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Discussion Starter #1
Hoping for some insight as to what to check.
On Monday I was riding to work in a curve in the car pool lane. Going about 70. Hit a deep groove/seam crossing the lane. The front end stared wobbling horribly. Thanks to posts here, specifically one from Liam, I didn't panic. Let off the throttle, gently held the bars and once it got under control proceeded to work.
Decided after work to take streets home, the front end felt jumpy, like it was too easy to maneuver. Parked the bike until Wednesday, checked and added air to front and rear tire, front was down to 25psi, filled to 35, Back was at 35 filled to 41. Though better still feels a little jumpy.

The other symptom I've noticed is that hard stops cause the front end to wobble a little. The bike has been doing some of this for awhile, but nothing like the tank slapper on Monday before.

Recent changes: Went darkside with a Potenza RE92 165/65 SR 14. At the same time adjusted the rear suspension going from a 1 to a 5. Since I ride 2-up on the weekends I didn't want the new tire to rub.
Can either of these contribute to making this happen?

I have the bike at my local scooter shop. They have never dealt with a darksided bike and aren't sure if it contributes.

Any ideas as to what should be checked?

Thanks,
John
 

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Glad whatever I posted helped you out.

Sorry, I'm not darksided. Can't help out there, but I wouldn't figure it be a factor. Maybe have your front wheel rebalanced. Could have lost a weight.
 

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Low air pressure is a factor. When the front tire is not in alinement with the back tire, dangerous wobble can and will happen esp. on a curve. Dark sided rear probably didn't help with low pressure, the side wall flex would probably be out of whack with the front my guess. Proper tire inflation is very important, no matter what you have on.
 

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Check for a separation/bulge on the rear tire by putting on center stand. With the engine running and turning the rear wheel, tire separation is easily seen. Could check front tire too.
 

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A combination of many small things probably attributed to the wobble. When you darkside the Burgman a couple of things occur. First you raise the back of the bike up due to the taller sidewall, this effectively steepens the rake of the front forks making the steering quicker and therefore slightly less stable also the CT has a softer sidewall that attributes to a smoother ride BUT is also susceptible to some side to side movement ( again this is small but it is there). You also stated that you had the shocks set at the highest spring preload this again keeps the back of the bike high contributing to a quicker (hence less stable) bike. All of this with a combination of low tire pressure on the front wheel is probably what cause the head shake. I realize that many riders have successfully darksided for many years with no issues but anytime you start altering steering design you will have to pay close attention to your bike and its maintenance items ( i.e. tire pressure ).
Greg
 
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It sounds like a simple case of steering head bearings not being pre-loaded right. All the other factors could have just exacerbated the issue. Check the Knowledge base above (in the BLUE bar).
 

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Neither bike I've dark sided has acted that way. I'm gonna go with a cord shift on the front tire. I think I read that BJack had a bulge in his when he went down too. I've run with anything from 20 to 40psi in the back with no indications but my front tire got replace early because it got a slight wobble after hitting a pothole. No problem since.
 

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In Bjack's accident the witness's said he was passing at a fast pace and started to swerve violently and then crashed. The Investagator did not find anything else wrong but just bulged front tire. From the way it was reported from the witness's is he got into a "Tank Slapper" head shake and could not recover. RIP my friend.

If you ever get into a tank slapper, slowly get off the gas, use NO brakes and loosly grip the bars while trying to stop the oscillations. Not all tank slappers can be saved and end in a crash.
 

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Discussion Starter #9
Thank you for the feedback. I will be passing all this info on to my mechanic on Monday and have him check those things mentioned.
 

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+1 on the head bearing preload. Had that happen to me on my '05.
 

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Discussion Starter #12
I passed on the information you all provided this morning.
In doing a test ride the mechanic let me know that removing his hands from the handle bars at a speed of 40 allows the bike to go into a wobble in a few seconds. This is behavior I had noticed several months ago and forgotten about.

He is planning on working on the steering bearings as suggested.
 

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Here are pictures of my tire that Dave was referring to. I started noticing a front end shake at low speed take off. It started getting more noticeable and continuing up to a higher speed. I did the air pressure, tire cupped checks. All were fine. I even did the scientific head bearing check, front wheel off the ground and checked the forks for wiggle. Nothing. I was riding with Dave and stopped to gas up. I always gas up on the center stand and when I started the bike to pull away from the pump the rear wheel was spinning and Dave saw the bulge. Tire was a Bridgestone BATTLAX with approximately 4,500 miles.

The picture is of the tire un-mounted and what the bulge looked like on the inside. (I couldn't get the video to load showing the tire spinning with the bulge on the outside).

Check you tires often, I was lucky thanks to Dave.
 

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Here are pictures of my tire that Dave Wilett was referring to.<<<SNIP>>>
Check you tires often, I was lucky thanks to Dave Wilett.
Just to clarify, It was not me. :D
 

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Discussion Starter #16
Got my bike back from the shop Saturday morning. They adjusted the steering nut, as suggested. It's better.

However I get a sort of drift to the right then to the left as I go along a flat patch of road at a steady speed. This is my first time darksiding, is this considered normal?

My first real ride on it was this morning coming to work. It was doing that drifting but when I got to a curve going about 50 it felt like it wanted to wobble a bit.

I also lowered my pre-load to 3. I will likely be taking the bike back to the shop to have them look at it more. There's a part of me that also feels I'm being a bit too skittish with how it rides.

Any insights are greatly welcomed.
Thanks,
John
 

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What tire pressure are you running.

On the darkside, it is more sensitive.

36-41 psi is typical.

PS for me, a pre-load shock of 5 works best, but others prefer 1.
 

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John, I can "No Hands" my Darksided 650 without drifting. I wonder if the pre-load is a bit too tight now? Check the tire pressures like Jim said. (you posted as I was typing)

The pre-load is meant to only put a bit of drag on the turning but if too tight it will make it notchie.
 

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Discussion Starter #20
I may be using the wrong term for pre-load. What I adjusted were the notched and numbered cylinders at the rear. Put the bike on the center stand and turned them from 5 to 3. Did look under the storage area and can see some rub so I will likely put it back up to 5 before I leave the office.
 
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