C&J Yamaha TT500
BACK IN 1977, C&J (aka Cole and Jentges) were right at the leading edge of aftermarket frames and other goodies for American dirt bike fans. Jeff Cole and Steve Jentges are high school buddies who went into business together in 1970. Both had been involved in motor sports, building Indycars, but when they decided to strike out on their own, it was into high-end marine fabrication – and motorcycles.
The pair set up in a workshop in Santa Ana, California, just yards from Kawasaki’s US R&D workshop. When the Kawasaki team needed someone to fit aircraft-style quick fillers to their race bike tanks, they were sufficiently impressed by the quality of Steve and Jeff’s work to entrust them with the job. Then came the gig to build frames for Brad Lacky’s works motocrosser and Yvon du Hamel’s road racer. C&J had arrived, with Evel Knievel among their high profile clients (they worked on the frame for his ill-fated Skycycle).
They established a formidable reputation for the quality and performance of their chassis kits for Honda’s XL range. So when Yamaha’s big thumper appeared, they turned their attention to the TT500, producing frame kits to for enduro, desert racing, motocross and flat-track.
Mark’s C&J TT500 may have been intended for desert racing, but when he got offered this one by Mitch at Huggy’s Speed Shop in 2020, he decided it would make a great bike for use on road and greenlanes. That’s not to say it isn’t a serious off-road tool, as the specification of the bike reveals.
“It was a rough rolling chassis with an incomplete engine thrown in it,” explains Mark. “But it was a genuine C&J frame. I knew it was rare – that was about all I knew – but I took a chance on it and bought it anyway. The engine had no crank or piston in it, but it had been bored out by about 10mm with a new liner and the crankcase mouth machined out. I’ve still got the engine, but I wanted to get the bike on the road, so I used a 1977 TT500 engine that came with the HL500. That was in pretty good condition and ran well with its period Motek CDI ignition, so I just pulled the head to check the top end and discovered it has a 540cc big bore, Webco race cam and race valve springs,
“Initially, I just put the bike together as it was, to fabricate the exhaust and get it running, but then I pulled it apart again, painted the frame, rebuilt the wheels and polished and painted the YZ400 fuel tank that came with it. I struck lucky with the forks. I thought they were just normal Kayabas, but research revealed they were Kayaba Pro-line units used by most of the leading works riders of the day. And they were in great condition, too. They just needed cleaning up.”
Mark makes it all sound easy, but a lot of work has gone into turning a tatty rolling chassis into this gorgeous bike. He’s swapped the 17in Sun rim that was on the back wheel onto his HL500 (it’s correct for that bike) and replaced it with an 18in DID rim. He’s also fabricated the side panels from sheet alloy, fitted an XT500 lighting system, using the redundant alloy airbox to house a battery, and made a new rear brake pedal. He’s fitted a 36mm Mikuni with K&N filter and sent the period Curnott shocks to America to be refurbished by former Curnott service engineer Scott Tremblay.
The result is well worth the hard work. It’s pretty much immaculate, so I’m only riding it on the road today; he’s only done a few shakedown miles on it himself. It’s a great bike for the back roads – lively from low revs, with good midrange punch. The top end is more than good enough to slightly overwhelm the stock TT brakes – but with plenty of engine braking from the high-compression piston, that’s not too much of an issue, and the long-travel suspension laughs at the worst of the potholed Lincolnshire lanes.
I’d be delighted to have this as a road bike. But I can’t help thinking that, once the first bloom of a fresh restoration has faded a little, Mark might not be able to resist the lure of a greenlane snaking away into the distance...