Barry Ditchburn tests the Gus Kuhn GS 1000 Suzuki

Motor Cycle News, May 10 1978 [Thanks to Chris Machin]

Barry rides the immaculate Suzuki GS 1,000-based racer constructed by Gus Kuhn, under the direction of Vincent Davey. This is the bike Chas Mortimer will ride in the Island.

The machine, capable of speeds over 160mph, incorporates a special fame design from Ken Sprayson of TI Reynolds Ltd.

The 1,000cc four stroke engine has been kept in its basic form apart from top end refinements. These are the raising of the compression to 10:1, some work on the heads and the inclusion of Yoshimura cams.

To cope with racing conditions, the machines has been fitted with a variation on the standard Suzuki front forks and now offers air, oil and spring adjustment. Leading link forks will be fitted in the near future.

Standard Girling Shocks provide damping at the rear of the machine, although the suspension unit manufacturers are working on new ideas to give the machine more limited travel for Isle of Man road conditions.

"It gives me the F1 bug"

Not having ridden a TT Formula One machine before I didn't really know how I would get on at Brands Hatch last week on Vincent's new creation. But the minute I saw it in the paddock my eyes lit up. It's obvious that Gus Kuhn haven't spared the cost in preparing this immaculate machine which really looks the part with its Campagnolo wheels.

As you know, I'm a committed superbike racer from my days with Kawasaki and more recently of course with Sid Griffiths on his Yamahas. But when I got settled in on the super-smooth bike I rapidly developed a taste for Formula One racing - in fact I wouldn't mind racing this very machine in competition of the opportunity arose.

Photo from MCN

The riding position was a bit strange at first but I soon got used to it and I found the front end a little heavy until we adjusted the front forks. Dave Sleat, head mechanic at Gus Kuhn, has modified them to give them air, oil and spring adjustment.

There's lots of bottom end power and it pulls really good from just over 2,000 revs right through to 8,500 with maximum power at 8,000.

One thing which really did impress me was the way it came out of the corners - really good. Ken Sprayson of Reynolds has built a frame specially for the Suzuki and although it did tend to wallow a little around Bottom Bend I remedied this by just opening the throttle!

The performance of the bike was particularly impressive when we take into account that the engine was only geared for the use of three or four gears.

I got down to a lap time of 53 seconds around the short circuit, first time on the machine, and a new lap record of 51.8 seconds was only set up there by Ron Haslam on a Honda at the recent Formula 750 meeting.

The highest gear I used was fourth along the straight and I'm sure I could knock a couple of seconds off my time with more practice.

It's one thing having a good powerful engine - and I would expect this bike to travel at over 160mph during this year's Isle of Man TT races - but you've also got to have good brakes! I had now worries here and in fact they were better than on my 750 Yamaha. Gus Kuhn have managed to come up with these superb brakes by fitting Suzuki RG500 discs front and rear. In fact I almost got caught out the first time I tried them: so powerful.

During the whole of the test session I didn't feel the back end move at all which is a real credit to Ken. We ran Dunlop tyres front and rear - a KR124 on the front and a slick on the back proved an ideal combination.

All in all I think Gus Kuhn have come up with a winner here. Obviously there are mods to be made but with a few weeks left before it big test in the Isle of Man, they'll have it in proper racing trim.

I did feel that the motor was a little tight because of its newness but with another couple of races scheduled for Chas before TT time it should be nice and loose and a little more eager to rev.