Service
SERVICE
Paul Dean
Battling the rattling
In the June, 2001, issue, you answered a letter from the owner of a 2000 Honda CBR929RR (“‘RR’ means rattle, rattle”) that was making a loud rattling noise at 5000 to 5500 rpm, and you told him that the noise was caused by the bushings in the Honda Titanium Exhaust Valve (HTEV). Well, I have a 2001 Honda CBR600F4Í, and I’m wondering if it also has one of those valves, because it is making a similar rattling noise. It’s loudest around 5000-5500 rpm and seems to be getting worse. The bike only has 3500 miles on it, but the noise is louder now than it was 1000 miles ago. Any suggestions? My dealer is clueless. Dan Feeney
Palmdale, California
No, the F4i does not have an HTEV system or anything similar, so the noise obviously is not originating there. But take some solace in the knowledge that you re not alone; I 've gotten letters from other CBR600F4Í owners complaining of the same rattling sound—and of their dealers ’ inability to find its cause.
I talked to several key people at American Honda about this noise, and they all claimed to know nothing about it. They said the company has issued no service bulletins regarding such a problem, but that the symptoms described by you and the others point to a problem with the camchain or its tensioner. They recommended that you take your bike
back to your Honda dealer for diagnosis and have them call American Honda ’s tech people if they need help in diagnosing the problem. If you still don 't get any satisfaction, contact Honda ’s Customer Relations Department (310/783-3000) directly.
Like a little whine, sir?
The tires on my ’98 Yamaha YZF600R were recently replaced. In order to remove the front wheel, the mechanic had to detach the brake calipers from the fork, but left them supported and connected to the brake lines. Now that the bike is back together, the front brake has a high-pitched whine under light braking pressure. Brake feel, smoothness and stopping power is as before; only the noise is different. The whine does not occur during hard braking and only happens when I’m using the front brakes. I’ve checked the caliper bolts and the rotor bolts for tightness, and checked pad fit and thickness. The bike has 17,000 miles on it and the rotors show no signs of abnormal wear. I would appreciate any help you could offer. S. Butts
Posted on www.cycleworld.com
A couple of abnormal conditions could have resulted from the removal and reinstallation of the calipers and wheel. But first, understand that many bikes with ventilated rotors emit a whirring sound during light braking due to interaction between the pads and the holes or slots in the rotors. The noise is more prevalent on certain bikes and with somepad/rotor combinations, but it ’s not uncommon.
When the mechanic reinstalled the calipers on your YZF, he might not have gotten them positioned exactly as they were before their removal, due to the fact that the caliper-mounting bolts are not a snug fit in their respective holes. Though very small, that clearance can allow the caliper’s alignment, relative to the rotor, to be altered just enough that the rotor then wipes across the surface of the pads in a slightly different path than before. That mating of somewhat unfamiliar surfaces can cause a whirring sound, just as new brake pads sometimes do until they are fully bedded-in. It’s also possible that the mechanic inadvertently scored one or both rotors while handling the wheel. I’ve often seen careless tire-changers scuff brake rotors either through misuse of tire tools or by flopping the wheel around on a concrete floor.
If the whirring is caused by the aforementioned shift in caliper alignment, it will gradually go away with use. If it is due to scratches or gouges in the rotor, it probably will remain until those marks are removed. In either case, I don’t think the noise is anything to lose sleep over.
Dog day afternoon
I very much would like to know what it is about motorcycles that makes dogs so mad. Incidentally, I ride a 1987 Honda XL600R that still is in mint condition.
Alan Spencer
Santiago, Chile
Did you ever notice that dogs only get mad at bikes that are being ridden, not bikes that are parked? Evidently, they ’re mad because they want to ride but can’t; their legs aren’t long enough, and they have trouble working the clutch. Hey, if you doubt this, put a dog on your XL and see for yourself.
Just forkin' around
When I started riding-too many years ago-most bikes still had girder forks. Then, around World War II, telescopic forks made their appearance in Great Britain, where I was brought up. Until I left G.B. in the Sixties, those first forks had the upper tube going down over the lower tube. Somewhere along the way, this got reversed, and forks with the upper tube going inside the lower tube became the standard for decades. Then the original, upper-tube-over-lower style returned on many motorcycles and is called the “reverse” or “upside-down” fork. Why is this, and what advantages, if any, does one have over the other? Colin Ford
Crestón, BC, Canada
Actually, the vast majority of those early telescopic forks did not have larger-diameter upper tubes sliding over smaller lower tubes. They may have appeared so, but their large upper sections were just sheetmetal dust shields or beauty covers; the real fork tubes inside them were of smaller diameter and slid up and down inside the larger lower tubes. In later years, the outer covers were disposed of on many models, leaving parts of those small-diameter upper tubes either fully exposed or covered with rubber gaiters. Then, in the 1980s, the “upside-down” fork debuted, so named because it reversed the traditional arrangement, with large upper tubes sliding over smaller lower tubes. This “inverted” design is still used today on many competition-oriented off-road and high-performance onroad models.
The primary advantage of the upsidedown fork over the conventional style is rigidity. Large-diameter upper tubes offer considerably greater clamping area for the triple-clamps, which helps make the fork much more resistant to side-to-side twisting under the severe loads of fast cornering or rough terrain. But inverted forks are more expensive to manufacture, and they also complicate certain aspects of front-end design. The brake calipers and front fender, for example, are located far from their closest possible mounting points, which are down toward the axle rather than nearer the tops of the lower slider legs as on conventional forks.
Cold medicine needed
I have a 1990 Honda CBR1000F that has approximately 35,000 miles on it. I love the bike. I’ve done all of the maintenance myself, and it runs great. My only complaint is that it occasionally is reluctant to start when cold. If it sits in the garage when the outside temperature is 60 degrees or below, it cranks for a while and then usually starts. If it sits outside overnight (such as at a motel) and the temperature is 60 degrees or below, it sometimes will crank until the battery goes dead. The Honda dealer told me the problem is the carburetion, so I completely disassembled and cleaned the carbs-twice. But the problem still occasionally happens. 1 checked the charging system with a voltmeter and it is working just fine, and 1 have replaced the battery twice. I’ll take any advice you might offer.
Andy Krumm Bakersfield, California
When faced with a cold start, your CBR 's engine either is getting too little fuel or too weak of a spark. Since its reluctance to start seems roughly proportionate to the drop in temperature, mvfirst tendency is to agree with the dealer and speculate that the problem is somehow linked to the carburetion.
Next time the engine fails to start cranking for about five seconds with cold-start enricheners (the “choke ”) the full-on position, remove one of the sparkplugs and inspect it for the presence of fuel. If the plug is perfectly dry\ the problem is in the enrichener circuits, which are failing to er the necessary> extra fuel the intake tract. The first thi to check is the adjustment of the cable and linkage that operate the enricheners to ensure that all four are being fully opened you pull the choke knob all the If they indeed are opening to the max, you 'll then have to remove the carbs and closely inspect the enrichener circuits to determine why they aren 't working-although the odds of all four malfunctioning at once are astronomical. It’s far more likely that either they were not assembled correctly during a rebuild or the linkage is i
If the sparkplug is wet, the culprit is most probably a weak spark. If the plugs have not been replaced during these fits of hard starting, install a new set. But if that’s not the cure, the problem could reside in any one of several ignition system components, such as the pulse generator, the ignition control module and the coils themselves. The shop manual describes a series of tests that can be performed on these components with a volt/amp/ohmmeter; I suggest you either buy a manual and a meter and conduct those tests yourself or take the bike to a Honda shop and have them do it. With a bit of logical troubleshooting, you should be able to track down this cold-starting problem.
IIOMESREWS
In response to Jay Miller’s December, 2001, letter about squealing disc brakes, I’ve found a cure using fat pencil leads that are about 1/i6-inch in diameter. Drill three or four holes in the pad material in a random pattern across the width of the surface that contacts the rotor. Drill most of the way through the pad, but not into the backing plate. Then insert the leads into the holes and cut them off flush with the pad surface. I suggest first drilling a few test holes in a piece of wood with different-size bits until you find one that allows the lead to slide into the hole snugly, with no sideplay. With this modification, a tiny amount of the graphite is released between each pad and rotor every time I use the brakes, which kills the noise, especially with metallic pads. I’ve noticed no reduction in brake performance, either; everything seems to work properly, but without the screeching. rcgonzal
Posted on America Online
Things that go “clunk”
After a few days of inactivity, my 1988 Yamaha FZR400 makes a mechanical clunk in the right engine case when I attempt to start it, after which the starter fails to turn the engine. Pushing the bike in gear, turning the crankshaft with a wrench or blipping the starter button several times seems to free it up and allow it to start readily. Nothing has been found on inspection of the electrical system, starter, idler gears or starter clutch. It never fails to start once warmed up, and it runs well enough to win races on the track. All my friends have heard this problem, but no one seems to know why it occurs or how to fix it. Any ideas? Andrew Currie Edmonton, Alberta, Canada
line indeed are in good condition, your FZR is probably experiencing “hydraulic lock.” This is a condition caused by at least one of the curb float needles not sealing properly, allowing fuel to leak into its respective cylinder when the bike sits for a while. A liquid can 't be compressed, so if the amount of fuel that accumulates in the cylinder is greater than the volume of the combustion chamber at Top Dead Center, that cylinder’s piston will be stopped cold before it can reach TDC. Once the fuel is under pressure from the piston, it begins seeping past the rings and valves; thus, turning the engine slowly and gradually-as you do with a wrench or by bumping the starter motor or pushing the bike in gear-helps bleed off enough fuel that the piston will then move up and through TDC, allowing the engine to turn over normally.
My suggestion is to install new float needles and seats in the curbs, and to turn the fuel petcock to Off when the bike is parked. And do it soon: One of these days, the sudden, violent stop caused by hydraulic lock will be severe enough to bend a connecting rod. □
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