It has nothing to do with whether they are race compound or street.

As I mentioned, as long as they are warm enough, you can roll it right to the edge, slowly and it will scrub in just fine. The same applies to race tires. If you put 2,000 miles on them, but never roll the tire to the edge, it still won't be scrubbed in.

All I am saying is that miles is an irrelevant measurement of when a tire is scrubbed in or not. It has to do with what percentage of the tire that you have had on the ground.




That just means that you aren't leaning the bike over enough to scrub them in to the edge until you get to Deal's Gap. Go faster.

You only need to roll through four or five turns going from edge to edge on both sides before a tire is scrubbed. Which means that the top layer of sealant/coating that the manufacturer puts on the tires so it properly separates from the mould wears off.

Specifically speaking about street tires: as long as you are turning in slow enough, and the tires are warm, they shouldn't be slippery at all, even when scrubbing them in.

If they feel slippery or squirm around it means you probably don't have the right pressure, or that your suspension isn't set up correctly.

Damn. Exhaust on the K100RS has cracked /again/; this time in a different spot.

Unfortunately the after market exhausts available for that bike are just too damned loud.

So I'm going to have them weld it again and reinforce it some more. We'll see if maybe it holds this time.

This may be the beginning of the end for that bike. A new factory exhaust system will have the same problem.

Oh well. It's only money I guess.

Sucks about the crack in the exhaust. Sorry to hear that.

Seems like there must be an aftermarket exhaust system for it that is quiet. Do you have it on good authority that this is not so? Otherwise, would a new factory exhaust really have the same problem? Maybe it is cracking due to general fatigue and 50,000 miles of vibration and a new one will buy you another 50,000 miles. Maybe.

Sorry to hear it. Perhaps this repair will last for a bit though. Fingers crossed...

@Ian there is only the Remus exhaust available for that bike which is really loud, from what I understand.

Oh well, I ran that bike with a cracked exhaust for years and years. Maybe that's what it'll come to.

Or maybe I'll slap the remus on there the next time it cracks. Or maybe I can try to engineer something to relieve the stress.

The problems stems from the torque the engine puts on the exhaust as it twists slightly. The exhaust is rigidly mounted the frame so it tends to crack where the four pipes go into one.

Yea, sucks. Turning into a non-trivial amount of money.

At least it looks like the 'S is done. They found a bunch of problems. The clutch was toast, a bunch of seals were failing, some gear in the final drive was toast causing a bit of lash. It's all tuned up.

And @Duncan, yes, they fixed the clock so I am free to set it +/- 15 minutes randomly just to bug you.

Is this an option?

http://cgi.ebay.com/ebaymotors/Luftmeister-4-1-Exhaust-...

yea, no. That's strictly for the 2 valve bikes. After market options for the 4 valves are very limited.

Glad to hear the S is OK, sorry to hear that the clutch (and I assume the rear main seal) were hosed.

Weirdly, I was curious and looked at the parts fiche for the K100 exhaust. According to the diagram, the mounting bolts appear to go through rubber grommets, perhaps to help relieve stress from engine torque.

Theory: the rubber engine mounts are now getting really tired and allowing more movement of the engine than they used to, which in turn is allowing the exhaust to get further twisted, and stress crack sooner.

How hard would it be (or expensive) to replace the rubber engine mounts with fresh stiff rubber and the rubber grommets on the exhaust mounts, thereby reducing stress on the exhaust?

I'm guessing with the lash problem fixed in the S drive train, it'll shift better now, which is good.

Randomly, I've also heard that the remus exhaust for the K100 has a choice of a variety of mufflers, some of which are supposed to be very quiet, and compare favorably with stock exhaust noise levels

Thanks for fixing the clock on the S, now I can go back to compulsively setting it to the atomic clock

Lastly, Lance has an idea to modify the K bike's exhaust mounts to make it more like the S, where there's allowance for the system to move with the engine.

Remember that this is the second exhaust on that bike. The first exhaust fell apart completely after the '92 hell ride.

This is a known factory defect on the 16valve K100RS's. The exhaust systems crack and break.

I did not know about the quieter Remus exhaust options. If this latest fix fails I may give that a try. I really don't want to give up this bike. I like it too much.

Ah yes, I remember now about exhaust #1.

From what I've been able to gather about it, the Remus system should be lighter, breath better, and be quiet.

More Remus exhaust info:

There are two pieces, the header and the muffler.

Remus BMW K1004v part numbers and prices:

The header:

BMW1 K100 RS (89-92), K1100 RS/LT (92-on), K1 - all 16 valve! Header only, standard position, panniers possible. Must purchase a header for use of Remus muffler. 0101-087589 $529.99


The muffler choices for use with the above header:

Aluminum:

BMW1 K100 RS (89-92), K1100 RS/LT (92-on), K1 - all 16 valve! Innovation Round Street (quiet) Muffler (Aluminum) Must purchase the Remus header to use this muffler. 2102-087086 $359.99

or Titanium:
      
BMW1 K100 RS (89-92), K1100 RS/LT (92-on), K1 - all 16 valve! Innovation Round Street (quiet) Muffler (Titanium) Must purchase the Remus header to use this muffler. 2102-087086LT $469.99

They have at least two louder choices, but I'm betting you'd want the street muffler.

I got this from the website below:

http://www.motorsports-network.com/cgi-bin/dbsearch.exe...

Thanks for posting that. If/When this latest fix fails I'll probably just go ahead and order an exhaust. As I was saying, I really don't want to retire this bike if I can help it.

Maybe I can learn to live with a louder exhaust when the time comes.

Not having heard the Remus myself, I can't directly say how it lines up with the stock exhaust in terms of noise. But most reviews/comments you can find to read about it say it's comparable with the factory unit noise-wise.

In most cases aftermarket exhaust system are far better quality than OEM. Manufacturers are most focused on meeting emission and noise requirements while controlling costs than they are building hi performance and long lasting exhaust systems.

Duncan had a very good idea. If your bike has rubber engine mounts and they have never been replaced, they are certainly oxidized and probably not within operational spec.

You would probably be just fine by replacing the OE exhaust with the Remus while replacing the rubber engine mounts.

Replacing the rubber bits sounds like a good idea, but still, the original exhaust cracked after what, six months and 20,000 miles or something? I wonder what they charge for the rubber parts are.

Like Harleys, replacing the exhaust on a Ducati is almost mandatory, which people mostly just do for the sound. Mine is one of the few with the stock exhaust. I do like the sound of Ducatis with a nice aftermarket exhaust, but I'm with Yermo in that I want it to be quiet. Call me crazy...

To my knowledge the engine is a stressed member and the frame sections are rigidly mounted onto it.

I will probably end up going the Remus exhaust system route if this latest weld cracks, which I fully expect it to. In retrospect I probably should have just had the exhaust replaced, but the Remus exhaust doesn't have a catalytic converter ...