Service
Service
DOUBLE-CLUTCH? AVGAS AND ETHANOL BEST USED BIKE ASK KEVIN HOT DIAVEL
RAY NIERLICH
With motorcycles, the best way to reduce wear on gears and dogs is to shift smoothly. Roll-off the throttle on upshifts; blip it when going down.
BUR DOWNSHIFTS?
When I learned to ride dirt bikes in the mid-1970s, an experienced buddy taught me that the correct technique for downshifting was to blip the throttle before releasing the clutch during downshifts, which he called "double clutching." I have been using this technique for 40 years now on all my motorcycles, and I notice quite a few other riders do it as well. I reason that this makes downshifting smoother, but lately I've started to question the possible consequences, such as increased wear on gear dogs.
My 1987 Honda Magna has begun slipping out of second gear, and I've read online that rounded off gear dogs is the likely cause. This is apparently a fairly common transmission problem with that era of Honda street bikes. Do you think that my double clutching practice may have caused or accelerated the gear wear? I'm also wondering if there is any real value to blipping the throttle during downshifts (besides sounding cool) and what are the other potential negative effects?
ROYSON PARSONS CYCLEWORLD.COM
Not your fault; you ride 'em, you break 'em. When shifting up, or down, the best practice is to attempt to match the differing speeds of the rotating bits and reduce loading as much as possible to minimize clash between said components. A true double clutch is when the clutch is briefly reengaged, in neutral, before selecting the next gear. This is impossible to do with a sequential shifting gearbox as fitted to all motorcycles. We do what we can by reducing throttle on upshifts and blipping the throttle on downshifts. Practice smoothness when shifting to minimize wear. If it feels good and sounds good, it is good.
ODE TO AVGAS
As the owner of several older u motorcycles and a few pieces of * gas-powered lawn equipment, I find myself constantly fighting the effects of ethanol in today’s pump gas. My solution has been to pick up some
low-lead avgas from my local airport.
It has a long shelf life, doesn’t absorb water, and allows my almost-40-yearold BMW to run better. All my smaller engines start and run without the annual rebuilding of the carburetors.
A few well-respected shop owners and tech gurus I’ve talked to pooh-pooh the idea because of the illegality of it and the lead content, but for me, “The proof is in the pudding.” Yesterday, I pulled my old Kawasaki KLX250 out of the shed. It probably hasn’t been ridden more than 10 miles in 15 years, but it started on the second kick and ran flawlessly. Also, the original plastic gas tank mysteriously developed cracks after only two years, probably because of the ethanol. I know that Big Brother is probably reading this note, but I would appreciate your comments on the matter.
JOHN MORCAN
HOCKESSIN, DE
A a About 50-plus-year-old 10 years ago, avgas some from B stored WWII-era bombers and transports was drained and sold for use! That avgas was slightly different from the current too lowlead avgas, but any will last in storage almost indefinitely in a dry climate.
The problem is the lead in the fuel.
The EPA doesn’t want millions of Americans using leaded fuel daily in their Escalades. The only reason pistonengine aircraft are still allowed to use it is they haven’t found anything else that works. Evidently having fuel boil off at altitude isn’t a desirable trait.
The ethanol pump fuel that has been foisted on us has many bad side effects, including being absorbed by most plastics (sorry, Ducati owners). There was a huge uproar when the first boaters to use it had their fiberglass fuel tanks dissolve and it glued their engines together. Try to find and use nonethanol fuel. Marinas have to have it for boat use. Failing that, use fuel stabilizers all the time. Drain the mower tank and carb dry for storage. Maybe if enough people vote with their pocketbooks, we can put this whole ethanol nightmare behind us.
GOT A MECHANICAL OR TECHNICAL PROBLEM with your beloved ride? Perhaps we can help. Contact us at cwservice@cycleworld.com with your questions. We cannot guarantee a reply to every inquiry.
MORE ETHANOL LOVE
I live in Nebraska, and ethanol fuel is sold at every gas station. I try to go to stations that have regular unleaded fuel without ethanol, but sometimes out on the road in this part of the US, ethanol is the only fuel available. Are there any fuel additives you would suggest for my injected 2009 Kawasaki Vulcan to keep the fuel injectors clean and prevent carbon buildup?
"NEBRASKA MIKE" SIMON CYCLEWORLD.COM
A Ethanol bites, but if your bike (or car/truck/tractor) has EFI and is B in regular use, the side effects aren’t usually noticeable. Ethanol does lots of bad things, but fuel-injector deposits and carbon buildup aren’t even on the radar. The most common problems are corrosion and varnish deposits in the fuel system, primarily the rusting/dissolving of the fuel tank, and varnish in carburetors and on inlet valve stems. These bad effects stem from how quickly it evaporates, how easily it absorbs moisture from the atmosphere, and the phase separation it goes through after as little as six months. Try to find non-ethanol fuel. Write your congressman. If stuck with ethanol, run your tank all the way empty before storing for the winter. Failing that, fill it to the brim with stabilizer in it. Any of the brand-name fuel stabilizers sold for ethanol will help negate the bad side effects.
SWEET SISTER
My sister passed away a year ago. " She left me her 2001 Kawasaki B ZR750S. I would dearly love to take it for an occasional ride for sentimental reasons. The problem is that my 29-inch inseam isn't compatible with the seat height. I’ve checked the Internet and haven’t been able to find any aftermarket lowering kits. Any suggestions would be appreciated. What do you think of cutting the rear spring down to reduce the preload?
jIM SARCE
LAKE ORION, Ml
A Why isn’t my sister that cool? First, I don’t advocate lowering this or any other streetbike, especially wide ones with four-cylinder inline engines. Wear proper boots and slide that butt off the seat! Valentino Rossi can still do it; so can you. But if you must: Buy some Muzzy or Soupy lowering links for the rear and raise the fork tubes in the triple clamps a bit. The kickstand will need shortening to match. Don’t take any passengers on a ride. Don’t have a beer and forget you went and lowered it. Do put a warning label in big letters across the gas tank for your unsuspecting buddy when you loan it to him.
ASK KEVIN
AN EARLES FORK? NOT!
QBPlease let Technical Editor ■ Kevin Cameron do more technical editing. I’m sure he would have corrected the erroneous labeling of the Creeves leading-link fork in “Motocross Memories” (July) as an “Earles” fork. The Earles patent of 1953 specifies a link pivot behind the wheel, which clearly is not the case with the Creeves. BMW and MV Agusta licensed the Earles design, but Creeves did not.
MICHAEL MOORE SAN FRANCISCO, CA
A People have gotten into the ■ habit of calling any leadinglink motorcycle fork an Earles fork. It is clear, as ourcorrespondent points out, that in section 35 of his patent Earles specified a link pivot behind the wheel. Best therefore to use the generic “leading-link fork.”
Many leading-link forks have been used. Among them, those used on some postwar BMWs (pivot behind the wheel), 1950s Moto Cuzzi CP bikes (short links), and on Honda’s first Isle of Man TT entry, the 125 twin of 1959 (also short links). The weakness of all such forks is the difficulty of providing adequate resistance to side-to-side tilting of the front wheel. The usual attempt was to either put the pivot behind the wheel as Earles did, in effect using a forward-pointing swingarm, or, if the links were short, to continue the links rearward to form a U-shape behind the tire. This U-shaped affair can be seen in the photo on page 62 of our July issue (and also above).
The English have always had a thing about constant wheelbase, as seen in the patent. Hmm, let’s check to see what kind of fork is used in World Superbike, MotoCP, British Superbike, etc. Oh, my, the use of the telescopic fork appears universal, even though such forks are notorious for wheelbase change.
In the later 1940s and early 1950s, there was justifiable dislike of telescopic forks in certain circles, mainly because of their flexibility and lack of stiffness. Cilera went so far as to make for their four-cylinder racers a single steel weldment of upper and lower steering crowns to more strongly hold the two fork tubes parallel under stress. Anyone who has familiarity with British teles of the 1950s and even ’60s knows that you can hold the front wheel between your knees and turn the handlebars a considerable distance either way-and when you release the bars, much of this deflection will remain! —Kevin Cameron
TO REMAP OR NOT?
QI " some have time been about wondering when an for engine modification requires remapping of the computer. This of course applies to modern EFI bikes. For example, I installed Yoshimura slip-on exhausts and a K&N air filter on my 2008 Hayabusa (exhaust manifold and catalyst unchanged), and it runs fine. I assumed the computer, which monitors a number of engine parameters, would make the appropriate changes to the fuel mixture, timing, etc. to keep the engine running well. I realize this approach has its limits, but it seems like engine modifications that are not major, like the ones I made, should be accommodated by the computer. Maybe another way of asking the question is what sort of modifications require remapping?
BOB GILES ESCONDIDO, CA
Alt really depends on the particular bike and expectations of the owner. If it runs well by the seat of your pants, it isn’t all that far off from optimum. It might not have been very optimum stock. Now as far as your bike being the underpowered, poorly built, and engineered wimpy thing it is: It probably never sees super highcombustion temps or WFO throttle for sustained periods (if you still have your license). If your motor wasn’t quite as bulletproof (read: air-cooled) or was of lesser capacity, it would have to work
harder and might be more likely to see exhaust valve and seat longevity issues resulting from the higher exhaust temps.
When you ask a manufacturer rep this question, any modification requires a remap. But they have to say this to please their corporate bosses (lawyers). In the real world, I’m betting south of 50 percent of modifications get a proper remap. If a modern EFI bike has few, if any, noticeable drivability problems before a minor modification, such as a slip-on pipe or air filter upgrade for example, it most likely will still run well and longer than any reasonable expectation of the average owner. If the bike’s EFI incorporates an oxygen sensor for feedback, odds are it will have a wider ability to compensate for mixture changes from modifications.
HOTTER THAN HELL DIAVEL
My 2013 Ducati Diavel " temperature indicator goes off * scale in stop-and-go congested traffic and simply reads “HOT” without
warning me to stop and/or to turn the engine off. Can you please give me your thoughts on this situation? I did pass this question to the Ducati mechanic without really getting a satisfactory answer.
WALID C. ASSAF BEIRUT, LEBANON
It’s up to you to know to stop and turn the poor thing off. Serious dmage can and will be done if this scenario is ongoing. Ducati had a service bulletin regarding stuck thermostats on this model. This should be the first thing checked. If still under the Ducati twoyear warranty, you’re covered. If you are slightly out on time, they may goodwill some or all of the repair. Ducati also had an issue with coolant a few years ago. The coolant was formulated too strong and will corrode right through the water jacket into the exhaust port. Look in the coolant reservoir window. If the coolant is blue, it is bad. Change and flush the coolant thoroughly ASAP. If it’s pink, it is the newer spec stuff and is okay.
