1988 Suzuki SP200 EV Conversion

spongebob

100 µW
Joined
Aug 30, 2021
Messages
7
Location
Ontario
Hello,

Over the past year, I've been converting a Suzuki SP200 (very similar to the DR200) to electric. I'm not looking for crazy off road performance, just something fun to commute to work and school that is capable of taking on trails.

I picked up the bike for $200 CAD. (you get what you pay for):
20210725_115800[1].jpg
It's missing some odds and ends but has a solid frame.

Electric components:
6000w QS hub motor (needs to be laced to the stock wheel)
72v 46ah battery from 3.2v 5ah LiFePO4 cells from Battery Hookup
Sabvoton 72150 Controller
24s JK BMS (with active balancing)
White Rogers Contactor
and some other odds and ends.

To date, I've assembled the battery and (almost) mounted the hub motor.

Battery:
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I've also made adapters to hold the motor onto the original swingarm. These were made out of 1/4" steel and I plan on adding a thin layer of rubber or silicone on the axle flats to cushion the axle. The adapters will be bolted and glued (using construction adhesive) onto the old swingarm.
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(yes i know they are very pretty and you are jealous of my welds)
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Right now, I'm working on the battery housing (made from steel and fiberglass) and restoring some things on the bike. Progress is VERY slow because I only get to work on it a few hours a week with school and work.

Open to your comments/suggestions!

Thanks for looking
 
spongebob said:
I plan on adding a thin layer of rubber or silicone on the axle flats to cushion the axle.
I strongly recommend against this; the axle will end up spinning in the dropouts or actually breaking off after it rocks back and forth in it.

You will want the axle to be completley and securely clamped in those dropouts, preferably with a pinch-bolt, and the dropout faces need to fit against the axle flats as precisely as possible along their entire faces.

I also recommend increasing the thickness of the dropouts as much as possible. Increasing the surface area in contact between dropout face and axle flats increases the area for the torque load to be spread across, decreasing the stress on any one spot and making it less likely for axle spinout to occur.

The above is still true even if you use the little "torque arms" QS may have provided with the motor.

I have a ***much*** lower power motor on my SB Cruiser, and I actually *have* a pinching dropout on one side for the entire axle length, and a thicker-than-1/4" dropout on the other side, yet it still allowed the axle to pry them apart and spin, cutting thread marks into the metal of both dropouts' faces.

Admittedly, I make even more beautifically-welded stuff than you do ;) :oops: :p but it does effectively show how motor torque can pry things apart.

https://endless-sphere.com/forums/viewtopic.php?f=2&t=67833&hilit=%2Acruiser%2A&p=1711799#p1711798
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Axle flats are a terrible way to transmit motor torque...but it's what we have to work with for almost all hubmotors, unfortunately. :(

There are much better ways to do this (which also give safer ways to pass wiring thru that also easily let much larger wires be used), but you'd have to modify the motor yourself (replacing the axle at minimum, possibly the bearings, and possibly modify sidecovers) if you wanted to do them because the manufacturers don't see a reason to spend the money on it.
 
Great project :thumb:
And I fully agree with Amberwolf: make much thicker dropout plates with a pinch bolt to clamp the axle tight!
 
https://www.instagram.com/p/CQjaMqNrRDL/?utm_source=ig_web_copy_link

Thicker but the bolts needs to be able to crimp the axle also.I went with alloy for that very reason and works perfectly even jumping the bike.Also make the slot vertical being as its harder to snap in that orientation :thumb:
 
Thanks amberwolf for the feedback, I've started working on some CAD designs for the axle adapters and will get them CNC'd out of a stronger material, like speedy1984. :thumb:

I've made some progress on the battery box:
The "frame" of the battery box is made from 1/8" angle steel
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I've also started mounting it to the bike using the original engine mounts. I'll add more supports between the box and frame later.
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I'm not sure what to make the walls of the battery box out of, aluminum sheet, fiberglass, steel sheet? Thoughts?
 
spongebob said:
I'm not sure what to make the walls of the battery box out of, aluminum sheet, fiberglass, steel sheet? Thoughts?
Fiberglass.

Then you can make it into the shape of Pikachu, and run your battery wires like this:

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:bolt: :lol:
 
amberwolf said:
spongebob said:
I'm not sure what to make the walls of the battery box out of, aluminum sheet, fiberglass, steel sheet? Thoughts?
Fiberglass.

Then you can make it into the shape of Pikachu, and run your battery wires like this:

m_5edd198aff8304114dcda125[1].jpg


:bolt: :lol:

:lol: :lol:

It's a long weekend in Canada (to celebrate some dead queen's birthday) so I had some extra time today to work on the CAD models of the axle adapters. Using tinkercad because im a noob

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These will have thicker contact points between the motor axle and adapter as well as clamping on the sides.
I uploaded to Xometry.com to get a price quote, and using steel 4130, its $760 USD . . . yikes, anyone know a cheaper place for cnc?
 
For testing, I've modified the existing swingarm adapters, they are now wider with clamping on the motor axle.
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I spun the motor over by hand and was pleasantly surprised at how in line it was (like a trued wheel). There was almost no side to side motion while spinning. The next biggest challenge is lacing the wheel around the hub motor, I might have to do that myself if I can't find a place nearby, fun stuff.

Thanks for looking
 
The clamps look like a good start. :)

Lacing isn't hard, just tedious, and best done with good tools (such as a good spoke wrench made for the size spoke you're using, not the universal ones which I've yet to find a good one of).

There's a lot of websites, YT vids, etc., that teach various methods of lacing (for both bicycle and motorcycle wheels). I started at Sheldon Brown's site for most of my bicycle wrenching knowledge; Chalo's posts here on ES are also full of good lacing / wheel info.
 
Been a while since I last posted. I laced the wheel, used the grin tech spoke calculator for spoke length.
I ran into some issues with the spokes, some of the spokes (not all) bend at the nipple like so:
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anyone have a solution for this?

should've just gone with the 17 in hub motor without any spokes :roll:
 
To straighten out the nipple angle remove the spoke and take a small round file and shape the hole to the correct angle then replace spoke.
Do each spoke one at at time.
The reason to do one at a time is it's easier to verify the angle.
It's a slow process but if the wrong angle is left in place it tends to break the spoke at the last thread.
Part of the custom build fun.
 
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