Service
SERVICE
Paul Dean
Lean machine
I am 18 years old and own a 1993 Honda CBR600F2 sportbike, and I have noticed that the bike seems to have a slight left lean when I’m riding it. You can see this in the rear tire, because the remaining tread grooves on the right side are longer than those on the left, and the overall wear pattern is slightly offset to the left of the rear tire instead of in the middle. Can it be that the wheels are not properly aligned, or do I just need new tires? I have asked several motorcycle shops in the area about alignment and they claim there is no precise way to check the alignment on a motorcycle. Please help.
Daniel Byrd Durham, North Carolina
Without personally inspecting your bike, 1 have no way of determining if any part of its chassis is out of whack. To my knowledge, F2 Hondas have no inherent misalignment problems, and no one makes tires that tend to wear more quickly on one side than on the other. Contrary to what your local dealers say, however, it is possible to check a motorcycle ’s wheel alignment with reasonable accuracy. I have outlined the procedure several times in
Service, (most recently in a letter titled “Shake & break” in the October, 1997, issue), so I won’t repeat it here; but even a visual alignment check should detect a problem severe enough to wear the tires asymmetrically.
Truth is, there may be nothing wrong with your Honda at all. Most roads are crowned—that is, higher in the center than on the sides—to allow adequate runoff of rainwater. Consequently, when you re riding in the right lane of a typical two-lane road, the surface is neither completely flat nor level; it’s slightly curved and cambered to the right, causing the tire’s contact patch to be slightly offset to the left of center. And if you ride in a lane’s right-hand wheel track more often than in the left one, the wear will be even more offcenter because the amount of roadsurface camber is greatest closest to the shoulder.
Smoky...
I recently bought a new 1996 Triumph Tiger Triple, and right from the start, it had a mechanically loud idle that would quiet down once the bike was under way. The bike now has 500 miles on it and is even louder, knocking away at idle in neutral or with the clutch pulled in, but quieting down as rpm increases. The noise seems to emanate from the clutch area, and the dealer claims it is caused by lash between the primary drive gear and the driven gear on the clutch basket. He says it is quite normal and nothing to worry about.
Also, when the engine is first started in the morning, it lays down a dense cloud of blue oil smoke. The dealer says this is normal, too, and that the rings won’t be seated until 1000 miles. What do you think about all of this? James Hurley
Goleta, California
Current Triumphs use straight-cut primary gears, whereas most other contemporary streetbikes with geared primary drives employ helical (anglecut) gears. The straight-cut design is somewhat stronger, but it tends to be a little noisier. Your dealer was correct, then, in proclaiming the primary drive as the source of the noise.
But if the knocking is as loud as you indicate, he is wrong in his assessment that the noise is “normal.” If the engine is not in an optimum state of tune, particularly if the carburetors are not precisely synchronized, it may refuse to idle at a steady speed; instead of each curb contributing equally to a consistent idle, small differences in individual carb adjustment will cause the rpm to fluctuate. The engine will speed up very slightly when it fires a cylinder being fed by a carb that’s delivering more than its fair share of mixture, and slow down slightly when firing a cylinder fed by a carb delivering less mixture. Thus, the engine actually speeds up and slows down during each revolution. And although comparatively small, these rapid fluctuations in rpm can cause the teeth of the primary-drive gears to rattle back and forth against one another at idle, resulting in a noise that is particularly loud with the straight-cut design.
The obvious solution is to have your dealer (or another Triumph agency if your current one is uncooperative or incompetent) balance your Tiger’s trio of carbs. Properly done, that synchronization procedure should eliminate most, if not all, of the noise at idle.
As far as the smoking is concerned, the symptoms indicate problems with the valve guides and/or valve seals, not with the piston rings. If an engine smokes when started after sitting for a while, it does so because oil is getting into the combustion chambers while it ’s not running. Your Triumph s oil sump is beneath its vertical cylinders, so the oil obviously is not defying gravity and traveling upward past the rings and into the combustion chambers. Instead, it is entering from above by seeping past the valve seals and valve guides.
What’s more, the Tiger has only a sidestand, so the bike always tilts to the left when parked, and this traps as much as a half-quart of oil in the left side of the cambox chambers. Plus, the oil is hot and at its thinnest right after you shut the engine off. So, if the valve seals on the left side are not doing their job, the oil simply runs down the valve stems and into the combustion chambers. This condition very definitely is not normal and should be corrected by your dealer under warranty.
...And the Bandit
I own a 1997 Suzuki Bandit 1200 and I love it. But I noticed in your August, 1996, issue, and in a couple of English magazines I receive, that the Bandits sold in Europe and Canada have a lower engine mount that has been left off of the U.S. model. From what I can gather, this mount was eliminated to ease vibration. But as I see it, using the lower mount would add stiffness to the frame-a good thing, in my eyes.
Should I add this mount? I have friends in Canada who could order the necessary parts for me, or I could have the mounts made of aluminum.
Donald M. Medeiros Cranston, Rhode Island
You are indeed correct: The lower mount was omitted as just one of several measures intended to reduce the amount of vibration felt by the rider. Those measures included heavier bolton weights on the handlebar ends, built-in weights on the footpegs and the omission of the lower motor mount.
As an overall package, claims Suzuki, these steps reduced vibration just enough to make the Bandit acceptable to riders here in open-road-plentiful America, without any significant compromises in handling. In Canada and Europe, however, where rider priorities lean more toward secondary-road handling than interstate smoothness, distributors preferred to retain the mount.
Sources at Suzuki say that if you install the mount, you ’re likely to notice little difference. They claim the mount has less effect on vibration than the handlebar weights and the weighted footpegs; they also contend that any improvements in handling are perceptible only when the Bandit is either ridden on a racetrack, run at flat-out speeds like those possible on the German autobahn, or has its neck wrung at ten-tenths on twisty backroads.
Wee wiper
I got caught in a rainstorm during a recent ride on my Suzuki RF600, and I met up with a guy on a Kawasaki 600 who had a neat item I’d like to find. It was kind of like a short, windshieldwiper blade attached to a small rubber sleeve, and he could slip it over the thumb or forefinger of his left glove and use it to wipe the water off his faceshield, just like a windshield wiper on a car. This gadget had no name or markings on it, and all that the guy knew about it was that he had bought it at a swap meet in California. He let me use it briefly and I was impressed. Do you know where I can get one?
David Newsome Puyallup, Washington
Sure do. It’s called the Vee Wipe Squeegee and is available from Riderwearhouse (Eight South 18th Ave., Duluth, MN 55806-2148; 800/2221994) for $4.50 apiece.
