Five valves... Five stars

Yamaha's five-valves-per-cylinder FZ was top dog in the fiercely-contested 750 class of the mid-Eighties. Bob Berry hops on to a carefully modified version and gets all starry-eyed.

IN THE mid-Eighties, the 750cc class was an area of intense rivalry between the big four Japanese manufacturers. The MCN Superstock championship - and the American Superbike series before it - started a hi-tech war that lasted to the end of the decade, accompanied by sky-high prices.
In 1989 Yamaha's latest street legal racer - the FZR750R - would have lightened your bank account by some £12,500, making even Honda's RC30 seem like a snip at a mere £9500.
Going down the model range revealed similar rivalry at more affordable prices and Yamaha's 'cooking' FZ750 (if that's the right word for a 150 mph bike) became top dog in the 750 class when it first went on sale for £4500 in 1985 with only the Honda VFR750 (at £300 more) offering a slightly better all-round package.
The five-valves-per-cylinder engine was always the FZ's outstanding feature. It is ferociously quick at the top end but as docile as an overfed dog at lower revs. It will pull strongly in top gear from 30 mph with a definite but barely noticeable increase in power at 7000 rpm. Such a smooth delivery, in fact, that I was frequently fooled into thinking I wasn't in top (sixth) gear and tried to change up.
That power delivery makes brisk A-road cruising a doddle. It disposed of traffic effortlessly and just a nick down by one gear gobbled up lines of cars with ease, screaming happily to the 11,000 rpm red line. What more stomp could anyone want?
The five valve technology was so unique that it even made it into the world of F1 at one point. The in-line bank of four cylinders is canted forward at 45 degrees putting the weight low and well forward.
The carburettor arrangement is down-draught with much of the space under the tank being taken up by the airbox.

Liquid cooled, of course, and Yamaha claimed a power output of 105 bhp. As one tester of the day put it, "For all types of road riding from commuting to flat-out back lane attacks, it is not possible to fault this power plant - it's one of the best ever fitted to a modern motorcycle."
The same bike hack reported that the engine could stand fearsome abuse too. "I went production racing on an FZ I'd been using as a road hack for a year. It was serviced from time to time and thrashed to death all the time. By the time it reached the race track it had 20,000 hard miles behind it.
"The only problem encountered racing it was the clutch which let go after I had fitted some supposedly stronger springs to it.
"It started to let go in the first hour of a six hour race but held on just long enough for us to be sidelined by a freak accident in the pits. The motor itself was perfectly up to the task and had lost very little of its edge. After track duties it went back to being a road hack and continued to perform trouble free once it had the original springs back in the clutch."

Words: Bob Berry
Pictures: Terry Joslin

LAST month I managed to dismantle Mark's Kawasaki Z650F1 down into big lumps - and not without some difficulties.
The major problem was two of the front engine bolts which were seized solidly into the crankcase and I had to resort to carefully cutting through them with a hacksaw blade squeezed between the engine and the frame tube in order to get the engine out.
Now I've got the bike into smaller bits I can really start work on the renovation.
As various bits will have to be sent out for powder coating and plating, I've decided to get those bits prepared and sent out first, then I was able to work on the engine while I waited for them to come back.

1: I've started by separating the cycle parts into piles, sorted according to how they need to be refinished. This sounds easy, but remember it may be some months before it all goes back together again and it's worth taking lots of photos and making notes as a guide when it's time to reassemble everything. These are all the parts for powder coating.

2: To make the job easier for the powder coaters, everything has to be degreased and washed before it goes off to them. I'm using a small electric parts washer filled with Miller's Millsol Green cleaning solvent. It's a bit smelly, but it's a fast and effective way of quickly degreasing parts and is an invaluable workshop resource.