OCC Stingray hotrod

[Barncat]

Time to resume ebike builds for the FL "winter"

Picked this up last season for 40 bucks. If there's a bicycle out there begging to be amped up this is it. The Teutels being chopper builders and all...

Will be bolting on another MY1020 inrunner rated for 72V and will be sharing the 20s5p MJ1's custom battery pack I built previously for my Mongoose Girder build. The ebay motor came with a standard issue Chinese controller rated at 65A, which is nominally +10 over the other build so should be a few more max watts. I have about 1000 miles on the "Girder" build, and am very pleased with the performance of these components, and you can't beat the price. The only caveat is to wire up the 3 speed switch they're designed for to smooth out the otherwise sharp hit from standing starts- it's an electric transmission... The Girder maxes @ 45mph with a light tailwind with 13/80 sprockets; this build should hit close to 50mph with 12/80 due to the extra amps and larger diameter rear tire. 25H chain works fine. Just be damn sure you use Razor chain guide plates on your rear sprocket. Speaking from experience.

I welded up an aluminum bracket that will hang the motor under the frame just in front of the rear tire. Still finishing that setup. The battery pack sits on top of the flat lower frame member and the controller will U-bolt in front of the downtube. Fixed footpegs will attach non-destructively through the bottom bracket. No pedals. Will fabricate a lexan tractor style seat to replace the uncomfortable stock chopper saddle. Moving the rear V brake bosses from lower to upper stays for chain clearance. Then it's just paint and wiring...

 

[Barncat]

Moved the V brake bosses and added the motor mounting plate to frame today. Will likely finish other miscellaneous welds tomorrow.

 

[Barncat]

Doing the final motor fit-up. Chain is just draped over sprockets for alignment purposes. Still have to drill and tap the 4 holes in the aluminum bracket but it's all going exactly to plan.

There's a before and after pic of the drilled motor end caps. Gotta have ventilation, plus the aluminum bracket will provide additional heat sinking.

The only annoying job left is sanding off all the frame decals and prepping the rusted chrome forks for paint...

 

[markz]

I dig the build, but 72V 65A on a MY1020 motor, a quick google on my part comes up with 500W for that motor, but yours is a Vevor MY1020 so different then https://www.electricscooterparts.com/motors-my1020.html which are Unite.

I also never seen v-brakes on any wide rim, but you cant beat the $40 price for that bike. A bit long for my liking but I still like yours, a good cruiser.

I would have put the motor inside the triangle.

Paint the everything black will make it stealthy.

Then custom make a battery for whats left inside the triangle, or make just a shelf to place whatever multi-purpose batteries you have to use on multiple bikes. I'd make a shelf to easily take battery off and put on, but enclose it like the suitcase ebike frames you see (Sondors, Stealth etc)

What kind of fabrication are you doing for the seat? Its not a customary bicycle seat configuration for your bike, did you cut that off or did it come like that. I personally wouldnt do a motorcycle looking seat like what Stealth does.


Your feet will be so far ahead if that hole on the top bar is where your placing your seat.

edit
https://www.vevor.com/collections/brushless-dc-motor
Specifications - Model: MY1020D - 48v 1800w 4500rpm - Rated Current: ≤ 33A
https://www.vevor.com/collections/brushless-dc-motor/products/vevor-electric-brushless-dc-motor-kit-48v-1800w-4500rpm-motor-controller-go-kart

Working Temperature: < 120 °C / 248 ℉
Motor Net Weight: 9.48 lbs / 4.3 kg
Motor Mount Bracket Size: 2.2 x 4'' / 56 × 102 mm
Motor Dimensions(L x W x H): 6.7 x 4.2 x 4.3'' / 169 × 107 × 110 mm

Similar to this bike
https://www.kijiji.ca/v-ebike/calgary/chopper-ebike/1596795827
For when the link goes away

 

[SlowCo]

Interesting build. Curious to find out the performance of that motor so I'll follow your thread :thumb:

 

[Barncat]

Hey guys- per the motor, not to worry. I already push one of these pretty hard on my previous build mentioned in original post above. It's rated for 3000W but can handle twice that for 10 second bursts, and with the gearing and 20" rear tires they pull uphill just fine. At 83V or so hot off the charger times 65A it's producing a nominal 5400W @ full throttle. On 90 degree days the motor can get pretty hot, so I keep the punishment under control then but the original motor still runs like new. Street riding as it happens consists primarily of bursts of throttle and lots of coasting; a well set up bike really rolls...

I had to put the motor where it is in order to put my existing rectangular battery pack where it's going- down low instead of on the top tube.

It will be a chopper semi recumbent riding position. The foot pegs will extend about 5" forward of and 3" below the bottom bracket.

This bike comes with V brakes front and rear. Original plan was to lace a new disc brake rear hub in and weld a caliper mount at rear dropout. Opted not to bother with all that work. Salvaging and moving the rear bosses was tricky enough.

I removed the original seatpost tube since I wasn't using the stock saddle. The frame should be slightly more compliant over bumps though this is still a hardtail. Exact iteration of seat TBD but as mentioned above, tractor style.

 

[Barncat]

Found some spray paint that looks like vintage Kawasaki green. Got the wheels and other miscellaneous parts cleaned up. Will take the angle grinder to the rusted fork tubes to get them down to bare steel then clearcoat them. May be able to reassemble most of it tomorrow.

 

[jdmvette]

The Teutels being chopper builders and all...

 

[Barncat]

I guessed and spelled their name wrong. It's actually Teutul.

All the exaggerated drama and fake deadlines notwithstanding, I did watch the show a bit back in their heyday for fabrication tips. I've never owned or wanted a chopper, but have built about 20 Japanese cafe racers in the last 15 years. I figure the Stingray will get some looks though and will be a fun inexpensive toy...

 

[Barncat]

Getting closer... probably be test riding within a week.

 

[Barncat]

Figured I'd just use a plywood seat platform from a previous project. They're relatively comfortable due to surface area. Fabbed a couple aluminum parts to mount it to the frame.

 

[Barncat]

Seat assembly and footpegs complete other than a bit of paint...

 

[Barncat]

Yesterday evening was the brief maiden voyage, and after a bit of tweaking I put 10 miles on it this afternoon. Top speed is around 45mph, as in miles not kilometers. My proprietary 20s 5p battery is still under wraps...

As I knew from decades of experience, the long wheelbase would not be/is not a high precision ride but the extended fork tubes and tires make it pretty forgiving of road vibration and moderate bumps. I wanted to keep the Teutul designed handlebar as a nod to the Schwinn OEM look, but I'm either going to cut it up and modify it or find a suitable cruiser style flat bar that will put my hands roughly 5" forward and below the current position. As is, the geometry is tailored towards kids and is causing low back strain without something to lean back against. The handling will be improved also with a closer link to the front wheel. I had considered shortening the forks slightly but jury is out on that, as is moving the controller under the battery pack. Maybe. Most of the wiring is temporary.

Spent a lot of time fussing with the V brake rehab and wheel truing etc. Fortunately the front brake is now basically dialed in and provides very good stopping power, but the back wheel is sort of half-assed and difficult to true. Not a big surprise given the extreme width... I still don't want to lace in a disc hub though so more refinement to do there.

Rear axle adjusters are absolutely necessary to lock wheel precisely in place. See pic.

Controls are as basic as it gets. Brakes, throttle with key and V indicator, and a 3 speed rocker switch under left thumb.

Anyhoo, a few more rides and tweaks and it's done.

 

[SlowCo]

Great result so far :thumb:
And 45mph is impressive!

 

[99t4]

As is, the geometry is tailored towards kids and is causing low back strain without something to lean back against.

Maybe you could use a seat like this? (minus the stand):

Drum throne.

 

[Chalo]

That won't help. He has figured out empirically why bikes aren't like this thing.

 

[Barncat]

Yeah, I'll skip the drummer's throne for now

I prefer a neutral to slightly forward torso lean while riding. And since I'm not a fan of the sissy bar look, I'm about to do some surgery on the handlebars this afternoon.

Also 90% sure I'll move the controller under the battery, which was plan A. It's tempting to get one of those new Flipsky $99 FOC
100A controllers since it would be way smaller and a bit more efficient, but 5p of MJ1 cells is only rated for 50A with brief higher bursts, so rather than whip the battery too hard and also overheat the motor, will just stick with the trap unit...

 

[99t4]

Sissybar does have some ergonomic-positive attributes.

 

[Barncat]

I usually don't nap while riding.

Rather than cut up the stock handlebars and breathe all the vaporized paint while welding, I relocated the bar clamps with a piece of 3/16 aluminum angle to the lower triple tree. It's rock solid, retains the OEM bars, and looks trick IMO. Handles great now.

During this process I noticed the headset is coming loose while riding so will fix that permanently asap. All the cables and wiring in pics is temporary and rest assured all will be tidied up shortly...

 

[Barncat]

Went down to the local bike shop to see if they had a thin locknut for 1-1/8" steel steerers as a solution to the loosening headset. No go. So I preloaded the upper cone nut, marked the nut and steerer tube, and ground a recess into the nut with the Dremel for a 1/8" roll pin, or spring or tension pin as they're known. A handy fastener for various applications. The nut is of course hardened steel and cannot be drilled. Should solve the problem. Stack space was limited in this oddball pseudo-motorcycle fork design.

Relocating the controller and doing final wiring etc...

 

[Chalo]

Went down to the local bike shop to see if they had a thin locknut for 1-1/8" steel steerers as a solution to the loosening headset. No go.

You don't need that. You only need to use a 36mm plate wrench on the adjustable race and a big crescent wrench on a regular top nut to tighten them against each other.

 

[Barncat]

yes, absolutely agree, and i was very surprised that didn't work. long story but i discovered the bottom caged bearing had broken because the fork crown race was slightly wrong size for some reason and provided marginal centering for the bearing... nothing was obvious when assembling, and even though it's a cheap headset there was no pitting or wear. this fork design is unusual and not worth describing in detail. i had some other parts around and it's all fixed now. will post updated pics in a day or two with a "finished" product. the new handlebar layout makes this a sweet handling ride.

 

[Barncat]

All done. Battery obviously not mounted but takes about 3 minutes with zip ties at each corner.

Wish I'd put the controller where it is the first time rather than basically wire the bike twice. A couple dozen soldered lineman's splices in 24ga wire are sort of a pain. One other delicate procedure where you don't want to err is removing the insulation to shorten the motor cables, given the easily damaged hall sensor wires. It's easiest to put a brand new blade in your razor knife and carefully slit the insulation lengthwise along the heavier phase wire. It comes right off.

I'll monitor the headset closely over next test rides. Have a better headset in the mail and will probably swap it out later.

The ergonomics are perfect for me now (I'm 5'11"). I figure it weighs about 45-47lbs as it sits w/o battery, which adds about 12. I tend to wear out back tires fast, so finding replacements may be an issue. And I need to fashion a kick stand. Only one place left for that to go- lower left chainstay...

Will put some miles on and make a final report in a while :thumb:

 

[Barncat]

just a few more or less final observations after putting 100 miles on it...

bike certainly does get noticed, in a good way, so that's no surprise.

at almost 65lbs, it's no flyweight, but there was no way to make this project lighter. it's an ultralight motorcycle. it can be quickly hauled down from speed with just the front V brake, which is a very pleasant surprise, so i use primarily that as opposed to wearing on the unique rear wheel rim. and as motorcyclists know, 75% of your braking is through the front wheel. i picked up a very inexpensive ($8) set of 4 V brake pads on amazon that go under the name Hapelby that work incredibly well and are squeal-free.

the headset is staying adjusted as expected and the handling is fun and very stable even at maximum speed- which is just a shade under 50mph with a 20mph tailwind. bicycles, and the upright human body, are of course wretched in terms of streamlining, so you can add or subtract roughly 25-30% of the wind speed to your performance in still air based on wind direction. this will whine up to maximum in about 10-12 seconds running downwind. these MY1020 motors are by no means torque monsters but the acceleration is brisk for street use, and good luck finding this turn-key performance for anything near the price with other components.

i put a layer of foam padding on the seat. the feet forward position puts more pressure on the "sit bones" than is desirable.

one part that i wish existed off-the-shelf is a beefier higher quality freewheel. the sprocket itself and guide plates are fine but the tiny bearings, poor tolerances and and just two weakly sprung engagement pawls are not high performance items. i may see how i can improve on that... a while back i picked up a high engagement bmx freewheel to experiment with which is very well built, but they also add a lot of drag and noise when coasting. i'd have to TIG tack the 80T #25 sprocket to the freewheel teeth, which would damage the heat treatment of the ratchet teeth to some extent... i also have a one-way bearing in the mail to play with.

since i have 20 more MJ1 cells lying around i'm going to slap together a 20s1p booster pack to piggyback on the battery in parallel to reduce amp load and sag and add even more range, which is already more than adequate.

:thumb:

 

[Barncat]

i did indeed invent an improved freewheel setup. if interested, see the "bike mechanical and structural" category on site and look for "high-engage bmx freewheel", which some of you may have read. so that's all good, and no welding required.

plus these 20 x 4-1/4 tires are still available fortunately and have a back up arriving later today.