Service

SERVICE

We welcome your technical questions and comments, and will publish those we think are of interest to our readers. Because of the volume of mail received, we cannot return any personal replies. Please limit your "Service" letters to technical subjects only, and keep them a~s brief as possible. Send them to: "Service," CYCLE WORLD, 1499 Monrovia Ave., Newport Beach, Calif 92663.

CX, GL INTERCHANGE

In the Jan., 1981, issue of CW detailed reference was made regarding the 1981 Honda GL500 and GL5001 motorcycles. My only regret with my own CX500 Custom is the small gas tank capacity and uncomfortable seat over long distances. Thus an alternative to relinquishing my otherwise faithful steed and the possible purchase of a replacement comes to mind. Can the GL500’s large capacity gas tank and wide seat (and for that matter, the top box) be interchanged or fitted onto my 1979 CX500 Custom’s chassis?

Michael David Peck Houston, Tex.

Honda tells us the Pro-Link chassis on the GL500s is a completely new design with different attachment points for tank, seat, etc. and no effort was made to standardize brackets or mountings between models. They say the GL seat and top box will not fit at all, while the tank could possibly be made to fit with some modification, but they doubt it. Your best bet is probably to go for a seat and the larger tank off an early Standard or Deluxe CX, which would give you a little more of the range and comfort you are looking for.

GS450 CARB AID

While reading through your January is sue, I noticed your article about a carb fix for the Suzuki GS450. I'd just like to pass on to you that Yamaha's Exhaust Gas Analyser (EGA) will fix your carb prob~ lems. The Suzy's Mikuni carb is just like the Yamaha's, and the plugs for the fuel screws can be removed with a factory plug tool, the jets adjusted accurately, and the plugs replaced with Yamaha's replace ment plugs. This lean hesitation has been a common problem, but easily fixed wit~ the EGA. I've fixed many Kawasakis, Suzukis and some Hondas with this ma chine. All you have to do is locate a Ya maha shop and for about $25 you can have your carbs fixed, still within the EPA's regulation.

Wayne Katsura Service Manager Sunshine Yamaha Morgan City, La.

STAR QUALITY

My Bell Star helmet was made in June $f 1977 and I bought it in 1978. I have never dropped it and have kept it waxed.

■ How long can I expect good protection with this helmet?

Bob Seim

Hopkins, Minn.

Bell tells us that unless a helmet is crashed or similarly mistreated there is no reduction in protective capability with age. A 1968 TX500, for instance, will pass the 1968 Snell standards with no problem if the helmet has been used normally. Bell will not warranty components if the helmet >is more than 4 years old because constant use can cause liners, foam padding, etc. to wear out, but the outer fiberglass shell and the energy-absorbing styrofoam liner do not degenerate with age.

There are only three good reasons you might eventually consider replacing your ¿Star. One is if you crash with it and sustain an impact to the helmet; the helmet is considered an expendable item in a crash, designed to absorb the trauma that would btherwise have been dealt out to your skull. Another reason is wear. Unlike the outer shell and the styrofoam liner, the rubber foam comfort padding inside the helmet will deteriorate and compress slightly from age and perspiration. The rubber foam has no effect on the helmet’s ability to absorb crash energy, but when the foam is worn out the helmet may not fit as comfortably or snugly as it did when new. The third reason is the possible introduction of new helmet models which meet updated Snell standards.

GS1100 HANDLING

How can I modify my GS1100 Suzuki so it will handle as well or better than a Honda 750F? Both bikes’ specs are remarkably similar (i.e., rake trail, wheelbase, weight) so I don’t see why the Honda should be so much better. Would strengthening the frame help? Shocks? Fork springs? Weight reduction? Are there any aftermarket frames available—would GS1000 aftermarket frame fit the 11QÍ) motor?

Volker DegethoSi,

Calgary, Alberta The Suzuki GS1100 and the Hondcr 750F are both excellent handling bikes, and we can’t think of any real handling problems inherent in the GS1100 design. The GS suspension, however, does offer tremendous range of adjustment in damping and preload for both front and rear. We’ve found that too little damping at ther end can give the bike a vague, slightly wallowy feel in corners, and too much damped spring preload can reduce suspension compliance. Try setting your pressure in the front forks at 7.1 psi, front and rear damping adjustments at number 3 notch of their 4 settings, and dÿjil in a moderate amount of preload on springs. If you still have a handling problem there may be something else wrong; wheel alignment, worn tires, etc. With suspension properly adjusted, high quality tires will probably make the most notice■*able improvement in the GS1100’s handling, and no other modification should necessary unless you are building the bike as a race project.

BMW COMPRESSION

I own a 1977 BMW R100RS and it ha~ a compression ratio of 9.5:1. I would like any information on how to lower the com~ pression ratio so I can run it on regul~r leaded fuel. The only high octane fuel you can buy now is unleaded and my bike needs the lead. Can I buy and install thicker head gaskets from BMW or any other company? Or would I be able to in stall two head gaskets, one on top of the other, to simulate a thicker head gasket? Simon Langmea~ Port Alberni, B.C.

The easiest way to lower compression o~ the BMWs is to change the cylinder bas gaskets rather than head gaskets. Th higher compression S and RS model~ came from the factory with no base gas kets, so the addition of one on either sk! will lower compression for reduced deto nation. If pinging problems persist a sec ond base gasket may be added under eaci barrel; also true for those models that al ready have one base gasket installed at th factory. Part number on the base gasket available from your BMW dealer 1! 11-11-1-335-650, and the list price pe gasket is $3.75. If you want to lower th~ compression to about 8.2:1 but don't wan to use two gaskets (with their extra oppor tunity for oil leaks) you can also buy a lo~i compression base gasket, part numbe~ 11-11-1257-092, which was intended f~ the R75 and R60 and a number of earlie~ models, but willfit the RI 00 series bikes i you cut about 2mm of material away fron the inside bore circumference for pisto? clearance. List price is $5 per gasket.

HAWK REARSETS

I am writing to inquire if you could sup ply the name of a company which could supply a set of 400 Honda Hawk Til foot pegs that are standard equipment in Eu rope. Those that came standard on my `78 Hawk are about 1-2 in. too far forward. Evan Thompson Anderson, md.

So far, the only Hawk rearsets we knc~ of are available from Ontario Motor Tech Corp., on special order from Japan at th un-low price of$150. If you are still inter ested, you can write Ontario Motor Tech at 6850 Vine/and Ave., Unit 16, NortJ Hollywood, Calif. 91605, phone (213 766-7101.

XL TIRES, SUSPENSION

I own a 1980 Honda XL185S which pends most of its time in the dirt. My problem is that in this area we have an *erabundance of sand and whoops. The ;tock Honda tires are worthless in the ;and. Since the bike spends very little time n the road, do you think I'd be better off Funning knobbies? Also, do you know of ny good replacement shocks? Does any ne have a fork kit on the market to in ease fork travel?

Pat Rush Myrtle Beach, S.C.

The best replacement tires for your bike or strictly sand and off-road use would be set of knobbies, though they may give ou reduced roadholding on pavement, es Pecially in the rain, and they may be illegal or highway use in your state. Trials tires re still best for all-around use, but for the vpe of terrain you describe we've had very ood luck with Metzeler knobbies. They hould give you better handling, traction nd improved steering stability in sand nd on other loose surfaces. The only dis dvantage is that the tread will evaporate retty fast if you also do a lot of pavement (ding.

Works Performance Products, 8730 hirley Ave., Northridge, Calif 91324, ?13) 701-1010, can put together a high erformance spring and shock combina on for your bike if you write or call and ive them your weight and describe the `pe of riding you plan to do. The less ex ensive non-gas, non-reservoir shock will robably work best on a bike the size of the `L185S; we haven't been able to fade one n lighter bikes. Cost will be from $125 to 149.95, depending on what springs are sed.

Al Baker Racing and Development 6878 Santa Fe Ave., No. E., Hesperia~ Calif. 92345, (714) 244-5425, makes fork modification kit for the XLI85S. Fo, $39.95 you get springs, washers, a drill bi~ to drill your fork rod, fork oil, complet2 instructions, and even sandpaper to clew out the drill bit. The kit provides 9 in. oj fork travel.

MANUAL TRANSMISSION

I recently bought the very fine Hond2 XR200 ( your test for it was correct i~ every respect). My problem is that I can'l find a workshop manual in Greece (th owner's manual is not adequate for seriow work). Would you be kind enough to in• form me if there is a commercially avail able workshop manual and how I might obtain it, or must I write to Honda i~ Janan and to what address?

Aristides Kostaki~ Athens, Greece

We've had as much trouble locating shop manual for the XR200 as you have~ Neither Clymer Publications nor Hayne.~ Publications, the two big shop manuai publishers, has one in stock yet, thougt~ Haynes says a manual is in the works an~ will be available by the end of 1981. Hay nes address is 861 Lawrence Dr., Newburj Park, Calif 91320, if you want to hold ou~ and write them later in the year. Honda~ own factory manual for the XR200 is no~ out yet, but is also due sometime withi, the next year. Your best hope of findin~ one may be to check back with your near est Honda dealer periodically until th book becomes available.

CX REVS

I would like to know if you have an: information on how I can reduce the rpn to mph ratio on my CX500C. It turns at screaming 5000 rpm at 56 mph. I believ it would have plenty of power, get bette gas mileage, and would definitely increas engine life by about 30 percent if it turne about 3500 rpm at 55 mph. I realize that i would be easy if I had a chain drive bike. have thought of changing to an 18 in. rea wheel such as that on the standan CX500, but because of the difference i: tire size it has almost the same overa] height as my 5.10-16 in. rear tire.

Changing the gear ratio in the transmis sion or the drive shaft seems like my on!: choice, but I am afraid this would be quit~ a job. If you have any information on ho'v difficult or expensive this would be, pleas let me know

David L. Milk Hawesville, K~

We had heard rumors that the 198~ GL500 Silver Wing would be comin~ hrough with a slightly higher (numer ally lower) final drive ratio, but prelimi iary specs from Honda show final drive nd transmission gearing identical to that n the CXs. Without that option, we can't -h~nk of any other way to lower your cruis ng rpm. However, the change in gearing vou suggest is not something we would rec )mmend, even if it were possible. The X500 motor makes most of its power at he high end of the rev band and can han le its 10,000 rpm red/me with no prob !eçi. At 5000 rpm the engine is turning at nly half redline, which is a pace it can i,aintain with excellent reliability while till providing some roll-on power. Cruis at 3500 rpm, the engine would need lownshifting into its powerband for pass g, slight upgrades and most acceleration. ?~cause of the size of the engine and its nigh power curve the CX engine is actually under less mechanical stress at 5000 rpm than it would be lugging down around 4500 rpm on the highway. Very low engine peeds under load are hard on bottom end omponents and cam chains.

Also, lower cruising rpm on midsized to iall engines does not always improve fuel mileage because larger throttle open rngs are needed to maintain road speed and the engine is running less efficiently. A Honda 400F owned by one of our staff for i,1~stance, gained about 5 mpg on the high way when it was geared down two teeth on tihe countershaft sprocket. The CX500 en gine is a smooth, reliable powerplant and )j~3L~ needn't fear revving it.

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