Starter Frustation

I need your help once again. I am still working on 72 R75/5 that I purchased last month. The bike ran when I looked at it and when delivered it wasn't running. Seller felt bad and credited me $500 to repair. Initially, I thought it was the starter since I get a click sound from the starter flywheel area. I kicked it and it turns so the engine is not seized. The compression is pretty high since the top end was just redone by the seller so I haven't tried to crank it with the kick starter since I am worried it might damage something.

Yesterday, I replaced the starter relay, coils, voltage regulator and engine wiring harness. All the items are new from EnDuraLast through EME. I checked the battery voltage (also new) and it was 12.8V and has been on a tender that says it is fully charged. I turned on the bike and pressed the start button and again the click-clock sound from the starter against the flywheel.

Any suggestions? I just ordered a new power and negative cable for the battery since the ones on the bike look original and could be the issue. Also, does the red wire from the battery go directly to the relay? I may replace it too but don't want to rewire the entire bike.

Thanks!

C

Looks like a brand new starter...is it? There are different teeth on starters depending on years...8 versus 9...so hopefully it's the right match.

What voltage showed at the battery when you hit the starter button? It might be 12.8v at rest, but it shouldn't drop below 10-10.5v during cranking or attempting to crank.

As for the red wire, yes a small red wire from the battery goes to terminal 30 on the relay. From there a small black wire from the relay goes to terminal 50 on the starter...I think this is the solenoid. The solenoid should close, which brings heavy power into the starter at terminal 30. You could check voltages all along this path to ensure you're getting 12+v at starter terminal 30. If not, then something is wrong going back to the battery. If you are getting 12+v there, then something is wrong with either the solenoid or the starter motor itself. I'd suggesting using a plastic handled screwdriver to short connections at the starter, but I'm unclear on which those are. That would tell you if the starter will turn or not.

Snowbum has some articles are starters and troubleshooting:

http://bmwmotorcycletech.info/boschvaleostarter.htm
http://bmwmotorcycletech.info/startingprobs.htm

There is also the issue with the /5s and the "cricket" noise issue. See his article here:

http://bmwmotorcycletech.info/slash5cricket.htm

This might be your problem.

Have you taken the front plate off? Might want to check to make sure you didn't pinch a wire from the Ignition Sensor wiring harness when you reinstalled it.

Remove the starter and check its operation on the bench.

Starter tooth count is sounding guilty from here.

Starter

yourpalcal said:

I need your help once again. I am still working on 72 R75/5 that I purchased last month. The bike ran when I looked at it and when delivered it wasn't running. Seller felt bad and credited me $500 to repair. Initially, I thought it was the starter since I get a click sound from the starter flywheel area. I kicked it and it turns so the engine is not seized. The compression is pretty high since the top end was just redone by the seller so I haven't tried to crank it with the kick starter since I am worried it might damage something.

Yesterday, I replaced the starter relay, coils, voltage regulator and engine wiring harness. All the items are new from EnDuraLast through EME. I checked the battery voltage (also new) and it was 12.8V and has been on a tender that says it is fully charged. I turned on the bike and pressed the start button and again the click-clock sound from the starter against the flywheel.

Any suggestions? I just ordered a new power and negative cable for the battery since the ones on the bike look original and could be the issue. Also, does the red wire from the battery go directly to the relay? I may replace it too but don't want to rewire the entire bike.

Thanks!

C

View attachment 72338View attachment 72339

Click to expand...

What kind of battery?
Have you load tested the battery, like take it to a NAPA and have them do it?
You can also do a voltage drop test when starting.

I worked on a R75/5 years ago that had the same issue. Owner put in a new battery that showed 12.8vdc with the key on, but slowly dropped voltage JUST with the key on. That should have keyed me in, but I troubleshot other areas and wasted a lot of time. In the end, I took the battery to be load tested and it failed.
Battery was a cheap Chinese knock off. Replaced with a brand new Odyssey and all issues were resolved.

+1 on load testing the battery. A multimeter can show plenty of voltage that is just a surface level. Load testing (you can get these from Harbor Freight for $20) reveals all.

First level load test is to monitor battery voltage when hitting the starter button. After doing that, decide what to do.

I've never needed to upgrade my airhead starter, but when you look at Motorad Electric's web site, you get the impression that the OEM Bosch starter leaves something to be desired:

http://www.motoelekt.com/starter.htm

Join the Airheads Beemer Club (MOA 214) at www.airheads.org. There are a number of knowledgeable, skilled members in your area who would be glad to assist and educate you. Dues are only $30/year, a whole lot less than you have already spent blindly replacing everything you can see. You will be happy you did.

Friedle
NY AM
ABC BoD

Cal, that's a beautiful bike! Don't put any more money into it until you know what's wrong. Follow the suggestions of the posters above. No more new parts!

Update

I pulled the battery out this afternoon and took it to an automotive shop. It tested fine and doesn’t seem to be the culprit. I put the bike back together and finally tried the kick starter to see if it would even crank. On the third kick the engine came to life. I did notice a spark from an area of the choke cable that had worn to bare metal. It was sparking were it touched the gas lever. I quickly turned off the engine and wrapped the exposed area with electric tape. Guys I’m at a complete loss on the starter. I fear I’m going to have to throw in the towel and take it to a mechanic. I’ve tested all the wires, verified the voltage of the battery and cleaned and dielectric lubed the connections. Frustrating to say the least.

Are these actually better than the Bosch starters? My '83 R80 G/S could use some new life in the starter.

Anyname said:

I've never needed to upgrade my airhead starter, but when you look at Motorad Electric's web site, you get the impression that the OEM Bosch starter leaves something to be desired:

http://www.motoelekt.com/starter.htm

Click to expand...

For your consideration-

https://forums.bmwmoa.org/showthread.php?69483-A-peek-inside-your-starter

OM

Guys I’m at a complete loss on the starter. I fear I’m going to have to throw in the towel and take it to a mechanic. I’ve tested all the wires, verified the voltage of the battery and cleaned and dielectric lubed the connections.

Click to expand...

You now know the bike runs. But have you removed the starter motor and tested IT ?

armartel said:

Are these actually better than the Bosch starters? My '83 R80 G/S could use some new life in the starter.

Click to expand...

I actually replaced the starter with one of the 8 tooth Enduralast from EME. I guess I didn’t mention that in my prior post. Although I did test the old Bosch starter and it was working although looked rusty.

Is there a noticeable difference in starter strength?

yourpalcal said:

I actually replaced the starter with one of the 8 tooth Enduralast from EME. I guess I didn’t mention that in my prior post. Although I did test the old Bosch starter and it was working although looked rusty.

Click to expand...

Sent from my iPhone using Tapatalk

No Start

I have a 1978 R100/7 had same problem, hit the starter switch than the dreaded click, hit the starter switch 5 or 10 times in a row and sooner or later bike would start to turn over you think starter switch the problem or bad spot in starter, starter relay. The starter and relays both under tank so hard to tell where click is coming from, in my case it was headlight starter relay ( relay cuts power to headlight as it sends power to starter ) replaced it starter worked as it should, you replaced relay new one could be bad, socket thing relay plugs into could be bad or bad ground.
Other possible problem bike looks way to nice and clean for its age, so Teutonic Beemer God’s may just be messing with you.

"I did notice a spark from an area of the choke cable that had worn to bare metal. It was sparking were it touched the gas lever. " That should not be happening. Do this: Follow and inspect the positive lead from the battery along the main frame to where it drops down to enter the engine housing just above and behind the diode board - actually through a 'u' shaped opening at the rear of the aluminum timing chain cover. Check to make sure that there is a rubber grommet surrounding the positive battery lead to isolate it from the engine through that opening. Next, make sure the grommet is intact and that the battery lead is not rubbing against the aluminum. Try the starter and watch closely around the starter solenoid where the battery lead terminates with a large ring connector on a large threaded pin at the back of the solenoid. If that connection is loose or in contact with the case or other connectors it will spark which equals a high resistance connection. It takes full battery voltage to activate the starter motor. If someone replaced the starter recently, the routing, insulation and connections for the positive lead might be the problem.

armartel said:

Is there a noticeable difference in starter strength?

Click to expand...

I tested both the old and new starter and both seem to work properly.