CO-BUILT YAMAHA RD370
Words: Gary Inman
Photos: Sideburn magazine
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‘What I like about flat trackers,’ says Nigel Cowley, ‘is they are the pure essence of motorcycle. There are no frills. So, my dream bike had to be a flat tracker. I decided that I would give myself a present to compensate for a milestone birthday. Essentially, I am talentless as a rider, but I enjoy ripping around on a bike just for the bloody hell of it. Therefore, the bike had to be minimally road legal.’
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Nigel had planned to build a Champion-framed Yamaha MX360, but the bike he bought turned out to have a PDV engine, a 1970s knock-off of the Yamaha. The plan was then to replace the 360cc single with an air-cooled RD250 twin, but it wasn’t going to fit very easily, so Plan C (or was it Plan D?), was concocted.
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‘I found out about Geoff at Co-Built via Sideburn articles and word of mouth. Long and short of it, I commissioned Geoff to build me a frame. It was one of my better decisions, because the man is an engineering artist, a welder extraordinaire and a genuinely awesome bloke.’
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Nigel incentivised Co-Built with a bonus payment if they hit the desired delivery date. They did.
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While the frame was being nickel-plated, the tired, old RD250 engine was torn down. The barrels and crank were sent to Ron at Fahron Engineering, Nottinghamshire. ‘Ron’s 370 conversion for RD250s is legendary. He bores and sleeves the barrels, so they run DT175 pistons. The engine then displaces 370cc. He ports the barrels to his recipe, resulting in a very peppy engine. You can wait a considerable amount of time, though.
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‘The gearbox was slipped in a batch of stuff being superfinished and the cases were refinished,’ says Nigel. He’d also imported a replica DG head from HV Cycle in the States, and Fahron modded it to suit the barrels. ‘I also acquired a set of DG pipes and had Geoff modify them so that both of them came out on the right side of the bike.’
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Tank, seat, footpegs/controls and triple clamps all came from Red Max. The forks are from an old Yamaha R6, and one leg is shaved to make a single disc set-up at the front. A period Brembo caliper is used, fitted to a custom adapter plate, and 19in rims were laced to an XS650 front hub, carrying a drilled disc.
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‘Life was getting in the way,’ admits Nigel, ‘so, I decided to hand the whole thing over to Simon at Track-Pro to disassemble and build it back up to his exacting standards. The bike was delivered back to me earlier this year.’
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It is beautifully put together, with the kind of fine detail that only the best street tracker builders manage to get right.
‘The process of building my dream bike was a fun journey in itself,’ says Nigel, ‘Meeting great people, messing around with bike stuff, and lots of laughs.’
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The power isn’t quite what he had hoped for, a dyno run for 2T engineering to set up the old carbs confirmed mid-40s horsepower. ‘The obvious problem is the pipes. They look quite period but are far from efficient,’ says Nigel. ‘The bike will probably never be finished and the first development might be to get some pipes designed and made and maybe replace the carbs with some flatslides.’
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For now, he’s just going to ride it and work out what he might like to improve.
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‘I love the bike. I find myself standing in the shed just looking at it, but I also rip it around the lanes. It’s small and light. The engine starts very easily and the throttle action is fast. Snick it into gear with a slight jolt, feather out the clutch with a twist of throttle and holy moly she’s off like a startled pony. Big grin.’
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THE BOTTOM LINE
Nigel explains the major costs. Kind of.
'I daren’t add it all up, but the project spanned a few years so the costs were spread out. The engine was about £3500 including the Fahron work, DG head and Powerdynamo electronic ignition. The pipes were about $700, but by the time they were shipped and import tax paid they were about the same in pounds. The forks were secondhand and didn't much. Co-Built's bill in the end came to around £4000 I think, including the nickel plating. Steve at Red Max prised probably another £1000 out of me for those bits. Wheels, rubber and suspension another grand and a bit. Paint and decals about £700… The litany of expense rolls on. Somebody at the Bike Shed Show laughingly offered me £10 grand for the bike, but I think if I really sat down and did the accounts it would show the cost was way north of that. But I don’t care. It’s my baby and she can have whatever she needs!
NIGEL’S HIGHLY RECOMMENDED LIST
Simon Green, Track-Pro
Geoff Cain, Co-Built Fabrication
Ron Phillips, Fahron Engineering
Andy Ball, 2T Engineering
