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Old 02-05-2014, 06:20 PM   #1
princessofwow OP
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BMW R65 noobie coil question

Hi everybody, have to say this forum is an awesome wealth of knowledge but am finding it hard sifting through it, with other info from the interwebz sometimes contradicting it. My issue, as far as I can tell is a faulty Coil, I have tested it with the multi meter and the test range is outside of what the manual says it should be....So I'm trying to replace it and for the life of me can't figure out the resistance for the aftermarker coil.
I've been told THESE guys are good, but just finding if I need the 3 or the 0.6.

HERE
They say a 0.6 primary resistance is what I need and then HERE Datchew alludes to the Harley one been a 3ohm??? And HERE again there seems to be some conflicting info ;(

Please help simplify this for me, I'm going around chasing my tail with something that should be relatively straight forward.

A rundown of the problem just for a bit of history is It rode out perfectly to a job one day, and the bike was left out in solid rain that day (silly n00b mistake) and then it was running on just one cylinder, struggling to hold idle, and heating higher than normal on the side that was firing.

Took the carb off on the faulty side after checking spark and cleaned it all up, all the jets and no luck, everything has pointed toward a faulty coil-but the part that's come off seems to be the replacement model from 91 on?? Model no. Bosch 0 221 500 203-there doesn't seem to be any visual cracks on the coil, but the ohm readings as stated above were significantly different (when testing the Secondary output) The manual says for HT coil secondary windings on the twin coil I should be getting roughly 7.5-9.15 ohm and I was testing somewhere in the 12-and supposedly that's enough to count the coil f*cked

I'm so confused, bought the bike so I could try and learn my way around an airhead but sheesh this electrical problem has been killing me.

Would greatly appreciate any help getting me back on my first bike!

Thanks POW

princessofwow screwed with this post 02-05-2014 at 06:39 PM
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Old 02-05-2014, 06:45 PM   #2
bmwrench
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I've run anything from the stock coil, @.6 ohm, to a Dyna Coil, @3 ohms. If anything, the higher resistance of the Dyna-or other brand-should protect the ICU by reducing voltage to it. I was concerned about cold starting with the 3 ohm coil, but that has not been an issue.

Is your coil grey or black? If it is grey, it should be binned. I wouldn't consider 12KOHM through the secondaries excessive. This could just be caused by a bit of corrosion in the towers.
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Old 02-05-2014, 06:51 PM   #3
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Quote:
Originally Posted by bmwrench View Post

Is your coil grey or black? If it is grey, it should be binned. I wouldn't consider 12KOHM through the secondaries excessive. This could just be caused by a bit of corrosion in the towers.
Can you elaborate on the grey vs black? My bike is equipped with the grey version, which as I understand it is an older one and is replaced by the black one.
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Old 02-05-2014, 06:55 PM   #4
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Thanks BMWRENCH, it's the black one, I can get a replacement from the wreckers close to me, but I'm hesitant to fork out $165AUD for something that sounds like it'll shag itself before long, so that's why I'm inclined to go for an after market one, so seems like the 3ohm twin output single coil is the way to go, and I'll just forge a bit of alloy to mount it to the frame..
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Old 02-05-2014, 07:13 PM   #5
Warin
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Quote:
Originally Posted by bmwrench View Post
I've run anything from the stock coil, @.6 ohm, to a Dyna Coil, @3 ohms. If anything, the higher resistance of the Dyna-or other brand-should protect the ICU by reducing voltage to it.
Nit picking ..
The voltage (it comes from the battery) wont be reduced by the coil .. the maximum current will be reduced by the increased primary resistance of the coil. But the voltage remains the same.

---------------------
Quote:
Originally Posted by princessofwow
A rundown of the problem just for a bit of history is It rode out perfectly to a job one day, and the bike was left out in solid rain that day (silly n00b mistake) and then it was running on just one cylinder, struggling to hold idle, and heating higher than normal on the side that was firing.
As the coil fires BOTH plugs it is unlikely to be the coil?
Sometimes the water gets to the sparkplug caps and/or leads. Once they dry out things work - until they get wet again.

Check spark plugs, plug caps and HT wire .. (cap and wires for resistance from coil connection to spark plug .. expect ~5kiloOhms). If it is running normally while dry .. spray the cap and wire with some water while the bike is running.. preferably when it is dark and you can see the discharge.

The bike can be left outside in the rain (and snow) and still reliably start up the next day .. and then run through the now flowing creek in the rain all the way home after a rally. Leaving the bike outside in the rain is not a mistake and the bike should run afterwards, if it does not then something is wrong.

-------------------
You should be able to get a cheaper coil from a wrecking yard? A new one from motobins is ~$180 http://www.motobins.co.uk/bmw-parts....20valve%20Twin .. second hand should be cheaper than 160.

Warin screwed with this post 02-05-2014 at 07:28 PM
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Old 02-06-2014, 05:10 PM   #6
princessofwow OP
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Thanks for that, I got some second hand HT leads and some new sparks, going to give that a go today and if that fails its safe in my mind to say the coil is shagged, ill report back later today. Thanks again!
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Old 02-07-2014, 04:09 PM   #7
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Take a look at the chart on this page. http://www.nology.com/profiremotor.html

See the coil models that say "current limited" - You definitely DON'T want any of those.

Small, very modern, high performance ignition coil are not a good match for our old bikes. They expect different things.
The one listed for the early Harley electronic ignition would probably work, but see how they don't list a coil for points at all. I would go with a company that has a specific recommendation for your model.

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Old 02-07-2014, 04:41 PM   #8
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Unless I missed something, the R65 could be either point/condenser, or an electronic ICU. Each has it's own coil requirement...


But having said that, I agree with Warin that it's not likely to be a coil if only one side is effed. The quick/easy diagnosis is to swap the plug wire from side to side, leaving it plugged into the coil. It could be the plug itself, the cap, the wire, or the coil (or any of the connections!) My bet would be on a bad wire connection: push the HT wire firmly into the cap and into the coil...

Good luck, it can be aggravating, but a simple "rained-on" bike should run absolutely fine. I rode mine through enough rain in the Tennessee mountains to soak through a very heavy leather jacket, the shirts and undershirts, underwear and pants, and the bike never missed a beat..... I freeekin' froze....

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Old 02-07-2014, 05:26 PM   #9
princessofwow OP
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Under close inspection of the coil, there are some cracks on it...
Also I figured sure a bike can handle torrential rain when it's movin but if its stationary water has the chance to work it's way down and pool in places it shouldn't??
My R65 is '84 and from '81 on? They swapped from points to ICU.
Picked the bike up from where it was yesterday to bring a little closer to home so I can work on it easier, need to trickle charge the battery before I can start any tests. 40degrees here for a few days in Melbourne ):
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Old 02-14-2014, 12:08 AM   #10
princessofwow OP
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Okay, so a little update.

Finally got the chance to test out the new plugs and known to be fine HT leads with the battery charged.

The right side accelerator cable when pulled doesn't have any reaction, whereas the left does...So switched the HT leads across and still no dice on the right.
I'd been lead to believe that if it were a coil problemo, then once the HT leads had been switched then the no response from accelerator cable being pulled should switch too...
Also the new plug on the right side (dodge side) when pulled out was a little wet whereas the left was a little black-have to service that carby)
.....So could the problem I'm still experiencing be still related to the coil? Or should I go back to the drawing board with the right carby? Or potentially the ICU???
Any help would be greatly appreciated-keen to get to Tasy before it gets cold again.
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Old 02-14-2014, 10:12 AM   #11
bpeckm
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With a wet plug and "no reaction", it sounds as though you have a problem with ignition, somehow.
  • Try swapping the plugs, or new plugs, using the same "no-go" wire and coil in place.
  • Then try crossing the wires, so that the coil is firing the other side.
  • Then try pulling the wires out and putting the L wire on the R side and vice-v
.

What you are trying to do is isolate the component that is not working.



A key thing to know is that both spark plugs should fire at once, this is a wasted-spark system. It is more likely that you have a bad wire/boot or connection at the coil, or a bad plug... if one side of the coil fires, most likely the other will, as well.

This is a great (and cheap!) tool to use: it attaches to the plug, and the wire attaches to it, and it is instantly visible whether there is a spark. When chasing ignition and spark stuff, it is the best tool to have!!
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Old 02-14-2014, 08:27 PM   #12
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Quote:
Originally Posted by princessofwow View Post
.....So could the problem I'm still experiencing be still related to the coil? Or should I go back to the drawing board with the right carby? Or potentially the ICU???
Not a coil/ICU problem. As you have put a new spark plug in the right side and still not got a response ... that indicates it is something else (assuming when you swaped HT leads the spark plug caps went with their attached leads).

---------------------- Easy confidence check
Using one of your spare spark plugs - pull the HT lead and cap off the right side spark plug - connect the spare spark plug there and tie the spare spark plug to the fins so that the spare spark plugs' body is earthed. Then operate the starter motor and check for a spark on the now exposed spare spark plug. Now your are 100% sure it is not the ignition system.

-------------------
As the plug was wet .. too much gas? Choke circuit correctly assembled?
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Old 02-14-2014, 08:37 PM   #13
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Quote:
Originally Posted by princessofwow View Post
Please help simplify this for me, I'm going around chasing my tail with something that should be relatively straight forward.

A rundown of the problem just for a bit of history is It rode out perfectly to a job one day, and the bike was left out in solid rain that day (silly n00b mistake) and then it was running on just one cylinder, struggling to hold idle, and heating higher than normal on the side that was firing.
Welcome to the forum.

First thought was water in the carbs, but you've cleaned them, so maybe not. I'm presuming you've dropped the bowls.
Secondly, it took a while to work out what model/year your bike is. Very important to know this and it's handy to have that in your signature.
Points bikes pre Sept '80 and use the 3.0 ohm coils.
EI from Sept '80 use the 0.6 ohm coils.
Mono's are EI too. You can check your exact d.o.m. but inserting your VIN into here...http://realoem.com/bmw/select.do?kind=M&arch=1

The 650 EI bike uses the dual outlet coil and if it's gray was called the "crack-o-matic" It was replaced in later bikes by a similar black coil that was "Made in Slovenia" and was marked accordingly. Now this is all from memory mind you and it's also telling me the gray coil was used later than '84, so I'll happily stand corrected.

Do you know the fellow in Carrum with a few parts? He's likely to have a spare to suit at a fraction of new cost.

One way to sort what you need is to review http://www.motobins.co.uk/index.php who are an excellent parts service and you'll often be able to decide what you need after checking their site. They're usually cheaper to buy and post to Oz than buying new locally. 4-12 days post.
The other site to cross reference when unsure is http://www.maxbmwmotorcycles.com/fic...7&rnd=04302013

For the fiche @ Max's ensure you select your model (R65 78-84) but also ensure your parts are listed from 9/80. The listing covers them all.

If the coil is cracked you will need to replace it of course. Otherwise, simple things first. I'd disconnect the battery then remove them from the bike noting the connections, remove the HT wires, checking they were well seated and the coil orifice isn't badly corroded. They can get very green in there.
Once you're happy with that, put them back on. Then start moving and swapping and changing systematically. Side to side leads & plugs, then new plugs correctly gapped and then new leads.

Good luck. You'll sort it with time, patience and hopefully very little money.

Check this too. http://advrider.com/forums/showthread.php?p=23297996

boxerboy81 screwed with this post 02-14-2014 at 08:55 PM
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Old 10-06-2014, 05:13 PM   #14
princessofwow OP
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Sooooo, been a long time but finally got it fixed, with all my efforts coming up short I took it to Phil and K&R and the problem was ultimately a snapped rocker arm on the RH side, inlet valve was completely closed off, she's all better now-thought I'd post to let any future thread searchers with the problem and the resolution.
Thanks for all your help
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Old 10-06-2014, 09:31 PM   #15
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Goes to show that doing the timing, valves then carbs to get things 'right" before other troubleshooting might sometimes be the shortest way to resolution.

Just in time for the nice weather!
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