From two-stroke to EV, at home


Electric trials

How hard can it be?

That’s the question Jamie Jones asked himself when he first had the urge to switch to shifting electrons rather than pumping pistons.

With more and more people using electric vehicles, and the technology seemingly now pretty well sorted, it wasn’t too much of a gamble for Jones to switch power sources for his Gas Gas trials bike – which originally ran a two-stroke petrol engine.

“I decided to do the conversion because I have an interest in electric vehicles and found the noise of a two-stroke irritating,” he said, “It was quite a simple task really, I’m not an expert fabricator, I just bought a second-hand mig welder from eBay and gave it a go…”

Nevertheless, it still shows skill and mechanical understanding to even think about this, let alone to go ahead and do it.

“I first bought my son an Oset electric trials bike but they only did kids bikes at the time and I loved the simplicity and maintenance free nature. Just charge and ride and repeat, no oil changes, filter changes etc.”

Jones’s business is in software, but he’s always liked tinkering with everything and anything, and admits this has been a great learning experience.

“I had a new rear sprocket machined up by UK Bike parts to match the bolt pattern on my wheel,” he recalls “I just had to post them the old smaller sprocket – and the new one gives me a gear ratio of 1:7.

“I had to make the mounting for the motor, and, I made the battery pack from remote control car batteries!”

So how powerful is it?

“It runs at 72v nominal. The motor controller is a Kelly KBS which claims 200 Amps for 10 secs, and is rated at 110 Amps. This means rated power is 7500W with a peak power of 15000W.

“The character is brilliant now. It’s almost silent and gives instant power. It also weighs just 43kg now – not much more than half its original weight.”

Despite being unfinished, It’s certainly a fairly simple-looking job to do – not that we’d recommend it without a decent background in engineering at least, but it’s incredibly satisfying to say there’s life in the tinkering world yet – and when the almost-inevitable switch to EV comes there’ll still be people just like Jones with their bike in bits in a garage as they sort any issues and upgrade their vehicles themselves.

Jones claims the whole conversion cost £900, but he got £200 for the old engine so a net cost for this EV trials bike conversion of just £700.

Is this the start of a new hobby, then?

“I’d love to have a go at converting a VW transporter next,” he muses, “but battery packs that are suitable are prohibitively expensive, crashed Nissan Leaf packs are about £4k and ideally I’d want two to give me the range I’d need to replace my old diesel Picasso.

“Maybe I’ll do a road legal motorcycle next instead…”

So does he have any regrets with the Gas Gas – like missing the 2-stroke smell, character, etc. or is it going to stay electric?

On this point, Jones was quite clear;

“I don’t regret it one bit.”

Gas Gas bike converted to electric trials bike