R1100S Pulls to the right

[roger albert]

(other ballast could include pyramids, brisk plugs, or amulets with high octane gas >= 108 RM)

Of if twin spark, pull one of the plugs on that side.

[bradzdotcom]

Finally someone who uses plain common sense and has the most obvious answers! This Roger guy knows EVERYTHING!

[Bob Hancock]

Originally posted by bradzdotcom
Finally someone who uses plain common sense and has the most obvious answers! This Roger guy knows EVERYTHING!

That's why he's the list Regulator.

[1967 R50/2]

It seems to me that ALL BOXERS will pull to one side...if the engine is running.

Stand at a stop and rev the engine in neutral. The crank will want to turn the bike around itself. While this effect is minimized at speed, it does not go away.

[CowboyKyle]

Originally posted by 1967 R50/2
It seems to me that ALL BOXERS will pull to one side...if the engine is running.

Stand at a stop and rev the engine in neutral. The crank will want to turn the bike around itself. While this effect is minimized at speed, it does not go away.

I thought something was wrong with it when it did that the first time I sat on the bike. Later I learned that actually every other bike is actually wrong, and Boxers are the only ones that are right! (thanks PP!)

[pwillikers]

It has nothing to do with engine rotation.

Try this on a deserted, straight road with no crown (even if you think you are King):
accelerate up to 50,
pull in the clutch,
hold it in,
down shift to neutral,
let out the clutch,
kill the engine and coast.

Observe that it still veers off to the right.

I believe this phenomenon is entirely attributable to the fact that the rear tire and the front tire rotate in parallel, but not coplanar, planes. I measured that, on my S, the plane of rotation of the front tire is translated 2.5mm to the left of the plane of rotation of the rear tire.

I've always hoped that someone (motoyoyo, you need another project since the clamps are now ancient history?) would construct a 2.5mm rear hub spacer to correct F/R alignment to confirm that this eliminates the annoying need for continuous counter steering.

[Guest24]

Well there you have it. So that's why my left arm gets tired on the long prepositioning hauls to the twisties. Whoda thunk it. Somebody please get me a 2.5 shim. That sounds so gringo. Our moto is build for form and shim to fit.

[bigscience]

I think we've been throught this one before. Do a search on this and you should find a thread with diagrams and part numbers for the spacers. my recollection is that the shims are a dealer part.

[bigscience]

here it is:

Help... R1100s steering angle

[Dan Alexander]

Originally posted by pwillikers
It has nothing to do with engine rotation.

Try this on a deserted, straight road with no crown (even if you think you are King):
accelerate up to 50,
pull in the clutch,
hold it in,
down shift to neutral,
let out the clutch,
kill the engine and coast.

Observe that it still veers off to the right.

I believe this phenomenon is entirely attributable to the fact that the rear tire and the front tire rotate in parallel, but not coplanar, planes. I measured that on my S, the plane of rotation of the front tire is translated 2.5mm to the left of the plane of rotation of the rear tire.

I've always hoped that someone (motoyoyo, you need another project since the clamps are now ancient history?) would construct a 2.5mm rear hub spacer to correct F/R alignment to confirm that this eliminates the annoying need for continuous counter steering.

You're a little more eloquent than I was but same idea

[pwillikers]

Thanks Mr. Science. I missed the prior thread.

Were any of you who tried the spacer able to confirm that it eliminated the bias for right turns?

[Bob Hancock]

Years ago I removed the spacer from my '98 R1100RT to put the rear wheel more in line with the front. Seemed to help just a bit. If I thought a spacer would really help, I'd just make one....should be a simple lathe project, but I don't notice it when working the bike and have learned to just sit crooked when "resting".

[squall_line]

I had to double-check and make sure that I was on the Pelican boards, and not on i-BMW again... There was a VERY lengthy thread over there about K12RS's that PTTR, spacers for 5.5" wheels, blah, blah, &c, &c...

[Ole Bike]

The old thread covers this topic pretty well and, as often, Big Science has the big picture.

In addition to being in the wrong direction, adding a spacer adds unwelcome forces to the hub bearings and they are already marginal. No reasonably-sized spacer can do much good. Just see how far you need to shift your backside off the saddle to balance the bike. I think that the bike's weight distribution is the culprit.

In the earlier thread, I said 15 lbs in the saddle bags will balance the bike. But at crawling speeds, even that is on the low side.

About coasting, that's about the only time you are hands-free on an S (unlike the /2 which had weak slide springs in the carbs and adjustable friction in the grip) and so it is the only time you'd really notice a pull. But somewhere at 50 mph or faster, wheel gyroscopic forces will balance the bike just fine and so you need to try coasting at different slower speeds to see how bad the effect is.

[roger albert]

I'll dissent and call the spacer still a good idea. The hub bearings aren't great, but not so poor as to be called marginal, I believe.
While they may be marginal for the heavier, more severe duty RT or GS (still very few failures there), they're not too close to the edge for the lighter, generally-less-pounded S model. And the shim amount is small enough that leverage is not greatly increased.
If you have the wherewithawl, mechanically (machinst like Bob)
it's not a bad move. I've never bothered, as it doesn't really bug me. But if you're struggling, it's a safe and judicious mod.

[Steve Carlton]

Surely BMW has to know the two wheels are not in the same plane. I would think there has to be a reason, but have no idea what it would be. On the 2000 K1200RS I had, the rear wheel was shifted to one side to compensate for the uneven weight distribution from the engine to keep it from pulling...

[pwillikers]

So, can anyone provide empirical evidence that a spacer corrects this behavior, ie. the need for continual countersteering?

[Rapid Dog]

the burning question...does the R12S do the same...

[Steve Carlton]

Needs a heavier front wheel. Pulls to the sky.

[frozen-nomad]

If you start the bike and leave it on the side stand, it will rock a bit and if you twist the throttle, the bike will pull harder to the right. Since you're not moving, I can't see how the non-aligned tires plays any role in the movement.