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Offline Lee

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De-buzzing Australian style
« on: September 11, 2018, 08:56:33 pm »
Could we make this a sticky if not already done so?

Australian Kawasaki GTR Owners
July 26th, 2003, 10:54 am #1
De Buzzing the GTR
Excellent reading, covering points mentioned by Chris in settings for carbs etc.
De-Buzzing the Concours
One of the most requested topics on the COG mailing list is the alleged buzziness of the Concours. The general consensus of the list server subscribers and fellow Concours owners is that this "problem" has been greatly misrepresented by the motorcycle press. It is possible that the motorcycles the magazine writers have ridden were buzzy, but as a general rule the problem stems from poor manufacturing control at the factory and not from an inherently poor design. With a few simple adjustments and modifications the Concours can be as smooth as almost any bike on the market.

Vibration Origins

The Concours has a frame that uses the motor as a stressed member. If you look there is no frame in front or below the motor. The motor is the frame in this part of the bike. Because of this the engine can not use any type of isolated mounts. The claim has been made that the in-line four is naturally vibration prone. After owning in-line Kawasakis since 1977 I have never found this to be true. The Kawasaki 550, 650 and 750 were all based on the same basic in-line design and I have owned at least one model of each. The motors in these bikes were rigidly mounted but the bikes had full frames. None were as buzzy as my '97 Concours when I purchased it. The Concours also uses a mechanical balancer to help cancel out some of the vibrations, something that was not necessary on the older designs. For whatever the reason the Concours can be fairly vibration prone if not adjusted correctly.

Stop that Buzz

When trying to track down what is causing the excessive vibration it pays to stop and think about what is actually happening. The underlying cause of the vibration reaching the rider is that harmonics are being generated in the rotating engine parts which are being transferred from the motor to the frame and then from the frame to the handlebars. So the obvious place to start is at the root of the problem, the motor.

The Motor: Balancer

The most obvious place to start is with the system that Kawasaki designed in to help with the problem, the counter-balancer adjustment. In theory the counter-balancer should create a vibration exactly opposite that which the motor is creating. In order for it to do its job it must be carefully timed to match the vibrations created in the engine. The adjustment is easy and only takes 30 minutes to do. The hardest part is taking the plastic off.
Do this on a Cold Engine only
Remove the lower right fairing plastic.

It is not necessary to completely remove the belly pan but it makes the job easier.
Remove the inner plastic splash guard to gain access to the lower front of the engine.
At the lower front of the engine the balancer shaft torque arm should be visible, Fig 1.

Figure 1. Balancer Shaft torque arm.
Photo courtesy of Rick Hall
The position shown in Figure 3 is the "initial position". This is where it is set upon assembly of the engine. It is then adjusted while the engine is idling. This is where mine came from the factory.

Loosen the bolt at the end of the torque arm and the pinch bolt at the shaft end.
Start the motor and let it idle. CAUTION have a screwdriver holding the shaft before starting the engine. The shaft will turn very easily and can wreak havoc if it spins and binds up.
Turn the shaft counter-clockwise until an chirping/clicking/squealing sound is heard. Back it off clockwise until it stops, then go a bit more for insurance.
Shut off the motor and tighten the bolts without moving the shaft.
Reinstall the plastic.

I have tried adjustments from the squealing noise counter-clockwise to the clicking noise if turned clockwise and find the factory specified adjustment to be the best. (imagine that!)

Figure 3 Initial Shaft Position

The Motor: Carburetion

A: Mixture

Important: Changing the position of the carb mixture screws violates EPA regulations. I am only outlining the procedure, not recommending it.
An engine that does not have all of its cylinders running in harmony can cause vibration in the motor as well. The engine spends some of its energy fighting itself rather than propelling its rider down the road. The following may be politically incorrect but here goes anyway. Remove the carbs, knock out the idle mixture plugs and set the idle mixture screws to 1 3/4 to 2 turn out. The first thing that comes to mind is "that is where the screws are set for the EPA requirements and clean emissions". The response is "may be". The factory setting for the idle mixture screws can be anywhere from completely seated in (where my #4 carb was) to several turns out. It can almost be guaranteed that the screws were not adjusted on the bike when it was built. The best bet is that they were set when the carbs were assembled and the settings come from an air flow meter bench test. The carb synchronization was probably done on the bench as well. The exact method for determining the position of the mixture screw is probably a complicated and on going process. Lets just say there were probably a lot more factors than satisfying emission standards when these carbs were built and adjusted at the factory.
The next statement that comes up is "the manual says to count the turns and put them to the same position upon reassembly." The rebuttal is "not exactly." The core manual does state this, but if the supplements are read the following is stated.

1989 and 1990-93 Model year
1994-97 Model year

2 turns out

1 1/2 turns out Austrian model

1 1/4 turns out Swiss model

----- US model (guess it means don't screw with it!)

1 1/2 turns out (Unique to European models except Austria and Swiss models)

The consensus is that 1 7/8 to 2 turns out seem to be the best.
The hardest part about this job is removing and reinstalling the carbs. The older the bike is the harder it becomes as the rubber intake air horns lose their elasticity. The secret is to buy a special tool.

A radiator hose tool is the perfect tool for this job, fig 4. It is actually made to be slipped between the radiator hose and the radiator nipple to help break the seal between the two without damaging the nipple.

Snap-On part # SDD2
Figure 4

To get the plugs out of the bottom on the carbs either poke them with an awl or carefully drill small holes in them, taking care not to drill into the screw head below, and thread in a small #4 screw. Grab the screw with a pair of Vise-Grips and carefully rock the plug out.
It's not a bad idea to write down the factory settings in case you decide to put them back to the factory position at a later date.
Reinstall the plugs with a dab of RTV and reinstall the carbs using the hose tool to roll the intake boots onto the carbs.
It also takes a little dexterity to manipulate the throttle cables back into place but it is not impossible.

B: Needle Valves

Every Kawasaki that I have owned since my 1981 KZ750 has suffered from a lean midrange. The Concours is no exception. There are a couple drawbacks to richening up the midrange.
1) It is against EPA regulations

2) It reduces fuel mileage by about 2%-3%
The easiest way to do it is to purchase some #4 brass washers from the hardware store. They are usually about 0.020" thick.
Remove the top carb cover to expose the CV piston, diaphragm and spring. Note this can be done without removing the carbs

Pull out the CV valve piston.
Make a note of its orientation so it can be reinstalled the same way.
The needle valve protrudes out of the bottom of the CV valve. It is held in by a plastic retainer which also supports and centers the CV spring. Carefully remove it and remove the needle valve.
The washers need to be filed down to the same outside diameter as the "E" clip on the needle valve so it will fit in the recessed area of the CV valve, Fig 5. (It is not really an "E" clip on the Concours since it is past the days when the needle was adjustable from the factory. The Concours uses a fixed shoulder that is not removable. I will call it an "E" clip 'cause old habits die hard.) Possibly a hobby shop would have washers that do not need modifications.

Figure 5.
Once the washers are the same OD as the "E" Clip slip the washer up the needle valve so it rests against the bottom of the "E" Clip.

Install the needle valve back in the CV piston and put the plastic retainer for the CV spring back in place.
Reinstall the CV piston in the same carburetor as it was removed from, install the spring (this is an easy one to forget!) and the carburetor cover. NOTE: Put several dabs of grease in the groove around the top of the carb body to help hold the diaphragm in place when installing the carb covers. Do NOT over tighten the cover screws.
Do the same for the other three carbs.

C: Synchronization

When the carburetors are synchronized the throttle plates (not the CV pistons) are individually opened or closed so that each allows the same amount of air to flow into its respective cylinder. The only accurate way of doing this adjustment is with a special tool. The tool usually consists of four tubes that contain mercury. From the top of the tubes are hoses that are connected to the vacuum ports which are located in the rubber intake manifolds between the carburetors and the cylinders. One of the ports usually has the hose that connects to the vacuum operated petcock for the gas tank. Two others have emission equipment hoses connected to them if you have a California model. While the last has a vacuum plug sealing it. Once these hoses are disconnect and the synchronization tool is connected to the ports the adjustment can be made.
Once you get good at doing this adjustment it can be done with only the gas in the carburetor float bowls. Most likely it will be necessary to temporarily install the gas tank and run the engine with the petcock in "Prime" since the vacuum port for the petcock is being used for the adjustment. Once the float bowls are filled again remove the gas tank and continue with the adjustment. Shops have special tanks that can be attached to the bike being worked on but for the backyard mechanic I would not recommend trying to make one of these tanks out of jugs laying around since it is not that hard to put the tank back on. It beats watching your garage going up in flames.
Regular needle type vacuum gauges will pulse the needle all over the place. It may be possible to put a restrictor in the hose to use make it usable but it will be necessary to have four of them at one time. Dennis Kirk (955 South Field Ave; Rush City, MN 55069; 800-328-9280; has gauges for $39.00 and will last a lifetime.
There are a couple of possible ways to sync the carbs. One is to sync them at idle. The most logical solution is to sync them at the RPM where the motor spends most of its time. Around 3500-4000 RPM for most people. The problem here is that the Concours seems to be the most resistant bike I have ever seen using this method. When the carbs are synchronized at 3500 RPM they are way off at low RPM and the bike idles rough. The best place seems to be a compromise. Sync them at idle and make a note. Sync them at 4000 RPM and make a note. Try it again at idle and if it idles rough split the difference with the 4000 RPM adjustment.
Synchronization Spec:
< 2.7 kPa (2 cmHG) between any two cylinders.
I find this spec to be too loose for smooth running. Try to get them as close as possible at both idle and 4000 RPM conditions.
Adjust the screw between the #1 and #2 cylinder carburetors until these cylinders are within spec (preferably closer).

Adjust the screw between the #3 and #4 cylinder carburetors until these cylinders are within spec (preferably closer).
Now adjust the screw between the #2 and #3 cylinder carburetors until the left and right bank of cylinders are synchronized.
Repeat if necessary.
Set idle up to 3500 - 4000 RPM (this is where the fuel runs out FAST)
Repeat above steps.
Set the idle to 1000 RPM. Check adjustment.
Split the difference with the 3500 - 4000 RPM adjustment if necessary.
Reinstall hoses and plugs
Reinstall fuel tank.

The Frame:

Now that the motor is running as smooth as possible the next logical step is to determine how the remaining vibrations are transmitted to the rider. There are only a few places where the motor is solidly attached to the frame.
Two front motor mounts at the cylinder head

Two rear motor mounts near the footpegs
The exhaust system header bolts near the footpegs
The mufflers near the rear footpegs
The very first thing to check is the clearance between the header pipes and the underside of the engine cases and oil pan. My '97 gave me vibration fits (where most information on this page was derived from) and it turned out the right hand header pipe was solidly pinned against the bottom of the engine.
Loosen the four engine motor mounts.

Loosen as many of the exhaust header pipe to engine head nuts as possible. Some of them are a nightmare to get to.
Remove the exhaust header bolts above the footpegs.
Loosen the muffler clamps, remove the muffler hanger bolts and remove the mufflers.
When the motor mounts are loosened the motor probably rolled ahead in its mounts.
Pry the motor backward in the front mounts as far as it will go. Tighten the front mounts so the motor stays in place.

Get the trusty scissor jack from the car and jack up the rear of the motor until the play in the rear mounts is taken up. Let is down slightly, sort of center the motor in the free play of the bolts. Tighten them to specs: 54 N-m (5.5 kg-m, 40 ft-lb)
Tighten the front bolts to specs: 54 N-m (5.5 kg-m, 40 ft-lb)
Check how the exhaust header bolts above the front footpegs line up. If it is necessary to apply any pressure on the pipe to line up the bolt, stop. If the header pipe is too close to the oil pan, stop. If either of these conditions exist it is time to do some modification. I used a dremel tool with a grinding wheel to carefully oblong the exhaust header bolt hole until the above conditions were met.
Once happy with the fit install the bolts but do not tighten.
Install the mufflers.
Tighten the muffler clamp and check for alignment of the muffler hanger mounting hole.
If any pressure is necessary to start the bolt oblong this hole too.
Start the motor and rev it up a few times to settle the exhaust into position. Do not get the pipe too hot to work on.
Tighten the exhaust starting from the cylinder head bolts and work back.
After this sequence of adjustment my '97 was incredibly smooth. Before I finally found this, at about 3000 miles, I was almost ready to trade it in on a BMW that was how badly I hated it and the vibration. There was no way I could have gone on any long distance rides with it.
Why did I place the motor in a particular position before tightening the mounts?
I rolled the motor back because it seemed like the cylinder head could possibly be grounding out against the frame in the "U" shaped area where the mount is.

I jacked up the rear of the engine to help with the alignment of the exhaust header pipe.
One other possible origin of the excessive buzz made it self clear when I noticed my right front motor mount bolt was gone. After the shop replaced the bolt some of the buzz came back. This got me thinking. On the left front motor mount here should be a shim installed between the cylinder head and the motor mount. There is two thickness shims available, a 2 mm and a 1.2 mm. I have not yet proven this to myself but I feel this may be an important clearance*. My bike either snapped the bolt on the right front or it vibrated loose and fell out. The bike had been taken on several 1000+ mile rides without knowing exactly when the bolt vanished. I had been SO happy since doing the adjustments described here because the vibration on my bike had been virtually non-existent. Once I found the bolt missing the dealer ordered one and installed it. Since it was installed the buzz is back. My theory is that if the frame is pinched when tightening these front mounts it is putting stress in the frame near the steering head, where the buzz gets to the hands. My best analogy is it is like tightening a string. The tighter is is the easier it is to set up and maintain vibrations. I plan to do some fine shimming in this area and see if it helps. If it does I will post the results. It may be I just need to redo the previous frame adjustment since things surely moved with the one bolt missing.
*UPDATE: The shimming idea was as bust. It seems to make no difference.

Steering Head:

Although I have not experienced this personally several members have found that excessively loose steering head bearings can contribute to the vibration in the handlebars. Actually one of the symptoms of loose bearing in the service manual is " The handlebars seem to vibrate more than normal". This adjustment is not one that can be explained in a "cookbook" fashion. It is an adjustment that is more of a "feel" than a number. The manual puts it like this "the bearings will have no or little free play and absolutely no preload". That can have an infinite number of interpretations. My method is to tighten the preload nut until it is obvious that it is loading the bearing, ie the bars will stay in any position they are placed with the wheel off the ground. Then back it off a little bit at a time until they will stay were they are put but the slightest nudge will make them fall to full lock. Some shops and individuals feel the preload should be tight enough to maintain a pound or two of pressure while turning the bars. I'll stick with the shop manuals suggestion.


The simplest thing to do is replace the skinny stock grips with some thicker foam grips. My favorites are Johar Superbike Grips. Again Dennis Kirk (955 South Field Ave; Rush City, MN 55069; 800-328-9280; comes to the rescue.
They come in three colors:
Dennis Kirk part #





Although the Concours is still not as smooth as my GPz550 with the above modifications it was transformed from something that I hated and was ready to unload at any price into a bike that I enjoy riding on a daily basis. If I had to rate the effectiveness of the above modifications they would rate like this:
Frame adjustment.

Counter-balancer adjustment
Add foam grips.
Sync the carbs
Shim the needles
Adjust the idle mixture
Adjust steering head ?? (no personal experience)
Either to work, to the store or to the next state I thoroughly enjoy riding my Concours and the buzz is something that I have to actually think about before I notice it.

Note: I'd like to thank Guy Young for checking over this page for me and adding a few tips and pointers.

GTR1000 '97
Ulyssian: 32132

Happy Aussie (QLD)

'97 GTR1000 "Griff"
Ulysses #32132 ~ GTR-AUS #01 ~ WP MERC #039  ~ IBA #22575

 July 26th, 2003, 11:19 am #2
David, I would like to point out that the tappets MUST be adjusted , on the loose side within specs; preferably, PRIOR to balancing the carbys or else you will not get a true synch of all four carbys. It is important...

Offline GeorgeRYoung

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Re: De-buzzing Australian style
« Reply #1 on: September 12, 2018, 12:16:05 am »
The balancer adjustment is to adjust gear mesh. It has no impact on vibration.

What the Concours really needed is two balance shafts, one can never do it all.

Offline Pbfoot

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Re: De-buzzing Australian style
« Reply #2 on: September 12, 2018, 02:24:05 am »
Thanks for sharing. Great info.
If you don't have time to do it right, when do you have time to do it over.                                                                17" wheels, Nissin 4 piston calipers.1kg Sonic Springs.Cartridge Fork Emulators. KB Brace. Galfer brake lines  Free power mod.