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Stevo replied to the thread Aprilia RS125 2-STROKE conversion.
" The shim stacks will need to be redone like I said. Heavier oil and reshimming the valves will do the trick, but it will take some experimenting and that means shock rebuilds. Lots of time and nitrogen refills. It would be a challenge and expensive for sure. That's why I chose to stay away from hub motors.
With that said, there are still some advantages to hub motors that are compelling. I think they are perfect for smallish scooter type builds,but that's just my 2 cents of opinion. "

11 Hours Ago

Spoonman replied to the thread 1979 XS750 electric conversion.
"
Quote Originally Posted by biothundernxt View Post
I might go with keeping the foot brake stock and adding a second throttle for variable regen.
In case it's useful, the Vectrix throttle is available here:
http://www.shop.vectrixparts.com/thr...-and-grip.html

Rolls about 90degree back for acceleration and about 30degrees forward for deceleration/regen in normal use.
Output is the standard 0-5V range so it's ostensibly something like regen from 0-1.5v and motoring thereafter. "

19 Hours Ago

biothundernxt clicked Likes for this post: 1979 XS750 electric conversion by gregjet

1 Day Ago

biothundernxt clicked Likes for this post: 1979 XS750 electric conversion by Richard230

1 Day Ago

biothundernxt replied to the thread 1979 XS750 electric conversion.
"
Quote Originally Posted by Richard230 View Post
I can understand why the engine is missing from that XS750 chassis. As I recall, the 750's engines were not one of its strong points from a reliability standpoint.
It was actually in really great shape until the guy who owned it before me got his hands on it. It needed some routine maintenance, so he took it to a mechanic, and the mechanic suggested a couple things could stand to be rebuilt. He asked if he wanted him to get started so he said sure, but after the mechanic got done taking the top end apart, they started talking about money and the guy balked and just asked for the parts back. So then they sat in a box outside for over a year.
Needless to say everything in the box rusted. "

1 Day Ago

biothundernxt clicked Likes for this post: 1979 XS750 electric conversion by Spoonman

1 Day Ago

biothundernxt replied to the thread 1979 XS750 electric conversion.
" I am not set on using a strain gauge.
My only real experience with them was with auto leveling 3d printers... which never really worked very well anyway.
I mostly just want to retain the foot brake and the feel.
I might go with keeping the foot brake stock and adding a second throttle for variable regen.

I did get a BMS, I just forgot to post it on there.
I wanted to get an Orion 2, and likely will for my second build, but the expense was too much to justify for this build.
I am using a 300A rated ant bms with a screen and bluetooth.
I've heard good and bad things about them, but i figured it would be better than no BMS, and it was about 1/10 the price of the orion 2.


My first inclination was to use the shaft. I could not find a motor with enough oomph that would fit without some serious modification to either the frame, or the shaft. I mocked up the ME1616 and the AC-20 but nothing would fit to the input of the shaft.
I considered mounting the motor transversely, and using the AC-20, but I had concerns with the torque leaning the bike over in corners.

I plan to do another build after this one is complete, but it will be much more long term, and very expensive, so I wanted to build this to get me riding in the mean time. "

1 Day Ago

gregjet replied to the thread Hi from Tasmania BMW K100 Electric..
" Interesting. Very interesting "

1 Day Ago

gregjet replied to the thread 1979 XS750 electric conversion.
" I got all excited when I thought someone was going to use an inline motor and a shaft drive. I was thinking centralized motor and a short belt drive to the drive shaft. Bit disappointed now.
Good chassis for a conversion though. Good and strong in the right places. Old school suspension though. "

1 Day Ago

gregjet replied to the thread Aprilia RS125 2-STROKE conversion.
" Spring rate is the least of the problem. 43kg+ of unsprung weight on the end of a swingarm, will require really custom damping curve and complex SSV. Even on a flat road, if you get brake chatter, the damper will be severly stressed.
Getting the CoG anywhere near the pendulum axis will be a feat in itself. "

1 Day Ago

Stevo clicked Likes for this post: 1979 XS750 electric conversion by Spoonman

1 Day Ago

Stevo replied to the thread Aprilia RS125 2-STROKE conversion.
" Finding the right spring is key and will take some experimenting ($$$)
Heavier oil and reshim the dampening and rebound shim stacks translates into more time experimenting.
Hopefully you can get it close in a few shock rebuilds. It would be an expensive project to get it dialed in right. "

1 Day Ago

Richard230 replied to the thread 1979 XS750 electric conversion.
" I can understand why the engine is missing from that XS750 chassis. As I recall, the 750's engines were not one of its strong points from a reliability standpoint. "

1 Day Ago

Richard230 clicked Likes for this post: 1979 XS750 electric conversion by biothundernxt

1 Day Ago

Spoonman replied to the thread 1979 XS750 electric conversion.
" Looks like a nice easy fitout dude - great job so far - and well done on the parts selection.
That motor marries pretty much perfectly with those modules and that controller in terms of what they can each draw and source respectively.

WRT the strain gauge notion - have you worked with them before? They can be a real PITA at the best of times.
I'd be more inclined to put a pressure sensor onto the brake line. There's no shortage of vendors out there doing custom lines - all you need is a split line terminated with the appropriate fitting.
Far more reliable measurement.

The other route you could go would be similar to the Vectrix approach - they use a throttle which goes both directions. Roll back for acceleration, forward to deceleration. Added bonus is that the latter allows it to reverse as well.

Whatever way you go, I'd stay well clear of strain gauges unless you're well accustomed to working with them (I have quite a few hard yards with the things in custom applications) - they'll only break your heart.

I don't see any mention of a BMS in there - they aren't a must, but if you're not using them then you'll want to leave yourself with the ability to easily check and balance manually.
Doesn't have to be anything fancy, but you will want to have something. Those leaf modules are unbelievable good at staying in balance, but you'll still get variations. "

1 Day Ago

biothundernxt created the thread 1979 XS750 electric conversion.
" Alright, lets get this thread started.
I recently acquired the aforementioned XS750
I will add pictures later this week.

I have ordered the following parts:
17" by 6" 12kw rear hub motor from qsmotor (configured for 145kph)
300a ANT bms with screen.
Kelly KLS96601-8080I
A 220v charger for 96v lipo at 20A
Swingarm from a fazer since my bike stock was shaft drive.

I already have lying around:
A pile of matched nissan leaf batteries to make my battery
The bike itself

Things I still need to get:
Brakes for the rear wheel (I'm in contact with some suppliers right now)
J1772 adapter to feed the charger
throttle (considering either a domino pot throttle if i can find one, or a cable throttle pot module)
Dcdc converter (suggestions welcome)
Main power contactor


I did some looking about but I could not find any mention of anyone using this motor.
https://www.qsmotor.com/product/17-inch-12kw-hub-motor/

I plan to document my entire build process thoroughly with lots of pictures and data.
There is a local place that is willing to let me use their dyno too when I get it put together.

For variable regen, I plan to use some kind of strain gauge on the rear foot brake. I havent figured out the details yet, but I am sure emulating the potentiometer input to the controller for that with a microcontroller based on the output of the strain gauge should not be too hard.

I don't expect this to be a drag strip monster, but having some actual data out there should be informative.



Any other suggestions are welcome too.

Here are some photos of what I have so far:
This is how it looked the day I bought it:
Attachment 8466

Then I started stripping things down:
Attachment 8467

Here I tried fitting one of my leaf cells for reference to see if they would fit, and what orientation might be best:
Attachment 8468
Attachment 8469

More recently, I assembled the pack itself.
At 96v nominal, I estimate that the pack should be around 4.3Kwh. I plan to build another pack at some point later with LG chem cells that would be around 11kwh, but those cells are expensive and I already have these, so...
Attachment 8470

Here is a cardboard box made to the dimensions of the aforementioned battery module for scale reference.
I need to build an enclosing box to hold this and some of the other electronics in.
Attachment 8465
Attachment 8471

And lastly, here is a picture of that fazer swingarm I ordered:
Attachment 8472

I hope it fits. Some other conversions from shaft to chain for the XS750 used this swingarm, so fingers crossed that it will not require much modification.
We'll see. It should get here pretty quick, it is only going across town. "

1 Day Ago

biothundernxt replied to the thread Chinese E-Vader/E-Grom/E-Monkey.
" Well that's disappointing...
The company I ordered from canceled my order because they miscounted inventory and cant get any more in stock because of covid...

Oh well...
Back to plan A then.
Plan A was my other motorcycle project: Yamaha XS750 conversion.
Ill post another thread for it.

Sent from my GM1915 using Tapatalk "

1 Day Ago

gregjet replied to the thread Aprilia RS125 2-STROKE conversion.
" Definitely can be resuspended. You need a friendly experimental and knowlegeable suspension person hands on.
The big problem with suspending it properly is the crazy unusual weight distributions
. You have a crazy light chassis and swingarm, mated to a crazy heavy wheel, with massive torque across the rev range. It is completely out of the realms of the experience of almost everybody. I am NOT saying it can't be done, just that it is going to take a VERY intelligent and clean slate approach. Pretty much every chassis and suspension parameter will be wrong for optimium handling.
Good luck. It is the sort of problem I would love to be involved in solving and ,I bet, so would any creative suspension person .
My approach would be a mid engine but I would love to see an elegant solution to the rear hub motor problem. "

2 Days Ago

Stevo replied to the thread Aprilia RS125 2-STROKE conversion.
" Can the rear shock be resprung and dampened? I checked my suspension go to RaceTech and they only have kits for RS250 "

2 Days Ago

gregjet replied to the thread Aprilia RS125 2-STROKE conversion.
" Take one of the best handling motorcycles on Earth and add 43kg to the back wheel of a bike that weighs not much over 100kg total. Unsprung to sprung mass is not exactly ideal. Rear suspension will be completely overwhelmed. "

2 Days Ago