?


----------



## frodus (Apr 12, 2008)

85bmw528edude said:


> Thanks for the imput. I like your vfr, its very good looking and well thought out. Your prices are very good for your stuff you have for sale but I am just in the planning stages right now. I am sure you will sell your stuff before then. I am not purchasing anything probably till next February or March. I am just seeking imput now, so I don't make a big costly mistake or have a poor result. I would like to do a streetbike like yours but my streetbike days are over because of a bad car wreck, not my fault, a couple of years ago. I have a 30 mile 1 way commute and a boss who would not be supportive of at work re charging. The Kawasaki will be a neighborhood plaything. I would still like imput on my unanswered questions about the sprocket/belt set up on the Quantya's. whats the purpose and do I need it on my bike?


Let me know...

As far as the belt/chain changing sides, sometimes its because the motors used are meant to run one direction, and the sprocket is on the other side. Also, its so that you can use stock rear sprockets (cheaper aftermarket) and do the ratio up front near the motor and easily chang out gears without removing the main chain.


----------



## 85bmw528edude (Oct 17, 2008)

So, are the E-teks and perm132 non reversable? I thought they were? The Lemco on the Quantya is supposed to be, so I am not sure why they did that unless it was to change the gearing. I really will not be sure what battery packs will fit until the motor is mounted. This is just going to be a fun no stress project.


----------



## frodus (Apr 12, 2008)

85bmw528edude said:


> So, are the E-teks and perm132 non reversable? I thought they were? The Lemco on the Quantya is supposed to be, so I am not sure why they did that unless it was to change the gearing. I really will not be sure what battery packs will fit until the motor is mounted. This is just going to be a fun no stress project.


I think the old eteks aren't, I'm not sure of others, its something to check.

Can't wait to see what you create!


----------



## 85bmw528edude (Oct 17, 2008)

Thanks! I will post up pics when the actual build begins. I am going to clean up the frame this next weekend. I am going to start doing some measurements and trying to imagine where each piece needs to go. Does anyone know the measurements for that Alltrax controller model 7234. I want to mount it where the fuel tank went, and then use the front plastics and the top of the gas tank with some home made brackets. I guess the contactor will go up by the handlebars also. Can I mount a keyswitch up there also? I need to find or make a kickstand for the bike. I need to also make up some type of battery trap or box also but until I see how much room is available, that will not be possible.


----------



## TX_Dj (Jul 25, 2008)

85bmw528edude said:


> One other thing I have seen on some of the ev bikes is a belt or chain driven sprocket that goes from 1 side to the other, and some that don,t change sides but look gear reduction setups to me. What are they trying to achieve? speed reduction? or trying to increase speed? or?


I think you're talking about what's called a "jack-shaft".

I.E. the motor output is on the opposite side as the wheel sprocket.

This is often done then a motor rotates the opposite direction than what is needed for the bike it's being put into. I.E. if the motor cannot be run in reverse as efficiently as it's normal forward rotation, mount it such that it's output is on the side of the bike that provides forward rotation, which in turn moves the jack-shaft so that the opposite end of the jack-shaft has the sprocket which drives the wheel.

Yes, it can be used to facilitate gear reduction, though usually is set up as a 1:1 ratio between the motor and jack-shaft, leaving the final ratio from the jack-shaft output to the wheel.


----------



## 85bmw528edude (Oct 17, 2008)

Okay! I was just wondering. Can these be bought or is this a machine to order expensive part.


----------



## 85bmw528edude (Oct 17, 2008)

Well, I got the roller out yesterday and cleaned up the frame. In looking at it and trying to figure out how the pieces are going to fit I have come to the realization that until I have the motor in hand its going to be hard to doing anything else other than maybee mounting the controller and throttle once I get them. I found a E-tek mounting bracket from a robot supply company that would look good but without it in hand I am just not sure how all it will go together. I am still wondering about that belt drive set up from Quantya on their bikes. Its a belt drive that goes from the motor to a sprocket that drives the chain drive. I am wondering if the did that to be able to place the motor lower in the frame to make room for the battery pack or if their was too much interference with the chain rocking up and down?


----------



## Palalat (Nov 3, 2008)

85bmw528edude said:


> Okay! I was just wondering. Can these be bought or is this a machine to order expensive part.




Same question here. Can we buy a machine only to it?


----------



## 85bmw528edude (Oct 17, 2008)

I found a place called "The robot marketplace" that sells a lot of stuff like the sprockets, bearings , drive chains, shafts etc. to move the output from one side of the electric motor through a shaft mounted in bearings that I think could be mounted to the frame. I think that ordering any parts for this is going to have to wait until I have all the parts in hand except the batterys, so I can see where the optimal mounting points should be. Keeping in mind that the swing arm cannot be allowed to hit anything in the drive chain sprocket setup bearing blocks etc. I am sure that I will wind up ordering parts that I will have to exchange, but thats the nature of the beast I suppose.


----------



## 85bmw528edude (Oct 17, 2008)

So, where can I purchase these parts for this Jackshaft? I found a robot parts place that has what appears to be what I need, but I was and still am wondering if any of you have ran a jackshaft? If you have, where did you source your parts from or did you have someone make them at a machine shop? How much did you spend?


----------



## 85bmw528edude (Oct 17, 2008)

Still wondering about the jackshaft set up. anyone?


----------



## kp647 (Oct 21, 2008)

Best place is to get some 5/8 of 3/4 bearing blocks from surplus center
get the good cast iron ones http://www.surpluscenter.com/item.asp?UID=2008111706082032&item=1-2123-24-B&catname=powerTrans
then get a 5/8 or 3/4 keyed shaft 
then get the sprockets (surplus center)
I used #40 chain

make aluminum plates to hold bearings and motor that bolt into original motor mount locations

like so


----------



## kp647 (Oct 21, 2008)

BTW my setup is 
Motor : mars etek r 0708
Controller: Kelly KD72401
Batteries : 72v 18s3p 13ah lipos from RC application (actually 75v full charge)

Gearing: stock rear sprocket 46t
front sprocket 13t

Jackshaft: 11t on motor 24t on shaft
I think the current reduction is 7.7 to 1
That makes for great launches but a low top speed (around 35)


----------



## 85bmw528edude (Oct 17, 2008)

Thanks for the reply and info/pictures. Do you have any more pictures? That looks good. What bike is your roller? I am thinking about using (2) 14 tooth sprockets up front on the jackshaft and a 56 tooth on the back. would this work or do I need to use a 12 tooth up front and a 60 or 72 tooth at the back? I read some where that you need to use a 6 to 1 ratio, but I cannot remember why that was mentioned or seem to find why that was recommended.


----------



## kp647 (Oct 21, 2008)

how many teeth on your rear sprocket, and what size rear tire?

shoot for between 5.3 and 7.0 to 1 total ratio

Use the jackshaft for extra reduction to keep rear sprocket stock

dont try to use to small a front sprocket on the main chain

13t would be good, chains dont like real small front sprockets


----------



## 85bmw528edude (Oct 17, 2008)

Back tire is an 18 inch, back sprocket is a 52 tooth the front one off the 2 smoke engine is a 14 tooth.. I hope to be able to get up to 50 mph with the gearing. I do know that top speed burst do negatively effect range.


----------



## kp647 (Oct 21, 2008)

50 mph will require very powerful and light batteries and lots of volts/watts

gearing maybe around 5.25 to 1 overall

stock reduction is 4 to 1

so your jackshaft would need a slight reduction of 1.3 to 1 or so

You will need an etek RT or a perm 132 and 72v+ of powerful lithium batteries $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$


----------



## 85bmw528edude (Oct 17, 2008)

I plan on using an etek style like you have and an alltrax 7234 controller. I really don't absolutely need 50 mph continuously, but would be nice to have that speed , most of my running will be in the 20-25 mph range. Batterys will unfortunately be what I have room for. I definetely will need 72 volts. I need to get the motor and jackshaft in the frame to see what room is left, to be able to make a battery tray(s) and to figure out what batterys will fit. I hope 2 get a 20-25 mile range. I will mostly be trail riding in woods. This is just going 2 be a toy. this will be a learning experience before I do a car conversion later. I hope 2 do a BMW 5 or 3 series someday with a 30 mile range 1 way or 50 mile range 2 way


----------



## drewjet (May 25, 2008)

I think you may need to drop your top speed requirement. If you want to be riding trails then you are going to want a nice low ratio of somewhere around 8 or even 9 to 1. To get the top speed of around 50 you would need a 6 to 1 or so. 

You may want to look into a comet CVT as it would give you the jackshaft you want and also variable reduction.

For batteries at 72 volts you are going to probably need in the range of 30 to 35 AmpHours to get a 20-25 mile range, especially if riding trails where it will consume much more power than on the flats of a street. Either A123 or BMI would be my recomendation.

Sounds like a great project!


----------



## 85bmw528edude (Oct 17, 2008)

Well, I have plenty of time to make a decision about all the details. This project will not start until the Spring of 09. I am building a garage onto my house and I am pouring the concrete slab in February. I am refraining from buying any parts till thats been done. I will probably buy the parts individually as I can not fork out all of it at once. I will start with the Alltrax 7234 controller first, then the throttle, then motor after that I will have fabricated whatever drive components and the motor brackets. I do not expect to be riding it until the summer at the earliest. I will post pics and progress reports when the build continues.


----------



## 85bmw528edude (Oct 17, 2008)

Old thread but not forgotten project. I have had a lot happening since the last post and have had new ideas. I have since the last post became disabled and disability retired from my job, moved to Tennessee and had lots of health issues. Everything is pretty well sorted out now. I saw on YouTube a video where a guy did a yz 125 with a 10kw hub motor and it got me thinking. Enertrac 603 hubmotor, eliminates valuable space needed for mounting batteries being used to mount motor inside frame where the 2 smoke motor was. This eliminates chain alignment issues, lowers I think the center of gravity. battery technology has gotten better in the last 2 years also. Anyone see any negatives of trying a hubmotor with 10kw of power? Any comments?


----------

