Lightweight Emotorcycle ideas

[Jeremy Harris]

Having already converted my recumbent with a hub motor etc, I now want to move on to another electric project. Rather than go for a heavy motorcycle conversion, I'm toying with the idea of building a light weight electric motorcycle, using one of the small trials bike type mopeds as a base.

I've had a look at a Suzuki TS50 and also a Yamaha DT50 and it looks like either would be viable. The plan would be to strip out everything from the bike except for the frame and running gear, fit something like an Etek RT or Perm PMG132 motor, running at 48V, with a big LiFePO4 battery that will handle reasonably high discharge rates. I'm using a Ping duct tape pack in the recumbent and it's great, but would need something with a higher discharge rating to run the Etek.

At the moment, I'm leaning towards the Etek RT, as it's cheaper than the PMG132 and still has a reasonable rpm/V figure, which might mean I can get away with the standard rear sprocket.

I'm thinking along the lines of fully enclosing the frame (with ventilation) by making up very light composite panels, using the lost foam technique. I'd most probably make up a one-piece seat and dummy tank moulding the same way, to maximise space for batteries.

The advantage of using a moped that's already registered is that I'm reasonably sure that I can just declare the change of motor and fuel type, without having to go through the single vehicle approval process. Being a moped it would need speed limiting to be legal, but this should be easy to do (perhaps with a hidden defeat switch..........). It also means that it might be easier to insure, plus it can be ridden here on a car licence.

Does this look like a viable project for a fun commuter bike (I only need maybe 15 miles range)?

Jeremy

[Malcolm]

Hi Jeremy

Definitely a viable project, and it's about the same approach I'd take if were to do another conversion now. Lithium was totally out of my range when I chose my bike, so I had to go with one that was capable of carrying a good weight of lead. You should easily get 15 miles from a 1500Wh battery pack, so at 48V that means around 16 x 30Ah cells or parallel strings and a weight just shy of 20 kg.

Not sure what the legal moped power limit is, but my insurer asked to see the specifications of the motor I had installed (en Etek) just to make sure that its power output didn't exceed that of the original engine. I'm sure this varies from insurer to insurer, so you might want to check with Jozzer how he got on with his insurance company.

[Jeremy Harris]

Thanks Malcolm, you've confirmed (with the benefit of your practical experience) what I thought might be the case. I was thinking of trying to fit about 40 Ah of LiFePO4 (at 48V) in the frame if I can, but this will depend on the spare space in the frame and how much weight I can remove by shedding bits of the original bike. A combined motor, controller, and battery weight of 40kg seems reasonable, as a maximum, as I'm sure the frame will take this OK.

I'm in two minds as to whether to buy a complete bike, or buy a frame, forks, wheels and brakes etc and build the rest from scratch. The latter approach might stop me being tempted to re-use heavy bits from the original bike, but I'm more likely to get a V5 by getting a whole bike.

Reading the moped rules, it seems as if UK law says "no more than 50cc with a 50km/h speed restriction", rather than a BHP limit as applies to other motorcycle classes. I've found a reference to an EU moped definition which says "50cc internal combustion engine or electric motor not greater than 4kW, speed restricted to 45km/h". I'm hoping that someone has already done this and can give me an idea as to what the powers-that-be are likely to say. I've built a couple of kit cars (pre-SVA) and found then that the DoT people were reasonable.

If the 4kW limit applies, then I think that the Etek running on 48V might be shown to comply, if the controller is current limited to 80 amps. Fitting a Cycle Analyst, with it's optional limiter, might get around this, particularly if I can demonstrate that the motor delivers less than 4kW using the display. Mind you, the temptation to hide a delimiter switch, to remove the 80 amp limit, might be a bit strong!

Jeremy

[Jeremy Harris]

OK, time for an update.

I've taken the plunge and bought a Yamaha RD50MX frame, forks, set of RD50 alloy wheels (with new tyres and disc brake front) and assorted sundry parts (a stripped bike minus engine and tank, basically). It came with a V5, so all should be well when it comes to sorting out the legalities.

I've ordered a Mars ME0709, a Kelly KD48201 controller, 200A contactor and fuses plus a 48V to 12v 20A DC-DC converter. I can get a motor sprocket easily enough, but need to find a source of big blank rear sprockets to machine to fit the RD50 alloy wheel.

The remaining quandary is over batteries. My choice is currently split between 16 40Ah Thundersky LiFePO4 cells, 48 (or maybe 64) Headway 38120 10Ah cells, or perhaps some suitable Yesa cells.

I'm leaning towards the Thundersky cells, based on their good track record, at the moment.

Finally, a word of praise for John Fiorenza at Mars Motor LLC. Not only has he been very prompt and helpful, but he's bent over backwards to make sure I got a good shipping deal to the UK.

Jeremy

[gogo]

I think that's a great choice for a lightweight conversion.

For those that don't know what an RD50 looks like, here you are:


I had an RD60 and drove it on the freeway at 65 MPH (105 KPH) and it felt stable.

[Jeremy Harris]

Yep, that top picture's pretty close to what I've got, even has the same wheels, except mine are gold.

I've been doing a stock check of parts and found that most of what I need is there. It'll be the little things that will no doubt cause some hassle, like the odd missing special bolt. So far, I seem to have a surfeit of some parts, with only a few critical bits missing. It looks like I need to get a headlight, rear light, foot brake lever and a pair of the special big headed bolts that go into the top of the forks.

I've decided to cut the seat down and make up a new combined single seat base and dummy tank, following the shape of the original rear light fairing. This will give me some space under the rear of the seat to fit a small charger, with luck.

I need to sort out a new wiring loom, plus source a new glass for the instrument binnacle, but so far nothing looks too difficult. The instrument panel looks easy enough to mod. I think I'll be able to just take the rev counter out and fit some battery health monitoring stuff in it's place neatly enough.

Next step is to take all the sundry parts I'm going to use to the local bead blaster and get them cleaned up and hopefully powder coated.

Jeremy

[Jeremy Harris]

A long overdue update on progress.

Buying a complete basket case bike as a dismantled heap of bits in cardboard boxes has proved to have some good points and some bad ones. The good stuff is that it's forced me to rebuild everything, and not be tempted to re-use something just because of the hassle of taking it apart to check it out. The really bad point is the small, but seemingly irreplaceable, parts that seem to be missing. Believe it or not I've spent more time trying to locate an RD50MX stand spring than almost any other part of the bike...........

Anyway, the frame has been bead blasted, primed and painted, the forks have been completely rebuilt (including new stanchions and seals) everything has been sprayed and I'm part way through assembling things. The Mars motor fits really neatly, better than I'd hoped. It's a tight fit in such a small frame, but I've ended up with the sprocket pretty much exactly where it was with the petrol engine. I've not needed to buy a new rear sprocket either, the combination of a 13 tooth front sprocket and the standard 48 tooth rear will be OK to be getting on with, I may switch to a bigger front sprocket if it has enough torque to pull the higher gear.

The batteries (64 Headway 10Ah LiFePO4 cells) are all going into the seat base, tail fairing and fuel tank area. It'll be a bit of work, but I'm making up a new seat/tail fairing/"tank" from epoxy glass. This will (hopefully) be lighter than the old shagged out seat, plus I intend to make the seat just a solo, saving more weight and giving me more battery space. It also means I can bin the rear footpegs and their brackets, saving another pound or two.

The instrument panel is nearly done. I discovered that a "Watts Up" display (when ripped from it's casing) "just" fits neatly into the old rev counter dial face. I need to add a remote current shunt (suitably uprated) but this looks pretty easy to do. As I'm running at 48V nominal, the Watts Up will do fine, plus it is a really cheap way of getting comprehensive metering. I've been playing with ways to keep it powered up all the time, so that it doesn't forget the power used (allowing it to be a proper "fuel gauge"). This seems to be nice and easy, as the Watts Up has an auxiliary power supply connection. I've hooked this up to four small NiMH cells, which are kept charged by a small (60mm x 60mm) solar panel. The Watts up only draws about 7mA, so this little solar panel provides plenty of charging capacity. The NiMH cells on their own will run the Watts Up for a week or two, even without a bit of charge from the sun.

With luck the bike will be back on it's wheels by the weekend, so I'll be able to wheel it outside and take some photo's of progress to date.

Jeremy

[Jeremy Harris]

I managed to wheel the bike out and take a couple of pictures this evening.



It's taken a while to get to this stage - buying a bike as a box of assorted bits, all disassembled and in varying states of repair, has been an "interesting" experience. Still, at least I know that everything's in good condition now, as I've rebuilt just about everything.

Here's a picture of the Mars ME0709 motor installation:



The motor mount was machined up from 3/8" 6082-T6 alloy (pretty much the same as 6061-T6 which is more common in the US). The batteries are going to go into a custom built seat/tank/tail fairing, moulded from epoxy glass. I need to finish building the CD welder so that I can get the battery packs made up before I can make a start on the bodywork. I also have a stack of work to do cleaning up all the old plastic bits from this bike, like the mudguards (fenders in US-speak).

Jeremy

[Jay64]

I am doing a build on a Suzuki TS 185 at the moment. I'll have to look at mine and see if I could do a similar motor mount system as what you have. Right now, the Lifebatt pack I have fits perfect in the front portion of the frame so I'm not sure if I want to take that away, but maybe I could fit your motor mount design around the lifebatts.

[Jeremy Harris]

The hardest bit in making the mount was getting accurate dimensions for the relationship between the various pick-up points on the frame. I ended up by making up the plate with the motor hole milled out and the motor mounting holes drilled, plus the hole that picks up on the rear swing arm bolt. I then marked the top and front holes by fitting the plate and using a transfer punch. I got around the awkward bottom mount by fitting a separate bit of alloy, which allowed me to fiddle about to get things lined up.

The front of the plate is stiffened up with a bit of alloy box section, bolted to the plate and fitted with a pressed-in spacer tube that picks up on the front engine mount. All told it's probably a bit of an over-kill in terms of stiffness and strength, but I wanted to make sure that the motor stayed in alignment even if the bike hit a really bad bump at speed. The worst stress case for the mount is the weight of the motor if the bike hits a bump, not the chain pull loads, which are quite low.

Jeremy

[RealPeterPan]

Hey Jeremy,

nice work there.
And good to see there are more people on the european islands working in the EV area.

I´m currently based in Dublin planing to convert an old east german scooter:



I always loved these beauties and there still running everywhere in germany as they are handled as oldtimers and can run up to 60kmh rather than 45kmh with the new european law.
So to get them in germany with blown motor cost you less than 150€. My only problem to get them over here.
I´m still seaching for a shipper who is going to Dublin anyway and has space left for a euro-pallet.

The rest should be easy to do as they have the petrol tank under the seat which gives you lotta covered space rather than building a faked tank arround a battery pack.

This is the frame I will work with:



Well I hope you continue posting your progress that I can peep a bit more before I have all my parts together

And maybe we see each other here viewtopic.php?f=10&t=5037 next time.

So long

Sven Brinkhoff

[RealPeterPan]

PS
I´m spezially interrested in the noise of your front sprocket.

Let me know when it runned the first time.

Regards

Sven Brinkhoff

[bugbomb]

Hi Jeremy,

I’m interested to see what kind of range and speed your bike gets.

I have a similar project in that I am also using the ME709 motor and stock 37t rear sprocket. I have a titled, but non-running, 1981 Honda CM400. Here in Oregon all I have to do to register it as an electric motorcycle is pass a safety inspection. I’m moving the center post of the frame back 3 inches to allow room to mount the motor on the swing arm. This gives me room to build a good sized battery box for 16 Thunder-sky 90Ah LiFePO4 cells. It won’t be much in the looks department but I hope it will make up for that in range.

Tom

[northernmike]

Jeremy, did this ever go further?

[Jeremy Harris]

"Nearly" finished, Mike.........

I've had it running, but got side-tracked into trying to make nice bodywork for it, then fell foul of a whole heap of legal stuff related to it's registration - basically our Driver and Vehicle Licensing Agency simply can't get their heads around converting a motorcycle to electric power, so keep throwing legal spanners in the works.

After many 'phone calls, a visit by an inspector, at least a dozen letters and a great deal of frustration I'm nearly there, except they've now put the wrong engine number on the registration document, so I have to send it back yet again.

Meanwhile, I've been sidetracked on to the electric boat project, but will probably get back to the bike in the next few weeks, now that the weather's warm enough to do some glass fibre work on the body (new dummy tank and seat, plus side covers to keep the weather off the motor etc).

Jeremy

[northernmike]

Aha, exactly why I am able to proceed with my 50cc conversion.

In Ontario, E-bike and Moped legislation are very similar - in a nutshell, having pedals is my ticket to ride.

No registration, insurance, etc - the only "must" is that I wear a helmet.

...

(and keep it to "32 kph")





Very nice work on this, though, sir, well done!

[swbluto]

So, uhhhhh, what progressed have you made with this?

[liveforphysics]

Your project is my most favorite of all the E-motorcycle conversions I've seen.

Please give us an update!

[northernmike]

Jeremy, you HAVE to get this going.

50cc frames with eTek power are ... wonderful.

I just got off my Motobecane 40 conversion and WOW.

I need a drink!

[spinningmagnets]

Jeremy, you are far ahead of me, so I hope I don't sound pretentious, but I have a suggestion.

If you can lower the motor one or two inches, I would definitely recommend doing that. After you add the weight of the battery pack, and an adult, the bike would squat down some. Its at that point where the chain should be as centered as possible over the swingarm pivot. If the chain rubs the pivot when parked (180 lbs removed?), it wouldn't hurt at all because its not moving...PS, I am jealous !

[liveforphysics]

I'm wanting an update in the very coolest electric motorcycle conversion project!

Your bike is the first electric motorcycle conversion I've ever seen that I would actually be thrilled to throw my leg over and go carving.

[RemoteContact]

Hey Jeremy, Where on earth did you find that frame and other rd50mx parts? Waiting desperately on updates here btw.

[Jeremy Harris]

A delayed update.

I'm too busy with the electric boat stuff to get around to finishing this project, so it's up for sale - see the used stuff for sale section.

I'm in the UK, and I'd guess that it would be ridiculously costly to ship it overseas, so that's not really an option.

Jeremy

[Malcolm]

That's a shame, I would have liked to have seen this finished, but I know what it's like when you have several projects on the go. The one that gets least attention is always nagging...

Whoever snaps this up will be getting a real bargain I'm sure.

[Jeremy Harris]

To be honest, I've bitten off more than I can chew. I started this project before the boat propulsion idea took hold. Once I posted a bit about the electric boat stuff I have been inundated with work, quite apart from my own interest in building a solar power augmented river boat. It seems that the electric revolution is extending way beyond road vehicles!

You're right, it should be a bargain for someone, Malcolm. I've done most of the difficult stuff, like the refurbishment of all the running gear and sorting the motor mounting and drive, so all that's left is relatively straightforward. I'm obviously not looking to get my money back, I'm more interested in passing the project on to someone who will complete it and get some use from it.

Jeremy