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Strange issues with my beloved Sport 1100i

kecup

Just got it firing!
Joined
Dec 11, 2008
Messages
9
Hi to everyone,
this is concerning the Sport 1100i, thought to ask here since you guys hold a lot of knowledge.

The problem: I had two strange accidents recently - low sided my 1997 1100i two times, both at low speed during braking. The bike is a bit damaged and so am I, but more painful is not knowing why this happened. Hence the post in here.

Accident no 1: Went slow in a line of cars when suddenly the car in front of me decided to stop, I start braking, not much emergency, but suddenly the front wheel locked and I got a immediate left-hand tank slapper and ended on the ground. It was on a bit of a wet surface so I blamed it on this, although it felt weird. Just the front wheel broke the traction a bit fast. Anyway, repaired the broken shifter and continued riding. Not much other damage, no apparent fork problem, no weird handling afterwards.

Accident no 2: Riding at some 30mph, when I saw someone at distance crossing my path, start braking, again no emergency, dry conditions, perfect surface. I got a very quick, again left-hand tank slapper and low-sided, this time with a bit more damage to the bike and myself. THis was very surprising since it should absolutely not happen.

Bike and my conditions: 1100i 1997 Sport, 20K miles, recently serviced, plenty of front tire (do not know the age of it though - bought the bike with it few months ago), steering damper put on "no resistance". When bought the bike there was no signs of previous accident on it at all. I have 2 other bikes - Monster 1000s and S4R and ride almost daily for at least 15 years, brake mostly front end, always leaning forward to put a weight on front end. During my history of riding I has some accidents but never something so strange as this.
Questions: What can be the cause? Hardened tire, bad left fork leg? Design? I had a 2004 LeMans before and noticed the bike has a slight tendency for a left-hand tank slapper when hitting a bump or so. I need your imput:) Pavel
 
Pavel,

You ask a good question. Hard front tire, possibly, bad fork leg maybe. Also check that both calipers are functioning properly.

I think I'd check the age of the front tire, if it is over 5 or 6 years old, not good. If in the US, there is a Department of Transportaion date code stamped in the sidewall (first two digits equals week made, second two digits equal year, if only 3 digits, made before 2000). I don't know how the EU dates tires.

Without actually putting hands on the bike it is hard to tell exactly what is going on.
 
Jeepers, that's a different question. I don't have an answer, but let me thow out a few ideas for the sake of discussion.

I cannot see it being the brakes. If the master cylinder was compromised, you would lose braking power, not suddenly have the system get tight on you. I don't see the brakes as being the reason for the low-sides, but it could be triggering another problem.

Could it be a loose or damaged steering head bearing?

Shane
 
john zibell wrote:
Pavel,

You ask a good question. Hard front tire, possibly, bad fork leg maybe. Also check that both calipers are functioning properly.

I think I'd check the age of the front tire, if it is over 5 or 6 years old, not good. If in the US, there is a Department of Transportaion date code stamped in the sidewall (first two digits equals week made, second two digits equal year, if only 3 digits, made before 2000). I don't know how the EU dates tires.

Without actually putting hands on the bike it is hard to tell exactly what is going on.


Thanks for quick answer, could not find the date code on the tire. But I do not know - if hardened tire is such a danger there would be more accidents like this. What scares me is that it happened out of nowhere, twice. Calipper was my thought too, but brakes work nice, I installed new rotors recently, since one of the originals was warped. Let's say left calipper is stuck or something and starts braking suddenly after some pressure builds up - but there are bikes with single disc and braking on just one side does not produce any effect on steering stability. I really need to find answer to this.
 
Shane wrote:
Jeepers, that's a different question. I don't have an answer, but let me thow out a few ideas for the sake of discussion.

I cannot see it being the brakes. If the master cylinder was compromised, you would lose braking power, not suddenly have the system get tight on you. I don't see the brakes as being the reason for the low-sides, but it could be triggering another problem.

Could it be a loose or damaged steering head bearing?

Shane

Thank for answer, the steering head bearing was checked during the service few miles ago, found normal. Brakes are working nice, I do not know how callipers would do the effect - sudden and very rapid left hand tank slapper. I am totally confused.
 
kecup wrote:
[Thanks for quick answer, could not find the date code on the tire. But I do not know - if hardened tire is such a danger there would be more accidents like this. What scares me is that it happened out of nowhere, twice. Calipper was my thought too, but brakes work nice, I installed new rotors recently, since one of the originals was warped. Let's say left calipper is stuck or something and starts braking suddenly after some pressure builds up - but there are bikes with single disc and braking on just one side does not produce any effect on steering stability. I really need to find answer to this.[/quote]

I'm not saying it's the brakes, but picture this. If one of your calipers sticks, not only would you only have braking on one side of the wheel but because your master cylinder is sized for two calipers the ratio is wrong and the result would be wooden brakes with power but no feel. I tried that once.
I would check tire first, then brakes. Don't see how head bearings could do it but anything is possible. It is normal for the forks to go to full lock if the front tire locks up. Might be a good idea to pull the steering damper off and check it for smooth action and no binding. Just because it is set on light does not mean it can't cause issues. My wifes V11 had a damper that made her bike wobble in a straight line.
Good luck.
Michael,
 
GuzziMoto wrote:
kecup wrote:
[Thanks for quick answer, could not find the date code on the tire. But I do not know - if hardened tire is such a danger there would be more accidents like this. What scares me is that it happened out of nowhere, twice. Calipper was my thought too, but brakes work nice, I installed new rotors recently, since one of the originals was warped. Let's say left calipper is stuck or something and starts braking suddenly after some pressure builds up - but there are bikes with single disc and braking on just one side does not produce any effect on steering stability. I really need to find answer to this.

I'm not saying it's the brakes, but picture this. If one of your calipers sticks, not only would you only have braking on one side of the wheel but because your master cylinder is sized for two calipers the ratio is wrong and the result would be wooden brakes with power but no feel. I tried that once.
I would check tire first, then brakes. Don't see how head bearings could do it but anything is possible. It is normal for the forks to go to full lock if the front tire locks up. Might be a good idea to pull the steering damper off and check it for smooth action and no binding. Just because it is set on light does not mean it can't cause issues. My wifes V11 had a damper that made her bike wobble in a straight line.
Good luck.
Michael,[/quote]

I think that you might be right.
 
you say you fitted new discs recently ? Coincidence, did you fit new pads too ? the old ones could hve worn wedge shaped. Seems to me the brakes are binding or the pads are loose.
 
Not changed the pads since the old ones were good. But you have an excellent suggestion. Tend to think this is a brakes problem.
 
Thanks for the suggestion, an imput like this really help. Accidentaly I was going to get to the wheel bearings soon during the restoration of the bike. This might just speed things up:) Thanks again.
 
The 1100i has the WP forks with compression in one leg and rebound in the other right? Maybe check if the compression damping doesn't go to full block when applying the brakes or hitting a bump. That would definately throw your steering off like you say, since the other leg would still like to compress, and it would slide your front tire pretty much immediately when the brakes are applied.

I had something similar in old Koni shocks; some seal had disintegrated and plugged the damping holes enough to make it go on full block when hitting a bump., but low speed damping still kind of worked.

Let us hear what you find out.

JR
 
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