Motorcycle Technical Questions | Answers

By Motorcyclist Staff, Photography by Honda

Got a question for Answers? Send it to mcmail@sorc.com

Stopping the Nighthawk
My 1985 Honda Nighthawk sat unused for two years. After doing some wrenching, I got it running again. That’s when the trouble started (or stopped). The front brakes locked up on the test ride around the block. I bled the system; still locked. Pulled both calipers, cleaned them, and put new seals in. Replaced the brake lines. Pulled the master cylinder, cleaned that up, too. Everything seemed good on the first 5-mile test ride. I took the bike to the train yesterday (only 4 miles) and left it in the lot while I went to work. When I got off the train later that afternoon, the brakes were locked up again. I loosened the bleed valve and brake fluid shot out about 6 inches. After that, the brakes worked fine on the way home. I bled the system again (no bubbles). What would have caused that to happen? It was hot, about 95 degrees, but other bikes in the lot didn’t have this issue.
Thomas Sass
Chicago, IL

Look for debris in the pressure return hole in the master cylinder. There are two holes: one to feed the system with fluid under pressure and a second, smaller hole furthest from the lever side of the piston that relieves pressure built up in the system. As the fluid gets hot it expands and has nowhere to go but to lock up the brakes. Understand, too, that brake systems can be very finicky, and near-surgical cleanliness is necessary to ensure the system works as intended.


Live Long and Wobble
I enjoy riding my 1999 Vulcan 1500 Classic all over New England, but recently I hit the interstate and had trouble controlling my bike above 70 mph. My tires are good, pressure is correct, and there are no major modifications. Does my bike have a high center of gravity that makes it harder to handle at higher speeds?
Fran Rogers
Billerica, Ma

You didn’t say how many miles you have on your Vulcan, but something mechanical is a more likely culprit than center of gravity. Check the tires again. Heavy bikes like the Vulcan can be hard on front tires; cupping of the tread can lead to front-end instability. If the tires still look good, check the rest of the front end for worn wheel bearings, an out-of-true wheel, loose spokes, even a warped brake rotor. Check the steering-head bearings. Many Vulcan owners upgrade from ball to roller bearings in the steering head. All Balls Racing offers tapered-roller bearings ($33.56; www.allballsracing.com). Vulcan owners also complain of soft fork springs resulting in instability. Progressive Suspension makes a fork-spring kit ($92.95; www.progressivesuspension.com) that may help improve front-end stability. Eliminate the mechanical issues before you worry about your bike's center of gravity.


Don’t Blend In!
Often in a motorcycle collision involving an automobile, it is common to hear the car driver say, “I never saw him.” As a motorcyclist, I fully understand that it is harder to spot a bike than a car or truck. I always assumed that the drivers who said, “I never saw him” really didn’t look—until the other night, when I pulled up to a light in my car. I was going to make a right on red. All clear to the right, and the headlights of an SUV about 400 yards to the left—plenty of room for me to pull out. I looked right again as I was about to go, but something stopped me, so I stepped on the brake. As I turned my head to look left, a motorcycle passed right in front of me. I never saw him! The SUV was now about 300 yards away, and I realized that the motorcycle’s headlight had lined up with one of the SUV’s headlights, making the bike essentially invisible!

A few days later I saw a Suzuki SV650 that had mounted fog lights on both sides of the headlamp. Had the motorcyclist that I almost “never saw” had these as well, I would have been able to see him.
Jeremy Thorsen
Burbank, CA

By Motorcyclist Staff
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