R60/7 was running rough, now won't even idle

Discussion in 'Airheads' started by velo-hobo, Jul 24, 2021.

  1. Plaka

    Plaka Brevis illi vita est

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    I never buy gas at tthe cheap place. For one thing who is cheap keeps moving around. Then the cheap place is a nickel cheaper. Looks dramatic up on the sign but the bike only takes 6 gallons so I save 30 cents. And I gotta drive in-town traffic to do it. A load of bad gas can be immediate but intermittent. Gas is really only good for a month. Winter gas is not the same as summer gas if you live someplace with winter but I don't know how long it takes to change the tanks over. I never buy gas at a place where there is a truck loading the tanks and stirring them up.

    'round here you can borrow a comp tester at most FLAPS. might nee a deposit. Has to be the screw in type, not the hold-in type. Compression problems are not intermittent.

    If the bike ran and idled then you know the idle circuit is ok. look at the next circuit up. vacuum methods don't quite shake out the circuits in order and they account for mixture and spark poorly.
    #21
  2. Motopsychoman

    Motopsychoman Not a total poseur Supporter

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    You're always welcome to borrow my Harmonizer, timing light or compression tester. Don't have a leakdown tester though.
    #22
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  3. velo-hobo

    velo-hobo *_*

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    I dunno where you live, but the most expensive gas in the country (other than small, remote mountain towns) is right where I live. Going to a "cheap" place can save 40-50 cents/gallon. Not that I'm cheap and yes I realize not all gas is the same, but this gas station is right on my regular 1-hour hills loop, so it's quite convenient.

    I also don't know if they have winter/summer gas here in the bay area. You may or may not know, but SF is colder in July and August than many other months. Warmer the further you go inland, the bay is basically a huge air conditioner.

    As to the current issue, the bike did idle fine a couple weeks, then I was out of town for a bit and now it won't. Didn't touch anything on the carbs. The fact that it was stumbling/missing under load was what first inclined me to check the higher circuits in the carbs. It would rev to 5000 no problem in neutral, but it doesn't take as much fuel/throttle to do that as when underway.

    Anyhow, I will check through all the electrics and replace the condenser before I get into anything else. One thing at a time.
    #23
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  4. Plaka

    Plaka Brevis illi vita est

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    A cold day in Oaland is 40F. Lived there 22 years. A cold day in Colorado is quite different. I would never buy ga in SF, or much else, Everything silly expensive.

    Spark plugs have a harder times making spark at higher compression pressures. So weak sparks may crap out at higher loads. The time the coil got weak on my old VW I was commuting up a major pass every day (I worked on top). Car just kept getting weaker and weaker. Next day off I looked at the sparks and got yellow. Ran out and got a new coil and was back to fat blue. End of problem until the sunflower seed eater joined the carpool. Another story, and ugly. But you did check the air filter?
    #24
  5. velo-hobo

    velo-hobo *_*

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    Yes, that is my understanding of one reason it can be difficult to diagnose spark with the plugs sitting out on the heads. No compression, doesn't show actual operating conditions. If my electrics inspection doesn't show anything amiss, and a condenser swap doesn't remedy things, I'll order new coils. They are not terribly expensive for the good Bosch ones.

    I did check the air filter a while ago and I suppose I'll check it again.
    #25
  6. dave0

    dave0 Been here awhile

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    Pretty easy to dump the old gas in a car and put in fresh gas. Eliminates that variable. March was a bit ago.
    #26
  7. velo-hobo

    velo-hobo *_*

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    Yes, this is my thinking. I'll dump the old stuff in my truck and go fetch a couple fresh gallons. No reason not to do that.
    #27
  8. Plaka

    Plaka Brevis illi vita est

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    If you get fat blue sparks with the fresh set of correctly gapped plugs sitting on the heads the coils and dwell are fine. But the dwell can change kinda quick and a tach dwell meter is a quick, cheap and easy way to check what is really happening with your points gap. I would set with a feeler (the one in the toolkit is quite good for that) then confirm with the tach/dell and then again with the points broken in.

    If you have dual coils pay close attention to the wire connecting them.
    #28
  9. Dreossi

    Dreossi Been here awhile

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    Before you buy coils, I’d replace the points and condenser. Norris are one of the best options for points, but they are often miss aligned from the box, and can wear quickly as a result. It can be difficult to determine by eye if they are out of spec.

    Current points relay on a very thin coating on the contacts, once this coating is damaged they go to pot very quickly i’ve found.
    #29
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  10. velo-hobo

    velo-hobo *_*

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    So the Norris points I have are less than 1000 miles old. They were originally installed by a mechanic whose work I generally trust, though I suppose it's possible he was rushing or overlooked something. You think they could wear unevenly in that amount of time? Is it the contacts that wear in the manner you suggest or some other part of the mechanism?

    I have not tried filing the points or done anything heavy handed. I did slip a piece of 400 or 600 grit emery cloth in between one time and gently pulled it out. I don't think that's enough abrasion to damage the coating or shape of the points, or is it?

    The points are clean too, by the way. Business card test and all that. They are not expensive and I think I even have a spare set with my spare condensers but I want to be methodical and only change one thing at a time, so I learn what the root causes are. Changing a bunch of stuff at once, you can't be sure, and may introduce new problems.
    #30
  11. Dreossi

    Dreossi Been here awhile

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    I think your methodology is sound, and your trust in your mechanic bodes well. I think it’s possible for maladjusted points to act up even with such low mileage on them… in fact I’m certain I’ve had a set act-up with similar mileage. Perhaps my fault for not accurately checking the squareness of the contacts…but I’m certain I did check, for what that’s worth…so in other words they can be deceptively close to square, but fail quickly.

    The last issue I had with Norris points was that the crimped-on wire that heads up to the condenser was rotated outwards in such a way as to make contact on the back of the advance unit as it ‘opened up’ to full advance.
    perhaps examine the wire where it attaches to the points while checking the back of the advance arms to see evidence of contact.

    Using a file on new points is a ‘get you home’ deal, I think once the coating is damaged/filed the contacts wear very fast.

    Of course this was never a problem with the old stock Bmw issue points.

    Your point of not throwing a bunch of parts on is sound, but points are so fundamental to the system I’d pull them for a very close look. I’ve found squareness in contact an issue, as well as misalignment as the arm holding the traveling contact can slide in its pivot point.
    #31
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  12. Disston

    Disston ShadeTreeExpert Supporter

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    We are not supposed to file points anymore because the coating on them is now super thin. Still see it recommended all the time so maybe I'm wrong. I won't do it unless in an emergency but I cary a spare set of Norris points and I will put them in in a heart beat if I think I have an ignition problem. Has always worked for me.
    #32
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  13. velo-hobo

    velo-hobo *_*

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    wait, are you saying there could be sunflower seeds in my air filter?
    #33
  14. Plaka

    Plaka Brevis illi vita est

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    Are you driving a VW squareback and the guy sitting on the back right is spitting hi seed hulls out the window the whole trip every day?. They slip stream along the body and go in the engine air intake slots on the right rear that feeds the air cleaner. It's an oil bath air cleaner...
    #34
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  15. Plaka

    Plaka Brevis illi vita est

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    I didn't spec the condenser. just looked them over and grabbed a big one.
    #35
  16. velo-hobo

    velo-hobo *_*

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    Well today I dumped the few-months-old gas into my truck, put in 2 gallons of fresh stuff, checked all the wiring and connections for the ignition. More de-oxit on all the ignition terminals. I checked the coils again (resistance test) and checked for continuity/shorting among the few wires. No problems there, but the coils do measure ~7.5k from primary to secondary. That's a bit low by some info I've read, but within spec according to another source? These are the dual 6V coils, the big Bosch cans.

    I also checked voltage to the coil primary from ground - same as Vbatt, good. Minimal voltage drop through ignition wiring as well, so that's good.

    But the next check I did which I think was really helpful was I made sure the points gap was open, then I simulated their action by briefly shorting the condenser/coil lead to engine ground, then pulling it away while looking for spark at the plugs (grounded to the heads). I did this with and without the condenser in circuit. Not much of anything at the plugs, but strong spark at the engine case. So, suspect the condenser.

    Replaced the condenser with a "new" one from my stash - probably at least 10 or more years old, but the terminals had no scuffs on them, so I assume it was never hooked up to anything. Repeated the earlier test - better spark at plugs. Not great, I don't think, but also it was like noon, so not the best light.

    Didn't touch anything else. Battery charged up to 12.9V. Fired right up, idled smooth, rode fine up to 40mph just going around my neighborhood. No time for a longer ride today but I'm hopeful this may have been the main issue, along with the battery ground connection which I've already sorted. Those of you who said replace the condenser, it seems you were correct.

    I might still get new coils and electronic ignition, but for now I want to ride the bike instead of fucking with it, been too much of that for the past two years now really. Also it remains to be seen if I've really "fixed" it or not. Couple times already I've thought I had it sorted and then it let me know otherwise.

    Oh, maybe you all would like to see a photo? Totally forgot about that before. Forgive the horrible mid-day lighting:

    R60-7.jpg
    #36
  17. sizzlingbadger

    sizzlingbadger Boxer Fan

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    Good work, glad you got there in the end.
    #37
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  18. Beemerguru

    Beemerguru Beemerguru...G/S guy

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    So now you get to ride it down to the Airhead Tech Day this Saturday for a show and tell...and enjoy some bar-b-que. And I have a couple sets of EME digital ignitions on the shelf.
    #38
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  19. velo-hobo

    velo-hobo *_*

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    indeed i was planning to go for a ride saturday so this seems like a good destination!
    #39
  20. Beemerguru

    Beemerguru Beemerguru...G/S guy

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    Doughnuts and coffee around 9ish...lunch around noon.

    Should have at least 2 lifts open for show and tell.
    #40