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Old 10-30-2012, 03:19 AM   #1
a_bakla OP
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Joined: Oct 2009
Location: Turkey,Tekirdağ
Oddometer: 126
airhead Ignition Control Unit ( ICU)

My G/S runs with an ICU different than the stock one.I think bike previous owner changed it. I ve searched that what is it? İt is russian car Lada's igniton control unit????.I've found specs of this unit. (3620.3734)

Range of operating temperatures, С
-40 .. +85

Nominal supply voltage, V

Permissible limits of supply voltage, V
6,0 .. 18,0

Range of an uninterrupted spark formation, rpm of the crankshaft of the 4-cycle 4-cylinder engine
20 .. 7000

Commutating current, А
7,5 0,2

Time of a sparkless cutoff of a collector current, sec
1 .. 2

Maximum allowable influence of the increased supply voltage up to 5 min. at the spark formation frequence more than 200 Hz (6000 rpm of the crankshaft of the 4-cycle 4-cylinder engine), V

Maximum allowable pulse overvoltages of a positive and negative polarity, V

And schematics is there :

I wonder is this unit suitable for an airhead ?
I am planing to convert my g/s to twin spark.I ve already drilled the heads and and searching for second ICU and coil.
This unit is very easy to get and cheap (10$). Can I use this unit or is it better to get stock black ones?
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Old 10-30-2012, 05:20 AM   #2
Rob Farmer
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Joined: Aug 2002
Location: Loughborough, Leicestershire. England
Oddometer: 5,874
With the exception of the kickstart icu the ignition modules are the same as dozens of European cars from the 80s and 90s including Porsche. The most common variant is a Lucas dab400

Rob Farmer screwed with this post 10-30-2012 at 05:27 AM
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Old 10-30-2012, 05:55 AM   #3
Stay Horizontal
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Joined: Jul 2009
Location: Melbourne, Oz
Oddometer: 2,665
Not sure they're quite the same over the years. There were a few updates finishing with the turquoise lettered one being the last and covered all predecessors. Other versions may work, but they may not be the same despite appearances.

The turquoise lettered ICU
pn 12-14-2-325-284 with riveted heat sink instead of small bolts is the last one made by BMW. The heat sink is integral and doesn't require periodic servicing of heat sink paste. It has the latest updates and works for bikes with a kicker or not.
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Old 10-30-2012, 08:50 AM   #4
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You need a second coil, but I don't think that you need a second ICU.
R90s 1070 replica, R90/6, 1958 R50
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Old 10-30-2012, 01:14 PM   #5
because I can
Joined: Sep 2010
Location: San Francisco Bay area
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ICU's are not all the same. The torquoise ICU's from BMW can take lower coil primary resistance. Tha'ts the main spec to deal with regarding ICU's which I can't ascertain from those specs. The rev limit is too low as well if it matters? Run the same primary resistance as what the ICU was originally run with or a little higher but never lower. That will fry the ICU. Too high Primary resistance can weaken high rpm spark from what I have read although I haven't found this out for myself. I HAVE found out about matching ICU's to too low primary resistance myself!

I am running two .7 ohm dyna's on my dual plugged stock bean can with the weight stops bent in to restrict full advance. It is running good!
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Old 10-30-2012, 09:46 PM   #6
Loose Pre Unit
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Joined: Dec 2001
Location: New Zealand
Oddometer: 4,619
The Lada Samara uses the BIM 137, it's used in a lot of after market ignition systems because it adjusts dwell. It's the same case as the airhead module - you'd need to see a diagram of the pins to know if it relates to the one on airheads. Worth a try on someone else's bike.
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