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Cold tires, hot bike

Paul Dean

I’m the proud owner of a ’96 Honda VFR750F, the best motorcycle I have ever ridden! But are the stock tires that come with the VFR “sticky” enough for its torque output? I ask this because when I was leaving work (cold tires) the other day and accelerated out of the parking lot, the rear end slid sideways. There was no water, oil, sand, etc., on the road, and I didn’t slam the throttle open, but just accelerated normally. Did this happen because the tires were cold (42-degree outside temperature) and the bike is torquey, or should I buy stickier tires? And if I should, can you recommend a brand or model of tire for the VFR? Rob Preston Harwich, Massachusetts

Actually, the stock tires on a VFR are quite good and well-matched to the power output of the engine. What’s more relevant to the situation you have described is not necessarily how sticky the tires are, but rather how quickly

they warm up. Tires are their stickiest only when they have warmed up to the point where they are at or near their ideal operating temperature; and the stock tires warm up more quickly than most high-performance

race-compound tires. Besides, unless you went back to the slide area and gave the ground a thorough, downon-your-knees inspection, you can’t be absolutely sure that nothing on the surface caused the tire to break loose. >

We've found that the VFR responds favorably to most aftermarket highperformance tires, many of which are grippier when warm; but when cold, they may slide even more easily than the stock tires.

Timing is everything

Not too long ago, I bought a 1982 Kawasaki 1100 Spectre that burned oil and needed a new exhaust. I’m cheap, so I bought a nice, inexpensive 4-into1 exhaust to replace the stock system. The bike got great gas mileage, up to 48 mpg, though I had to add a quart of oil every 200 miles or so. I finally decided to get a basic engine rebuild and had the gaskets, O-rings and piston rings replaced, and the valves reseated. When I got the bike back, I noticed a dramatic difference in gas mileage. It now can’t get more than 31 mpg and averages about 28. It also has a flat spot at freeway speeds around 4000 rpm. It surges severely if I try to hold it at a steady speed. And if I open the throttle at about 75 mph, it first cuts out, then takes off like a rocket.

Is this normal? Could the cams be a tooth off? I added a 5mm extension to the cam-chain tensioner, but that’s on the slack side of the chain. The mechanics say nothing is misplaced and there’s no timing error. Give me a little help, please. I can barely go 80 miles on one tank of gas. Colin Clark Cedar City, Utah

The fact that your “mechanics ” delivered the bike to you in such poor running condition indicates that they possess a high level of incompetence. So, all bets are off. They could have fouled up the carburetors, mistimed the ignition, incorrectly indexed the cams or all of the above.

On the other hand, your admission of having to add 5mm to the camchain tensioner is clear evidence that the chain is a major problem in any event. If there is sufficient slack in the cam chain to require an extension of the tensioner, the chain is completely worn out and should have been replaced long ago.

On engines with chain-driven overhead cams, cam timing is dictated by the front run of the chain, which essentially “pulls ” the cam as the crankshaft rotates. (This is true if the crank rotates in the “conventional” direction, which is clockwise when viewed from the right side. If the crank rotates

“backwards,” cam timing is dependent upon the rear run of the chain.) Obviously, as a cam chain stretches due to normal wear, cam timing will be retarded accordingly. And nothing you do with the tensioner has any effect on the cam timing; all the tensioner does is push on the rear run to prevent the chain from flapping about and making a lot of noise.

Your bike s cam chain is stretched so badly that the mechanic who installed the cams would not have been able to time them correctly. He should have replaced the chain; but because he did not, he would have had to compensate for the stretch in the chain by either advancing or retarding the timing. The bottom line is that replacing the cam chain will probably rectify the problem; and even if it doesn't, you ’ll never get the engine to run properly until after you replace the chain and properly time the cams.

Car-carb question

I have a 1975 Honda Gold Wing that is suffering from the old, worncarb blues. Rather than invest in new slides, gaskets, etc., I recall hearing about a kit that allowed the use of an automotive-type two-barrel carb on Gold Wings. Do you know of this kit, and whether it is still available?

Second, does anyone rechrome fork tubes, or will I have to “spring” for new ones? Lee Graves Charlottesville, Virginia

I remember a two-barrel conversion for Gold Wings that was marketed a long time ago, but to my knowledge, it is no longer available. Besides, by the time you buy the manifold, the carb, the linkage, the fuel lines and the air cleaner, along with the time required for installation, minor fabrication and tuning, you likely would invest more to put the two-barrel on your Wing than if you simply replaced the parts in the stock carbs.

As far as your rechroming question is concerned, understand that despite its simplistic appearance, a fork tube is a precision piece of equipment. To slide freely in its bushings and allow the seals to work properly, a fork tube would have to be precision ground to an exact diameter specification after being rechromed. Again, between the cost of rechroming and the cost of precision grinding, the expense would exceed that of a new fork tube. □