# Planning 1971 Honda SL175 motorcycle conversion



## zohargolan (Jun 10, 2011)

Hi all,
This is my first post in this forum, and my first EV convertion. I wanted to start on a cheaper platform and I decided to go with a motorcycle conversion.
I spent the last couple of weeks searching for a donor vehicle that will fit most of the following guidelines: It should be Small motor size ~250cc for easier and cheaper conversion, It should be Complete as possible, and it should be titled and registered.
I ended up getting a 1971 Honda SL175 motorcycle form Fremont cycle salvage in Fremont california. The motorcycle cost was $270 and it came with a title although it was not registered for the last 7 years. From my research on DMV, the motorcycle is not in the DMV records anymore (it is falling off the system after 4 years), and I will have to take it to the DMV in order to re-register it. I still don’t know what to expect regarding the registration cost. 
Here are some pictures of the motorcycle:

















I came up with the following initial specifications:
1. original weight of the bike (with the ice system) is 113 kg
2. wheel diameter - 27”
3. I want to use a 24 – 36v system (2 to 3 batteries)
4. I want to use SLA batteries
5. maximum speed of 50mph
6. range of 30-50 m
7. direct drive system

I am trying to figure out how to calculate the required motor power, torque, RPM, gear ratio, etc., but so far I havn't found a good description for how to calculate those parameters.

I will appreciate any comments, suggestions, recomendation etc. that I can get.

Thank you
Zohar


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## frodus (Apr 12, 2008)

You'll need higher voltate most likely, because 24-36V won't get you the RPM you need with most of the motors you'd use for a motorcycle conversion. That means you'll have a low RPM motor, and potentially draw a ton of amps due to gearing a low RPM for high wheel speed.

The weight is going to me MORE than an ICE bike if you use SLA and have a range of 30-50miles.

For a range of 30-50miles, you're gonna need lithium. SLA tops out at about 30-35miles for most conversions, it's possible for more, but the weight becomes an issue.

Budget?


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## zohargolan (Jun 10, 2011)

Hi Travis,

thank you for your replay.



frodus said:


> You'll need higher voltate most likely, because 24-36V won't get you the RPM you need with most of the motors you'd use for a motorcycle conversion. That means you'll have a low RPM motor, and potentially draw a ton of amps due to gearing a low RPM for high wheel speed.
> 
> The weight is going to me MORE than an ICE bike if you use SLA and have a range of 30-50miles.
> 
> ...


My budget is around $2000. Can I fit a lithium pack in this budget?

Thanks, 
Zohar


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## frodus (Apr 12, 2008)

not a 50 mile range lithium pack, along with motor, controller, contactor, charger, some sort of battery monitoring (or management) device, cable, new rear sprocket, new chain, gauges...etc.


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## zohargolan (Jun 10, 2011)

frodus said:


> not a 50 mile range lithium pack, along with motor, controller, contactor, charger, some sort of battery monitoring (or management) device, cable, new rear sprocket, new chain, gauges...etc.


 yes... exactly what i thought. I guess I will start with a set of SLA. A range of 30 miles might be enough for what I need at this time (my initial specs called to 30-50miles anyway).
any pointers to links that explain the calculations?

Thank you,
Zohar


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## frodus (Apr 12, 2008)

It's going to take some heavy batteries to get 30 miles on 36V, but it depends on speed. Higher speed = more power from batteries = larger battery pack with enough energy for 30 miles.


The calculations will be hard to find, because they're all over the place and not many motors have an accurate motor curve. There are some sheets out there. Go to elmoto.net, we're all motorcycle guys there, and they'll help you out.

The best thing to do is calculate weight, frontal area, estimate the coefficient of friction, and estimate how much power peak you'll need and get a motor designed to do that. The fit in as many batteries as you can.

I think you'll have a harder time keeping the budget than you may think.


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## joegyoung (Aug 9, 2011)

This sounds very interesting as a conversion project. I have a spare that I might plan to do this with. But I am also working on a CD 175 to get it back on the road. So if you are not going to need the engine off of this bike and are not to far away I would be interested in it. Where are you located?


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## zohargolan (Jun 10, 2011)

joegyoung said:


> This sounds very interesting as a conversion project. I have a spare that I might plan to do this with. But I am also working on a CD 175 to get it back on the road. So if you are not going to need the engine off of this bike and are not to far away I would be interested in it. Where are you located?


Hi Joe,
I have some extra parts that I amtrying to sell from this motorcycle. among the parts are engine, gas tank, carbs, etc.
I am located in san jose california, but I can send the parts anywhere is the USA.
Let me know what you need.


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## joegyoung (Aug 9, 2011)

yea CA is where I thought you would be based on your post. I'm in Western NC Zip 28805) so shipping would be??? what parts do you have other than the engine?


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## zohargolan (Jun 10, 2011)

I have engine, gas tank, left and right switches, exhaust clamps, carburators, wire harness, coil, capacitor, regulator
You can email me directly [email protected] if you are interested in one anything


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## UCFdave (Aug 31, 2010)

I'm resurrecting a bit of an old thread.. I'm actually in the process of restoring an SL175 for my father and have been having a heck of a time trying to find some specific pieces. Please let me know as to the status of the bike and available parts because I might be able to help differ some of the cost of the LiPo's that you're going to want for your bike.


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