Service
SERVICE
Paul Dean
An idle threat
Recently, I purchased a 1991 Suzuki 750 Katana. I had the oil and filter changed, and new sparkplugs installed. My problem now is that when I start the engine, it won’t keep running. As soon as I release the throttle, the idle drops below 1000 rpm and the motor shuts off. I am new to motorcycling, so I have no clue what could be causing this problem. If you have any suggestions, could you please share them with me?
John Jones Posted on America Online
If the engine ran fine before the oil change and sparkplug replacement, something that occurred during that service is causing your Katana ’s unwillingness to idle. Perhaps the coldstart enrichener (“choke ”) cable accidentally got disconnected while the tank was being removed. Maybe a couple of the sparkplug wires were put back on the wrong plugs. Or the idle-speed adjustment may have gotten backed off enough to allow the engine to stall.
Here are some factors to consider when troubleshooting the problem: If the enricheners were not being activated, cold starts would be very difficult; thus, if the engine starts quickly and easily when cold, there probably is nothing
wrong with the choke cable. The enrichener circuits also cause the engine to idle much faster, so if they were working well enough to let the engine start, they also should allow it to continue running-provided, of course, that you leave the choke on until the engine is warm enough to support a normal idle. If you are using the choke to start the engine but turning it off right away, that will cause stalling, since the lean fuel-air mixture won't permit the engine to idle on its own until it gets jdirly warm.
When you said that you’d “had” the oil, filter and sparkplugs changed, that indicates you had someone do the work for you. If the suggestions I’ve offered don 't remedy the problem, you should take the bike back to the mechanic who performed the service and have him or her try to determine the cause of the stalling.
Bleeding hearts
I have been working on motorcycles and cars for a bunch of years, and have done lots of brake work in that time. I’ve always made it a practice to change the brake fluid on my motorcycles at least every other year to optimize performance. Recently, several of my friends who own BMWs (R1100RS and RTs equipped with anti-lock brakes) have asked for my help in changing the brake fluid on their bikes. I always use a vacuum pump to bleed the brakes on my bikes, but I’ve heard that bleeding antilock brakes with a vacuum pump can cause damage to the brake system. Is this true? If so, what is the recommended method for bleeding anti-lock systems?
James Wesley Posted on America Online
Bleeding any braking system-anti-lock or otherwise-with a vacuum pump causes no damage; the worst thing that can happen when using a vacuum pump is that a minute amount of air could enter the system around the threads of the bleeder valve to which the pump is connected. Although the chance of such an occurrence is extremely small, BMW nonetheless recommends a procedure in which fluid is pushed into the system through the master cylinder rather than being drawn into it by vacuum acting through a caliper bleeder. BMW’s concern is that even a small amount of air in the system could prevent the ABS from functioning properly.
Personally, I think that BMW is being extremely conservative in its recommendation, probably as a hedge against possible product-liability suits. Regardless of the method used, if the ABS system is carefully bled, no system failure or damage will occur.
Keeping a high profile
I have a question concerning tires for my 1977 Harley-Davidson FLH, a bike that I’ve been riding-and putting tires on-for 12 years. The big Honda Gold Wings look good and seem to handle better than my old Glide while running low-profile tires. Can I use similar tires, and if so, what effect will they have? My Harley has the H-D factory ninespoke mag wheels that came out in ’78 or ’79, and I’ve been using Continental 130/90-16 tires front and rear. The ride is nowhere near as sweet as it is with a like-year Gold Wing, and my FLH also seems a bit squeamish on curves. If you can advise me on another choice of tire, I would very much appreciate it.
Tony Phillips Cookeville, Tennessee
The lower-profile tires used on Honda Gold Wings will neither work nor fit on your FLH. The Wing uses a larger front wheel (18 inch) than your Harley and a wider 16-inch rear wheel, both of which permit shorter sidewalls without any sacrifice in load capacity. By today’s standards, your FLH's wheels are extremely narrow-too much so to allow the use of tires with the same aspect ratio as the Wing ’s.
Besides, most of your FLH’s handling shortcomings are not the result of its tires. The Continentals you have been using are reasonably competent tires, but their ability to perform on your H-D is limited by the bike’s outdated chassis. Even though Harley’s current touring models look much like your 23-year-old FLH and even use the very same tire sizes, the later frames, suspension components and steering geometry all are vastly improved.
Having said that, I can tell you that I ve been very impressed with Michelin s Commander line of tires, which were specifically designed for use on HarleyDavidsons. They come in OEM sizes to fit all H-D models, and they provide a pleasantly surprising combination of straight-line stability and curvy-road handling. I’ve never sampled them on a 1970s touring model, but I think they’re an option you should consider the next time you ’re ready to spoon a new set of hoops onto your trusty FLH.
Leaning tower of Ninja
I’ve got a 2000 Kawasaki Ninja ZX-6R with just over 3000 miles. It runs great except that it needs to be leaned to the left in order to go straight. If I let it sit upright with no bar input, it pulls to the right, hence it has to be leaned to the left all the time. This is in all lanes of the roadi.e., the slant of the roadway is not the cause. I’ve tried moving to one side in the saddle just in case it was me throwing the balance off, but to no avail. The mechanic at the local shop messed with the tripleclamps but didn’t solve the problem. I’ve also made sure the chain-adjuster marks are equal on both sides of the swingarm. I’m concerned about uneven tire wear, plus it’s really annoying to have to keep the bike leaned to the left all the time. Any suggestions? Jason Wentzel
Posted on America Online
None of the ZX-6R test bikes we 've ever ridden have exhibited such a problem, so this condition would seem to be unique to your bike. But I don’t think it s terminal; I suspect your Ninja 's wheels merely are not in proper alignment. If the rear wheel is adjusted so it aims off slightly to one side or the other, the bike will not go straight on its own. This misalignment of the rear wheel makes the bike “dog trot” (track slightly sideways) down the road, and the natural self-centering tendency of the steering geometry’ constantly resists your attempts to compensate.
Yes, I know you've carefully matched the chain-adjuster marks on both sides of the swingarm; but in doing so, all you accomplished was to ensure that both sets of marks were indexed equally. That doesn’t guarantee that the wheels are in proper alignment. Actually, it doesn’t even guarantee that the final-drive sprockets are aligned.
Why? Because there is a whole slew oj chassis components between the front and rear wheels, components whose combined manufacturing tolerances determine the actual locations of the wheels. There are minute variations in the dimensions of the fork legs, the triple-clamps, the steering head, the swingarm pivot, the frame structure between the steering head and the swingarm pivot, the pivot-bearing bosses in the swingarm, the distance between the swingarm pivots and the axle slots, etc., etc. Each of those variations is extremely small; but when you add them all up, it s highly unlikely that simply matching the chain-adjuster marks (which are installed while the swingarm is being manufactured) will put the wheels in perfect alignment.
Instead, you must verify and, if necessary, adjust the rear wheel’s alignment by disregarding the marks on the swingarm. You can achieve a reasonably close visual alignment by sighting along the sidewalls of the tires, but more accurate results require either two long, perfectly straight pieces of wood or steel, or a long piece of string pulled taut along the sidewalls. If you want to get really precise about it, you could locate the closest GMD Computrack frame machine and have the alignment of the entire chassis checked and corrected.
To get the wheels on precisely the same centerline, you ’ll probably have to mismatch the right and left chain-adjuster marks, and possibly even compromise the alignment of the chain itself. But that’s probably a worthwhile tradeoff if you hope to eliminate the constant need to steer to the right.
An engaging problem
I have a 1999 Yamaha YZF-R1 that will not shift down when I’m at a complete stop. Usually, I shift down while I’m coming to a stop, unless I have to make a sudden stop. When that happens, I’ll push on the shift lever to shift down, but the transmission usually won’t go into the next gear unless I let the clutch out slightly. This has been a problem as long as I’ve had the bike. It now has 1200 miles on it and has never been raced or abused. The clutch doesn’t slip, stick or do anything else unusual, and the bike is entirely stock. My ’95 Kawasaki ZX-9R shifted a lot better than this bike and it never had this downshifting problem. Got any ideas? BCtristan
Posted on America Online
What you are experiencing with your R1 is perfectly normal behavior for a motorcycle. Bike transmissions use a method of gear engagement involving pegs or wide lugs-called “dogs ’’-on the sides of the gears. The shift forks, which are activated by the shift lever, move the gears from side to side, and the gears engage one another when the dogs on one gear lock into matching slots or dogs on an adjacent gear.
This is an entirely different concept than a car transmission, which uses friction rings, called synchronizers, to facilitate the shifting of gears. On a car, you can shift gears while the vehicle is not in motion because the synchronizer rings are designed to work under those circumstances. But with motorcycle transmissions, which are more simplistic in design, you can only shift gears when sitting still if each gearset ’s adjacent dogs and mating slots are in near-perfect alignment-a condition that rarely occurs. That ’s why you have to rock the bike back-and-forth slightly or start letting out the clutch, either of which lets adjacent gears move just enough to permit engagement.
I’m not entirely sure why you never experienced this phenomenon on your Kawasaki other than my suspicion that it had a lot more clearance beleen its engaging dogs. In other words, the dogs on gear A mated into slots on gear B that were quite a lot wider than gear A ’s dogs. That technique tends to allow easier gearchanges, but it also produces more “slop ” in the driveline, which can be very unsettling for a rider trying to corner smoothly on a racetrack or at fast backroad speeds. The RI ’s designers apparently chose to sacrifice sheer ease of engagement for better cornering control.
A final drive that sucks
In reference to Bill Bradford’s problem with the Honda Shadow that leaks oil out of the final-drive vent (“Venting his rear end,” October, 2000): I had the same problem with my ’97 Shadow Spirit. The mechanic at my dealer said he’d seen this several times with Shadows, and felt it was caused by the wind blowing over the top of the final-drive housing, creating a suction effect. He said that Honda Gold Wings and ST1 100s have their final drives shielded to the point that this isn’t a problem, but the Shadows, with everything hanging out in the wind, sometimes experienced this. He removed my bike’s vent cover with a heat gun and inserted a small piece of foam air-filter material into the vent, then reinstalled the cover. It’s two years and 14,000 miles later, and the vent still doesn’t leak and the oil level stays right where it is supposed to stay.
Frank Jones Sparks, Nevada
Great tip, Frank. Thank you very much.
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.
