Motorrad Elektrik Ignition

Discuss all things 1970 & later Airheads right here
Roy Gavin
Posts: 386
Joined: Tue Aug 03, 2010 11:21 pm
Location: Adelaide Australia

Re: Motorrad Elektrik Ignition

Post by Roy Gavin » Mon Nov 13, 2017 9:40 pm

Those who have tested find that optimum timing varies up to 6 degrees from bike to bike, from -2 to +4 , so go dont fret about these marks.
The factory manual says line up the Z mark at either 3000 or 3200 revs, it does not say that this is either max advance or that it should occur at these revs.
Standard grade fuel can burn around 2 degrees faster than some premium, so if you were to try a tankful or two you might get some idea what difference a couple of degrees advance will do.
And it is a uncontested fact that running an air cooled two valve motor at the leanest setting for max power will give reliability problems if you actually use the power you are chasing.
Remember too that some of the later carbs with weak setting also had a different part number for the piston return spring, which is a good bit stiffer than the earlier one and will richen up the mixture in transition, where the motor spends at least 99% of its time.
Some folks like the stiff spring with the early rich settings, some like to set the carbs in warmer times and drop the stiff springs in for the colder months, depends on how accurate you have the carbs set up.
Adelaide, Oz. 77 R75/7. 86 R80 G/S PD, 93 R100 GS, 70 BSA B44 VS ,BMW F650 Classic

User avatar
Gibson
Posts: 91
Joined: Tue Apr 19, 2016 11:45 am

Re: Motorrad Elektrik Ignition

Post by Gibson » Wed Nov 15, 2017 11:57 am

Thanks Roy, that is great info and very helpful. I have not yet had a chance to re time the ignition. I do not believe it is running lean. The carbs are synchronized and in good clean shape. No vacuum leaks. Plugs look good.
Bike never had any pinging issues under normal running conditions.
I am going to set up the "Z" slightly above the timing mark on the case and let the idle timing fall where it winds up. I may need to re-adjust the idle speed on the carbs if the idle speeds up.
When timing for max advance I use 3400 rpm because that is after full advance.
Honestly, I think due to the mildly tuned nature of these bikes, and better cooling than many other air cooled machines, a range of acceptable timing settings will be fine. I will listen carefully for pinging and keep an eye on the plugs.

Roy Gavin
Posts: 386
Joined: Tue Aug 03, 2010 11:21 pm
Location: Adelaide Australia

Re: Motorrad Elektrik Ignition

Post by Roy Gavin » Thu Nov 16, 2017 12:17 am

In the days when auto distributors had a click knob on them which let you change the timing one degree at a time, and no one had either a rev counter or a timing light, and rolling road dynos weren't around, all that was done was to set the static timing to give the fastest tickover, then take the car to a decent test hill .
A few runs were done, advancing timing a couple of degrees at a time until there was no improvement in the speed at the top off the hill. Then we went back to the previos setting.
If you mark the the adjustment slots on the bean can you can do the same, and it works as well as any other system.
Or you can fit a ignition system with a knock sensor, but you will have to assemble it yourself.
In Oz Jaycar sell a knock sensor ignition kit which runs from a hall sensor but I imagine any decent auto technician will know of a system which also does and is easy to source from a auto wrecker.
FWIW done on a test hill I ended up with the Z mark on my twin plug 1000cc G/S so far down at 3000 revs I cant see it - probably 24/25 degrees, with the curve on a Boyer Micro Power system.
Adelaide, Oz. 77 R75/7. 86 R80 G/S PD, 93 R100 GS, 70 BSA B44 VS ,BMW F650 Classic

User avatar
Gibson
Posts: 91
Joined: Tue Apr 19, 2016 11:45 am

Re: Motorrad Elektrik Ignition

Post by Gibson » Thu Nov 16, 2017 10:45 am

Yea, Twin plugs reduce the distance the flame needs to propagate by 1/2 on the airhead. Considerably less advance is needed. Reduces detonation tendency on old airhead combustion chamber shape and domed pistons as well. Great mod.

User avatar
Gibson
Posts: 91
Joined: Tue Apr 19, 2016 11:45 am

Re: Motorrad Elektrik Ignition

Post by Gibson » Fri Nov 17, 2017 7:10 am

Last night I re-timed the ignition. Burned myself a few times on the headers. I strongly recommend wearing gloves and a long sleeve shirt! I did a 20 minute test ride. Only about 50 degrees out. Not only does the bike run great, but it starts easier too. No sign of pinging so far. I am very happy with this system!

Wobbly
Posts: 125
Joined: Mon Aug 07, 2017 8:48 pm

Re: Motorrad Elektrik Ignition

Post by Wobbly » Fri Nov 17, 2017 9:33 pm

Glad t hear it.
After 20 years as a professional bike mechanic and 30 years as an engineer I know just enough to be dangerous !

Foxy
Posts: 30
Joined: Mon Dec 02, 2013 6:55 am
Location: South West Victoria

Re: Motorrad Elektrik Ignition

Post by Foxy » Sun Nov 19, 2017 3:29 pm

I thought you’d be happy with it. I put one on my Seibenrock kitted 72 R/75 a few years back and it is perfect. No twin plugging required. No pinging, detonation whatever you wish to call it even on 91 oct fuel here in Oz.
I tried a couple of other electronic ignition units prior and they were flakey at best.
They are sold under different names around the world. Alpha here in Oz I think.

User avatar
Gibson
Posts: 91
Joined: Tue Apr 19, 2016 11:45 am

Re: Motorrad Elektrik Ignition

Post by Gibson » Mon Nov 20, 2017 7:42 am

I just wanted to make it clear that all of the issues I had were MY fault and not the system. I was rather cavalier about setting the timing initially. After racing outboards for 20+ years I should know better!! I did learn however that BMWs timing timing specs work best. That's not a surprise either! When I finally got it right, I took my time and carefully highlighted the timing marks on the clutch carrier with a soft yellow pencil. Turning the unit on the front of the engine to adjust timing is VERY sensitive, but getting it perfect pays off. Thanks everyone for all the help and good advice. I now just have to make the carb changes suggested above to make it as good as it can be....

Wobbly
Posts: 125
Joined: Mon Aug 07, 2017 8:48 pm

Re: Motorrad Elektrik Ignition

Post by Wobbly » Mon Nov 20, 2017 10:44 pm

Gibson wrote:
Mon Nov 20, 2017 7:42 am
I now just have to make the carb changes suggested above to make it as good as it can be....
And that's the exact correct order of things. You can't effectively tune the carbs until you are 100% sure the timing is absolutely correct, the wires, caps, and plugs are in perfect condition, and all other static adjustments are completed.

;)
After 20 years as a professional bike mechanic and 30 years as an engineer I know just enough to be dangerous !

Post Reply