timing issue and points question

[ThompsonJP]

Hey,
I wanted to post about a problem I've listed before, but needed to clear up confusing information, so here goes.
I have a 1974 R90/6 with 82,000 miles. A few months ago, my Dyna III ignition system failed. (It was 12 years old.)
I installed a "Digital Ignition System - BMW Airhead with BOSCH Alternator / EnDuraLast & Sachse" from Euro Moto. It is an optical system with a disc mounted on the front of the crankshaft.
Since installing it, I've had intermittent problems with sputtering, stalling, and exhaust backfires. The bike runs fine at initial startup and for the first few minutes, then the symptoms appear. When I run the bike at high RPMs (4,000 plus) they mostly disappear.
I really have two questions.
Question 1 is finding the problem with the ignition system. I've gone through the troubleshooting list in the guide and communicated with Euro Moto. Here are the things I've done:
- checked proper installation of unit
- checked for loose or pinched wires
- replaced older plugs with correct non-resistor plugs
- checked resistance of plug wires
- checked resistance of coils (they are original, should work according to the user manual, and were doing fine before)
- installed a new battery (my old one was 6 years old)
- check timing at idle and 3800 rpms and both are good
- did ignition module self test described in manual
- I also recently rebuilt the carbs and worked hard to balance them, which I think I did
I think that's it. I'm getting pretty frustrated with a system that is supposed to be trouble free once set up.

Question 2 is about reverting to points to see if I can get that to work. I've never had them and don't know much about the system. I don't even know exactly what it is I have now, so I'm including some pics.
Any help would be greatly appreciated.

[schrader7032]

What you currently have is the Dyna III system. It consists of the advance weights, which are stock, and that round blue plate underneath. It has the pickup points (Hall effect sensors) on it...those curved black modules. Something you can't see is a donut that has been tightened to the shaft of the advance unit.

To convert back to points, you will reuse the advance unit but without the donut. Then you need everything else in this picture:

https://www.realoem.com/bmw/enUS/showpa ... Id=12_0743

Another round plate with is the plate to mount the condenser and the physical points which is shown already attached to the round plate.

If you don't have these parts, it's going to be hard to convert back. I have a Dyna III system on my /7 but I carry around on the bike all the parts I took off for the conversion. Not sure where to get those parts, especially the round plate. There are salvage yards, one called Airhead Salvage and a guy by the name of Joshua Buck in California. The condenser can probably be source...maybe BMW. The points are something that someone like Max BMW probably sells. Max shows condensers and points on their site. The round plate is NLA.

[ThompsonJP]

Thank you. I know some places to chase down those parts.

[schrader7032]

EME is usually pretty good on customer support. You might have a faulty unit from them. Seems like they should step up and send you some new modules to figure out what is wrong.

[toolmandoug]

I installed the same system last year on my 93 RT conversion and was so impressed with it that I installed the same system on my R60/5 this spring, in fact just finished a test ride and read your post while eating lunch. I had the dyna system on the /5 and never could get the timing right, always ran sluggish. With the optical system it runs like a totally different motorcycle. Couple of thoughts, if coils are original replace them even if they ohm out correctly and check to see if they are wired correctly. Check coils when hot and cold and see if values change. When it comes to old electrical components I generally replace them before problems begin, I do not want to be stranded along the road. Make sure valves are adjusted. Looks like you have done all the right steps so far.

[srankin]

I am going to assume your ignition system is OK aside from the suggestions of others in the post. It has been suggested you check your valves. 83K is pretty decent milage and maybe they are worn out? Have you noticed you have had to adjust them more frequently than the usual 15K interval? Can you do a leak down test? Do you maybe have a vacuum leaks somewhere? The big inlet rings between carb and heads do wear out or crack with age causing leaks.

Also when was the last time the carbs were rebuilt? The diaphragms get old and can cause problems, o-rings internal can get old with age. Yeah, I know, it is more work to look at. In tune up for airheads always check valves first. Then ignition finally carbs. Are the chokes working properly? Good luck, St.

[ThompsonJP]

Thanks for the suggestions. I recently had the engine rebuilt, and I've checked valve adjustment since then twice. Also, the carbs were rebuilt while the engine was being worked on.
I think I'm down to ignition coil incompatibility with the optical ignition system, which Euro Moto says can happen, though it's not supposed to with the original coils. The other likely culprit is the brains of the unit, though that passed a self test.
I'm waiting word from Euro Moto, at this point.

[srankin]

I am installing a EME package of charging, ignition and starter on a project bike right now. With the package I got a new coil.

The instructions are pretty neat as they cover a lot of variations between bikes and years. I have the components installed and today or Monday I hope to start reinstalling the bike's main wiring harness. Then I will know if I got things right or messed up, LOL.

Looks like you are covering the bases, I hope you find your issue. Good luck, St.