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Airhead ICU
Posted: Fri Oct 05, 2012 4:39 am
by SteveD
These are made by Telefunken.
They come with white, blue or pink lettering, with different combination of numbers written on them.
How interchangeable are these parts? Even the mono R80RT ICU's have different identifiers written on them.
Some info from Anton Largiader here...http://www.largiader.com/articles/ignition/
Re: Airhead ICU
Posted: Fri Oct 05, 2012 5:59 am
by ME 109
One difference between them is that kick start and non- kick start are different.
Re: Airhead ICU
Posted: Fri Oct 05, 2012 6:52 am
by StephenB
The earlier ones (1981+) were designed for 1.5Ohm dual coils, later ones were designed for 0.7Ohm dual coils, so if you need one get the 1992+ (or so) type.
Re: Airhead ICU
Posted: Fri Oct 05, 2012 8:07 am
by SteveD
ME109 wrote:One difference between them is that kick start and non- kick start are different.
StephenB wrote:The earlier ones (1981+) were designed for 1.5Ohm dual coils, later ones were designed for 0.7Ohm dual coils, so if you need one get the 1992+ (or so) type.
Do you know if the later ones consider the kick starter?
Re: Airhead ICU
Posted: Fri Oct 05, 2012 8:15 am
by SteveD
ME 109 wrote:One difference between them is that kick start and non- kick start are different.
The Maxfiche make no mention of it. I wonder if Snowbum has some info. I'll be back in a day or so!
edit: 
Back already from Snowbum territory. He's got all the info...who'da guessed! http://bmwmotorcycletech.info/Ignition.htm 'bout a quarter way down the page.
The kickstart version just shut off a little later than the other one, but that was later changed to be the same anyhow.
Re: Airhead ICU
Posted: Fri Oct 05, 2012 8:20 am
by StephenB
They should, because kickstarter gearboxes were always available optional. But I don't know. Anton said in his article:
"3) Around 1991 the black coil (BMW 12 13 1 244 426, Bosch 0 221 500 203) was introduced. This coil has a 0.5~0.6 Ohm primary resistance. The ICM was simultaneously upgraded so that it cut off coil power after 1.2 seconds of inactivity, to prevent overheating damage to the coil, and presumably was rated to handle the higher current draw of the new coil. These ICMs have turquoise lettering (shown here) rather than white or pink. BMW recommended against using the new coil with an older ICM lacking the time cut-off. It's a good idea to periodically remove the module and apply some heat-sink paste between the module and the cooling plate (on older models with separate heat sink).
Newest ICM
Even more recently, the ICM was upgraded again, now marked with the current part number 12 14 2 325 284 (Temic #1885A2) and integral heat sink.
Based on that I'd say all of them 1991+ will have the cut off time feature integrated.
Re: Airhead ICU
Posted: Fri Oct 05, 2012 8:57 am
by SteveD
Snowbum says the latest turquoise coloured ICU will cover all the previous models, but some of the others may not. It's all there to read and learn what's appropriate. Just takes time and patience to read.