Author Topic: THE HIPPY HIPPY SHAKE  (Read 4857 times)

Offline elvin315

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« on: May 17, 2011, 07:49:15 pm » Hippy hippy shake - the beatles on YouTube

Does your Connie like to dance? The wind will always have it's way with us but a wobble that consistently occurs at a given speed, usually during deceleration, is another matter. First check the free stuff.

The best way to troubleshoot a chassis problem is to set everything to neutral. Kawasaki recommends tire pressures of 36F/41R psi but experience has shown us that higher pressure (regardless of brand or model tire) helps reduce tire cupping and wiggling. Try 40 psi up front and 42 psi in the rear. Check the fork oil level in each tube. They should be equal. Make sure your Fork's preload adjusters are equally positioned. Set them so 3 to 4 lines are showing. That's about the midrange. If you have a pre-94 model with air forks, check the fork air pressure. Use a bicycle pump or other low pressure pump and set them at 4 psi to start with. This isn't an accurate sag setting but it should get you close enough to eliminate it as a cause for the wobble.

Check and tighten the steering head bearings if necessary. To do this lift the front wheel off the ground using a small bottle or scissor jack under the crankcase. Loosen the pinch bolts on the lower triple clamp and the lock nut on the steering stem. Tighten the castle nut until the fork resists turning then back off an 1/8 of a turn. Remember to retighten everything. Also, and I know this sounds strange, check that the tops of the fork tubes are even and flush with the top of the clip ons. Check, you never know.

Lift the front wheel off the ground same as before. Check the wheel bearings for smoothness. If they feel notchy or grind while spinning replace them. Grab the tires at the 12 and 6 o'clock positions (approx). Try to move the wheel side to side (top away/bottom toward and visa-versa). There should be no play. If there is replace the bearings.

The front tire's tread pattern can contribute to the situation. Tires with a center grove tend to wander more than those without. Do you know how old those tires are? Even new tires can be old depending on how long they sat around in a warehouse before being mounted. The aromatic compounds in the rubber eventually evaporate and leave the rubber harder. The bike could also have been exposed to UV rays or ozone gas. This will prematurely age a tire. Increasing the tire pressure will aggravate the situation because it will stiffen the already nonpliant sidewalls. Check the tires for cracks on the sidewalls and inside the tread sipes. If the tires require replacement have the wheel bearings changed too.

This was told to me by an old black leather biker. Might not help but it can't hurt. Position the bike so it's facing a wall with the front tire touching. Loosen the front axle and pinch bolts. Straddle the bike and bounce on the seat while simultaneously pushing the bike forward against the wall. Stay off the front brake. This stunt will let the brake discs find a happy center with respect to the calipers and align the wheel and tire between the fork legs. Tighten the axle and pinch clamps according to the manual.

The fork is squared away so now it's time for the rear suspension. Set the pressure in the rear shock at 25 psi (max is 50 psi) and the damping to 2 or 3. Again, this is an approximate setting. You can fine tune the sag later. Check the wheel bearings as you did the fronts. Lube the shock linkage to eliminate any binding there. A long shot possibility could be worn swing arm bearings/bushings. Play in the swingarm could translate into a wobble in the fork just as a sloppy fork can cause instability in the rear.

Check are the engine mounting bolts. They have been known to loosen and/or break. There are 2 (1 each side) in the top front corners of the cylinderhead, 1 long one in the rear of the upper crankcase half, and 1 long one in the rear of the lower crankcase half. Contrary to the brochures the engine is not rubber mounted. These mountings are rigid. The frame needs the engine to reinforce it or it will flex.

Now, if neutralizing the bike hasn't eliminated the wandering you can play with some adjustments. Set the front and rear sag by changing the preloads. Change the rear damping and see if that helps. Change the tire pressures one at a time. Record all the changes you make and take a test ride. Follow the same route on each test ride and maintain the same speeds. Record your impressions after each ride. Compare the results and return to the best of them.

If after these adjustments, the wobble hasn't decreased or disappeared, a fork brace might help. It ties the fork sliders together, prevents the axle from flexing, and the wheel from wobbling. Besides reinforcing the fork, it improves the Concours' handling.

It's possible the fork springs need replacement. They may be too soft for your weight, your passenger's weight, and that of your load. I use Race Techs but Progressives are popular too. Sonic Springs makes 1.0, 1.1, and 1.2 ratio springs for the Concours. Your fork oil may be worn out too. Try some fresh 15 weight. The rear shock fluid is replaceable even though the shock isn't rebuilbable. Try 15 weight suspension fluid there.

One thing we can't do much about is the affect of pushing that barndoor of a fairing through the air. Since we don't ride in a vacuum, whether its nature's breath or a tandem truck's wake, turbulence is part of our reality. At high speed, pressure builds up in front of the fairing and the bike can't cut though it cleanly or push it aside as easily as it did around town. Instead of the bike pushing the air from its path, the air compresses and resists, and pushes the bike back. (Newton's Law of Action & Opposite Reaction) Like a leaf fluttering from side to side on its way to the ground, the motorcycle will shake and shudder. It's subtle but it's there. I'm afraid the bags add aerodynamic drag too. Eddies back there will tug at the bike possibly inducing a wobble or shake.

Turbulence from other vehicles compounds the problem. Add air wings, trunk, driving lights, fairing extenders, etc., and it only gets worse. You can cut the shield down, way down, to reduce your frontal area and gain some cooler air to the chest as an added bonus. The Rifle windshield system is supposed to pass high pressure air under the shield and reduce turbulence in the cockpit. It could also lower the pressure ahead of the fairing. Honda used to mold holes in the front of the CBR900RR fairing for the same reason. Some recommend removing the foot scoops but at the cost of roasting your tootsies. I think the turbulence is part of high speed touring and I just put up with it.

Finally, there's good old pilot induced wobble. Without realizing it you could be holding the bars too tight and tranfering unintended steering input. A whiteknuckle grip is unnecessary at any speed. Relax your grip and give Connie some leeway. She's usually stable if setup properly. Are you countersteering? If not you could be wrestling the bike instead of steering her and the result is instability.

Some of the things I've mentioned are simplistic and some are off the wall. It just goes to show how complicated the problem can be. There is no easy answer because the cause of the instability isn't easy to pinpoint.

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