The Top Banana Z1
Personally, I have always harboured a soft spot for those high bar monster muscle bikes that the yanks seem to have so much fun racing on throughout the 70’s and 80’s. Unlike the UK on the other side of the pond “proper” fully faired race machines regularly did battle with high bar naked monsters.
The period, in racing circles at least, was besotted with two-strokes of all shapes and sizes trouble is road bikes were and still are mainly four strokes, creating a huge void between the track and the road that wasn’t good for showroom sales. Street bike racing was most likely created to form a tangible link between the road bikes and race tackle.
This unique form of racing did enjoy a brief spell of popularity over this side of the pond with the MCN backed Streetbike series of 1981, convincingly won by the factory supported CB1100R ridden by Ron Haslam with riders like future 500 world champ Wayne Gardner and Joey Dunlop following spectacularly in his wake. It was all good stuff but never really captured the UK race audience’s attention and following that short lived series the high bar madness and mayhem all but faded away.
Before too long all road going sports machines came with clip on style bars, once and for all tying in the race machine with the road bikes, and the high bar muscle bikes disappeared from modern racing forever. There was no body even trying to recreate this period, I was most surprised during my period racing with the Forgotten Era boys that such machines with their wide disposition are actually disallowed from the very class that they should really be allowed to run with. Thankfully the Earlystock’s racing club do cater for this period so now there is a natural home for these beauties, the Top Banana team being the leading protagonists within this class with their beautifully prepared machines.
Between them they own a staggering array of machines from the late seventies and early eighties among them a pair of “Lawson replicas” albeit in a lurid shocking yellow rather than the more eloquent lime green. Whatever the colour scheme the effect on the track is the same with more conventionally mounted racers giving you that extra few inches of breathing space whenever two or more machines are forced into the same piece of circuit. The sheer physical size of the naked Z1 and its impact upon fellow riders means it has usually won any out braking or “argy bargey” manoeuvre often before the battle has really begun to get serious.
When first let loose on the monster I was not left feeling immediately at home, the rear felt squidgy and the front loose and not really in total command of the proceedings as handle bar movements refused to correlate with anything the wheel was doing. The combination of rear set footrests and the high bars gives a weird seating position not unlike some of those more extreme ones found in the Karma Sutra, legs wide and behind you while your arms are out stretched at chest height, only there is no partner involved! This position gives very little contact with any tangible part of the bike making evaluating exactly what it’s doing very difficult indeed.
Through the tight bus stop, I was also feeling the effects of the width being very reluctant to get stuck into the apexes, which in turn was ruining the line out of the corners, and down the straight. A few laps into this and the pussyfooting stopped, this bike needs a strong hold and a firm mind to make it have it. A more hands on and tactile approach was taken, no more sitting back and enjoying the ride it was time to take the big Z1 by the scruff of the neck. Once it was made clear exactly who the master was the Z1 became subservient and impeccably behaved. The front end has to be loaded up, as heavily as you dare, this then unloads the rear for tyre spinning shenanigans and the chassis becomes as light and airy as any smaller and lighter machine. With the narrow tyre up front firmly planted it did exactly your beckoning while generous throttle inputs made it steer faster still.
Not helping in this set up problem and lack of feel is the large and spongy rear seat which translates the goings on down under a little bit later than when it has actually happened. It might be a very small delay but decisions made in racing, or spirited riding, are over in a micro second so any advance warning, no matter how small, is most welcome. Loading the pegs more and relieving some pressure from the saddle helps the overall feel no end and one soon learns to sit down properly on the straights while adopting a semi standing position when away from the vertical. There is no problem weighting the pegs and moving up on to the back of the tank a bit once the end of a straight is reached as the up rated, Brembo Goldline four-piston brakes reassuringly grab the 300mm floating discs, demanding quite forcibly that you get you out of the armchair seat whilst trying desperately not to get a better look at the front wheel. The standard Z1 38mm front forks perform admirably throughout while the brutish, nightclub doorman looking JMC swing arm allows nothing to deviate from the straight and true.
There is also a slight mismatch in profile when fully leant over between the cross ply 18-inch front tyre and the radial 17-inch rear that causes the bike to walk around a wee bit, but never feeling out of control or dangerous, just a nice predictable rear sliding, over steer sensation provided by the fat, slick like, rubber fitted to the back wheel. All of this heavy use and attempts at tying the bike up in knots actually serves to demonstrate the Z1 chassis stunning abilities in the handling department as the completely unmodified frame, except removing some unneeded bits and lugs, does a superb job of holding all of the separate components in line with out fuss or commotion.
One thing that did impress was the little Avon’s desire not to be out done by its far superior, technically at least, mate at the back end, the Italian Pirelli should, by rights, have run rings around the dated English design but once again the stunning grip and feel of the SM22 was all too evident, easily the equal of any radial.
The big Z1 loves being ridden hard and aggressively, the bike literally comes alive every time the throttle is pinned back. The superb sounding Sebring silencer, helped by the Harris down pipe and collector box, howls its way up the box and burbles its way back down again in a most aurally pleasing manner. The four-man tenor section that is the open 33mm carbs, their breathy chorus mimicking the exhaust note faithfully, accompanies this raucous symphony. The engine is very revvy and happy to be wound fully on at any time, the crank has been welded to facilitate a useful over rev and the removal of the heavy flywheel from the left hand end of the engine once again aids this eagerness to provide get up and go.
The GPz1100 B1 model cylinders have been bored out slightly, using Wiseco pistons to give a total capacity of 1170cc while some mild gas flowing of the valve tracts and ports have been carried out. Hotter cams, also from the GPz1100, fit straight in to the Z1 head and liberate a few more horses, giving around 120bhp on a good day.
The static, bulky looks of this machine are deceptive to say the least as once on the move and riding approach altered to suit the big Kwak is as agile and competitive as anything from the same era. Every component works and works well having been developed over several seasons by the two Top Banana boys in the heat of competition, albeit with very limited resources and funds.
Kawasaki Z1 Specifications
- Engine: Wiseco 1170cc Big bore kit
- Bore &; stroke: 72mm x 66 mm
- Power: approx 120bhp@9000rpm
- Carbs: Mikuni 33mm Smoothbore carbs
- Ignition: Modified total loss ignition
- Frame: Z1000J2 Standard, subframe cut down
- Forks: Kawasaki 38mm
- Front Wheel: Z1000 Lawson rep, 110/80X 18 Avon Sm22 cross ply
- Rear wheel: Ducati 851 (Modified and painted to resemble Lawson Dymag) 160/60x 17 Pirelli Dragon super corsa
- Front Brakes: Brembo Goldline 4 pots on 300mm semi-floating discs
- Rear Brakes: Twin opposing piston Nissin caliper on 851 rear disc (To resemble Lawson set-up)
Kawasaki Z1 Racer Gallery
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