Harris Monoshock Kawasaki

Whoever noted the only constant is change was a very wise person. In this case, this space was originally slated for a multi-machine special frame rollout featuring Egli’s explosive MRD Turbo, the Swiss MoKo and Thunderchild – courtesy of Harris Performance. Each powered by Kawasaki’s DOHC Z-four, the decades researching performance specials has established some conclusions and turned up the abstract. None more outrageous than these. You’ll find pages on the MRD if you’re interested, and while the MoKo is rarer, there’s a verifiable connection. Somehow coming off as even more defiant, the Harris brothers made sure their prototype stood out when the new monoshock made its 1979 debut at the IOM. Basically a works level endurance racer fit with clocks and winkers, Thunderchild ran with TZ Yamahas on its way to 175-mph.

An unforgettable site even lashed to a trailer, I’d seen the bike online years back and had revisited the photos often. Although I’d studied Harris and photographed a few, I had no clue what it was. On a whim, a brief inquiry on social media sparked some magic from my friend Paul Miles (ace tester for RC, Classic Bike Guide and more) who kindly made the introduction to owner Nick Burgoyne. The photos I’d looked over so often were posted by Nick upon delivery, and I planned on using them them here, tiedowns and all. Luckily for us, Nick sent some current snaps of this stunningly preserved timepiece and the additional docs he included made it clear that Thunderchild would become a solo feature. “I bought it from Jeff, a lovely chap in Essex five years ago,” says Burgoyne, who breathed life into the old English racer. “Now it has returned to the road…even MOT’d and taxed! It had sat in Jeff’s garage for a very long time, so it was a special moment when I first got it fired up.”

(Five-years ago Nick trailered the Harris home after its long term storage. Much was done to return it back to running form, but the quality endured)

Background: Harris Performance
I’m told Harris was founded in 1972. Both being avid racers and trained as engineers, success on the track resulted in demand for brothers Steve and Lester Harris, who began offering specialty items to other racers. Along with director Stephen Bayford, the trio initially focused on competition, but seeing some race frames outfitted for road use inspired the British fabricators to offer kits. “Harris policy has always been one of constant development and improvement,” reads the official statement, “Many aftermarket accessories have been developed for standard motorcycles marketed by major manufacturers. In addition, over 3,000 road bikes have been sold – from one-offs to the famous Magnum range.” In June 2015, control of Harris was purchased by Eicher Motors Limited, better known as the parent company of Royal Enfield.

(I assume this Harris factory shot is from the Hertford facility, Magnum models under construction similar to this Kawasaki powered Magnum 2. Note color combination. To the best of my knowledge, the majority of Magnum kits were produced for Kawasaki and Suzuki engines.)

Inspired perhaps by the Martian-hunting ironclad in HG Wells’ fictional ‘War of the Worlds‘, my research suggested that Thunderchild marked the spot when Harris expanded into the four-stroke arena. Close, but not quite. According to a document penned in 1985 that has stayed with the bike since, the blazing racer (originally christened ‘Harris Monoshock’) made its 1978 debut on the cover of Superbike magazine, then took a trip to the Isle of Man that following summer. Clarification at last, we learn here that the bike was funded by John Angeletta and was based on the racing chassis developed for Harris pilot Andy Goldsmith. Entering 1980 with a fully knitted Pat O’Neil built engine, Thunderchild competitively ran in six endurance races that year. It is unclear who exactly penned this document, but it rings with authority to educate the potential new owner with build specs, instructions and more.

It is possible the 1979 outing was for chassis testing or simple promotion, but following Thunderchild’s splash on the scene, Harris Performance grew at an astonishing rate. Retired to show bike duty in 1982, Angeletta’s Harris was polished and ridden only on ‘fine summer days.’ At some point, select components were changed, including the TZ-ish ‘low-boy’ full fairing (perhaps just the top section?) and the Devil 4-into-1 exhaust. The ownership trail goes mostly cold until Nick enters, and Thunderchild rolls on today in its original Harris livery.

(Snipped from Superbike’s October, 1978 issue – some months before its IOM debut. Note deeply inset fairing with long windwings, stacked headlamps.)

Thunderchild: Chassis
As it was for Fritz Egli, Rickman, and many others, Harris built around existing engines to promise vastly increased performance. Some suggest it was 1973 when the brothers tacked their first commercial frame (mainly for Yamaha’s two-stroke TZ 250/350 works racers) but the decades saw Harris produce varying designs – from tube space frames to extruded beams. My press info states manganese bronze welded T45 and Reynolds 531 tubing was used, but in terms of layout, Thunderchild’s frame differs greatly from the Magnum kits that followed. Flying in the dark, a long (online) study of Harris production and practice began to tell an untold story. Every frame is a sequence, and it had to start somewhere. Focused on a strong load path, one tube per side bends in a pronounced radius to meet the first cross-brace/upper shock mount. Arching gracefully up and inward towards the stem, two smaller tubes connect just behind and run back to the shock mount, effectively tying them together. It’s a unique pattern I haven’t seen on any other Harris street frame, but Superbike’s test clearly labels it a prototype, Substantially cross-braced where the swingarm pivot and rear-engine mounts locate, Thunderchild’s nickle-plated side tubes attach a thick metal sandwich welded into the frame’s rear radius. This main component supports the triangulated monoshock rear suspension and subframe, all made in differing diameters.

(Current snaps prove Thunderchild’s hidden goodies have aged well, but Nick’s been busy. Main frame cuts in sharply, then braced between two cross mounts. Harris trees hold Ceriani forks, note oil cooler plumbing. Kawasaki clocks and switches are common – likely most of the stock Z1 wiring harness was carried over. Super strong pivot area shows artistic welds. Carbs are Honda CR/Keihin 31mm with ticklers and accelerator pumps)      


Filled with high quality components, Thunderchild’s suspensions were fit to meet the demands of endurance racing. Now commonplace, Harris’s cantilever monoshock was considered exotica in 1979 – a time when many works machines still used a twinshock system. Fully adjustable, a long De Carbon shock pairs with Italian Ceriani forks held by Harris machined trees. Special plates were made to adapt the AP Lockheeds (drool) and the matching iron rotors bolt to lightweight 3-spoke Dymag competition wheels. A long running Harris feature. Nick made no mention of it, but I’m assuming these are in aluminum, not magnesium. Looking closer reveals many detail; the front speedo drive, custom hardware and some very creative mounting solutions. Welded tubes with gussets take the subframe back to support the elaborate tailpiece, attach the exhaust, and rear-set foot controls. On the right brake are rose joints connecting to the rear Lockheed cylinder, the left a welded stub from which the flipped-backwards Kawasaki shifter is reached. Not all polish and shine, Thunderchild’s as-raced mechanical workings are indeed functional jewelry.

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