Service

SERVICE

JOE MINTON

Heavy Hawk

According to the owner's manual, my 1991 Honda Nighthawk 750 can safely carry 355 pounds in rider, passenger and accessory weight.

How conservative is this rating, and can the motorcycle be easily modified by tire and suspension changes so that 450 pounds can be carried safely? Rick Hathaway Stateboro, Georgia

The maximum load limit of your (or anybody's) motorcycle is primarily determined by the carrying capacity of the tires. That doesn't mean that you can increase the acceptable toad capacity of your hike by fitting larger tires. A property engineered motorcycle will have heen developed around a particular dross Vehicle Weight Rating (dVWR). Exceeding this limit could overs tress some component or affect stability in a negative wav.

It is true, though, that the dVWR of vour Nighthawklike those of most hikes—will be eonservative in that it assumes worst-ease conditions such as high continuons speeds and high tiretread temperatures. In reality, most

louring riders overload their motorcycles and survive the experience, though such overloading certainly reduces stability ami maneuverability. It also increases the chance that sonic-> thing will break and deposit you and your load on the ground. Play it safe when it comes to packing your bike.

Leftover Duck

I recently purchased a leftover 1987 Ducati Indiana 650, which, for a standard-looking Twin, delivers a very sporting punch. My problem is that I am experiencing annoying carburetion stumbles. I have re-fitted the rubber hoses to the carbs and tried carb-cleaning fuel additives, but the problem remains. Pete Hughes Jacksonville, North Carolina

Your Ducati has very lean carburetion settings, and you will need to alter them to cure your stumble. Earl Campbell, owner of Pro Italia Motors (3518 N. Verdugo Rd., Glendale, CA 91208; 818/249-5707) tells me that you will probably need to change the pilot jets and the needle jets, and perhaps change the idle-mixture screws. Pro Italia can supply these parts. It has been my experience that Italian motorcycles come to this country with very lean carburetion. I have always gotten a substantial improvement in performance as a result of retiming them.

Exhausting search

I own a 1989 Honda Hawk GT and am thinking of racing it. The problem is a distinct lack of aftermarket exhaust systems. Nothing is available from Vance & Hines or Kerker, and SuperTrapp has discontinued its system. Spec II makes a system for the Hawk, but I know little about the company. Michael Chesnore Janesville, Wisconsin

SuperTrapp does indeed make a system for your 650. These systems have been on backorder for some time, but are now available. The part number is 825-30651 and suggested retail is $325. Kerker does not make a Hawk GT system, but is considering putting one into production. Spec II exhausts are excellent performers. Owner Gary Schumake knows how to design systems that perform well, and his designs have been consistently effective.

Additionally, Two Brothers Racing> offers a system for $329. based on the one used on their very successful ProTwins racebikes.

Oil spill

I have a 1986 Kawasaki 1000R Ninja that I bought new in 1988 and have since put 20,000 miles on. In the three years I’ve owned this bike, the left fork seal has had to be replaced three times. The last time, the local Kawasaki dealer replaced the bushings, checked for scratches, etc. and put in a new seal, but it has started to leak again. What should 1 do?

Also, in the past four months. I’ve snapped the rear motor-mount bolt twice. Last time, I had a local machine shop fabricate a new bolt out of Hastalloy C36 alloy because it’s much stronger than the steel rod used for the stock bolt. Could torque, horsepower or hard riding on mountain roads have caused this problem? Andrew Comito Los Alamos, New Mexico

Seal teaks have become a constant problem since manufacturers gave up the good old pleated-rubber boots or telescoping metal shields that many bikes used to be fitted with. The most common cause of repeated fork-seal failure is damage to the hard chromium plating on the fork tube. An impact pit so small ibat it cannot be seen clearly without magnification can and will cut the rubber lip of a seal. Inspect the tube very carefully with a magnifying glass. I have usually been able to stone (I use a hard Arkansas stone) such pits smooth enough that they don 7 damage a new seal.

I would be concerned about the fact that your bike's rear motor mount has broken twice in a short period. It probably means that something else is wrong. You should check, or have checked, the rest of the frame and the other motor mounts. It is very likely that, for some reason, the stress the rear motor-mount bolt is subjected to has gone up. The problem could be as simple as an uneven distribution of stress among all the motor mounts, which could be cured by loosening and then re-torquing all of them. But it could also be something as serious as a cracked frame. Check it out. The cure shouldn 7 have to be a special bolt. E3