Electric GPz 550 Motorcycle

Stock GPz550

My Electric motorcycle
Late in 2002 I succeeded in going around the block a few times under electric power on a motorcycle I had bought (with a sick engine), de-ICEd it, added an electric motor and a few batteries and away I went!
course it wasn't quite as simple as that see below for the lengthy but enjoyable conversion process:

Initial Plans
After some scouting around mainly Internet research I rejected my initially very ambitious plans (which were: Plan A. Design my own three phase AC controller and use an AC motor. Plan B Design my own DC Chopper type controller [a la' Pulse Width Modulation] and use that to control a large series wound motor) in favour of putting a shopping list together of the major components required thereby buying in a proved design (and built components) those power *MOSFETs and IGBTs are EXPENSIVE. Well I did have some success playing with computer control of mains electricity using Thyristors years ago!
* Both Metal Oxide Substrate Field Effect Transistors and Insulated Gate Bipolar Transistors are power switching semiconductors.

My shopping list went something like this:
Donor Motorcycle Must be cheap: 2 to 3 hundred pounds, be complete and have twin disc brakes up front. Japanese make I guess!
Gears: Hi/Lo would be ideal or bolt on 4 ratio Brit pre-unit box
Electric Motor: Capable of driving the M/C at 60 MPH ish
PWM Controller: Capable of handling a few kilowatts at least
Batteries: Sealed Lead Acid Absorbed Glass Matt type
Charger: An on-board 240v AC charger would be nice.
DC to DC converter: To tap 12v off of my battery pack (for lights etc)
Controls/instruments: Potbox type throttle and voltmeter as a minimum

Donor Motorcycle
I spotted a local advert for one sick puppy of a Kawasaki: a GPz 550 UniTrak but the price was right, a 550 was half the size of most of the US conversions I had seen on the web. As the bike had engine problems (which wouldn't bother me at all!) it seemed a good deal, so I bought the thing. What did bother me was the knackered tyres and final drive chain (and sprockets of course), worn out brake pads and (sob) scored discs (only £220 each to you sir!) - which I belatedly noticed. Ah well, I removed the engine (badly needed a valve job) carbs, air box, fuel tank etc. (I've since sold the tank and alternator and clutch covers). I Gave the bike a much needed clean - I thought I let my bikes get dirty - Took hours.
Well, with the lump of a motor sitting in the corner of my garage, my thoughts turned to disposal (as it [the engine] was practically worthless). What a shame, I thought, here I am about to chuck away a perfectly good, modern, constant mesh,6 speed, lightweight gearbox (it's integrated with the engine) and start searching for some expensive agricultural item off a BSA or summat, when it occurred to me that maybe it could be 'extracted' intact with a bit of luck - and that's just what I did!
I disassembled the engine, removed the hyvo primary chain, then hacksawed the gearbox case off of the main engine casing. By removing the clutch I gained a splined input shaft that a final drive front sprocket fitted straight onto.
I then reassembled the layshafts in their original order (even still had the neutral indicator available) A single sheet of stainless steel plated the hole and (this isn't shown) fitted an oil seal (I found that the gearbox would't change rear unless it was filled with oil) to the output shaft. The outer part of the seal engaged with a suitably sized hole in the plate I mounted the motor on, and I had myself a gearbox! solved my final drive 'connection' problem too, as it bolts straight in and connects to the (renewed) final drive chain. I found I did have to fill it with oil, or it wouldn't change gear properly - this did make things more difficult, but at least oil seals are dirt cheap.

Primary drive now has a 1:1 ratio


Chopped Frame
(1) first butt welded the tubes together, ground the weld down level, then
(2) slid a socket over the weld and welded the socket in place as a sort of reinforcing gusset (I was using gas barreling tube) ending up with
(3) the welded, extended frame

I cut, jacked out and
(1) first butt welded the tubes together, ground the weld down level, then
(2) slid a socket over the weld and welded the socket in place as a sort of reinforcing gusset (I was using gas barreling tube) ending up with
(3) the welded, extended frame.

Click the pictures below for larger images:

Elevated view of the bike from the right

Bike Right Side
Electric GPz550 - Bike Right Side.

Click the image to see a larger picture. Shows a view of the assembled bike. The grey cable visible is mains 240v connected to the twin 24v chargers.


Electric GPz550 - Gearbox.

Here you can see the gearbox in situ, showing also how a standard final drive sprocket fitted the clutch/output shaft - thank God for tooling up economy!


Before the frame was cut
Electric GPz550 - Before the frame was cut.

Shows tank, panels and g'box in place. Note the uncut frame.


GPz GBox
Electric GPz550 - GPz GBox.

Same as the above picture, just from a different angle. This picture is an early one, before I swopped over the 550 forks for a set of forks off of a GPz 1100 - this was literally an attempt to redress the balance.. the bike was far too front heavy.

Note to self - next time fit the batteries amidships!

Latest Pictures - half the batteries taken off

GPz Latest Photo
Electric GPz550 - One pair of batteries removed.

Taken in May 2005. The controller I am using was described as a 48v controller. I was mildly surprised to note that I needed to supply the 48v as two short strings of 24v. When the weight overload situation became apparent, I wondered if I could take one pair of batteries off, and connect the remaining 24v to both ends of the controller - without blowing anything up. It was. Quite nimble now, but reduced range of course.
I have connected both of the 24v chargers to my one pair of batteries - it will charge twice as fast now.

Spent an enjoyable afternoon going up and down the access road. Chain thrash annoyingly loud - no I.C.E to drown it out!

Some more views of the bike, these are not clickable

GPz Side

A view of the bike from the right side.

GPz Side

The bike from the right side again.

GPz Front