Service

SERVICE

Paul Dean

Quest for clean air

I own a 1995 BMW R100GS and am in search of a K&N air filter element that will fit in the stock airbox. I’ve had no luck in locating one, and when I called K&N, they told me they had no listing for any R100 model of 1990 or newer. I find it perplexing that K&N makes air filters for bikes like a 1985 Cagiva Elefant or a 1955 BMW R500 or a 1971 Honda SL70 but does not have something for my bike. I am accustomed to rejection, but only from women.

Vincent J.VaIdes Lemont, Illinois

I’m wholly unqualified to diagnose your problem with the opposite sex, but I can help you chase down the correct filter element. The people at K&N were very apologetic about their inability to locate a filter for your bike when you called, explain-

ing that, for reasons unknown, their listings for later R100-series BMWs had not been updated. But we were able to track down the correct filter by starting with the stock BMW part number, then using a cross-reference chart K&N has compiled. Our local BMW dealer says the number for the

stock filter is 1372-1337-080. According to the cross-reference chart, that corresponds to K&N filter number BM-0300. This is the same filter used by all 1980-and-later R65, R80 and R100 models, including the R100GS, which was replaced by the R1100GS for the 1996 model year.

XS-ive drag

I have a 1981 Yamaha XS650 Special that has a seemingly unresolvable clutch-disengagement problem: I must take it out of gear before coming to a stop, not afterward. I have tried two different clutch-plate sets, and replaced

the cable and the left-side nylon disengagement mechanisms. Yes, the ball that contacts the pushrod in the center is there, and the clutch basket is not worn and does not have excessive play. I’ve bought new clutch springs which, according to three dealers, are the right

length at IV2 inches, but my Chilton manual says they should be 13/s inches long. I have owned many motorcycles in 37 years of riding and this one is a fun commuter, so I don’t want to abandon it. Lewis G. Pattison Moriah, New York

There are numerous possible explanations for this problem, one of which is the length of the clutch springs. My XS650 shop manuals all say that the correct unloaded length is 34.6mm, which is, for all intents and purposes, 1 Vs inches. So, the IV2inch springs you currently are using may be coil-binding before the pressure plate can be pushed far enough to release completely. Also, the outer clutch hub (the basket) rides on a bushing between the hub and the transmission mainshaft, and there ’s a needle-type thrust bearing between the outer hub and the inner hub. If for any reason, there is excessive friction between the bushing and the shaft, or between the inner and outer hubs via the needle bearing, the resultant drag on the mainshaft will make shifting into neutral difficult any time the engine is running.

You also need to ensure that the clutch lever and its attendant lever perch are the correct ones for your XS650. Many levers and perches of that era look exactly the same but have different pivot-to-cable centers.

If the center-to-center distance on your lever is shorter than what is intended for the XS650, the clutch pushrod will not be moved far enough to effect complete clutch disengagement.

Softail serenade

My 1995 Harley-Davidson Softail Custom is making a strange noise. Every time I hit a big bump when I’m riding alone, or hit anything bigger than a medium-sized bump with my 105-pound girlfriend on the back, the bike makes a strange squawking noise. I’ve tried bouncing up and down on the bike in the shop with someone listening closely, but it doesn’t make any noise then; it only does it when the bike is moving. Is something binding in the suspension or what? Dale Dyer Burlington, North Carolina

The noise you ’re hearing is the top run of the drive belt hitting the inside of the inner primary case as the suspension nears full compression. Usually, this occurs when the belt has too much slack, and in all likelihood, the noise happens more often when your Softail is on trailing throttle rather than accelerating. On trailing throttle, all the slack in the belt is on the upper run, which allows it to bow upward and more easily hit the inner primary.

Adjust the belt so there is between 5/i6and 3/8-inch of freeplav midway between the pulleys and the noise should go away. Unless, of course, your Softail has been lowered, in which case you may have to live with the squawk. You can minimize the noise-as well as reduce wear and tear on the belt-by occasionally spraying the outside of the belt with silicone.

But they wear like iron

I recently brought my 1977 Suzuki GS750 over from England, where it had been sitting in a garage for 10 years. Any thoughts on how the engine will work on unleaded gasoline? Also, the tires are 11 -year-old Metzelers that have extremely low mileage. The rubber looks to be in great shape, but I would like to know if there is any recommended time limit to the life of a tire. SUPWICK Posted on America Online

According to American Suzuki, your GS750 will have no problem coping with unleaded fuel. Leadfree gasoline was available even in the mid-Seventies, and Suzuki took such fuel into account when engineering things like the valve seats and valve faces on its four-stroke engines back then.

As far as your 11-year-old Metzeler tires are concerned, though, junk ’em. Unless your GS750 has been stored in a hermetically sealed or climatically controlled environment, the tires have probably gotten as hard as bowling balls, even if they haven't dry-rotted. Spring for a new set; today ’s tires are better anyway.