Service

SERVICE

Paul Dean

Katana katastrophe

I have a ’93 Suzuki Katana 600 that has 19,000 miles on it. Eight months ago, the idle began to fluctuate more and more frequently until the engine finally stopped running altogether. It has not run since then. I had the engine completely rebuilt to restore compression, and also had the carbs cleaned and synched, and the black box tested, but the engine still would not run. I then bought a 1997 Katana 600 engine and had it installed, but it wouldn’t run, either. It backfired a couple of times but wouldn’t start. All of this leads me to believe that my original engine was not worn out and that something else is wrong with the bike. The local mechanics do not have a clue as to what might be the problem. Your thoughts would be appreciated. Scott M. Paul Knoxville, Tennessee

Based on the information in your letter, I can’t help but reach a few conclusions. First, the people who have worked on your bike thus far are not just clueless; they re so unforgivably incompetent that you should never again allow one of them to lay a wrench on it. Anyone who is incapable of figuring out why an engine won’t run might be many things, but a “mechanic ” isn’t one of them. And anyone who claims that they synchronized the carbs on an engine that won’t run is a liar. Second, whatever was wrong with your Katana in the first place did not warrant a complete engine

rebuild followed by an engine swap. Third, it’s very likely that the original problem still exists, and that other problems have been introduced through the ignorance of the people who have worked on the bike. Finally, the chain of events you describe tells me that you ’re really not a mechanic, either, so there is no point in me attempting to walk you through what would be a complicated diagnosis of the bike’s unwillingness to run. Your Katana desperately needs the attention of a competent mechanic, especially considering that it may have been butchered by the inept.

So, although you’ve already spent way too much money on this problem, you need to find a good, qualified Suzuki technician. If you’ve only dealt with the Suzuki dealerships closest to your home, you may have to go out of town for better service. More often than not, really good mechanics are somehow involved in racing, so I suggest you attend a local club roadrace and question some of the better Suzuki riders about which shop or mechanic does their work. There are plenty of mechanics in and around Knoxville who can fix your Katana, and your challenge now is to find one of them.

EFI brain-teasers

I just bought a new Honda RC51. I’ve had many bikes during my 25 years of riding, but never one with fuel-injection. Two questions, then: 1) To check the mileage of the bike (whether on the odometer or the tripmeter), I have to turn on the ignition, thus priming the cylinders. Does this affect the engine in any way if I do not actually start it afterward? And 2) I am told that fuel-injected bikes do not require a choke/enrichener, but it appears that the RC51 has the latter. Do I really need it? MSgt. Jeffrey M. “Sparky” Machosek Posted on www.cycleworld.com

When you turn on the ignition of a fuelinjected motorcycle, you do not “prime the cylinders, “ as you put it; any sounds you hear are simply those of the electric fuel pump pressurizing the fuel system. The injectors do not squirt any fuel into the intake manifold until the starter button is depressed and the engine begins to turn over. So, you could switch the ignition on and off all day without

ever starting the engine, and the worst thing that’s likely to happen is that sooner or later, the battery will go dead.

As far as your second question is concerned, you are correct: Fuel-injected bikes do not need a manually operated choke or cold-start enrichener. On most injection systems, the information provided by one or more of the system ’s various sensors tells the engine-control module that the engine is cold, and the ECM automatically adjusts both the mixture and the idle speed to compensate.

The fuel-injection systems on all automobiles and some motorcycles work in this manner, but certain bike systems do not. BMW’s system, for example, automatically adjusts the mixture for cold starts, but the rider must operate a manual lever to raise the idle speed during warmup. On the RC51, the system neither adjusts the mixture for cold starting nor raises idle speed; the rider must manually operate the “choke ’’ lever. This opens two plunger valves that, like the enrichener systems on many modern car-

buretors, pass enough additional fuel to allow the engine to start and idle at a higher rpm than usual.

Honda apparently chose this design for simplicity and dependability, knowing that many RC51s would be turned into racebikes and thus have their fuelinjection programming altered. A manual cold-start system ensures that the engine will always start quickly and easily no matter how the engine or injection system might end up getting modified for competition.

Not ’N Sync

I have a 1992 Kawasaki KZ1000 Police Special that I ride regularly. I recently replaced the needle and seat in all four carburetors, along with the fuel valve, and I synchronized the carbs. Now the engine starts fine, runs smoothly on the road and has good power in general, but there are a few problems: 1) To start the bike, I have to open the choke to its first notch and leave it there until the engine is warm, and the rpm remains at 3000 the entire time. 2) Since doing the work, the engine has no power from idle to 2000 rpm. I used to be able to let the clutch out at 1000 rpm and the bike would start to move, but now it stalls immediately unless I keep the revs over 2000 when starting from a dead stop. 3) When I shift gears, the revs do not drop. That is, if I rev the engine to 3000 or 3500 and pull in the clutch with no throttle, the revs either stay at 30003500 or drop very slowly. 4) After the engine is warm, it sounds like a tank when it idles. It makes kind of a metallic noise. If I give it just a touch of throttle, the noise quiets down. Also, I re-synchronized the carburetors and checked to be sure that the throttle was working properly. Any ideas?

John D. Porter Posted on www.cycleworld.com

All the symptoms indicate that the carburetors are not properly synchronized, despite your insistence that they are. The lack of low-rpm power stems from the fact that some of the carbs are lagging, preventing their respective cylinders from doing their share of the work. Same goes for the failure of the revs to drop when you shift gears; the imbalance between carbs gives the engine a reluctance to rev up from idle; then, once it reaches a certain

rpm, that imbalance makes it hang there when the throttle is closed. And the metallic noise the engine makes at idle is yet more proof that the carbs are not properly synched. Carburetor imbalance makes an engine’s idle speed fluctuate dramatically from one cylinder to another, and that variation causes the clutch plates to rattle backand-forth in the clutch basket and the primary drive gears to bang off of one another as the crankshaft quickly and repeatedly speeds up and slows down.

You didn’t explain the procedure or equipment used in your synchronization efforts, so I can’t tell you why your attempts failed. All I can tell you is that they did, and that the aforementioned symptoms should vanish once all four carbs are performing equally.

Diaphragm dysfunction

I’m having a problem with the 1998 Harley-Davidson Softail Springer I’ve owned since it was new. The bike sat unused for almost a year while I worked outside the country, and when I returned recently, it started and ran well except for a tendency to idle erratically. I suspected that something in the carburetor had gotten plugged

up while I was away, so I took it off the bike, disassembled it and found some crud in the float bowl. I cleaned everything and blew out the jets, then reassembled the carb and reinstalled it. Now the engine idles just fine but won’t rev high enough to let the bike go more than 30 or 35 mph in high gear. By the way, the bike is 100 percent stock, including the carb. Can you offer any suggestions? D.J. Conifer, Jr.

Odessa, Texas

I suspect that during your reassembly of the carburetor, you accidentally pinched the neoprene diaphragm that attaches to the top of the throttle slide. The Keihin carb used by H-D is a typical CV (constant velocity) unit on which a twistgripcontrolled butterfly valve in the throat of the carb regulates the amount of air that passes through the venturi; and the slide, which is controlled by the pressure differential between the area above the diaphragm and the area below it, regulates the amount of fuel that is mixed with the air. When the throttle is opened, that pressure differential causes the slide to rise accordingly, thereby metering the requisite amount of fuel into the air stream. But if the diaphragm has a hole in it or part of it has gotten caught between the top of the carb and the carb body, the slide will rise either too little or not at all. This /flCsCflt5 such an obstruction to airflow through the arb that the engine will not rev very high. Either replace or free up the diaphragm and your Springer will run normally once again.

"RR" means rattle, rattle

I have a 2000 Honda CBR929RR, which is just as awesome as your tests of it have claimed. But it does have a problem I’ve not seen addressed in any of the articles I have read about the bike: It has a rattle between 5000 and 5500 rpm that supposedly is caused by the Honda Titanium Exhaust Valve (HTEV). When this distinct rattling noise first occurred, I thought something was loose in the airbox. But my Honda dealer told me that it is caused by the HTEY and that the noise travels up the bike and sounds like it is coming from under the gas tank. He said that he discussed this problem with the Honda service reps, who confirmed the noise’s source and claimed there is nothing that can be done about it. I was wondering if you have ever heard of this problem or if you think I should get a second opinion from another dealer. The 929 is really impressive, but at 5500 rpm (my typical commuting rpm), the noise tends to be annoying. Bobby Akin

Tulsa, Oklahoma

Your dealer spoke the truth: The rattle is caused by the HTEV, and there indeed is nothing that Honda can do about it. The company claims this noise is perfectly normal for a CBR929RR and is not an indication of any problems.

For those of you who may not know, the HTEV is a pivoting valve in the exhaust collector that helps broaden the powerband by altering the exhaust tuning according to engine rpm. Honda’s engineers were concerned about the extremely high exhaust-gas temperatures that could cause problems with the bushings in which the valve pivots, so they chose to use special carbon bushings that have an exceptionally high resistance to heat. The only compromise is that when these bushings reach normal operating temperatures, they expand enough to allow a small amount offreeplay in the valve’s pivot mechanism. The normal pulsing action of the exhaust then tends to make the valve move very slightly in the bushings, causing the rattle. It would appear, then, that unless you replace the entire exhaust system with one from the aftermarket, you ’ll have to live with the rattle.

M. Madlen's Suzuki

I own a 2000 Suzuki SV650. I love the bike, but it has one annoying problem: From just off idle to about 5000 rpm, the engine seems to surge up and down if I hold it at a steady throttle opening. From 5000 rpm on up, the surging goes away. Will a jet kit and an aftermarket pipe cure the problem or should I take the bike to my local dealer to inspect?

Michael Madien Posted on America Online

The surging you describe is caused by a lean fuel mixture at smaller throttle openings. This condition results from the extremely lean carburetor jetting needed for the SV650 to meet the EPA ’s current emissions standards. Quite a few latemodel motorcycles, especially those in the middle to lower displacement ranges, suffer from this same condition. Installing an aftermarket pipe will not cure this problem; matter of fact, depending upon which one you choose, a pipe may even make the surging worse. But whether or not you switch to another exhaust system, a jet kit definitely will help the surging. If a half-decent tuner does the work, the problem should disappear altogether. □

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