The Airheads Beemer Club is a non-profit club reclaiming the 'Legendary Motorcycles of Germany'

Topic-icon Elevated Engine Idle RPM

More
2 months 5 days ago - 2 months 3 days ago #5209 by Wobbly
Replied by Wobbly on topic Elevated Engine Idle RPM
Auto Advance Unit was my first thought at the very beginning, but I was assuming your model had electronic ignition, so I discarded the thought. But 'Yes', if you have points, then them being situated inside a "bean can" virtually assures us that they and the associated AAU haven't been properly serviced in 20 years.

At this point we need to change the conversation. If you are really serious about engine vibration, long mileage trips, and optimal performance then you should consider installing an electronic ignition. Unfortunately, a lot of myths about EI have built up over the years and lingered. First Gen units were plagued with chip set reliability. (I remember purchasing an EI in 1976 and printed right there in the instructions were "If this unit fails in the first 2 weeks, it's faulty transistors and we'll replace it free.") Second Gen units were susceptible to battery voltage issues. If the battery went below 12.0V then the transistors simply wouldn't fire. You'd have dim headlamps, but no spark. But all that is behind us now.

These days with battery start only, if your battery isn't strong enough to turn the engine over, then you're not going anywhere anyway. And with most riders opting for more reliable AGM, sealed cell, and lithium batteries, well, all the issues with EI are simply things of the past.

Don't hide 'em, Ride 'em !!
#15150
Last edit: 2 months 3 days ago by Wobbly.

Please Log in to join the conversation.

More
2 months 4 days ago #5214 by 895
Replied by 895 on topic Elevated Engine Idle RPM
I learned at https://www.bmwr65.org how to troubleshoot the centrifugal spark advance (ATU) as follows: Aim timing light into timing port.
With engine operating in high idle condition, select a gear and let out clutch a bit to drag down engine RPM. If the "S" mark isn't moving into view when engine is dragged down to 1000 RPM then the ATU advance weights are stuck and/or the springs are sacked.
[

Please Log in to join the conversation.

More
2 months 3 days ago #5217 by Wobbly
Replied by Wobbly on topic Elevated Engine Idle RPM
With all due respect, you are dodging the issue. The AAU has been ignored and as soon as it's running as good as it can, it will be ignored again.

My points....
• Mechanical advance was never precise, even when new it was only just barely "good enough"
• 40 years later it's flat worn slap out, and will never be "good enough" again
• Install an EI and be done with it

Don't hide 'em, Ride 'em !!
#15150

Please Log in to join the conversation.

More
2 months 3 days ago #5218 by 895
Replied by 895 on topic Elevated Engine Idle RPM
It's my riding partner's R65 and he has purchased an EnDuraLast electronic ignition system. He's a computer science engineer but I'll still help him :)

My preference would be to service the stock bean can but it's not my bike. I don't like electronic ignition systems because if/when it quits then you're dead on the side of the road. No one in the Airhead community and no amount of the Airhead's operating experience is going to get a dead electronic ignition functioning again.

My own bike is a 1973 R75/5 and I adhere to the KISS engineering principle which is the same as Canon #2. It has a mechanical ignition trigger (Norris contact breaker points) which are user serviceable. My experience is the reverse-engineered, far-east points are poor quality with incorrect dimensions. A mechanical ignition trigger system requires one to periodically lubricate the felt, check the gap and timing. Full disclosure: I'm a mechanical engineer and accept this concession in the interest of KISS.

If the points gap were to become too narrow then this system provides a warning (engine stumble when starting off). The engine doesn't simply quit running as would occur with an electronic ignition. I do carry a spare set of points with me.

Please Log in to join the conversation.

More
2 months 3 days ago #5220 by Wobbly
Replied by Wobbly on topic Elevated Engine Idle RPM
I'm not here to argue, but IMHO your thinking is out of date.

As I explained previously, there was a time in the 1970's that 1-2% of chips failed. I'm also an ME, and one of my first jobs was working at a company that supplied computers to the military. We had to run all those at extended temperatures (140°F) for 48 hours to stress the chips and hopefully force weaker components to fail. But that was the 1970's, and it's no longer true.

Consider the irony embedded in your statement: You tell me you won't use an EI with maybe 15 transistors because one of them might fail. And you defend your position by sending a message using a home computer having maybe 10 or 20,000 transistors. Connected to your home's wireless network with routers and modems through a million more transistors. None of which have ever failed.

Or did you use your smart phone ? :P

All the best.

Don't hide 'em, Ride 'em !!
#15150

Please Log in to join the conversation.

More
2 months 3 days ago - 2 months 3 days ago #5221 by 895
Replied by 895 on topic Elevated Engine Idle RPM
I want a machine that can tolerate the electromagnetic pulse of a nuclear blast :) My ignition points would take me to Prudhoe Bay and back.

If service was needed I hope I could do it myself on the side of a dirt road, in the dark while it was raining. No electronic diagnostic equipment necessary but bug repellent highly recommended.

There would be no help available from the Airhead community via computer or cell phone but it sure would be nice if a well-armed friend stood watch for grizzly bears :)

PS Computers, modems and wireless networks fail all the time. I like the convenience of an electric-start and the availability of a kick-start.
Last edit: 2 months 3 days ago by 895.

Please Log in to join the conversation.

Moderators: 8166Wobbly
Time to create page: 1.182 seconds