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.
EXHAUST FINISHES
I have been having quite a bit of trouble keeping my BSA’s flat black aftermarket headers from rusting. I’ve tried several different coatings, none of which proved to be satisfactory; all of them let the pipes rust again very quickly.
What is the porcelain type coating the Yamaha people use on their bikes, and will it work on mine? Also, my headers are single wall construction, while Yamaha uses a double wall to keep the outside surface cooler. Would this affect the material if applied to my pipes?
If this finish will work for me, or you know of another type, please let me know where to purchase it or who applies it commercially.
Wesley Lively
Gulfport, Miss.
The coating on the Yamaha pipes is a black chrome plate. While it’s more durable than anything you can apply with a spray can, it grays over time and use, and also scratches fairly easily. Finding a chrome plater who can plate black chrome can also be a problem, and when you do, you’ll find the process is expensive. A Southern California plating shop (Phil’s Custom Plating, 1214 W. First, Santa Ana, Calif, phone (714) 5470293) quoted a price around $175 to plate the exhaust system on your bike. The single wall construction of your exhaust system might lead to discoloration on the header pipe after hard running, but shouldn’t present any other problems.
After checking on the black chrome plating, we called Dennis Manning at Bub Enterprises (785 E. Brokaw Rd., San Jose, Calif. 95112, phone (408) 2982826) and asked about his experiences with exhaust system coatings. His company, like most other exhaust manufacturers, uses high temperature paint on its black exhaust systems. Manning said that the surface preparation of the pipes is the key to keeping the paint on. He recommended roughing the surface with 100 grit sandpaper and cleaning any oil residue off the pipes with lacquer thinner, MEK, acetone, or some other clean drying solvent. Before applying the paint, the pipe should be preheated to remove any moisture from the surface, either by heating it with a propane torch or by leaving it out in the sun if the weather permits. After the paint has
been applied, it will have to be cured or baked. To accomplish this, Manning recommends installing the exhaust system on the bike, running the engine until the exhaust system warms up, and then letting it cool off to room temperature. Following this procedure should give a fairly durable painted surface; Manning offered to repaint any exhaust pipes manufactured by his company for a $15 service charge if the paint comes off.
An alternative approach to painting the pipes yourself is to send them to Kal-Gard (16616 Shoenborn St., Sepulveda, Calif. 91343, phone (213) 894-3615) and have them painted with the same Kal-Gard coating used on the latest Kerker pipes. This particular coating is a more durable version of the Gun-Kote available in stores, and our experience with it on Kerker pipes is that it withstands normal abuse, but flakes off the head pipe if it’s severely overheated. We managed this by running an engine at fairly high rpm for 10 or 15 min. while synchronizing carburetors, which heated the head pipes far more than any riding condition where air is flowing over the pipes would. Kal-Gard charges about $35 for this service.
To complete the list of possible exhaust coatings, two other techniques should be considered. Bassani Mfg. (3726 E. Mir aloma, Anaheim, Calif. 92806, phone (714) 630-1821) has developed a coating they call plasma black. Aluminum is plasma-sprayed onto the exhaust system to a thickness of several thousandths of an inch. Onto this
corrosion-resistant white-colored layer normal high temperature black paint is sprayed. The plasma-sprayed aluminum is a standard industrial process to protect steel from corrosion, and the rough surface (equivalent to about 320 grit sandpaper) gives the paint something to grab onto. The only problem Bassani reports for this process is a tendency for the paint to gray on the head pipe, which can be cured by applying fresh paint. In any case, this black matte finish should eliminate rusting as a problem. Cost varies from $25 to $45 depending upon the complexity of the pipe, and as for the Kal-Gard coating, the price includes stripping the old finish.
The final coating that is in current use is the Sermetel coating on the Harley XLX and XR1000 exhaust systems. Harley adopted this coating after what the Harley engineers considered disappointing results with the black chrome used on the XLCR cafe racer. Sermetel is a company that supplies corrosion resistant coatings to the gas turbine industry for long lived aircraft and industrial engines; in this particular case they apply a two step coating to the Harley exhausts. The first layer is a solution containing aluminum powder which is chemically bonded to the exhaust jy.stem with a high temperature cure. This finish is a smooth, dull gray color; the second layer gives the flat black appearance. The engineer in charge of Sportster projects is reasonably satisfied with the Sermetel coating, but he mentions
that it is possible to scratch it. The only drawback to the Sermetel coating is that the company is not really set up to handle retail applications; they have a $150 minimum charge for coating services. If you're still interested, Sermetel’s main office is located on Limerick Road, Limerick, Pennsylvania 19468, and their phone number is (215) 948-5100.
TUBELESS TIRES ON TUBE-TYPE WHEELS?
I have a 1981 Suzuki GS1100EX which has mag-type wheels with tubetype tires. If I replace the valve stem with a tubeless type, can I run a tubeless tire on these rims? If not, please explain why.
Jan Miller
Wentworth, Wis
No, tubeless tires aren’t recommended for any wheels that don't have the special bead seat contour designed for tubeless operation. These wheels have been labeled by DOT requirement since the late 1970s with the designation TL (tubeless) or MT (motorcycle tubeless) next to the wheel size, and generally carry the caption “suitable for tubeless tires’’ stamped or cast into the wheel. The rim contour these wheels use holds the tire bead more securely in place than the old tube type rim contour. (This is definitely noticeable when you’re trying to break the bead for a tire change.) While people have run and continue to run tubeless tires on cast wheels machined to the tube type contour, there is less safety margin against leakage at the bead seat with this configuration, and the mere mention of this adaption makes tire company representatives (and their lawyers) very nervous.
A second reason for running tubeless tires only on tubeless wheels is the possibility of porosity leaks in the old style wheels. Because these wheels were never intended to be used without tubes, the manufacturers didn't make any special effort to make the rims absolutely air tight; there's a chance of slow (or occasionally even fast) air leaks when these wheels are used without tubes.
CARB CHANGES
Is it possible to change from the standard Bing carbs on BMW 800s and 1000s to the accelerator equipped DelFOrtos? I can find no one who knows.
I know BMW at one time fitted DelFOrtos as standard and I believe the BMW superbikes used them, so I assume there is real flow advantage that aids performance. There seems very little I can do to the Bings to gain power and* don't want to use Mikunis or Keihins. >
I would also like to know if it is true that cylinders on all BMWs will interchange. If so, does this mean the lOOOcc jugs can be put on the new R80ST? If so this could result in a 403 lb. lOOOcc Beemer—very interesting!
AÍ Stern
Dayton, Ohio
There are several suppliers of high performance equipment for BMWs, and we talked to one, RPM, run by ex-BMW superbike racer Reg Pridmore. They told us that the Dell'Orto carb swap is. practical, and that they offer kits including DelTOrto carbs and all necessary manifolding. Kits using the smaller Dell’Orto sizes (suitable for 650s and 750s) run just under $300, and kits with the large carbs go for $325. Not all BMW cylinders interchange, but RPM has built a few conversions much like the one you mention—in this case, lOOOcc R80GSs. Cylinders and pistons from a lOOOcc BMW are required, so the most basic version of t-his modification is going to cost over $600 if new parts are used. In exchange, according to RPM, you receive a very strong running, lightweight street bike.
If you’re still interested, we’d suggest you contact RPM, 1946 E. Thompson Blvd., Ventura, Calif. 93003, phone (805) 648-2895.
JUMP STARTS
While glancing through the Sept, issue of Cycle World, I read the letter from Lee Moore in the Service column, and would like to comment on some additional considerations if one should find it necessary to jump start a motorcycle. If conventional booster cables are used to connect the batteries just long enough to start the bike as you suggested in youf response, the risk of damaging the bike’s battery can be reduced by turning on the bike’s ignition and headlight before the final booster cable connection is made; this way, some of the current from the car’s battery that would otherwise have gone to the motorcycle battery will be diverted to the load. Better yet, if your
bike is equipped with a kick starter, you may want to make an emergency “jump start“ cable set to carry on your bike; a 12-15 ft. length of 18 or 20 gauge lamp cord with a cigar lighter plug at one end and the appropriate sized alligator clips at the other end will work well. Be sure the battery clips are properly colorcoded red and black and check for correct polarity with a test light or meter before attempting to use the cable set. The small gauge lamp cord will effectively limit the current from the car’s battery, but will provide sufficient current for the bike’s ignition, provided the kickstarter is used. Don’t expect this emergency cable to furnish the high current demanded by the starter motor, however.
The best way to minimize risk of damaging the bike’s battery when using conventional booster cables (capable of supplying enough current to power the starter) is to isolate the battery by disconnecting the battery cable from its ground terminal. The booster cable connected to the car battery’s ground terminal is connected to a good ground point on the motorcycle frame. The bike can then be started and warmed up for a minute or two from the car battery; finally, reconnect the bike’s ground cable while simultaneously disconnecting one of the booster cables. That will prevent the battery from seeing any excess current at all.
Don Bordenkircher
Houston, Texas
All the parts required to make the emergency jump start cable set could be found at a Radio Shack or other electrical supply store; it sounds like a good idea to us.
Speaking of jumper cables, last month we ran a list of three companies that manufacture and sell them. This month we can also add a fourth name to that list: Col. Fredrick Lutz, 3903 Tedrich Blvd., Fairfax, Virginia 22031. Col. Lutz’s cables are small enough to fit into a motorcycle tool kit, and sell for $9.95. ®
