Electric Trail 70 - a distraction

So this all starts years ago when I end up with the guts to a street legal electric scooter from a wreck.  I throw everything in a bucket and put it on the shelf. Someday...

Fast forward about 5 years, January, this year.  Outside my shop next to the dumpster I spy the carcass of a Honda Trail 70.  Being the hoarder I am, I grab it and roll it in my shop. 

It spends a few months leaning against the wall.  The neighbor that threw it out sees it and laughs at me.  It turns out a friend of his had found it next to a dumpster 10 years ago and started tinkering with it.  It got to the taking apart stage and then the project stalled. 

I'm in the middle of doing an engine in my wife's X3.  90K miles and it spun a bearing, crank has cracks.  Not really happy.

I need something to keep from kicking a puppy or something and I spot the CT70.  Perfect!  While I'm waiting for the new long block and misc parts to trickle in I'm going to electrify the Dax.

Here are the parts I've had, and new purchases, to make it my new pit bike.

Excellent! 

In for more!

The first steps are really just a "proof of concept."  The scooter drive system is only 24V but the motor is rated at 2hp(1500W).  I'm shooting for 30mph and bought gears to get me close to that.  I found a 45 tooth rear sprocket that fits the stock way and a 10 tooth front for the motor.  The motor has a strange 15mm shaft so I had to buy a sprocket from McMaster Carr that could be machined to fit.  I bored it out on the lathe and drilled and tapped for a set screw.  The next problem was making the 420 pitch motor cycle chain fit on the 40 pitch sprocket.  420 is the same pitch as 40, it is just narrower.  I ended up turning it on the lathe, had to take about .050 off IIRC.  I took it slow thinking I might crash the tool on the teeth but it just gave off a slight buzzing sound as it passed each tooth.

The motor mount was the biggest puzzle.  Stock it was face mounted but I didn't have room for that. I ended up making a big clamp out of a piece of 6" aluminum tube.  The motor is only 5" dia so some spacers were needed that would still transfer heat.  I rolled some stuff I pulled off the scrap pile for the test phase.

Power is going to be supplied by a DIY Li-ion battery with the help of a Vruzend kit.  42 LG 18650 cells will give me 25.9V and 21Ah to start with.  I liked this option because I can take it apart and reassemble it as a higher voltage set up if I don't get the speed I want.  I will also add to it to increase range after testing.

This...Looks... Awesome! 

Carry on.

Here is a shot of the motor mount in its test form.  The 6" tube was split to give it some flex and I'll add some angle to run bolts through to tighten it later.  I made some spacers that fill the gap in the frame the engine normally bolts to and The motor clamp will get welded to them.  For testing, it gets held together with big hose clamps.  I'll control motor torque with a small arm running from the face of the motor to the chassis.

Chain installed and was thinking about the possibility of a test ride.  I got the front brake working and found I couldn't adjust the play out of the headset.  I take it apart and find no bearings at all.  Stock they have 21 loose bearings top and bottom.  Since everything I have needs to be high speed/low drag and NASA approved I ordered a tapered bearing kit.  Hopefully it will be here by the weekend.

Any idea on the range ?

Is it for up and down the driveway or a beer run to 7-11 ,?

The battery as it is right now will probably give me about 10-13 miles.  Its pretty flat around here so that helps.  Additional battery capacity is already being planned if needed.  I want to see if I get the speed I want first, then I'll decide on voltage.  The controller manual says it cuts off above 30 Volts.  I can build a 29.6V battery by switching things around. The charger on the way can be programed to handle anything up to a 48V pack so I can get a little more speed from more volts on this motor without the smoke escaping.

It would be nice if you could hide the batteries inside the frame, but I suppose there are too many of them to all fit in there.

Is there something other than friction keeping the motor from rotating? 

I think you might be building a wheely machine and that is awesome.

Adam

stuart in mn said:

It would be nice if you could hide the batteries inside the frame, but I suppose there are too many of them to all fit in there.

That was my first thought when I was looking for a battery pack.  I could fit this pack in the frame where the stock gas tank  and battery go but the controller needs a safe spot.  The engine and carb fill the area under the frame pretty well and many years have a pair of bars that run from the frame right behind the forks to under the engine.  After considering I will probably want more battery I decided to put the controller under the seat and make a battery box that will fit where the stock cylinder is.  I think I can keep the stock look from a distance with the right design and also keep the weight of the battery low in the chassis.

Here is what mine looked like new.  The color of the year was Yellow in 1979

And here is one with the bars I'm going to add.  The frame even has the holes the mount them in front.

MrJoshua said:

Is there something other than friction keeping the motor from rotating? 

Right now no, I'm going to add a torque arm to keep it from spinning before I do any drag racing starts, lol.

The head set kit came in late yesterday.  I installed it and threw the triple tree back together.  I started wiring the system up foe a potential test ride.  The biggest concern was anything with voltage touching the chassis.  I covered the terminals with hunks of hose and used a half roll of electrical tape as insurance.  Not my finest work but it will work for speed testing.

I installed the new front tire after I pictured my obituary saying I died on a scooter when the 40 year old front tire blew.  I was ready to attach the warp core to the outside of the frame and it started raining.  So test flights are put off until this weekend.

I also got to meet the first dumpster diver that took it apart.  He loves the project and said he might still have a sticker set that he bought.  A few hours later I get this picture from my shop neighbor.

Can you have a 3d print of a Honda 70 motor to hide the battery pack in ?

californiamilleghia said:

Can you have a 3d print of a Honda 70 motor to hide the battery pack in ?

Damn!!! Thats GENIUS!!!!!

we have guys here with 3d printers. Bet you one of them could help out.

I have one.  I love the idea.  Even a simple model that would give me the general shape would be enough. I could stretch it here and there to fit the cells.  I was thinking of making a box and putting a picture of the engine, carb, and air box on the sides.

Ok, but can you mount a speaker to play nice Honda 70 noises as you go down the street......

Vrooom vrooom

Funny you mention the sound. I did a quick spin up with the guts laying on the floor and the back tire off the ground a couple days ago.  The motor howls like a banshee and the frame acts like a megaphone.  It will be interesting to see if the seat muffles the sound coming out the top.

Awesome project,  hope the test ride goes well,  wear some safety gear,  you know, for just in case something doesn't go quite as planned,  looks like you will have a very cool pit bike.  Love it that PO saved those stickers,  they will be the icing on the cake 

 I had issues with the controller kicking off so I pulled everything out of the frame and cleaned up the wiring.  It still was acting up so I left it on the floor and went home to shop for a new controller. 

I decided to try one more time this morning.  I don't know what I did but it works now.  It either healed itself overnight or it was tired of my crap yesterday and went into hibernation for its own well being. 

I took a couple short runs at walking speed to make sure nothing fell off. All good.  My first high speed runs got me up to 15 and 18mph on my phone speedometer app.  Both times it was still pulling but the contact relay would cut out for about 5 seconds then come back on.

There is a bunch of safety circuitry built into the controller so I'm thinking that may be an issue.  The system is designed for lead acid batteries and they can do different things the Li ion batteries can't.  Mainly barf out lots of amps, the Li ion's are touchy at high amp flow.

I had to stop testing because I had an issue when installing the battery management system (BMS).  I don't know if it was defective, or if I screwed up, but some smoke got out of it during the install.  The BMS protects the battery during discharge and charging and without it I didn't want to hurt anything. 

My charger arrived but I need a new BMS to charge the battery.  I'm also going to get more cells to experiment with battery voltage and a different controller to see how it reacts.

I ordered a new fancy BMS with a display and bluetooth programming.  I wanted one that was more than a one trick pony voltage-wise.  This one will handle 24v up to 84v and 300 amps.  That will give me the same flexibility as my battery kit, anything goes!  I also ordered another 40 18650 cells.

While I'm waiting for parts I will entertain you with glamour shots of the parts I'll be powder coating in the next few days.

Pretty slick!  Keep working!

I've been a little busy with a rental property but I had some time to work on the battery today.   The BMS is on the way from the other side of the world.  I used the charger to bring the voltage up to match the new cells and then started building.  You can see how much bigger the pack is now. You can see the old buss bar pattern.

Here we are feeding the beast with the most expensive charger I've ever purchased.  It can be programed to charge any kind of battery down to 1/10th of a volt.  I'm playing with it to sneak up on the 30V limit in the controller.

I should have some powder coating shots tomorrow.  I need to fire some pottery for my wife and I don't get any grief for being at the shop for 4 or 5 hours while I run her kiln.

Here is a quick shot of the parts I coated today.  I tried a powder from a local supplier and I'm not too happy with it.  Even after pre cooking the parts to control out gassing it still didn't lay down as well as the stuff I've been using.  A couple parts don't matter because they won't be seen but I'm going to have to order some B17 stripper to get the screwed up finish off. 

So the project this is the distraction from is pushed back a few days longer.  I was watching cable news the other day and I see the reporter up to his nuts in a flood reporting from a town in Oklahoma.  I see the location and realized it is the town that my BMW engine is supposed to be being built in. A couple texts back and forth and the shop is OK just shut down for a few days because half the workers couldn't make it in.  Living in Florida I understand weather delays so I wished them well and will check back later.