Author Topic: BMW R90/6 no start -solved, loose wire on solenoid (Read 5418 times)

Schnell · « **on:** August 29, 2014, 01:35:59 PM »

1976 R90/6, parked in garage over winter, ran fine last year, won't start now,

new battery, battery ground good, starter relay replaced,

relay makes a click sound when starter button is pushed, that's all that happens

Starter engages when a jumper cable is used between battery and starter

What's wrong?

calj737 · « **Reply #1 on:** August 29, 2014, 01:39:49 PM »

The likely culprit is a battery with too low of voltage. Despite being "new" it may not be carrying enough charge, as demonstrated by the external source making it fire. By chance, have you checked the POS connection for corrosion and tightness?

70CB750 · « **Reply #2 on:** August 29, 2014, 01:41:12 PM »

With new battery, likely connection of the plus cable to the starter. Clicking is typical for old battery, enough power for the relay, not enough to turn the starter.

Since battery is new, you are not getting enough curent to the starter.

Schnell · « **Reply #3 on:** August 29, 2014, 01:42:13 PM »

Will check +'ve connection, and charge battery. Thanks!

cheftuskey121 · « **Reply #4 on:** August 29, 2014, 03:53:59 PM »

quick way to verify weak battery is using jumper cables from your car's battery. do NOT turn the car on, just pos to pos, neg to neg to use the car battery to jump the starter. if it fires up you pretty much have your answer about any weak battery. if it does not fire then it's time to bust out a checklist.

70CB750 · « **Reply #5 on:** August 29, 2014, 05:14:33 PM »

Quote from: Schnell on August 29, 2014, 01:42:13 PM

Will check +'ve connection, and charge battery. Thanks!

Thats a nice Bayerische Motoren Werke you got there, hope you get it running soon.

Schnell · « **Reply #6 on:** August 29, 2014, 05:20:12 PM »

Thank you!

Had the battery on a charger for a while, still just a click. I even switched the charger from trickle to 10 amps while trying the starter button. I'll clean up the wires to the starter tomorrow.

HondanutRider · « **Reply #7 on:** August 30, 2014, 05:42:06 AM »

You mentioned in your first post that the starter relay was replaced. Why? And is there a problem there as it now seems to be clicking and not switching power to the starter motor.

Schnell · « **Reply #8 on:** August 30, 2014, 05:48:28 AM »

I replaced the starter relay because I assumed it to be the cause of not starting. It wasn't.

HondanutRider · « **Reply #9 on:** August 30, 2014, 06:07:55 AM »

As mentioned earlier, a clicking relay when trying to start (without turning the starter and motor) is usually the result of a low battery voltage. What happens electrically is that there is enough current available to energize the relay coil, but when it connects the starter motor/secondary circuit the battery is unable to supply the current. The result is a clicking recycling of the relay.

One other thing that will also cause your problem is a major short from the secondary switching circuit of the relay. In other words, check to make sure the relay is correctly hooked-up to the starter and that it isn't grounding out when activated.

Here's a circuit diagram of what it should be like:

Schnell · « **Reply #10 on:** August 30, 2014, 06:28:17 AM »

No wires were switched between when it ran last year and when it wouldn't start this year. First, I replaced the battery. Next I cleaned the old starter relay contacts, one at a time. Then replaced the starter relay, switching over the relay wires one at a time.

70CB750 · « **Reply #11 on:** August 30, 2014, 07:08:43 AM »

Did you take reading with ohmmeter of the power side of the relay? With the starter button pushed, there should be almost zero between ground and + side of the switch.

Schnell · « **Reply #12 on:** August 30, 2014, 08:40:02 AM »

Good news! The motor is now turning over. There was a black wire disconnected from the solenoid. I'm not sure if I disconnected it and forgot to plug it back earlier this summer when I first looked at the issue. That was before my trip.

Anyway, thank you for your input. It is very reassuring when faced with a motorcycle problem to know that you aren't alone!

I dumped out the old gas in the float bowls, and am charging the battery. Even though it was new, after I abandoned it for 2 months over the summer, I could hear that it wasn't too strong when I used the starter just now to turn over the motor with he spark plugs out.

Hopefully it'll spring back to life by tomorrow.

HondanutRider · « **Reply #13 on:** August 30, 2014, 01:44:02 PM »

Good to hear that you've got it sorted. Now to start.

BTW I've re-posted my diagram above to make it a little clearer that the starter relay is connected to the Positive terminal for the switch side, as well as for the starter motor side. This Positive power line usually comes from the keyed ignition switch. The ignition switch and the starter switch can't handle the high current drawn by the starter motor, which is why a relay or solenoid is used to make the connection. Sometimes the headlights are also run through a similar relay system, since their high current can be diminished by running through all the switch wiring which dims their output...besides possibly extending the life of those switches. The Hondaman Ignition uses a similar principal on the points, but in this case using an electronic transistorized relay instead of a mechanical one, which wouldn't be fast enough. (His circuits also do some other things to boost the power to the coils/sparks.)

Sorry for the theft and long explanation.

Schnell · « **Reply #14 on:** August 30, 2014, 02:45:55 PM »

Why is there an iPhone above the word "starter" in your diagram?

HondanutRider · « **Reply #15 on:** August 30, 2014, 04:52:24 PM »

That's a connector.

Schnell · « **Reply #16 on:** September 01, 2014, 10:56:24 AM »

Charged up the battery, hooked up the gas, and she fired right up. I mean immediately! This, after sitting for 12 months. Impressed.

70CB750 · « **Reply #17 on:** September 01, 2014, 12:52:50 PM »

To be fair you must ride her the same route as your CB, I would CCW now if I were you.

Schnell · « **Reply #18 on:** September 01, 2014, 01:13:32 PM »

Hi Procop, I'd have to become single first!

HondanutRider · « **Reply #19 on:** September 01, 2014, 01:29:07 PM »

"Becoming single" and "CCW" just do not go together.

Schnell · « **Reply #20 on:** September 01, 2014, 02:39:55 PM »

What does ccw stand for?

Bob Wessner · « **Reply #21 on:** September 01, 2014, 03:30:18 PM »

Wondered what meant also. ??

calj737 · « **Reply #22 on:** September 01, 2014, 03:39:00 PM »

Counter-clockwise

70CB750 · « **Reply #23 on:** September 01, 2014, 03:43:50 PM »

Yeah, means to go West first and come up the East coast.

Funny, wifes make the effort to change a man and then say: you are not the wild guy I fell in love with anymore

HondanutRider · « **Reply #24 on:** September 01, 2014, 04:48:06 PM »

CCW - hmm, lets see if the old west concealed or not. Then I might want to carry something in any case.

News:

Author Topic: BMW R90/6 no start -solved, loose wire on solenoid (Read 5418 times)