65 Honda Dream conversion: thoughts and suggestions on a basic plan.

[DCDreamer]

I'm doing a first build...definitely at the beginning stages and definitely learning a lot. I'm looking at this motor/conversion kit for the a 65 Honda Dream.
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Was considering the hub motor, but read a few things that convinced me to go the mid mount motor ( I can do some basic frame/motor hang building. The Dream frame is actually fairly light once you drop the motor and the stamped steal construction is fairly amenable to mods.
Looking to build a bike for around town.. errands, commuting etc. Might have to run from on exit to the next on the Beltway for convenience. So it will need to do a decent clip for a short time, but mostly riding city streets--40 to 50 mph top end. I think the 3kW motor will be plenty fast.
What are the relative benefits and liabilities of the 60V vs. the 72V? And are there any suggestions for battery setups? Would love to get as much run time as possible out of the setup, but not looking at super long rides. I think there is sufficient room to get a pretty decent size battery pack. Will probably use the tank as cover for the controller etc. might even be able to get some battery cells in there.
Another crazy idea a friend had was to add a small propane generator (hiding small tanks under the gas tank). I personally think it's a little far fetched. Any thoughts?

 

[gromike]

Off hand, I'd say you will need more kw for the motor.

 

[classicalgas]

Most of the E-mopeds that are claiming 50- 60 mph are running five to six times your 3KW. That's peak. About a third that sustained. I think you'll want more.

 

[DCDreamer]

Thanks! I was really concerned about that. What i liked about this set-up is that there are 4 gears. Good torque at the low end and better speed at the high end.
But.... There are a few other motors I'm looking at. This is one:
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I like the idea of gears, because it's more "motorcycley". I love the feeling of being able to shift--the lack of that kind of control, to me, is the biggest liability of electric.
So... 10 to 12 kW? What does that mean for the battery set-up? can I realistically expect to fit the battery I need in this bike?

 

[DCDreamer]

Is that peak? or is it sustained? From what I've been reading, that's sustained, with higher potential for short bursts. But I am new to this and could be misunderstanding. It looks like they're sayin 12kW max.
But I hear you. I may be looking for something more powerful.

 

[DCDreamer]

Off hand, I'd say you will need more kw for the motor.

how much do you think?

 

[gromike]

I don't know. On my Grom I'm planning on a 6kw hubmotor. I could just as easily do a 9kw hubmotor, but with more power requires more battery. That 10kw motor you linked is 20kws peak. So roughly 140 amps continuous, 270 amps peak at 72 volts. When you figure how long and at what speed/terrain you'll ride you can size your battery, and then cry.

It has been routinely recommended to use the Grin motor calculator at ebikes.ca to help figure all that motor stuff out.

 

[DCDreamer]

I don't know. On my Grom I'm planning on a 6kw hubmotor. I could just as easily do a 9kw hubmotor, but with more power requires more battery. That 10kw motor you linked is 20kws peak. So roughly 140 amps continuous, 270 amps peak at 72 volts. When you figure how long and at what speed/terrain you'll ride you can size your battery, and then cry.

It has been routinely recommended to use the Grin motor calculator at ebikes.ca to help figure all that motor stuff out.

I'm already getting teary...

 

[SlowCo]

See this thread here on E-S:
Honda Dream hub motor conversion
And read through some of the threads of (almost) completed conversions to get an idea of the possible ideas and solutions: Conversion threads

 

[gromike]

I found the build thread linked below quite interesting, as he built three batteries before he got the performance he desired: 1987 Yamaha FZR250 .
As I am currently attempting to build a 72v 36ah battery for my moto conversion my take away from the above thread is my first battery attempt is probably just that -- the first of maybe several.

 

[DCDreamer]

Watched the mannydantyla youtube video and it's actually what inspired me to try this build. There is a lot of great stuff in the conversion threads, thanks for the suggestion. Some of the technical stuff is a little daunting, but I'm learning with each read.
I think I'm changing my mind about the mid-drive motor. The hub motor seems more than sufficient for the way I plan to use this bike.

 

[DCDreamer]

Yes, the batteries are a little intimidating and seem to be the touchiest part--as well as the most important. I'm looking at the QS 6kW and 8kW hub motors. They seem to do a pretty good job at helping you make sure you have the right controllers etc. Most people seem to be very happy with them. It's just a matter of figuring out how much battery I'll need and how I'll fit it all in--and pay for it.
We have some pretty significant hills here, so I might need more than I initially thought.

 

[gromike]

I suppose it will be a QS273 motor if you do a hubmotor build. I would do more than 5 kws for the motor. 5 kws seems to be the 50mph Grom equivalent bike that is in production now.
It all depends on what you want to do. If you want to flatten the hills with a DD hubmotor -- get some watts!

 

[DCDreamer]

I agree gromike. I'm leaning toward the QS 8kW hub motor. It's not as powerful as some people are suggesting I use, but it seems to be the strongest hub motor they make. Once it's all stripped down, the Dream is actually pretty light, and there is room to build a decent frame for the batteries. I've been looking at some off the shelf batteries instead of trying to build something out of multiple cells. It might cost a bit more, but if, in the end I have to build several iterations it might be worth it. Something like this...or this......though maybe not these exactly.
Thanks for the input.

I'm also curious about the front wheel. Aesthetically, I'd like to keep the spoked look. But I'm wondering whether it would be worth it--or even possible-- in terms of price, weight reduction, and ease of retrofitting, to get a new front wheel with a disc brake. The bike won't be super fast, and I won't be doing a lot of rough riding, so I shouldn't need anything too crazy.... or am I totally deluding myself there?

 

[harrisonpatm]

I'm leaning toward the QS 8kW hub motor. It's not as powerful as some people are suggesting I use, but it seems to be the strongest hub motor they make

If you can fit a 17in wheel (perhaps you can't) they make a 12kw continuous hub motor. But, like you say, the Dream is lighter than it looks. You'll be fine with the 8kw. I run the 8kw on a 365 pound bike going 55mph continuous, and it only draws 5-7kw, barely gets warm after 30 minutes straight.

 

[gromike]

From what I learned here at endless sphere, and amberwolf did school me a bit:

1) Figure out how much peak power you need for what you want to do;
2) Figure out how much power that you will use over time;
3) Size the battery electrically, then see where you can physically fit it;
4) Finalize the motor you will use, and how to mount it. A hubmotor requires a fair bit of attention as to the clamping of the wheel into the swingarm.
5) Then buy all the stuff for the conversion.

As far as my build, I got lost in a battery building dark hole. I like to believe that I will build a suitable battery from the 200 used LFP cells that I bought. To this point I have burnt up two inexpensive spot welders. I balked at the $1000 battery, and instead bought the aforementioned cells for about $200. When I do succeed in my battery build, that store bought battery will probably seem like a bargain.

It seems like a production emoto that would suit my needs, will be here in the US sometime this year. But what fun would that be!
If I can build the emto, me supplying the donor, for about $3000 , and the thing works--that would be a win.

 

[classicalgas]

Is that peak? or is it sustained? From what I've been reading, that's sustained, with higher potential for short bursts. But I am new to this and could be misunderstanding. It looks like they're sayin 12kW max.
But I hear you. I may be looking for something more powerful.

The bike I've ordered (after looking for a year for a good donor for a DIY ) is this one...

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18 kw peak, 6kw sustained, and only 65 mph top speed, and briefly at that. It does have a thermal shutoff and metering. I picked this one over several others largely due to the mi drive. Decades as a gearhead have taught me how important low un-sprung weight is. Hub drives over 500w or so just add too much weight in a bad place. 24 hp peak, from standstill, in a bike that weighs 165 lbs is quick enough for me. And with the mid drive, I can tweak that a little if I end up wanting to.

 

[gromike]

Well, maybe I'll be doing it the wrong way with a 6kw hubmotor, but I much prefer the truck of my Grom to that $7k Voodoo bike.
My use would be a lot of short trips. Hop and go like my gasser Grom, but without sludging the oil because I never go far enough to cook the moisture out of the crankcase. I also don't do chain maintenance like I should....and I do love regen braking.

 

[classicalgas]

Look ( and driveline priorities ) are a real individual thing. I'm old (Mike Hailwood was bringing Ducati back from the dead when I started riding ) sixties cafe racer is what bikes "should" look like, IMO.

Or even older, like my "1915" replica.

 

[DCDreamer]

Decades as a gearhead have taught me how important low un-sprung weight is. Hub drives over 500w or so just add too much weight in a bad place. 24 hp peak, from standstill, in a bike that weighs 165 lbs is quick enough for me. And with the mid drive, I can tweak that a little if I end up wanting to.

Yeah. That was a big concern I had when I started looking at motors as well. As I learn more it seems that there are different, but almost as many build considerations and mods I'll need to do for the hub motor as there are for a mid mount. One of the things I'm thinking about is that the heaviest parts on ths Dream , after you lose the engine, are the wheels/brake drums. Not ad heavy as a hub motor to be sure, but not insignificant.

 

[DCDreamer]

1) Figure out how much peak power you need for what you want to do;
2) Figure out how much power that you will use over time;
3) Size the battery electrically, then see where you can physically fit it;
4) Finalize the motor you will use, and how to mount it. A hubmotor requires a fair bit of attention as to the clamping of the wheel into the swingarm.
5) Then buy all the stuff for the conversion.

Great checklist. My riding will be mostly city, with some not insignificant hills--after years of riding my bike around town I recognize that hills are often longer and steeper than people realize, and there are more of them. The pricetag on the ev batteries is more, and can be daunting. But like you say, in the end it might not be as big a difference as you'd think.

 

[classicalgas]

Yeah. That was a big concern I had when I started looking at motors as well. As I learn more it seems that there are different, but almost as many build considerations and mods I'll need to do for the hub motor as there are for a mid mount. One of the things I'm thinking about is that the heaviest parts on ths Dream , after you lose the engine, are the wheels/brake drums. Not ad heavy as a hub motor to be sure, but not insignificant.

Yep. In a retrofit of a powerful hub motor, securing the axle is not a trivial operation.

Rims and spokes are in addition to the weight of a hub motor. Its easy to get fooled by the weight of a bare hub motor compared to a wheel minus tire...your drum brake alone isn't all that heavy. It's almost all aluminum, and mostly hollow. Unlike a hub motor of the same size. Steel motorcycle rims aren't light.

You can mid mount a retrofit mid drive in a small old motorcycle without ever needing to weld, it;s all bolt together (with the right adapter plates ) I don't think you could mod a rear swingarm to tie in a 3kw hub motor without welding. Maybe if you put in some sort of reaction link, like you see on some drum brakes.

 

[DCDreamer]

You can mid mount a retrofit mid drive in a small old motorcycle without ever needing to weld, it;s all bolt together (with the right adapter plates )

Any suggestions on reasonable mid mount motors with enough power? I'm still going back and forth on this one.

 

[classicalgas]

No specific recommendations. I'd look at what the Surron hot rodders are using, and what other retrofit projects used. I'd use a motor with a reduction drive, to keep the rear sprocket size somewhat normal looking (and available easily)

 

[DCDreamer]

I found the build thread linked below quite interesting, as he built three batteries before he got the performance he desired: 1987 Yamaha FZR250 .
As I am currently attempting to build a 72v 36ah battery for my moto conversion my take away from the above thread is my first battery attempt is probably just that -- the first of maybe several.

I think I'm going to actually go with an off the shelf battery from Amorge. The quote for two 72V 24ah batteries came in much more reasonably than I expected and I've heard good things (we'll see, I guess). Apparently they can also customize size. But as I said, I'm pretty new to all this so I'm playing it safe--especially when it doesn't bust my budget.