View Full Version : Honda ST1100 Project

02 December 2011, 1513
I am in the initial planning stages of an EV conversion of a Honda ST1100 shaft drive, water cooled motorcycle (ICE curb weight ~700lbs) for commuting. I've looked at a lot of different motors and AC-15 or AC-20 look like they might be a good fit. I'm not sure yet what voltage I'll be running, but I'm shooting for somewhere between 72-120VDC and at least 10kWh. I have to get the ICE out so that I can measure and mock up pack and motor configurations. I'm sure I can find the ~75 liters of volume for a 10kWh pack of LiFePO4 prismatics, but I want more than 10kWh.

I believe that the shaft drive ratio is either around 1.8:1 or 2.8:1, I'll be measuring it after I pull the ICE. I think I'll need a gear box fabricated rather than a direct connection to the shaft. I think that I may be able to mount the drive vertically and have a 90 degree gear box attached to the shaft. I think that configuration would leave the maximum space available for a battery pack. I would really appreciate some thoughts/ideas about this. What type of gears should I look at for this type of configuration? Would such a mounting position require thrust bearings to be installed in the motor? I've found one example of a similar setup, but chain instead of shaft. http://www.diyelectriccar.com/forums/showpost.php?p=197005&postcount=2

I will not be using the bike for racing, likely will never have it over 100mph, and am looking for range rather than acceleration. For a fairly large commuter bike like this, is the AC-15 or 20 a good fit? I've also looked a the NetGain and Kostov 9" DC Series motors, but the weight on those seems excessive for a motorcycle. If I end up with a DC Series motor, I'll likely use a SolJr controller. Whatever direction I end up going in, I plan on using the existing water cooling system for the controller and charger.

What motor/controller combo would you guys recommend? Have I overlooked any good options? Am I nuts thinking about the 90 degree gearbox?

02 December 2011, 1526
If you do go with DC we build the Zilla Z1k that would be PLENTY of power for your bike. Although a nice AC20 system or maybe the AC35 (due to the extra weight of your bike) would do very nicely.

Look forward to seeing picks and other great ideas from the group here.

Best of luck

02 December 2011, 2115
Ah the ST-1100. My first love. (My ICE ride now is an ST-1300). What do the guys at st-owners.com think of this swap? :-)

Looking forward to the pics on this one.

02 December 2011, 2149
Haven't told 'em yet. ;) A lot of them are "Iron Butt" enthusiasts and might not understand a sub 100 mile ST1100.

I'm going to be asking Mellow for some help with some frame maintenance items while I have the engine out.

02 December 2011, 2227
Sounds like fun Stan. I believe the final drive is 2.83:1, so you will want another 2:1-ish reduction in your primary drive.

IMHO a 90 degree set of gears is going to be a bear to fabricate/adapt, and a hassle to maintain. A belt type primary drive would be fairly simple, maintenance free and allow you to keep the motor mounted low.

03 December 2011, 0100
I've also been looking at the Goodyear PD belt system for a belly mount similar to the LithiumHawk (http://www.nappepin.com/LithiumHawk.htm) but I think I may have more room vertically, I'll know more after I remove the ICE and do some measurements.

30 December 2011, 0017
I've moved the bike from storage to the garage and started working on it. I've got the back half naked, and will be stripping the front over the holidays.

Here are a couple of pix:

2210 2211

30 December 2011, 0249
Thanks for the photo update.

Looks to be a interesting project.

02 January 2012, 1852
It is going to take me several sessions to strip this beast down. I've got an injured thumb on my right hand, so not having an opposable thumb is slowing me down a bit.

I've got the front half of the plastic off now. The next step will be getting the exhaust, intake and fuel systems off.


06 January 2012, 0108
I've got a few nuts soaking in WD-40 before I can remove the exhaust, but I did get the air filter and gas tank out. That tank is a monster.

2239 2238

06 January 2012, 0855
i just love this part - another gasser gone bye bye... kewl work Stan...

08 January 2012, 2206
I'm exhausted.


09 January 2012, 0039
Nicely done! Keep up the good work!

09 January 2012, 0818
I'm exhausted.

LOL. Keep at it man.

09 January 2012, 1254
I've started http://ST1100ev.blogspot.com/ and will put more detailed information in it, but will put milestones here as well.

13 January 2012, 0051
Carburetors, coolant and radiator removed. Upper motor mounts removed, I'll need an impact wrench to remove the lower mounts.



Jack Riggi
13 January 2012, 0108
Carburetors, coolant and radiator removed. Upper motor mounts removed, I'll need an impact wrench to remove the lower mounts.

Just use a torch & burn them off no need for a inpact!

13 January 2012, 0837
Impact drivers really are useful if you like to collect tools, like me.

13 January 2012, 0908
Well doooood. That's why you can't afford a decent beer! :O

17 January 2012, 1528
Still working on getting the ICE out, but I've made some measurements and the motor isn't going to fit vertically... so a longitudinal mount with a Goodyear PD belt system for a 2:1ish reduction is going to be the way I'm heading. (ETA: I haven't measured the shaft to wheel ratio yet, but it is supposed to be 2.83:1)

If anyone has any recommendations, hints, etc. on belt reduction systems, I would really appreciate them.

(Ted, no comments about pushing away from the dinner table to reduce the belt... I'm already working on that. ;) )

17 January 2012, 1534
I've ended up deciding on the AC-20 motor system from HPEVS for this project.

I think it will be adequate for commuting and will give me a little regen and will add a simple reverse to help move this beast around in tight places. Most of all, it weighs about half of the DC motors I was looking at.

17 January 2012, 1550
AC-20 is a nice option. You should enjoy it.

17 January 2012, 1946
Great choice indeed!

Jack Riggi
17 January 2012, 2329
i wish i could have got a AC 20 but i can't complain on my DC motor for now for $300 maybe later i can upgrade to one if i need enjoy yours!

20 January 2012, 1250
Thanks to the generosity of one of the Dallas Makerspace members bringing his impact tool and strong arm, the engine mounts are all loose on the bike. This will let me get the engine out the next time I get some time to work on it.

I've updated my project blog at http://st1100ev.blogspot.com/ for anyone that wants to follow along. Right now it is pretty sparse with the boring disassembly stuff, but as I get into the EV conversion portion I'll have a lot more detail.

21 January 2012, 1515
Motor order is in, bet you're excited :)

For the chiller plate on the controller, have you seen this?


(and thanks for the shout-out, I'll try to beat anyone's prices)

01 February 2012, 1727
I'm still fighting that darn ICE, it lacks about 1/8th of an inch just dropping out on the floor!

My HPEVS AC-20 arrived from Electro Motive Force (http://emf-power.com/), as well as some other parts. More info can be found on my blog at http://st1100ev.blogspot.com/

01 February 2012, 1735
Not such a bad idea to pull the swing arm. It's a good time to check the bearings and pack everything with fresh grease.

01 February 2012, 1933
Yeah, I know... I just don't have the Honda swing arm tension tool to put it back together properly. Maybe one of ST-Owners guys will have one I can borrow.

19 February 2012, 1738
I finally got the ICE out of the frame and have started playing with positions for the AC-20 motor and batteries. There is a huge amount of space in the frame, I'll just have to be careful and not extend the pack out past where the plastic goes. As you can see in the attached pictures, I can put the motor either just below the seat, facing forward... or I can place it very low facing backward. The mounting would be easier with it facing forward, but the machining for the pulley system would be harder. I've got to mock up some more 60Ah and 100Ah batteries to see exactly how many will fit... and where. The "tank" is just a plastic cover for the the air cleaner and carbs, so all of it is empty and just begging for the Curtis 1238 and battery charger to snug up under it.

See my blog (http://ST1100EV.blogspot.com) for more details.

Nuts & Volts
19 February 2012, 1822
I kinda like the motor under the seat, that opens up a lot of room for a large single battery box which can make the mounting of them less complex. Also I have never seen a motor mount there. Not having the shock in the middle really adds a lot of volume to that bike

From what I have read about motorcycle handling it is better to have mass centralization than trying to get everything mounted down low. Low weight can make the bike more stable at low speeds thou, but can make turn in harder, but for street riding that probably wont matter much.

Also I think going with the 100Ah cells would be awesome and much better than 60s since you have all that room. Maybe even mount the curtis controller right above the motor under the seat. This would keep wiring short and also open up the tank for more batteries. Just some ideas, I think that bike is turning out to be a pretty good platform for a conversion.

20 February 2012, 0325
Sounds fun. That's almost exactly the spec I'm looking at for my conversion (hopefully a Suzuki GS1100 if I can get ahold of the guy selling it). I'll be very interested to see how they work out for you.

01 April 2012, 2152
I've finally updated my blog to info on the paper mockups. I couldn't get 100Ah cells to fit, so I am going to go with 60's. Below are some pictures.


01 April 2012, 2156
I decided to use the gas tank to mount some of the electronics, and to keep the existing front mount point for the seat intact.

The first step was to remove the fuel pump/filter and the float, then completely empty the gas residue in the tank. I then put a few cups of water and a little liquid soap in there and sloshed it around to make sure no gas was left behind... then to make really sure I put a heat gun on low and ran it into the tank for about 15 minutes to completely dry the tank. A Sawzall then made quick work of cutting the bottom half of the tank off.

I then took a grinder and cut the filler connector off and ground it flat to the top of the tank. This will let me mount the J1772 connector where the fuel inlet used to be. I needed the 1/2 inch of room so that the J1772 would drop low enough for the fuel door to be able to close.


02 April 2012, 1503
My charger kit from EMW came in today. I was really excited to see it arrive...

until I opened it and discovered that they had accidentally sent the wrong version. I was expecting the water cooled version and as you can see it came with the air cooled heatsink. It is also missing at least one part, I'll have to pull the BOM off their website to see what all is missing.

I've got an email out to Valery, and I'm confident that he will get this straightened out quickly.


06 April 2012, 1150
I bought a ST1100 transmission off of ebay for less that I could get just the transmission output shaft by itself. It took about 30 minutes to get it all apart and remove the shaft. This leaves my original motor and transmission intact, which should make it easier to sell. Below is the pile of leftover gears.

Now I need to take some measurements of the shaft and get it machined for some bearings and a pulley. I did a really crude mockup of the plate I need to build to mount the face of the motor and front bearings for the jack shaft. This will give me a better idea of what diameter pulleys I can use. The frame member is going to be the limiting factor there.

I put a piece of tape on the shaft, and on the tire, and spun the shaft while watching the wheel spin. ZoomSmith was right, I measured a 2.83:1 ratio for the rear gears and a 6'9" circumference on the tire.


07 April 2012, 1503
moderator's note: removed "advice wanted" from thread title, at Stan's request.