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Old 06-10-2012, 11:26 AM   #1
teenager from mars OP
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Omega ignition high speed stumble

long time lurker first time poster. Have been monitoring the board for a long time to try and learn something. My current daily driver is a 76 R75/6, and have been experiencing a intermittent high speed hesitation at highway speeds. Around town, stop and go, mostly no problems. Toward the end I was getting stalling and hard start after the engine was nice and hot.

Though it had all the symptoms of fuel starvation or torn diaphrams. Adjusted the valves and rechecked after a few hundred miles. rebuilt the carbs, checked timing, cleaned the petcocks, new air filter, new fuel lines and in inline fuel filter. Symptoms of high speed hesitation became less dramatic but still very noticeable.

Finally traced the problem to the omega electronic ignition that I installed over 5 years ago and has been problem free. Purchased the ignition unit from Mr. S. Bottcher when he was the north american distributor. I know it is coming from the unit because I change the one wire and run points without a problem. Convert it back to the omega and the problem persists.

Omega has been changing hands for two years now, so I might be out of luck. But has anyone else experienced similar problems??

thanks-
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Old 06-10-2012, 12:20 PM   #2
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Sorry to hear your story but thankfully, my Omega is working perfectly so far.

Sorry that I cant help.
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Old 06-10-2012, 01:06 PM   #3
StephenB
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Quote:
Originally Posted by teenager from mars View Post
I know it is coming from the unit because I change the one wire and run points without a problem. Convert it back to the omega and the problem persists.
Sorry to hear that, sounds like the electronic advance isn't advancing properly. You can check that with a timing light, see what the F mark does when you rev up to 3000+ rpm. If it doesn' advance use the switch to change the setting for greater advance. Maybe it needs some convincing.

Not much else you (or I) can do.

Your next best solution is adding the DnaBooster to your points setup. I used that on one of my bikes. Many believe it is the perfect solution, beating any Electronic Ignition from a reliability and serviceability point of view. Increases points life too (25k+ have been reported for points life).
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StephenB screwed with this post 06-10-2012 at 01:15 PM
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Old 06-10-2012, 02:57 PM   #4
teenager from mars OP
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Quote:
Originally Posted by StephenB View Post
Sorry to hear that, sounds like the electronic advance isn't advancing properly. You can check that with a timing light, see what the F mark does when you rev up to 3000+ rpm. If it doesn' advance use the switch to change the setting for greater advance. Maybe it needs some convincing.

Not much else you (or I) can do.

Your next best solution is adding the DnaBooster to your points setup. I used that on one of my bikes. Many believe it is the perfect solution, beating any Electronic Ignition from a reliability and serviceability point of view. Increases points life too (25k+ have been reported for points life).

checked the timing with a timing light. S mark dead on at idle, and dead on F at 3000+ RPM. The advance curve is set way past "4" to whatever the made the F drop in at 3000+ RPM. I still think the OMEGA is a great product and would buy a second if still available.

Thank you Mr Bottcher for your quick response. Maybe I'll look into a dynabooster.
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Old 06-10-2012, 03:59 PM   #5
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FYI,
My POINTS currently have 50,000 MILES on them......they WILL be replaced sometime this summer.
The bike still runs very well!

Your points may vary....

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Old 06-11-2012, 04:50 AM   #6
StephenB
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Originally Posted by teenager from mars View Post
checked the timing with a timing light. S mark dead on at idle, and dead on F at 3000+ RPM. The advance curve is set way past "4" to whatever the made the F drop in at 3000+ RPM.

Hm, you could have a coil(s) that is giving you trouble at high rpms or heat because of an internal short. If "S" and "F" are dead-on there might not be a problem. I once had a R80G/S that needed about 3-5min of starter movement before the bike started. Traced it to an internal short of the coil: it needed to get warmer for the short to close, no problems at operating temperatures after that.

I'd try the coil next if I were you. What have you got to loose?

One would think, that you should have the same problem when running points (you only swapped one cable), but then, dwell times are diffferent between points and the OMEGA: points have a fixed dwell, the OMEGA has variable dwell time depending on rpm. With a dodgy coil, the shorter dwell times at higher rpm might cause a problem manifesting itself as high speed stumble feeling like fuel starvation. That goes in line with your observation: "... have been experiencing a intermittent high speed hesitation at highway speeds. Around town, stop and go, mostly no problems."


Stephen
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... i'm not touring around the world, but neither are most of the guys i see running overloaded spam cans ... [bmwblake]

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Ontario, Canada

'72 R75/5 The Blues

www.stephenbottcher.net

StephenB screwed with this post 06-11-2012 at 04:58 AM
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Old 06-11-2012, 03:56 PM   #7
teenager from mars OP
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Quote:
Originally Posted by StephenB View Post
Hm, you could have a coil(s) that is giving you trouble at high rpms or heat because of an internal short. If "S" and "F" are dead-on there might not be a problem. I once had a R80G/S that needed about 3-5min of starter movement before the bike started. Traced it to an internal short of the coil: it needed to get warmer for the short to close, no problems at operating temperatures after that.

I'd try the coil next if I were you. What have you got to loose?

One would think, that you should have the same problem when running points (you only swapped one cable), but then, dwell times are diffferent between points and the OMEGA: points have a fixed dwell, the OMEGA has variable dwell time depending on rpm. With a dodgy coil, the shorter dwell times at higher rpm might cause a problem manifesting itself as high speed stumble feeling like fuel starvation. That goes in line with your observation: "... have been experiencing a intermittent high speed hesitation at highway speeds. Around town, stop and go, mostly no problems."


Stephen

i'll look into the coils. it's an easy trade out. The coils where new bosch 6V "silver" (i guess the blue replacements)installed a few months to a year before installing the omega. It's an easy enough switch since I still have the original BMW stock coils. Sometimes not throwing things away is helpful. I'll let you know what I find. Thank you again.
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Old 06-11-2012, 04:51 PM   #8
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My Omega failed big time. So did a few others that I know of.
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