Service

SERVICE

How hot is too hot?

Recently, I was on the last leg of a 4000-mile tour and found myself, and my FJ 1100 Yamaha, in Barstow, California, in the middle of the Mojave desert, where temperatures were above 110 degrees.

When I wasn’t wondering if my clothes would catch fire, I was wondering what effect the heat was having on my beloved FJ. I realized that I didn’t even know what the symptoms of overheating would be. My FJ apparently did better than I did, as I gave up and holed up until the sun went down. I still wonder what the upper heat limits might be, and if my bike would signal me in some way before seizing? Is there any way to tell if an air-cooled bike is running too hot?

Stephen J. Groschowski

San Francisco, California

The most likely effect of running an air-cooled bike like your FJ in extreme heat would be to shorten oil life; it's extremely unlikely that operating in temperatures that are 30 degrees warmer than a more typical summer day will cause engine failure. Nevertheless, in 110-degree temperatures, you should keep engine revs down (don V charge down a twisty road in second or third gear; use fifth instead) as a means of maintaining lower oil temperatures and providing a wider safety margin.

As for symptoms that an engine is running too hot, there are few if you don't have an oil-temperature gauge. Unusual, rattly sounds from the engine could indicate an excessive oilviscosity drop from high temperatures; unusual engine pinging would be a sign that cylinder-head temperatures have gotten so high that detonation is setting in. In either case we'd suggest stopping and giving your engine a cool-off break. But once again, even desert temperatures are unlikely to faze a big, air-cooled streetbike that is being ridden normally.

Gear drive conversions

I own a 1983 CB 11 OOF and have been unable to find information on aftermarket camshaft gear-drive setups for my cycle. Do you have any knowledge of how and where I might purchase this item?

Paul D. Hartshorn Green Island, New York

Unfortunately, we know of no one making gear-type cam-drive conversions for any motorcycle, with the single exception of the very expensive Superbike racing kit Honda formerly offered for the VF750F Interceptor. Converting from a cam chain to a gear train requires a very thorough re-engineering of an engine, and even if such a kit were available, it would very likely cost thousands of dollars.

How fast will they go?

I would like to pose three questions to you: First, do you believe that production motorcycles will ever reach speeds of 200 mph? Second, do you believe power or aerodynamics will be the determining factor in achieving these speeds? Third, do you think that a current production motorcycle with modifications only to its engine could reach this great speed?

John P. McArdle

FPO New York, New York

It is certainly technically feasible to build a 200-mph streetbike, but we don't expect to see any such creature in the next 10 years. Then again, few people 10 years ago expected to see the 160-plus-mph production bikes we have today.

To go 200 mph, both power and aerodynamics are important. As an example, for a Ninja 1000 to go 200

mph, it would either have to make 95 percent more power than it does now (or, about 200 horsepower at the rear wheel) or the product of its frontal area and drag coefficient would have to be cut in half. Of the two, the aerodynamic approach might be the easiest for a usable motorcycle.

But if you all you wanted was a single, 200-mph run, a Ninja 1000 could certainly be boosted to the 200horsepower level for the few minutes required. It might require a turbocharger, or alcohol as fuel, or nitrous oxide, but it certainly could be done.

Tire-size confusion, revisited

In reference to your September Service column, and the letter “Tire size confusion”: Dunlop does produce the original-equipment tire size 110/90-16 for the CB700SC Nighthawk, and it is available from Dunlop through authorized Honda dealers only.

As engineered by the factory, the original-equipment tire size makes the CB700SC handle at its best.

George R. Shepherd AÍ Rodi Honda Decatur, Georgia

You're right. Original-equipment tires are usually available through a manufacturer's parts system, and, by definition, could be the ideal replacement because they're an exact replacement. But it's just as true that aftermarket tires are popular because they're not an exact replacement; they often offer better performance than the OEM tires. 0