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 as brief as possible. Send them to: “Service,” CYCLE WORLD, 1499 Monrovia Ave., Newport Beach, Calif. 92663.
INJECTING EXCITEMENT
After reading two articles on fuel injection in the September, 1980 Cycle World, I was curious to find out about converting my ’78 KZ1000ZIR. Initially I was considering turbocharging, but after reading several articles concerning overheating and the cost, I’ve changed my mind.
The fact of good gas mileage, morning starts without waiting an hour for warmup, and changing exhausts without reworking the carbs, sounds real good in favor of fuel injection. I do have a few questions: is there an aftermarket setup made, or would it be better to go stock Kawasaki as on the Classic? If possible, would you have an approximate cost on this conversion and do you think it would be advantageous?
Jeff Clemens Indianapolis, Ind.
The cost for Kawasaki to install fuel injection on a new motorcycle is much less than it is for you to install fuel injection on your present motorcycle. In the case of the KZ1000 Classic, it sold for about $504) more than the similar KZ1000 LTD. But Kawasaki didn’t have to pay more for the fuel injected bike’s different cylinder head, and in exchange for the electronic fuel injection pieces, Kawasaki didn’t have to buy carburetors. If you want to buy all the parts and install the Kawasaki system cm your motorcycle, better expect to pay at least $1000. There are no aftermarket systems we’re aware of. Now we’ll offer some advice. If you want a fuel injected motorcycle, you ’d be better off buying a KZ1000 LTD or the new GPzl 100. You wouldn’t be out any more money and you’d have a motorcycle that is designed just for the fuel injection. Kawasaki deserves a lot of credit for adapting the electronic fuel injection on its motorcycles and we wouldn’t want to tamper with one.
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HESITANT F
My 1980 Honda 750F, when not ridden for a few days, refuses to start. Doesn’t fire at all, unless 1 drain the float bowls. Then when 1 turn on the gas it starts right up, even in winter weather. My dealer blames it on poor gas, but I’ve added an octane booster and stabilizer and changed brands of gas, but it doesn’t help. Any ideas?
Kurt Kentner Endwell, N.Y.
If you don’t have water or other contamination in your gas, the trouble is probably sticky or gummed up needles and seats
in your float bowls. Remove the float bowls and floats from the bottoms of your carbs, taking care not to lose the float pins or bend the float arms, drop the needles out and unscrew the seats. If the tapered tips on the needles are worn at all, with a pronounced ring around the tip, the needles and seats should be replaced. If they appear to be in> good shape, clean them with denatured alcohol, lacquer thinner or contact cleaner and blow the seat orifices out with compressed air. Put everything back together and try it again.
If you find much foreign matter in the float bowls or needles and seats, it might be a good idea to drain your gas tank, remove the petcocks and wash the tank out, just to make sure you didn’t get a load of sludge and water with one of your fillups. We recently got a tankful that was ?bout 20 per* cent water and 5 percent unidentifiable debris while on a road trip with a test bike.
OIL ADDITIVES
I would like to use the additive STP in the crankcase of my Exciter I to increase lubrication and ease shifting. Can this additive cause clutch plate problems in cycles with wet clutch designs?
Ken Cone
Fort Collins, Colo.
An oil additive such as STP increases an oil’s viscosity. That is, it makes the oil thicker. If you have a motorcycle that’i worn out and is burning oil, a viscosity increaser can cut down on oil consumption. A 10w-40 multi grade oil should provide adequate lubrication for your motorcycle under any conditions you are likely to meet. Heavier weight oil can add drag to a disengaged wet clutch and make shifting harder when the engine is cold.
TOO TALL CL
My wife's '75 CL360 Honda is a bit too tall for her to feel comfortable with (read confident) at rest. Would shorter aftermarket shocks be a solution? In conjunction with this, could the fork tubes protrude above the triple clamp to lower the front? I'm somewhat concerned about fooling around with the steering geometry. If riding styles might influence your recommendation, 99 percent of the riding is on paved roads for short commutes or pleasure rising. (My pleasure more than hers!)
I'd also like to increase the range somewhat. Is a CB tank larger? Would it be a simple switch or would the seat require replacement also?
Dan Baker Pullman, Wasl^.
Shorter shocks and springs are the best solution to lowering the rear end, thougrL expensive. A cheaper, if less desirable, alternative is to install a set of shock lowering blocks. These are simply small metal bars that bolt to the bottom shock mount and extend the shock rearward an inch or two setting the shock into a more laid down position, thereby lowering the rear end. Lower* ing blocks are available at most wellstocked dealerships or cycle accessoryshops.
When the rear end is lowered, the front should he dropped a corresponding amount by loosening the triple clamp pinch bolts and sliding the fork tubes upward in the clamps. Measure the distance from the top shock bolt and the bottom of the steering head to the ground while the rider (your wife) is sitting with her weight on the bike. With the shorter shocks or lowering blocks installed, measure the distance from the rear shock mount to the ground (rider still on bike). If the rear end is lower by l in., slide the fork tubes upward in the triple clamps until the bottom of the steering head has also dropped l in. and tighten the pinch bolts.
Another possibility, though at the loss of some comfort, is to peel back the seat cover and cut away a I or 2 in. thick block of foam from the front h, T of the seat padding.
The CB360 ta at 2.7 gal., is 0.3 gal. larger than you, CL tank, which means about ¡5 extra n 'es per tankful. The CB tank is longer thi the CL’s and would interfere with the L seat. You can replace both seat and tar , but the small increase in range may not b worth the expense.
SOFT DT
The monoshock spring of my 1978 Yamaha DT125E is too soft, even with the preload adjusted to the firmest setting. According to all the dealers here, no stiffer springs are available from Yamaha. If this is true, is there any manufacturer that makes higher quality springs; if not, what is the part number of the stiftest Yamaha spring available? Also, is there any place I could get a higher quality air filter than the stock one?
Rick Stiehl
Waynesboro, Va.
White Bros, makes a long travel kit for the DTI25 monoshock, which increases rear suspension travel from just under 6 in. to 8 in. The kit comes with three spring options, soft, medium and heavy. You can install the entire kit, which retails for $44.95 and includes spring, collar, a larger shock eye and a preload ring, or you can merely install the> heavy duty spring from the kit and get stiffer suspension but no increase in travel. The spring alone sells for $32.95 and White Bros, recommends you use the 200 lb. “silver coded’’ spring. The cost of the spring includes a new collar. White Bros, address is 11611-M Salinaz Dr., Garden Grove, Calif. 92643, phone (714) 638-1653. Your dealer is right; Yamaha lists no spring options for the DTI25.
Check with D.G. for the air filter; 1170 Van Horne Rd., Anaheim, Calif. 92806, phone (714) 630-5471.
OILED FILTER
I own a ’78 Yamaha XS750E and I have been very satisfied with the cycle; however, what started as a few drops of oil coming from the airbox has turned into a loss of one quart every 400 to 500 mi. A good deal of the oil being blown out through the airbox ends up on the rear wheel, which is not a very comforting thought when I enter a left hand curve.
I take good care of the cycle, ride 65-70 mph and replace the Pennzoil 20W50 fourstroke motorcycle oil every 1500-2000 mi. The engine continues to run well at 20,000 mi. with compression at about 130-133 lb. which jumps up to 150 lb. with a squirt of oil in each cylinder. The local Yamaha dealer could not suggest a solution to my oil problem. Any help you can give me would be greatly appreciated.
Ronald E. Shortz
Gladwin, Mich.
The Yamaha XS750s are prone to blowing excess oil into their filters through the breather system if the crankcase is overfilled by even as much as half a quart. But as you haven’t had this problem, apparently, until recently it is more likely your engine has developed a blow-by problem. As piston rings wear combustion gasses push past the rings into the crankcase and create strong pressure fluctuations that tend to blow oil out the breather system. This blow-by further accelerates ring and cylinder bore wear by burning away cylinder wall lubrication. The 20 psi compression rise you are getting from oil on the rings indicates you have a fair amount of ring wear, so blow-by may be the cause of your oiled rear wheel. Sounds like it’s time for a new set of rings.
BMW DOUBLE PLUG TIP
I just read your April Service letter from a fellow with a 1977 R100RS BMW concerning the high octane fuel problem. I have a 1977 RS also and had the same problem finding high octane fuel. To solve the problem I first put jug gaskets on the cylinders to lower the compression. The result was a substantial loss in power and fuel economy. I called San Jose BMW in California for advice. >
Their suggestion was to drill the cylinder head to accommodate an additional spark plug per head and to buy an electronic ignition (cost about $ 1 30 for the head work and $198 for the ignition.) I decided to do the conversion myself and had a reputable local machine shop drill and tap the heads for less than half the cost. The addition of a Martek ignition and Martek Blue Goose coils (The coils are for a four cylinder bike) was a good combination.
I am now getting between 55 and 60 mpg on regular fuel and no pre-ignition, compared with 43 to 50 mpg with pre-ignition on high octane fuel as before. There is no substantial increase in power, but there is certainly no loss, and finding regular fuel is no problem.
There was an excellent two-part article by the BMW Motorcycle Owners Assn. (BMW MOA) about the conversion, which may be some help to those owners who are having this problem.
Michael Schnegelsberger Columbus, Ohio
TUBELESS WING
I’m considering a change to tubeless type tires at my next tire change for my 1979 Honda GL1000. My question is whether or not tubeless tires will work safely on the 1979 ComStar wheels. 1 have received conflicting advice from local dealers concerning the proposed swap. One dealer feels that the wheels will not properly retain the tubeless tire under certain conditions, allowing the tire to blow out between the rim and tire. Another dealer thinks the combination would work without problem. Neither dealer has first-hand knowledge of such an installation, however. Any light shed on my problem would be appreciated.
Tom Owen Douglasville, Ga.
There is a difference between Honda’s tubeless and tube type ComStars, the tubeless rims having a different bead angle than those on your GL. Also, the outer bead area on the tubeless rims is machined smooth for good sealing between the bead and rim, rather than grooved for tire retention. You may be able to get the tubeless tires to seal and hold air for a while on your tube-type rims, but using tubes and the right tires would be safer and more reliable. We'd stay with the tubes, unless you want to go to the trouble and expense of changing wheels. EH
