Service

SERVICE

Paul Dean

Cam grinder

I have a 1997 Harley-Davidson Dyna Wide Glide. About two months ago, I had a local Harley mechanic install a Crane cam, a Mikuni carb and a set of Vance & Hines pipes. The bike ran okay for a couple of hundred miles, but then it started making mechanical noises that kept getting worse. I attempted to take the bike back to that same mechanic, but he had moved out of state, so I decided to try to fix the problem myself. When I pulled off the cam cover, I found metal filings all over the place. When I removed the cam, the part on the left end that fits into the little bearing was gouged and the bearing was falling apart. Was this damage the mechanic’s fault or did something else cause it? Dale Clayton

Metairie, Louisiana

More than likely, that damage was caused by the mechanic failing to do either—or both—of two things: replace the stock cam bearing and relieve the engine case just above the bearing. Any time a new cam is installed in an Evolution engine, the cam bearing should be replaced. This is especially true if the bearing is the original one installed at the factory; it’s a lower-grade unit that works just fine with the stock cam, but it’s marginal when subjected to the greater loads imposed by higher lift and more-rapid opening and closing of the valves. The preferred aftermarket replacement is a top-quality Timken bearing that is much more durable.

There can be another problem caused

by the lobes on high-performance cams, which are taller than the Stocker’s. If they’re tall enough, the innermost lobe will come in contact with a bulge cast into the right-side crankcase, just above the bearing. The lobe acts like a milling tool and grinds metal off the case until it cuts its own clearance. If your Crane cam has enough lift to make contact with the crankcase, and if the mechanic didn 't grind the case to give it sufficient clearance, that would explain the metal chips you found in the cam case.

There also could be a problem with cam spacing. Pre’88 Evo cams were fitted with a thrust washer and a .050inch-thick shim, while ’88 and later engin es-such as your ’97— used only the

thrust washer. But all aftermarket Evo cams require both spacers; so, if the mechanic didn’t buy the correct shim and install it on your Crane cam, the cam would be able to drift too far to the left, allowing the inner lobe to cut into the crankcase even farther. The cam also could move out of alignment far enough to cause lifter damage.

Replacing a cam in a Harley isn’t as simple as it might seem. I suggest you take the bike to an established H-D shop or-despite your previous experience-a reputable Harley mechanic. Without the proper tools and the knowledge to use them, you 're liable to wreak as much havoc as the mechanic who did the work in the first place.

Haywire in Hayward

I am having a problem with the taillight on my 1989 Yamaha FJ1200. The left bulb in the two-bulb light unit keeps blowing its taillight filament, but the right one is fine; both brake-light filaments are not affected. A new bulb will last for maybe a week or two, then it blows out. I’ve tried using a bulb that has a stronger filament, but to no avail. The socket is in good condition, and I’ve checked for a bad ground and inspected the condition of the wires all the way into the main harness, although I haven’t checked for amperage. Any suggestions on what could be the culprit?

John Eannetta Hayward, California

Vibration, most likely. Back in the Bad Old Days, before the advent of rubbermounted electrical components, blown lightbulbs were as commonplace as bugs on a windshield. The most prevalent cause was vibration, which would make lightbulb filaments fail due to metal fatigue long before they would burn-out through normal use as a light source. The practice of mounting lights with thick rubber cushions changed all that by isolating the filaments from the damaging effects of vibration.

My guess, then, is that this problem is being caused by vibration and not by an electrical gremlin. Only one of the two taillight bulbs suffers a regular burnout, indicating that a voltage irregularity is not the cause; if it were, both bulbs would be equally affected. Both get their current from the same source and—except for the last inch or two-through the same wiring.

Instead, it’s most likely that the rubber spacers in one of your FJ’s taillight mounts—probably on the left side of the light assembly—is worn, broken or

badly deteriorated and has, as a result, lost its ability to cushion vibration. And even though you already have checked the light socket, check it again, not for its electrical qualities but for the fit of the bulb. If the bulb is noticeably loose in its socket, engine and road vibration could make it rattle around enough to cause premature filament failure.

Gearing up or down?

Could you tell me how changing to a 14tooth front sprocket and a 48-tooth rear sprocket would affect a 1992 Yamaha FZR600? Stock, the bike came with a 15-tooth front and a 45-tooth rear, and would go 60 mph in first gear. I want the bike to be a bit quicker but not faster.

TA3TINMAN Posted on America Online

For the most part, some simple math provides the answer to your question. A 14/48 sprocket combination yields a 3.429:1 final-drive ratio, which is 14.3 percent lower (numerically higher) than the stock, 3.0:1 ratio. As a result, most elements of performance will be altered by a factor of 14.3 percent. At any given road speed in any given gear, engine rpm will be 14.3 percent higher. At any engine speed in any gear, road speed will be 14.3 percent lower. In all six gears, the amount of torque delivered to the rear wheel at any rpm will be 14.3 percent greater.

So, whereas your FZR previously was capable of 60 mph in first gear, it would only reach 51 mph after the sprocket change. If it turned, say, about 4500 rpm with the stock gearing while cruising at typical road speed, it would be spinning at nearly 5200 rpm with the lower gearing. If the Stocker’s top speed was in the 135-140mph range, the regeared FZR will do only about 115-120.

Calculating the bike s acceleration potential with lower gearing, however, involves a lot more guesswork than math.

Elapsed times in the quarter-mile will no doubt improve somewhat with the 48/14 combination, but the terminal speed might not.

Stock, a well-tuned ’92 FZR600 would reach about 115 mph in the quarter, but that's pretty close to the absolute top speed of the bike after the gearing change. Consequently, it’s very possible that the terminal speed may change very little, if at all.

Intercepting the vibes

I own a 1998 Honda VFR800 Interceptor with 3600 miles on it. I have made a few modifications, including Dunlop D207 tires, a Two Brothers slip-on muffler and a K&N air filter. The problem is the slight vibration I feel through the handlebars and footpegs between 5500 and 7000 rpm. 1 noticed this right from the beginning when I first got the bike, but I didn’t worry about it because most of my trips were short ones. But lately, I have been doing some longer touring rides, and by the end of the day, my hands and legs feel like they’re falling off due to excessive vibration. My dealer says this vibration is caused by the harmonics of the engine and that there is nothing I can do about it. I read many articles about this bike, in your magazine and others, before buying it, and the only thing ever mentioned was a slight vibration. Can you help me or should I limit my rides to short field trips? J.C. De Hoyos

San Antonio, Texas

Never before have I heard complaints about vibration on a VFR of any year, from the very first one in 1986 to the present model. That leads me to believe that either something is wrong with your Interceptor or that you are exceptionally sensitive to certain vibration frequencies radiated by the VFR. Those bikes do emit a slight bit of secondary vibration, but normally not enough to cause the level of discomfort you describe.

Before you take any other action, you first should determine if the level of vibration on your bike is greater than that of any other VFR800. Maybe your dealer will help you here, either by allowing you to take a short test ride on another VFR, or by putting you in contact with another Interceptor owner who might be willing to permit you a brief ride. One way or another, in a city as big as San Antonio, you should be able to wrangle a ride on another VFR just to compare vibration levels.

If you succeed in getting such a test ride and the other VFR clearly proves to be smoother than yours, check and retorque any fasteners whose looseness might amplify vibration. The enginemount bolts are the most obvious, but check all the exhaust-system mounting hardware, as well, and the bolts that attach the footpeg brackets to the frame. Also verify that the drivechain is properly lubed and adjusted; a too-tight, tooloose or too-dry chain can transfer a lot of engine vibration into the chassis.

If you find nothing loose, broken or out of adjustment—or if your test ride reveals that your VFR vibrates no more than any other—your options will be rather limited. You could: 1) Contact the people at Honda ’s Customer Service Department and see if they are willing to help; 2) trade your VFR for another bike whose vibrations aren’t as debilitating; or 3) experiment with some vibrationdamping modifications. You could try stuffing various amounts of lead weight inside the handlebars and then installing a set of those big, foam handgrips. Reducing the buzzing in the footpegs will be more challenging, although you might be able to adapt some rubber-covered pegs from another bike with only minor modifications.

Jetting a rocketship

I recently bought an exceptionally nice, used ’96 Suzuki GSX-R750. The guy I bought it from was a fanatic about taking care of it, so it was just like new and only had 2200 miles on it. Man, what a rocketship! It runs great and goes like hell except for a small problem: When I’m just cruising the freeway or going 55 or 60 mph on a long, straight road, it doesn’t want to hold a steady speed. Even if I’m really, really careful and hold the throttle motionless in one position, the engine either wants to speed up or slow down. That gets really annoying after a while. Is this normal behavior for this year of Gixxer or is something wrong? And no matter if it’s normal or not, is there anything I can do about it?

Roy R. McFarland Park City, Utah

What you are experiencing is indeed standard fare for a 1996 GSX-R750. As evidenced by its extraordinary performance, the engine in your Suzuki is in an exceptionally high state of tune for a stock streetbike. Combine that radical tuning with the ultra-lean carburetion the GSX-R needs to comply with federal emissions regulations and you get an engine that is abnormally sensitive to throttle position, especially in the lower and middle rpm ranges. In fact, improving the GSX-R ’s all-around ridability was one of the reasons Suzuki gave it electronic fuel injection in 1998.

Fortunately, this condition can be largely remedied with the installation of an aftermarket carburetor recalibration kit. These kits are available from several sources, including Yoshimura, Dynojet, Factory and K&N. The throttle response will still remain rather touchy after the installation of the kit, but you 'll find it much easier to maintain a steady pace when cruising at or near legal road speeds.

Got a mechanical or technical problem with your favorite ride? Can’t seem to find workable solutions in your area? Maybe we can help. If you think we can, either: 1) Mail your inquiry along with your full name, address and phone number to Cycle World Service, 1499 Monrovia Ave., Newport Beach, CA 92663; 2) fax it to Paul Dean at 949/631-0651; or 3) e-mail it to CW1Dean@aol.com. Don’t write a 10-page essay, but do include enough information about the problem to permit a reasonable diagnosis. And please understand that due to the volume of inquiries we receive, we can’t guarantee a reply to every question.