The New And Improved Unofficial R65 Forum V2
Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: pawepan2 on May 12, 2026, 03:31:23 PM
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Hello everyone and thank admin for adding me to the community!
I've been on the forum for a while, but now i have a problem i can't solve myself.
Recently i bought used BMW R45 from 1981yr. - the engine worked pretty fine; motor would start quite easily, i bought it with the new 12V battery.
However i wanted to maintenance it a bit: i serviced carburators (changed orings and gaskets; new gas, clutch and choke pulling lines; i refreshed wheels and put new tyres. I did not service electrical system. Now when I assembled everything all together - motor started nicely, but after a while it died. And i cannot start it with a electric starter or kickstarter.
Now after a little investigation i see that the problem is missing spark at the ignition. When i'm switching killswitch - there is a spark. I made a test with grounding middle connector on the wire leading to ICU - there was a spark at the grounded spark plug. I checked eletrical connections - it all seems fine. I even replaced ICU module. The coil seems to be fine, as the sparks show up when moving killswitch. The only time i could start the motor was when i launched it on impulse while pushing whole motor - then values shown on the tachometer were irrational. Even when i turn the bike with the key - tachometer shows about 1K for 1 sec without the motor running. The only thing i'm not certain about is the hall sensor - but it worked properly in the past. Can anyone help me solve my problem with the missing spark / lack of proper ignition? Thanks. Now I'm considering installing enduralast digital ignition system. :bmw_smiley:
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Hi !! Welcome to the site .
Sounds like you have an electronic ignition from your description .
Check to see if your ignition coil is a dual output black and gray coil .
Notorious for issues case cracking being the most common issue .
Do a check of the primary and secondary circuits of the coil .
Primary resistance 1.5 ohms, secondary resistance 11-13 k ohms .