Service
SERVICE
Seca chain size
I own a beautiful Yamaha Seca 550 with a K&N Stage 3 intake kit and Kerkers. If I change the size of my drive chain will it extend chain life? My bike accepts a 530 O-ring chain. Would if be wise to put on a 630? If so, how could I go about getting the right sprockets?
T.J. Cioffi
Mayfield, New York
There seems little benefit from installing a No. 630 chain on your 550 Seca. Chain wear can result from two separate phenomenon: actual wear at the chain's pin joints, and plastic stretching of the chain links and bending of the pins. A 630 chain effectively withstands any stretching even under the most arduous dragstrip starts on a 130-horsepower machine; but so does a 530 chain on any but the most powerful of superbikes. The other
potential advantage of a 630 chain is that it simply has fewer pin joints to wear for a given chain length, but that's partially offset by the greater rotation and higher centrifugal loads of the heavier chain around its fewertoothed countershaft sprocket. In the end, we'd simply recommend a highquality 530 chain for your bike.
However readers interested in making this conversion can find complete kits carried byJ.C. Whitney, P.O. Box 8410, Chicago, Illinois 60680; (312) 431-6102.
Chain-drive mad Max
I have a few friends who drag-race motorcycles, and most say they pre fer chain drive to shaft. I was planning on buying a V-Max, so I’d like to know if changing the V-Max from shaft to chain would be easy, efficient or beneficial. Any ideas on approximate cost?
Juan Morris
S. Fallsburg, New York
No, it wouldn't be easy; the V-Max's transmission output shaft rotates the wrong direction for chain drive. Fixing that would be very difficult for someone without the resources of a motorcycle company behind him. It's unlikely that chain drive is substantially more efficient than shaft drive; though this is a point of dispute, we've never seen any original research that proves one or the other is significantly better at transmitting power. The biggest benefits of chain drive are its relatively light weight, its flexibility in final-drive gearing, and its reduced effects on rear-suspension action when compared to shaft drive. And if you could convert a V-Max to chain drive without spending thousands of dollars, you V/ surprise us.
Center of gravity
A friend of mine and I have a question about center of gravity affecting the lean angle of a motorcycle. Say we have two bikes that are identical except for the height of the center of gravity, and they are traveling around a corner of identical radius at the same speed. Will the bike with the lower center of gravity be more upright in the corner, or will the lean angles be the same?
In drag racing, tire spin seems to be a problem. Isn’t that sort of the opposite of tire lock? Couldn't something similar to anti-lock brakes be applied to tire spin? Of course, it could be turned off for burnouts.
John Willoughby Prairie Du Sac, Wisconsin
The effect of center-of gravity height is very counter-intuitive. If a bike were using tires as skinny as knife edges (so the tire contact patch wouldn 7 move outward as you lean), center of gravity height would have no effect on lean
angle. Both a top-heavy bike and one with a low center of gravity would lean the same amount. But with real-world tires, where lean moves the contact patch out from the tire center line, the bike with the lower center of gravity must lean further. To understand that, consider that the true lean angle (from the motorcycle's point of view) is between the contact patch and the center of gravity. The higher the center of gravity, the less any movement of the contact patch has on that angle. So for a given corner and speed, a bike with typically wide tires and a tow center of gravity must lean farther than a topheavy bike with narrow tires.
And you're quite right that some type of electronic anti-wheelspin device is a possibility. Such devices are offered by several European car manufacturers (Volvo and Mercedes, for two), and can use several different control strategies to prevent tire spin. For example, it 's possible to counteract wheel spin by automatically modulating the throttle, clutch or fuel injection, or even by applying some braking force to the spinning wheel. Such .ST.Vterns may be seen on motorcycles soon after anti-lock brakes become common.
CX cam puzzle
What happened to the CX? In the September, 1986, Service column it is stated that the Honda CX500 and 650 have cam chains, yet in the January, 1987 Cycle World Moto Trivia, answer Number 20 states the CX line employs pushrods? Huh?
Joe Endres Madison, Wisconsin
Not to worry—the CXs have both cam chains and pushrods, just like most American V-Eight car engines. The cam nestles in the V between the cylinders, and is driven by a short chain. The cam in turn actuates the valves through short pushrods (about 4 inches or so) and rocker arms.
Hotrod Suzuki with mirrors?
In your March, 1987, issue you had Jay Gleason trying to break into the nine-second quarter-mile bracket on a 900 Eliminator, a VMax, and a GSX-R 1 100. On the VMax, the turnsignals and mirrors were taken off, and on the Eliminator the mirrors were removed. The GSX-R ran a 9.52-second quarter mile at 142.9 mph, using the NHRA correction chart. Why were the mirrors and turnsignals left on the big 1 100? Wouldn’t the E.T. have dropped without them on?
Jeff Barnhart
Greencastle, Pennsylvania
You got us. Perhaps all we can do is quote Ralph Waldo Emerson being snarky: “Foolish consistency is the hobgoblin of little minds. " We removed the mirrors from the other two bikes because it was an easy thing to do, and took the turnsignals off of the V-Max simply because it looked so much meaner without them. As “Into the Nines " wasn 7 a true comparison of these three machines' capabilities (instead, it used them as examples of possible configurations), we didn 7 worry if their setups weren 7 exactly equal.
We've been told by Suzuki engineers, however, that the mirrors and turnsignals on a GSX-R cost two to three miles an hour in top speed; so their removal would certainly have improved both E. T and terminal speed.
Fried PE pistons
I own a 1982 Suzuki PE 175 that I have also tried to use as a dualpurpose bike. After 2 or 3 miles at around 60 mph on the highway, the piston burned away on the top edge of the exhaust-port side.
One shop told me that dirt must have done this, while another person told me that the cheap two-stroke outboard motor oil I was using was the cause, and that something like Yamalube R or Bel-Ray MCI would have protected things.
Can I expect to be able to ride this bike on the streets with a clean air filter and quality two-stroke oil?
Chris
Ridgewood, New Jersey
The most likely cause of your burnt piston is neither dirt nor your choice of oil. Instead, your PE probably suffered from detonation (pinging) from either too much ignition advance or too lean a mixture. We'd suggest you make sure that your ignition timing is set to Suzuki's specification, or even slightly retarded from that, and also that you take some sparkplug readings to see if your carb is jetted and adjusted properly. Perhaps your jetting needs to be slightly richer.
If all else fails and you still hear your PE pinging on the road, the addition of an extra cylinder-base gasket would reduce the engine's compression ratio, and likely solve your problem. ®
