Service

SERVISE

Paul Dean

All screwed up

I'm trying to do a mild restoration of an old Honda CL 175, and I'm having trouble with buggered-up enginecase screws. Before I bought the bike, someone completely rounded out the Phillips heads on most of the screws. Not only do I not have a clue about how to get them out, but everything I try just messes them up even more. Do you know of any way of removing rounded-out screws that won't damage the engine cases in the process?

Ed Padua Irving, Texas

I use tuv similar methods for dealing with screws that hare chewed-up heads; both involve the use of a chisel, and both are surprisingly easy and f fective. Most of the time, I `e removed such screws by cutting a slot all the way across the remains qf the damaged head with a good, sharp chiseL I make the slot just wide enough and deep enough that a straight-blade screwdriver it'iIltit snug/v in the slot, then I simpli use an impact driver fitted ii'ith a straight-blade tip to loosen the screu' in U normal fashion.

Itt/ia! technique cloesn `t %`ork, find a smaller chisel that s' not quite as sharp.

Then, in the outer edge of the damaged screw head, cut a shallovi' notch that extends out%i'ard from the center of the head. Once the notch is deep enough to give the chisel reason able p urch a,s~e, continue tapping on it while gradually reangling the chisel so that the force of the blows is trying to rotate the screw counterclockwise. If you tap the hammer hard enough to slowly move the screw, but not so hard that you continue deepening the groove, the screw will gradually begin turning counterclockwise. Then continue tapping the chisel until the screw is completely loose.

Radian in drag

I own a 1989 Yamaha Radian 600. I am very pleased with the bike but have not been able to equal the quarter-mile performance (12.10 seconds at 108.88 mph) listed in the Radian test in your May, 1989, issue. The best run I've been able to post was a 13.57 at 98.77 mph at Cordova, Illinois. I don't have a wheelie bar, so I take off under 2000 rpm.

Now, my bike has 26,000 miles on it, but doesn't burn any oil. I have just had the valves adjusted, and the bike has a Dynojet Stage II jet kit, a Kerker 4-into-l and new clutch plates. I also play around with different sprockets and use a Dyno-shift light. We both know that on paper, 1.5 seconds looks small, but on the track, it looks like someone waving to you as they go flying by. I hope you can help me.

Ryan Johnson Rock Falls, Illinois

The greater part of this E. T. discrepancy is the direct result of your launching technique. Coming off the line at under 2000 rpm on a high-revving bike such as the Radian will cause the engine to bog severely; and until it can pull itself back up into the torquier part of the rpm range-above 5000 or 6000 rpm-your bike accelerates a lot more slowly than it should, all while the clock is ticking.

When our rider launched the Radian at the dragstrip back in 1989, he used a much higher rpm—somewhere up around 6000—and he slipped the clutch enough to prevent a wheelie while allowing the revs to stay up in that higher rpm range. Proper clutch modulation during launches is a precise technique that requires a lot of practice-and often burns up a few sets of clutch plates while you 're learning-but is necessary for anyone who hopes to extract the best E.T.s from any motorcycle.

There also are other factors that could have significant effects on your bike's quarter-mile times. The 26,000 miles on the engine mean that the cam chain has probably stretched enough to retard the cam timing. What's more, if you've not performed a leak-down test on the engine, you don 't know if it has anywhere near as much compression as it did when new. And our runs were made at a dragstrip that is just a few feet above sea level, whereas the strip you mention in Illinois is at a higher altitude. When you combine the effects of all those factors, a 1.5-second slower E. T. is easy to explain.

What's a V worth?

Metzeler makes some front and rear sport-touring tires that use the very same tread design in both H (130 mph) and V (150 mph) speed ratings. Obvi ously, no one gets to ride a streetbike or drive a car for sustained periods at either of those speed levels. So, the speed ratings are of incidental impor tance, although they do suggest differ ing levels of structural strength in regard to carcass, ability to dissipate heat, etc. But to a motorcyclist, trac tion is of utmost importance. There fore the question: Can one assume that in selecting the higher speed rat ing from any given tire manufacturer, one is also selecting a higher level of adhesion, with the same tread design, of course?

Carl J. Kotheimer Hudson, Ohio

No, one cannot make that assumption, because the tires in question use the very same rubber compound for both the Hand the V-rated versions. The V-rated tire may provide a slightly stiffer ride due to small differences in carcass construction necessary to let it achieve the higher speed rating, but the average rider may not even notice those differences. And for street use, both tires offer the same levels of cornering and stopping adhesion, even though the H-rated tire is generally a few bucks cheaper.

In the end, the deciding factors are use and application. If you own a big and/or very fast bike, and you ride it for long periods (at least an hour) at sustained high speeds of more than 130 mph (not likely unless you do your sport-touring on the high banks of Daytona), all while approaching the tires ' maximum load capacities, the Vrated hoops are an absolute must. But if you ride at lower, more reasonable speeds, the H-rated tires will get the job done just as well.

Constipated jets

Just recently, I bought a '92 Suzuki RMX250 that had been sitting unused in a garage for almost three years. To my amazement, it only took a tank of fresh gas and a half-dozen kicks to get it started, and after it sputtered and smoked for a minute or two, it cleared out and seemed to run normally. But the first time I ran it fairly hard on a fast trail, the piston seized. The owner said it ran perfectly before he parked it, and it appeared to be running fine until it seized. Got any suggestions?

any David Fitch Glasgow, Kentucky

Unless the "tank of fresh gas" you mentioned did not include the recom mended proportion of two-stoke oil, a clogged main jet is the most probable cause of the seizure. When a bike sits for a long time, the volatile elements in the fuel gradually evaporate and leave behind a varnish-like residue that can plug the fuel jets. The main jet in your RMX is likely obstructed by this type of contamination, but only very slightly, evidenced by the fact that the engine ran normally until it seized. But the orifices in jets are so small that even the tiniest ob struction has the very same effect as reducing the jet size, which would make the fuel-air mixture too lean.

This is why, after an engine has not run for long periods, you should remove the float bowl and clean everything inside, especially the jets, before running the engine. Some people try to clean clogged jets by poking a strand of fine wire through the holes, but you have to be careful when doing so not to enlarge or score the orifice. The safest method is simply to replace them.

Conical is not comical

I work at the local Harley shop and we have had a few 1997 H-D models with the same oil-consumption condition addressed in your April Service' column ("Smokey the unbearable"). The problem was caused by conical cylinder bores-/.e., a .005-inch variation from top to bottom. We sent the defective parts to Harley, and they sent us replacements and paid for the labor to install them. Alfred Tyo

Alfred Tyo Bay City, Michigan

Thanks a lot for the input, Alfred. We 'll pass the information along to the letter 's author, Mr. Velto. □