Any guesses out there? The tac and the rough motor at the same time seem suspect of electrical probs.I have never had any problems and the bike has been regularly at BMW. Any help is appreciated. I need a ride.

The first place I would look is the coils and the connections to them as that is what the tach and engine have in common that would cause that sort of problem. Clean all the connectors with deoxit and check the coils for cracks in the outer insulation.
If it ran fine in January then I assume it has not been riden since then till now so a corroded connector is quite likely.
Other than that a possibility is a wire that is shorting to earth intermitently and causing it. Look for chafed wire harness more so round the steering head as that is the likely place for that type of damage.
Unplug the computer (ECU) and clean the terminals with deoxit (from Jaycar) and replug it. Even just unplug and replug may do the trick.
If none of that works get back as there is heaps of help and knollege here and most are only too willing to lend a hand.

I'll check those out, thanks.

A heads-up for the folks who can't shop at Jaycar in Australia/New Zealand (like in the USA/Jaycar is sorta like your Radio Shack) you can get it from this source, and perhaps others:

http://www.caig.com/

Similar problem today. Check the battery.

Check your wiring harness connection into the EFI unit, mine got loose somehow and made the bike run intermittently.

Checked coils,battery(new),ecu plug,the bike is in limp mode. I'll check EFI connection next.Thanks for the replies.

still no dice!! argh

Hi,
There is no limp mode on these bikes AFAIK that only came on cars with full engine mamagement.

When you say it runs rough is that at rough all revs from idle to high revs? Are all the plugs sparking? Is the fuel injection pulsing regularly or is that also irregular? Are all injectors spraying cleanly? Did you clean and treat the plug from the chassis to the fuel tank to ensure the fuel pump has a continuous supply?

The way to fix these sort of problems is to work through them logically and carefully as you check and clean each connection with DeoxIT you are then able to be more confident that you have eleminated that as an issue electrically.
Regards,
K-BIKE

i just wonder if the earth cables (left hand side of the bike and under tank connections ) is not connected properly ...would be a good idea to clean this up...but seeing that it starts ok ..the primary cable at the gearbox must be ok .... so check the earth under the tank as well

going to install unrelated thermostat and put things back together again today. I'll have an update later today.Thanks again for replys and help.

Tach was coil related but I need a new ignition modual. 1400$$!! from BMW. Anyone know where I can find one used?

Dont go buying a new Ignition module there are quite a few around on places like fleabay, I saw 2 or 3 there a few days ago from around $50 - $100, it should not be hard to find one. It is very unusual for a bike to run at all if the CDI is fried.
Usually the CDI is either good or absolutely RS before you spend any money clean the CDI plug contacts with Deoxit and any plug that has anything to do with the ignition. That includes the Hall sensor plug under the tank and the plug from the right handlebar switch. and just about any plug you can find but skip any bath plugs you may find.

I would be very wary of a diagnoses like that when the engine runs in any fashion.

I agree with K Freak use the DeoxIT and dont use any abrasive on the contacts initially treat all contacts related to ignition and running and don't use dielectric grease after. If you want a follow on use DeoxIT Shield.
Regards,
K-BIKE

On the road again with the new I C M. thanks for the replys

hmm odd...... but good to hear you got a fix ... yay !!!