Handling Problem...

[MikeO]

The Adv is developing handling problems. It seems to follow any linear fault, making the front end extremely twitchy. The bike also feels uncomfortable over rough roads (I've ridden a lot of these recently - not 'off road' - just badly surfaced and pot-holed metalled roads). When going over a bump while accelerating, the back end suddenly 'tucks' and surges (sorry I can't be more descriptive).

Right, those are the symptoms - here's what has been done recently...

I've had Metz 880 Marathons fitted about 3000 miles ago and I've checked their pressures regularly - they've been fine. The bike handled well after these were fitted, so I don't think tyre choice is an issue.

I wound off the pre-load on the rear Ohlins and re-set it to make sure it was at the correct level (this was how Harris set it up last year, 9 turns from zero for normal load - a further 6 for fully loaded).

There are no signs of any oil leaks on either of the shocks.

Any suggestions or ideas??

Thanks,

Mike

 

[Fanum]

Too many Merkin sized portions?









You sure it's not a trait of those tyres as they wear Mike?
Might be worth finding if anyone with same tyres over there has had similar.


And give the doughnuts a miss too.

 

[Rabbitson]

Sounds to me like it might be the way that the front tyre's wearing. You said you were running the recommended tyre pressures, but have you tried changing them slightly to see if it helps?

 

[ferguscawley]

Mike

If you are constantly riding in high temperatures, then I would suggest you increase your rebound damping by a notch at a time to see if this helps. My GS had ohlins fitted when I bought it and it gave very similar symptoms to what you describe - especially the rear. It seems to me like your bike is pogo-ing due to decreased damping (can be caused by excessive temperature - shock oil heats up and loses viscosity). Try it a step at a time.
Another thing to look at is your tyre profiles - if they have become squared off, this will adversely affect handling, causing the bike to tramline on ruts and cause it to 'fall in' to a corner very unpredictably.

Ferg

 

[leigh]

handling problems

had a couple of incidents with metzlers fitted on K1200LT (or large marges as we call em).when the bike is vertical -no problems,start to lean the bike over say no more than 5 degrees started to get a vibration through the bikes like a crown wheel bearing goin etc. have you tried some other tyres ?

 

[(RIP) maverick]

Check your tyre walls for any "bubbles" or weird occurances. They might have develop a flat spot. A very small thing but have you been packing your panniers with the same stuff/weight as you have been from the start of the trip? If they are to heavy one side you can run into all sorts of misbehaviour.

Only ideas but strangely enough expierenced all of them before

 

[boundless]

It's the mid RTW syndrome.....

All in the head mate. Ted Simon described it very well in Jupiter's travels. Bike feels like it's wobbling all over the place and getting ready to flip you off the very next corner. This illusion alternates the following week week with the feeling that the bike really is part of your body, hasn't got any wheels and that what you are really doing is flying over the face of the earth like some sort of God.

You've got the opposite of that which us degenerate lot hunched over our screens have got, what you really need is to "get in more"

Have you tried letting a dispassionate, cool, composed, serene, temperate, moderate, impartial, unruffled 3rd party test ride the bike? ......like boundless; I'll fly out tomorrow.

Alternatively try a betablocker like propanolol.

 

[sjwb]

Do please check the swing arm and paralever pivots for side movement; they may need adjustment/ renewal. You may also have a check around the front end ball joint and upper (bush?)

 

[Darth_1100s]

Mike - as sjwb says.....check the lower pivots. The symptoms you describe sound exactly like my 1100S before I found the play in the rear wheel. I hope it's not that, but if is it'll need sorting.

Dave

 

[the celt]

Hi Mike,
Can you descibe the feeling better, are you getting a a low speed wobble at about 30mph in sand and loss dirt or is it on tarmac, if the lose
stuff then dont worry, if tarmac as said above check everything, the extra weight on the bike will make it feel alot different from before and depend how much fuel you have in it will also feel strange.

 

[DavidHolmes]

Mike

If you are constantly riding in high temperatures, then I would suggest you increase your rebound damping by a notch at a time to see if this helps. My GS had ohlins fitted when I bought it and it gave very similar symptoms to what you describe - especially the rear. It seems to me like your bike is pogo-ing due to decreased damping (can be caused by excessive temperature - shock oil heats up and loses viscosity). Try it a step at a time.
Another thing to look at is your tyre profiles - if they have become squared off, this will adversely affect handling, causing the bike to tramline on ruts and cause it to 'fall in' to a corner very unpredictably.

Ferg

I had a problem with my rear not staying in contact with the road (when fully laden with pillion & luggage) because I had increased the rebound damping. After Harris made me back it off (4-6 clicks) from the solo smooth road settings, all was fine. The excessive damping was making the suspension unable to cope with the rapid changes in uneven surfaces, ie would compress at bumb one, and then hit bumb two before it had a change to fully uncompress thus tying itself in knots.
Having said that, unless you have added more weight to the rear, or are riding 'rougher' roads (or equally rough ones at higher speed) there is no reason to see why this would suddenly show up now.

As too the front, I agree with the above suggestion of front tyre profile. My Tourances (used during the winter almost always upright) start to get very twitchy on the white lines of the M25 (let alone the ruts and ridges) when approx half worn.

The only other thing I can think to check is the head races...does a GSA have head races ?

 

[MikeO]

Thanks for all the replies.

The tyres appear normal, that is to say they aren't cupped, worn or sufferring from cuts/splits/blisters. The original recommendation for front tyre pressure was 42psi, which I thought seemed too high (front wheel felt skittish even around town), so I dropped it to 36psi - the rec press for Tourances (which I've been using so far). I'm going to increase the pressure to 42 again this morning before I set off...

Leigh - problem happens on 'slab' when the bike's upright - no instance of vibration.

Boundless, thanks for the psychobabble - this is happening, and not just in my head

The temperatures have not been excessive - 84 deg F is the highest so far, but the median temps have been high 60s to mid 70s, so I don't think temperature is a factor...

Jose, I'm not getting a 'wobble' as such, just a steering input from the bike whenever the front wheel finds a linear joint or rut in the road - it's very unsettling and just makes the bike feel uncomfortable (getting back into Boundless territory ).

Darth/sjwb - just been out and checked the swing arm for sideways play and movement (with the help of a bemused Texan passer-by ) - no sideways movement - feels fine.

Load is, broadly speaking, the same since the beginning of the trip - certainly since the tyre change. No change in handling after refuelling.

I'm going to stay with 'Arch' from AdvRider this evening, who apparently has a very good relationship with his local dealer in Houston. I think I'll get them to look at the front end.

I'm tempted to work on the assumption (dangerous, I know) that this is shock absorber related. The tuck and lurch I get when accelerating over a bump points to insufficient damping - although I'd expect to see an oil leak if this was the case. The rear shock has been on for over a year and 30k miles, so maybe the spring's shot It was rebuilt after blowing up in June last year, but has done at least 20k since then. Think I'll get it checked by the dealer as well...

Keep the thoughts coming..

Mike

 

[newman7096]

Buckled wheel or wheels???

 

[Panzer Patrol]

Mikey,

Spin the front wheel, check rim but also tyre. Make sure the tyre hasnt developed a fault ie. twisted. Check the spoke tightness, ding em with a spanner to see of they sound ok. Are the head race bearings ok. No stiffness in the bars when flopping from side to side, or the ball joint.

Best of luck on the trip, enjoyed your write-ups. Lucky git

 

[MikeO]

Sorted - almost...

First the 'tracking' over line features on the road - increased pressure in the front tyre to 42psi this morning - result, no tracking - this was the pressure BMW Daytona recommended - D'Oh!

I then backed off all the pre-load on the rear - way too spongy & bouncy. I then wound on 2 turns, rode it for 20 mins, wound on another 2 turns, rode for 20 mins, wound on another....you get the picture

Result - 6 turns off minimum gives an acceptable ride without any of the jarring and lurching. The ride over rough surfaces is better, though not ideal - it may be that the spring is beginning to weaken...

Many thanks for all your ideas & contributions...

Mike

 

[Aurelius]

Sorted - almost...

First the 'tracking' over line features on the road - increased pressure in the front tyre to 42psi this morning - result, no tracking - this was the pressure BMW Daytona recommended - D'Oh!

That makes sense. I've heard similar complaints about the front end tracking on other forums, and in each case it was due to insufficient air pressure. I regularly ran with 38 psi in the front (42 in back), but have recently switched to 42/42. I was concerned that 42 psi in the front might lead to a loss of traction during hard cornering, but my Sunday ride dispelled that notion. Lower pressure also leads to premature cupping; I'll be interested to see if I can get more than 20,000 miles out of the front now that I'm running 42 psi.

Result - 6 turns off minimum gives an acceptable ride without any of the jarring and lurching. The ride over rough surfaces is better, though not ideal - it may be that the spring is beginning to weaken...

I'm not sure if this is true of all Ohlins shocks, but there was near universal agreement on a Honda VFR forum I belong to that they're rather fragile and require a rebuild every 10,000 miles.

 

[MikeO]

I'm not sure if this is true of all Ohlins shocks, but there was near universal agreement on a Honda VFR forum I belong to that they're rather fragile and require a rebuild every 10,000 miles.

I fully expect to have them rebuilt at some stage, Andrew - I'm just hoping to leave it for a bit longer...

Mike

ps Any backfiring from that exhaust?

 

[Aurelius]

I fully expect to have them rebuilt at some stage, Andrew - I'm just hoping to leave it for a bit longer...

Mike

ps Any backfiring from that exhaust?

None at all. I'm starting to wonder if mine's defective.

Contrary to the dyno chart, the performance gains seem biggest from 6000 + rpm. In that range, the alleged gain of 15 hp seems entirely believeable. I did a top speed run two weeks ago and set a personal record of four times the posted speed limit (125 mph in a 30 mph zone!).