Handlebar wobble on deceleration?

[Giddy]

I have a 2004 r1200c that has suddenly started having wobble when I let off the throttle. At speed or while accelerating the bike feels like normal. 

I've ridden the bike every day to work for a month now with no issue untill today.

Last night was the first cold night in two weeks and I usually have to add air to my tires after a cold snap. 

Is there anything else I should check? I was also thinking of dropping one click in the rear shock for my skinny self to ride a bit smoother.

[DakarTimm]

Sounds like low air or a worn tire . Start with the easy stuff first. 

[dirtrider]

2 hours ago, Giddy said:

I have a 2004 r1200c that has suddenly started having wobble when I let off the throttle. At speed or while accelerating the bike feels like normal. 

I've ridden the bike every day to work for a month now with no issue untill today.

Last night was the first cold night in two weeks and I usually have to add air to my tires after a cold snap. 

Is there anything else I should check? I was also thinking of dropping one click in the rear shock for my skinny self to ride a bit smoother.

Afternoon Giddy

 

The front  tire (or hitting a bump) is probably initiating it but that usually isn't the entire problem. Motorcycle attitude (rear end high)  can figure in so check that, loose front wheel bearings can also figure in so check those for being loose,  loose upper tipple tree bearings are a definite contributor so check those, even a tipple tree or handlebar mounted windshield  can add to or sustain the problem.

 

If that motorcycle had (or should have had)  a fork damper then that would also be a BIG place to look. 

 

Usually the front wobble on decel is a mix of a few factors but the tire (or bent wheel) usually starts the wobble.   

[King Herald]

I had a Kawasaki 1000 shaft drive back in my youth, and several years into ownership it just suddenly started shaking its head at speed, a fast 'tank slapper' that felt weird, but never really got out of shape. 

 

After doing all the usual checks, wheel bearings, head bearings, tyres, tyre pressures etc, I randomly fitted a pair of different rear shocks. They were some aftermarket items called 'Street Strokers', flash looking, but not actually a matched pair. One was a touch longer than the other, I got them real cheap......

 

And on the test ride after fitting I found the tank slapper had totally disappeared. 

 

Who'd a thunk it, rear suspension affecting front forks. 

[JamesW]

My FJR was afflicted by a deceleration front wobble and it turned out to be completely tire related.  Of course most bikes don't have telelever front suspension which I assume yours does as does my '93 and also my '04 R1150RT now departed.  But I don't know maybe your '04 R1200C doesn't have telelever?  

 

In the FJR world the deceleration front wobble has been addressed by many that swear by changing out the front steering head bearings from ball to tapered rollers which I don't agree with at all.  They just change out the bearings then torque the steering head bearings until the wobble is damped out.  I say better to just leave your hands on the handlebars which usually damps out the oscillations. 

[dirtrider]

12 hours ago, JamesW said:

My FJR was afflicted by a deceleration front wobble and it turned out to be completely tire related.  Of course most bikes don't have telelever front suspension which I assume yours does as does my '93 and also my '04 R1150RT now departed.  But I don't know maybe your '04 R1200C doesn't have telelever?  

 

In the FJR world the deceleration front wobble has been addressed by many that swear by changing out the front steering head bearings from ball to tapered rollers which I don't agree with at all.  They just change out the bearings then torque the steering head bearings until the wobble is damped out.  I say better to just leave your hands on the handlebars which usually damps out the oscillations. 

Morning James

 

Some of the older Honda Goldwing's (mid 1980's) had a deceleration head shake problem, to address that there was a Honda service advisory to replace the ball-type tipple tree bearings with tapered roller bearings then over-torque them. That sort of worked but personally I was never impressed with that as it gave a tighter draggy/sticky feeling steering. 

 

I always thought that Honda should have fixed the root of the darn problem not try to use an over-tightened bearing as a brake to cover it up. Or at least add a proper steering damper.

 

The problem with the old GoldWing was that most of time there was no warning (like a little wobble that progressively got worse)  those things would act perfectly normal most of time with no dropped throttle shake at all then in a nano-second they could go into a full on lock-to-lock head shake that was so violent that it would oscillate lock-to-lock so violently that the rider couldn't even even grab the violently swinging bars to stop it.  The upside was that once it scrubbed off about 4 or 5 mph of speed  (if the rider could stay in the saddle) the bars would instantly snap back to normal center with no wobble at all, smooth as could be.

 

Back in my younger days most motorcycles came with adjustable steering friction brakes  (knob on upper tipple tree) to increase steering friction to reduce front end wobble issues. Some of the older BMW motorcycles had very elaborate over-designed steering dampers that allowed the rider to change the damper pivot geometry to increase or decrease damper effect (change damper stroke per degree of steering movement).

 

 

 

 

  

 

 

 

 

[Skywagon]

27 minutes ago, dirtrider said:

Some of the older BMW motorcycles

My old 1979 R100RT had that 3 position knob. On decel if you thumped the bars or hit a pothole it would shake back and forth. It turned out sticktion in the front forks was the major contributor. After addressing that and turning the knob to 3 it almost never happened. 

[taylor1]

Alot of the /5 /6 airheads were known to have the death wobble. A friend I use to ride with had a 74 r90. His would shake on acceleration @ 50mph. If it did, he would open the throttle and power through it. There were some articles written by a very respected dealer/mechanic that claimed it was due from front fork misalignment. He posted a procedure on how to realign. My friend followed his instructions and said that it totally cleared his problem. It seems that this problem has been around for a while and on different brands as DR has mentioned. Hopefully the OP will follow the guidance posted above and resolve that problem. I know from experience that it can be a scary thing.

[JamesW]

Interesting post D.R. I also don't like the idea of using a bearing as a steering damper.  My FJR never did the deceleration head shake at all if I didn't take my hands off the handlebars.  I went to Michelin PR2 tires and all was well now run PR3 tires also with no shake.  I also run 41 psi front and 42 rear.  Yamaha recommends 36 psi front.  In fact I run the same pressures in my R1100RSL with good tread life and little to no cupping.  Once owned a '76 R75/5 with tapered steering head bearings that developed a flat spot you could feel when rotating the forks stop to stop.  Now that bike would do an accelerating head shake that would Get scary real fast.  I always thought tapered rollers in the steering head wasn't a great idea because tapered bearings like to turn up revolutions so I like ball bearings in the steering heads and I certainly don't like the idea of using a bearing as a steering damper.  Oh, new bearings in the R75 fixed the issue.  Kind of wish I still had an airhead in some ways because of no ECU technology which is great until it isn't.