Service

SERVICE

Paul Dean

Where there's smoke...

I recently purchased a 1997 Yamaha YZF1000R with 4000 miles on it. I decided to change the oil and filter myself~ but I inadvertently overfilled the engine and didn't discover my mistake until the bike started smok ing. I immediately drained the oil to the proper level, but the smoking con tinues. I even checked to see if any oil got blown into the airbox. None did, but smoke still comes out of the pipe. It smokes when I roll off the throttle and when I get back on the throttle after slowing down. Do you have any suggestions as to what the problem might be and if it will be expensive to correct? Eric D. Mabry Goodman, Mississippi

You have omitted afew key pieces of information: 1) How much excess oil you put in the crankcase; 2) how long you ran the engine before you noticed the smoking and drained the oversup ply of oil; and 3) how far you have ridden the bike since draining the excess. If you overfihled the engine by a small amount-say, less than a quart-and only rode the bike a few miles before discovering your error, there should be no permanent damage. If that is the case, and f you have not ridden very far since, the smoke you are seeing now is most likely just the burn-off of oil that accumulated in the exhaust system. But if you added more than a quart and then rode for quite a while before draining the excess, the cylin der walls may have gotten glazed, pre venting the rings from sealing properly and causing the smoking you report.

Keep riding the bike and see if the oil consumption gradually tapers off to nothing. If it does, everything is okay, if it doesn `1', yes, you will be facing a fairly expensive top-end repair.

Gas tank symphonics

I own a 1992 Honda VFR75O that has an audible buzz between 4000 and 5000 rpm. It sounds like there's something loose under the tank but I can't find anything wrong. Got any suggestions? David Petrozza West Mifflin, Pennsylvania

If you've checked thoroughly to en sure that no wiring connectors or hose clamps are touching the underside of the tank, the problem is most likely with the tank mounts. The front mount involves a large, U-shaped rubber cushion, and the rear uses a rubberisolated mounting bolt. If either of these rubber pieces is missing, dam aged or badly worn, the tank could vi brate as you describe. There also are two small rubber cushions between the bottom outside edges of the tank and the side rails of the perimeter frame at about the tank s' midpoint. If either of these cushions is missing, the tank could make contact with the frame and vibrate at certain rpm.

If the mounting system is not the culprit, perhaps some part of the fuelgauge float assembly inside the tank has fallen off and is rattling against the bottom. And it is not beyond the realm of possibility that a piece of hardware-a bolt, nut or washer-has inadvertently fallen into the tank and is causing the buzz. Keep looking; you `11 eventually find the cause.

Getting the gum out

I have a 1985 Yamaha. The engine will start, but when you apply throttle it stalls out. The bike was in storage for several years and the gas tank was drained during storage. Don Camacho Pleasant Prairie, Wisconsin

I suspect that although the gas tank was drained, the float bowls in the carbs were not, and the main jets have gotten clogged as a result. When gaso line evaporates over a long period, it leaves behind a sticky "varnish" that can gum up any small or~flces that are submerged in the gas. The pilot jet, which affects idling and starting, oflen doesn `t gum up because of its rather high location in the float bowl, once a small amount of gas has evaporated, the jet is no longer submerged and so may not necessarily clog. But the main jet, which affects all throttle positions above idle, is positioned at the vcui bottom of the bowl; so, it remains sub merged until virtually all of the fuel has evaporated, allowing enough time for quite a lot of residue to form.

The fix is easi': Remove the float bowls and clean or replace all the jets.

Pipe dreams

On my 1980 Honda CR250, the ex haust pipe broke at its narrowest point. The Honda dealer tried to order a new pipe but says they are no longer avail able. The dealer also says the pipe can't be welded because the metal is too thin. Is there any way I can cobble up an exhaust system? Carol Stoll Muskegon, Michigan

Don `t believe the dealer. The pipe was welded at the factory, and there `s no reason it can `t be welded again, thin metal or not. It might require a patch of some sort in the area of the damage, but it definitely can be re paired. Take the pipe to a good weld ing shop in your area; they `11 either fix it themselves or direct you to someone who can.

Dipstickally correct

I want to inquire why Paul Dean doesn't correct himself when he gives incorrect information. In a recent Ser vice column, he advised that to check the oil level in all Japanese motorcy cles that have dipsticks, the correct method is to insert the dipstick to the top of the threads but not to screw it in. This is not correct for my 1972 Kawasaki 750 H2, the owner's manual of which says the correct method is to screw the dipstick all the way in. I sus pect this same method would apply to all of the H, S and KH series of motor cycles manufactured by Kawasaki be tween 1969 and 1977. Brian Furman Kingston, New York

You are incorrect in assuming that I wish not to be correct. But you are cor rect in your observation that my infor mation about Japanese-bike dipsticks was incorrect when it comes to those Kawasakis. I stand corrected.