Right - so when I last was here, I had the bike down to the engine and frame, the calipers were fully reconditioned (have pics, will put up), as were the forks after I'd had the bushes machined down to the right height. I was just at the point of starting to clean and prep all the brackets etc. for respray, and then I went quiet.
So - since then - I got sick of trying to get paper and wirebrushes into the small corners so I built a very basic sandblasting enclosure (pics to follow) from some old pallet timber and polytunnel covering. I'm pleased to say that it does the job of capturing the blasting media very well. The blasting gun I'm using is a draper unit which simply attaches to a standard airline. I have one of those el-cheapo Aldi compressors (2HP, 25L) which, whilst it's grand for the smaller parts, struggles to keep up with any larger surface area's. It's not the compressor but the volume that's the problem though so I'll likely look to pic up a 50/100L 2.5HP unit at some point.
In any case, the above setup is outstanding for removing old paint and rust and getting bits ready for primer and paint.
Beyond that, I got the engine out and it pretty much sat on the bench, with the frame in the corner of the shed, for about a year until I found the time to get a wee bit done over the summer (not nearly as much as I'd have liked mind).
Now - here's the contentious bit.
In May of this year - I bought an electric car. The Nissan Leaf to be exact - and whilst I'm not going to go discussing this car any farther than that on a bike forum (
), suffice to say its performance has been simply outstanding.
So much so in fact, that I've decided to design and construct an electric drivetrain for the '24.
Now before I get labelled a complete heathen, there is still enough of a purist in me that one of the principle policies of the design is that I will not alter, in any way shape or form, any of the original components of the bike. In short - everything will be entirely reversible and I will be retaining all the original hardware.
The vital statistics behind the project concept are as follows:
Conventional drivetrain mass including engine(wet), carbs, airbox, rads(wet), tank(half full), exhaust, reg/rec, etc... comes in aroundabout the 85-90kg mark.
All of the above to be replaced by a 6-pole induction motor, motor controller, battery pack, charger, battery management system and associated brackets and wiring.
The battery pack will comprise of 96 A124 LiFePO4 pouch cells in a 32s3p configuration for a nominal voltage of 115V and a max 10 second repeatable current delivery rating of 625A. This pack will weigh 45kg ex brackets & wiring (so about 50kg all told I expect), and will have a total power rating of 5.4kWh which, on conservative estimation (assuming a mean of 50wh per pack on a specified 66Wh) should permit about 80km range driven in a responsible commuter fashion (this figure allows for 7% safety margin at the bottom of the pack and 3% at the top).
The motor will be either the venerable AC15 or AC20 traction motor driven by the Curtis 1238R-7601 controller. This combination comes in at about 25kg.
The BMS is undecided yet, I may simply service the pack manually or go for whichever of the 32 cell options best suits my needs. Bottom balanced packs of this chemistry are well renowned for their stability so I don't anticipate that the BMS will be hugely taxed in any case. I'm allocating 3kg for the instrumentation and wiring regardless.
Finally then comes the charger - I'll most likely build two versions, one 1kW unit which can be mounted in the chassis and will serve as a charger for commuting, the other will likely be a 10kW unit which will be offboard and will permit delivery of a full charge in about 40mins. I would anticipate the use of this unit at track days etc...
The 1kW charger is expected to come in aroundabout the 7-8kg mark although this may be revised upwards to as much as 10kg during the design - it's a little open ended at the moment. In any case it will be a removable unit to facilitate weight reduction when required.
So all told, the EV drivetrain rings in at about 85-90kg and so, will serve as a direct mass replacement in the chassis.
Performance;
The conventional drivetrain is a (spec) ~50hp unit with ~25ft.lbs of torque. Realistically, it's going to be less than this on both counts in the average instance unless the motor has been rigourously maintained.
The replacement drivetrain will develop between 80 and 110 ft.lbs of torque and has a rev range of 0-6500 rpm with torque beginning to drop off dramatically after about 4.5k.
Now, with the above points in mind, we look to the conventional gear ratios and seek to optimise the new drive to match or exceed these ratios. I have all of these numbers on my computer at home so I'll come back to this point later however, as I recall, I concluded that direct driving the rear on a 4:1 reduction gear would provide vastly improved acceleration but would limit top speed to about 84mph, whereas a 3.5:1 ratio would provide comparable accleleration and a top speed of approx 100mph - the latter does present potential current loading concerns though on account of the longer period of heavy accleration presented.
Regardless, 80mph is perfectly appropriate as a roadgoing max speed, and similarly, on a tight circuit it would still provide plenty of grin factor. I'll inevitably refine these numbers through experiment once the drivetrain is operational in any case.
Suspension and handling:
The total mass will remain, to all practical extents, the same as it is on the stock bike, so no additional suspension works will be required over what would be considered in any case.
However - what is worth noting is that the engine is a stressed member of the frame, hence appropriate braceplates will be required in order to maintain the regidity of the frame in the absense of the engine block. These components will require significant consideration.
... I think that covers all of the more obvious technicalities involved - I have quite a few other notes done up but they're all on my home computer. I also have some shots of the progress so far which I'll post up in dribs and drabs as I expect that progress will be rather slow on this project on account of my time contraints and the costs of the various aformentioned components - expect 2-3 year project timelime - but I'll post up what I get done as I get it done.
