Service

duces more torque, lower in the rpm range, than the 180. My question is this: If I can find and install a 360degree crank in the VFR, how would it affect its acceleration and torque?

George Mihailofski Chicago, Illinois

Not enough to be practical. Such a swap is possible, but if you weigh the immense cost against the relatively small performance gains you might achieve, it definitely is not worthwhile. In addition to changing the crankshaft, you would also have to deal with the camshafts and the ignition system (both of which are timed to work only with a 180-degree crank), as well as the exhaust system (which is tuned for the 180 crank). On top of that, the crank, the cams and all the valve gear from a VF750 will not fit in a VFR750 engine. The crank from an RC30 (the limited-production, 88model “ Wayne Gardner Replica ” sold in Japan, Canada and Europe) would probably slip into the VFR 's cases, but its cams are entirely different. You could, of course, keep the VFR cams and have them remanufactured by a cam-grinding company to work with a 360-degree crank, but you'd then have to contend with some considerable differences in cam-drive design to link the RC30 crank to the VFR750 cams.

By time you were finished, you 'd have a monumental investment in a streetbike that, at best, would be only marginally faster in certain rpm ranges than the one you started with. Besides, the only reason why a 360degree crank results in more midrange torque is that it greatly simplifies the construction of an exhaust system with equal-length header pipes. But, if you simply must have a faster Honda V-Four with a 360-degree crankshaft, our advice is either to: 1) Contact Honda dealers in Canada and negotiate to buy an RC30, which will set you back about $12,000 (an amount you could conceivably invest in putting a 360-degree crank in a VFR 750); or 2) keep your VF750 and wait until 1989. In all likelihood, Honda will either bring the RC30 into the U.S. next year, or else introduce a new VFR-like 750 that incorporates many of the RC30's features—including its 360-degree crankshaft.

The one-inch dilemma

I own a Honda 1000 Interceptor. Could you tell me the pros and cons of replacing my bike’s stock 16-inch front wheel with a 17-inch wheel, as the VF 1000F has a 17-inch rear wheel.

Paul Anderson Wayne, New Jersey

Diameter-wise, the size of the rear wheel has no bearing on the size of the front wheel. And we know of no one who can tell you exactly what will happen if you bolt up a 17-inch front wheel on your Honda. Chances are that it will effect an improvement, but we can 7 say for sure. By slightly increasing the front-wheel trail and the amount of gyroscopic stability it provides, a 17-incher would probably slow down the Interceptor's steering, which is a bit too sensitive. In addition, you can use a slightly narrower 17-inch front tire than 16-inch, thereby reduc-

SERVICE

Gimme a brake

I recently purchased a 1978 Kawasaki KZ650 SR with about 4200 miles showing on the odometer. The dealer assured me that everything on the bike was original. It has a triple-disc brake system, but I’m sure that a semi has a shorter stopping distance. And when it rains, I have no brakes at all. I’m thinking of installing SBS brake pads to help my braking problems. Will this help, or are there more-efficient ways to make this bike stop better?

Bruce Rettig

Alexandria, Minnesota

Most of the modem, sintered-metal replacement pads sold by firms such as SBS, EBC, Lockhart, etc., will clear up your braking problems the instant they are installed. The disc brakes on most Japanese bikes of that era were fitted with extremely hard asbestos pads that the manufacturers preferred because they didn 7 squeal, delivered long pad life and gave a nice braking feel. But they tended to glaze over rather easily, which itself reduced their performance, and in the rain they often would provide almost no braking whatsoever until the pad-to-rotor friction generated enough heat to dry the pads. The sintered pads aren 7 always the longest-lasting or the quietest, but they consistently let the brakes do what they're supposed to do—stop the motorcycle.

Smallest piston

In your July ’86 issue, you ask the rhetorical question, “How small and light can a piston and rod be?” in reference to the Honda CBR250F components. It’s a bit silly, since a lot of mopeds and weed-eaters have smaller ones, but the real answer is inside a production Cox model-airplane-type engine that displaces .01 cubic inches, which is 0.16cc. The piston and rod, plus the whole crankcase assembly, weigh just .001 pound, and the whole motor weighs .002 pound. The entire engine is dwarfed by a quarter. Has anyone ever seen a smaller one?

What is amazing about the giant Honda parts is that they turn nearly the same rpm as those in this little Cox engine.

David Tier

Middlebury, Vermont

We certainly don 7 know of anything smaller; if anyone has knowledge of a smaller engine, please let us know, and we'll publish the details of the world's smallest piston engine. We'll also bet that a typical motorcycle engine turns at a far higher average piston speed.

Stripped sparkplug threads

I own a 1981 Suzuki GSX1100EX, and have not ridden the bike for two years now. I used to ride it every few months, and would try to remove the plugs to clean and check the gap, but I kept having problems with the plugs seizing in the cylinder head. When I would get one out, I would find some of the head threads fused into the plug threads. The result is that the threads in the cylinder head are almost worn away, and I’m wondering if this is a manufacturing fault of this model. This problem happened twice before I stopped riding the bike. I tried to remove the plugs the other day so I could put the bike back on the road, and guess what? The same problem again.

My bike has only 9045 miles on it, and the engine has never been tampered with, not even to adjust the valves. And the motorcycle is completely stock. As this bike is now 6 years old, and this sparkplug problem first happened two years ago,

I’m wondering if I should purchase a new cylinder head. Any suggestions will be appreciated.

Graham Tucker

Bridgetown, Barbados, W.I.

Don 7 replace the cylinder head; the existing head can be repaired with helicoil inserts by any competent machine shop that does car or bike work.

The plug-seizure problem you describe is not typical of Suzuki 1100s, but may be related to galvanic corrosion between the steel plug body and the aluminum cylinder head, corrosion that is intensified by the salt air in your area. In any case, a little antiseize lubricant applied to the plugs prior to installation will make their removal far easier. And after you fix your cylinder head, please adjust your valves.

A matter of degrees

I currently own a 1983 Honda VF750 Interceptor, and am contemplating purchasing a 1986 VFR750 Interceptor. My only concern is that my ’83’s V-Four engine has a 360-degree crankshaft configuration, but the ’86 has a 180degree crank; and I’ve read in your magazine that the 360 crank proing the front wheel's positive roll-steer (its tendency to flop inward in the turns). What we don V know is if a 17incher would cause any front-end twitches or wiggles by being mated to geometry calculated for a 16-inch wheel. But you 'll never know for sure until you try.

Radial daze

I have a 1986 Kawasaki Concours sport-tourer. It has 4500 miles on it, and the front tire, a stock Dunlop radial, seems to be wearing rapidly. When this tire is gone, is it necessary to replace it with another radial-type or can I go with a premium bias-ply tire? Also, the front tire seems small for such a heavy motorcycle. What about changing tire sizes at the time of replacement?

Kent Harrison

Mt. Carmel, Illinois

It isn't mandatory to use only a radial front tire on your Concours, but you should not go up on tire size. The front rim is too narrow to handle anything substantially bigger than the stock tire. Not all manufacturers have bias-ply tires in the Concours' original 110/80-18 size, however; so, should you opt for a bias replacement, something, say, like a Metzeier ME33 Laser, the 110/ 70 VI8 size would be a good choice. And if you want to try a different brand of radial, consider one of Michelin 's new A59X street radiais, which is available in the original 110/ 80VR18 size. S