Service

SERVICE

Len Vucci

. . . BY THE HORNS

The letter entitled “Horns of a Dilemma" in your November issue prompted me to write an alternative method. When I installed a pair of Fiamm horns on my Suzuki GS400, I used a different approach which is much simpler and cheaper.

Use the mounting brackets provided, but enlarge the mounting holes with a drill. Put a rubber grommet in the enlarged hole (to insulate the horn from the bracket) and install the bracket to the horn using plastic washers. It can then be connected to the existing wiring.

Dan David Van Nuys, Calif.

The horn relay fix we suggested may have been considered by some to be a case of overengineering— O K.

Your suggestion is indeed a good one. We'd guess a reader's choice between the two would depend on whether he's an electrophyte or a mechanophvte.

Thanks much for your fix.

STEP-THROUGH HELP

I recently bought a 1965 or ’66 Honda step-through 50 automatic. I’ve looked all over for parts but have had no luck. Specifically. I need a throttle slide, needle, spring and cover, and a set of rings.

I feel it's a shame to waste a motorcycle just because of a lack of minor parts. Help!

Mark Harrington 1030 N. Maple Ave.

Toms River, N.J. 08753

We're including your complete address in hopes that someone out there in the Garden State has parts for your little flower.

SOUND ADVICE

1 own a 1976 Yamaha RD400 which I am very happy with, but would like to know how to improve its sight and sound. What would you recommend doing so that I'm not the only one on the road who can hear my horn?

Also, is it feasible to hook up a quartzhalogen car headlight to my Yammy?

P. Dickens

Nova Scotia. Canada

Any 12-volt automotive-type horn can be mounted to your RD; about the loudest > we’ve come across is the dual-Fiamm setup on late BM Ws. Electrical hook up will vary between different footers, depending upon whether the horn has a single terminal, or two, as does the stocker. Installation tips can he gleaned from the horn letter elsewhere in this column.

An automotive bright-light is an even easier swap than the horns. Any 7-in. QH or sealed-beam reflector will fit with no modifications to mounts or electrical connections.

You should first consult local regulations on the legality of such a change, however, as it may be illegal. Several manufacturers produce units which are approved in some U.S. states for motorcycle use, and make the conversion both bright and right.

RD PIPES

I am the very proud owner of a stock RD350B. Where might I ñnd a set of expansion chambers for my Yamaha?

Barry Vassar Neqaunee. Mich.

A number of manufacturers build pipes for the RD—check through their advertisements for pertinent info.

For a first-hand test and evaluation of DG Performance pipes (and heads), read the RD350 hop up article elsewhere in this issue.

RL + TM = RM?

Is it possible to adapt a 1974 Suzuki R.L250 engine to a ’74 TM 125 frame? The trials engine would offer reliabilitv and the TM frame would give good handling and stability. The main reason I am looking for stability is the trials frame is infamous for shaking its head at speed, which recently caused me to crash, resulting in a broken collarbone.

Tom Run von Buttzville. N.J.

We receive many letters asking advice on engine/frame swaps, but because we rarely undertake such projects, we can offer only opinions.

Yes. It is possible to install an RL engine into a TM frame; if one is ambitious enough, virtually any en fine could be shoehorned in. But be prepared, as easy-looking swaps often turn into nightmares, both mechanically and financially.

If you were happy with the handling of the TM/TM, you’ll probably like the RL/ TM. But you'd most likely be better off if you sell what you have and use the money toward purchase of a later-model bike.

SHOCKING

For those of us who don’t relate well to shock absorber curves, how about including an overlay showing the curve relationship of the test shock to that elusive “perfect” shock. This way. the reader would learn not only what’s wrong with a>

component, hut what’s right about it also.

Lee Damuth West Harford, Conn.

Difficult though it was, we resisted the urge to print a truly shocking “perfect" curve.

As for a perfect shock curve, that's a bit harder to express. Just the varied riding st yles of our readers would negate the value of such a curve for all but a select few. Throw in other variables such as terrain and you have a perfect curve which is, for most readers, perfectly useless.

Your idea is a sound one. Its execution, however, is impossibly complex. We print the curves mainly for information purposes, so a reader can compare one shock's (or fork's) action to that of another, with both under controlled conditions. Any modifications we feel to be worthwhile are then stated either in the text or under the component graphs.

FRONT-END DIVE

My 1975 Yamaha RD200 is a fun little bike until it comes to a stop. Even though I apply the brakes evenly and as gradually as the situation allows, the bike dives down and forward. 1 bought the bike new in June of 1977 and it only has about 600 miles on it. 1 am smaller than the average rider (4'11", 110 lb.). Could mv size be related to the diving? What adjustments do you recommend? I would appreciate your help before I flv over the handlebars.

Nina Shoshana Franconia, N.H. PS: How about more women test riding bikes and equipment! We need suitable gear too!

Some nose dive is normal, and is caused by forward weight transfer during braking. All other things being equal, the amount of weight transfer increases with the rider's weight. In other words, the bike's front end should dive less with you aboard than with a heavier rider.

The bike's low mileage indicates the fork springs are probably in good shape, so the problem is most likely one of damping. Have the fork oil checked for volume and viscosity, or drain the legs and replenish them with 15 or 20 wt. oil.

The Kawasaki KZ200 in our February issue was tested b y a female. It's a start.

continued on page 144

TT500 LIGHTS

I own a '76 Yamaha TT500 and would like some information pertaining to its lighting system

Upon installing a Preston Petty headlight (6v 30 watt) and a 6v 2‘/3 cp taillight I began blowing taillight bulbs. Drawing upon my experience on Triumphs and Nortons I installed a 50 watt 8.2 volt Zener diode to limit voltage. The diode made the installation of a ‘/2-wave rectifier necessary.

This setup provides adequate head and taillights. The brakelight works fine, but only if the headlight is not on. When the brake lights are on the headlight output drops to a low flicker.

I realize my problem is available power. The only information I can get is that my lighting coil's output is 6v AC at 2500 rpm.

I would very much appreciate any information along the same lines as the PE250 lighting article in your August '77 issue. I know there are many TT500 owners awaiting your reply.

Steven Silverman Albuquerque. N.M.

A bright fix, similar to the one used on the PE250, was applied to Test Editor Ron Griewe’s TT500 raced in Baja. Like the PE, there are several methods which can be applied to the TT’s magneto to boost its output. The article is in the works right now, and should be appearing in C W within next couple of months.

HONDA 750 STEERING

I have a 1976 Honda 750F. I am not totally satisfied with the way it handles. It takes more effort to lean it over than I think it should, it doesn't like to change directions once into a turn, and it always feels like it wants to go straight.

Would raising the fork tubes a little above the triple clamps or changing the size of one of the tires help?

Randy Purrett Lyons, Colo.

Raising the fork tubes—lowering the bike’s front end, actually—will hasten the steering. Effective steering head angle will be steeper than the original 28 deg., and trail will be less. Because of the altered geometry, however, straight-line stability will be reduced. Your E may have a tendency toward the dreaded “speed wobble’’, if the change is severe enough, so a certain amount of caution is advised.

Installing a smaller front tire will have a similar eff ect, but is not very practical; the reduced traction and load capacity could pose additional risks. Swapping the stock rear rubber for a large grabber will produce a slight decrease in effective head angle, but probably not enough to be effective. EU