K11 Owners Group

[Flying Duck]

Riding down to CA, I over coked a turn on the Oregon coast forcing me to do some fiarly hard braking before/during turn entry and got a nasty little wobble. Then riding traffic in SF city riding
I had to do some hard staightline braking and once again got some nasty, very disconcerting side to side wobble inthe front. Not a full lock-to-lock tankslapper but very disconcerting to say the least.

I made it to the Palm Springs area but now I need to get it fixed before riding anymore since it certainly isn't very safe.

My two theories:

Tire cupping: The front tire is a Bridgestone BT020 with about 5k on it. The thckness of the rear of each tread block is about two fingernail thicknesses lower than the fronts of the tread blocks. I'm not a tire expert but this seems it might be a likely cause.

Steering head bearings: I dropped the belly pan and jacked up the front. There's no side-to-side looseness but the forks fall easily from side to side. On the plus side, there doesn't seem to be any notchiness. While I'm fiddling around, I plan to tighten up the steering head bearings until there is a slight amount of frcition per what I found over at IBMWR in the tech pages.

Anybody have thoughts on this?
_________________
93 LT (x2)
94 RS
86-97 K75F(K75/100/1100 Frankenbrick)
86 K75C w/paralever, hi perf cams,TURBO!
91 & 92 K75Ss
91 K1
86 custom K100
14 WR250R
IBA #17739 (SS1K, BBG, 50CC)
Buy parts HERE

[Off the grid]

Tire.

Swap it out.
_________________
Bane of your existence since July 2006
2007 Triumph Tiger ABS. "Sabertooth"
2009 Husqvarna TE610. "The dirty Italian mistress"

[jpberens1994K1100RS]

Just my opinion, experience based.
Both your observations are correct.
The tire wear pattern is trying to set up an occilation on hard straight line braking. The ever so slightly loose steering head bearings are allowing it.
It's just a small step away from going into the really bad slap ya around kind of wobble.
The frame geometry is conservative in respect to many of the sport bikes, that's helping.
A stabalizer would help, but not eliminate, some of the wobble as well.

Tighten up the slack if you can & try the bike again in a controlled area. Things should be better. Then ride it home, if you think it is safe enough to do so and change out the tire once there home safe.
_________________
1993 K1100RS that I'd rather be riding FAST!
2014 Moto Guzzi Norge

[BobZ(IL)]

I vote for properly adjusting the head bearing. And be sure rear shock setting is not too soft.

Loose bearing and soft backend is a great combination to experience a real tank-slapper.

If front tire is not uni-directional, I would just flip it.
_________________
'93 K1100LT
'78 R100S
'05 R1200GS
BMWMOA, CRBMWOA, ABC, K11OG #997

Live well, do good work, enjoy the ride.

[Shoganai]

How's your tire pressure?

Are your forks oil levels the same?

Check for un-even brake pad wear.

Check calipers for smooth even travel, and release.
_________________
1993 K1100RS aka The Shop Whore
1994 K1100RS aka Blue Streak

The long road is a rainbow and the pot of gold lies there.
So slip the chain and I'm off again,
You'll find me everywhere. I'm a Rover. - JT


Nana korobi ya oki

[bmwmick]

Drake,
Do you have access to a micrometer? I'd probably start by cleaning the rotors good with brakecleen and then mic the rotors, looking for a thin spot. I had a very similar problem on my R11RT about halfway through the 3Flags this year. Turns out, my left rotor developed a thin spot (about .004") in one area. Caused a VERY nasty pulse at low speeds and wobble under braking at higher speeds.

Here is the best instructions for our steering head bearings:
http://www.largiader.com/bearings/


Mick
Santa Paula, Passing through Palm Springs MOnday or Tuesday. )
_________________
Mick McKinnon
KOG#175
'93 K1100LT, '96 R1100RT, '84 R100RS, 2010 Kawasaki C-14
Tucson, AZ

[Flying Duck]

I'm pretty convinced that it's the wear on the BT020. The hegith difference between the front and rear of the tread blcoks is/was pretty pronounced.

I've tightened the steering head bearings and yesterday I put a new Pilot Road 2 on the front. This afternoon I"m going to take it for a spin up 74 to see how things are going. If the head shake is still there then I guess I'll have to bring some rotors down with me for Christmas and see if that's the ticket.

Mick: Drop me a PM if you want to hook up for a beer or something when passing through. I'll be here.
_________________
93 LT (x2)
94 RS
86-97 K75F(K75/100/1100 Frankenbrick)
86 K75C w/paralever, hi perf cams,TURBO!
91 & 92 K75Ss
91 K1
86 custom K100
14 WR250R
IBA #17739 (SS1K, BBG, 50CC)
Buy parts HERE

[Flying Duck]

Tightening the steering head bearings and mounting a new front Pilot Road 2 seems to have done the trick. Now I have to replace my wafer thin rear brake pads.
_________________
93 LT (x2)
94 RS
86-97 K75F(K75/100/1100 Frankenbrick)
86 K75C w/paralever, hi perf cams,TURBO!
91 & 92 K75Ss
91 K1
86 custom K100
14 WR250R
IBA #17739 (SS1K, BBG, 50CC)
Buy parts HERE

[jpberens1994K1100RS]

When I changed out my back tire after a puncture this early summer I changed the brake pads. They were so thin I couldn't have even spread cheese on them!! I watch closer now.

I know you know this, but when changing out & bleeding the system, don't move the foot lever through more travel than normal. Less'n the MC bore is a wee bit dirty or scored & then score or cut the seal & you start a leak. I'm guessing yours is in tip top shape though, but just sayin.

I think I got this tip from this forum AFTER I did that to my front brakes & had to do a re-build.
_________________
1993 K1100RS that I'd rather be riding FAST!
2014 Moto Guzzi Norge