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

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

  1. velo-hobo

    velo-hobo *_*

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    Greetings, I don't post often over here in airhead land though I'm pretty active on the F650GS Dakar thread. I searched around for similar threads before deciding to start a new one - if there's a better place for this please let me know.

    A few months ago the engine started stumbling, missing, backfiring, while riding at freeway speeds, gradually but inconsistently getting worse over time - bike would idle fine in my driveway, and rev up in neutral, but take it out and run it under load at city street speeds and the problems would crop up til it stalled basically.

    I adjusted the points and then the bike wouldn't even idle. @Motopsychoman who lives nearby came and helped me do some diagnostics and adjustments, including setting the timing and adjusting/syncing the carbs with his Katdash Harmonzier. The carbs weren't super far off to begin with but the timing needed adjusting and we got it to idle and rev smooth, but I didn't have time for a test ride that day. Since then, no good - it won't even start and hold an idle.

    Here's what has been done so far:
    • First I eliminated the possibility of fuel/carb issues. The carbs are somewhat recently overhauled and have all the correct parts and needle clip position as spec'd by Bing. There were no blockages or float issues. These are the smaller slide carbs mind you. Air filter appears fine.
    • Torqued heads and set valve clearances to .004" intake and .008" exhaust
    • Set points gap to .016" and set timing. Norris points were new less than 1000 miles ago, the gap had closed up a bit due to initial wear of the rub block, maybe down to .012"?
    • Advance unit had the springs replaced when the new points went in. The bob weights spin out and retract, full advance was visible in the timing window (slightly double image, I recall)
    • Checked and cleaned all contacts at condenser, points, coils with DeOxit. I don't think there are any pinched wires or bad connections, but I suppose I could check all this again.
    • Static multimeter/resistance test of condenser and coils - they seem fine? But I am suspicious of these...
    • 5kOhm NGK leads are relatively new, look to be in good shape, measure within spec
    • NGK BP6ES plugs are in decent shape, proper gap, though I keep having to clean the carbon off them from the rough running. I have two sets in play, they don't seem to exhibit any difference. Same group of plugs in the bike as before the problem came about.
    • Chokes cables have free play when choke is off
    • Throttle cable free play adjusted
    • New battery as of April
    Nothing else that I can think of is different from when the bike was running fine.

    However at some point working on the bike I realized the problem was likely my negative battery connection at the engine - the breather bolt hole is 90% stripped, turns out, and the cable terminal wasn't properly held fast to the gearbox.

    This would explain the intermittent nature of the problem. And in trying to sort this out, I'd have the ground disconnected at the battery end for front cover removal etc. and afterwards the problem would sometimes go away for a bit - clearly the ground connection to the engine was getting bumped around. But when the bike would run OK, this also may have fooled me into thinking I'd been fixing the problem by other means.

    So this week I made an adapter to bolt the ground to the gearbox cover, thinking that would cure my ills. No dice. (by the way, I could be making more of these, if people are interested...)

    adapter 1.jpg adapter 2.jpg

    In daylight the spark appears weak, smallish and more yellow than blue. Just checked in the dark and now I can't be sure, I'm not an expert on spark appearance. Problem seems to affect both sides equally, not limited to one side running poorly. Bad condenser? Bad coils? I'm stumped.

    Had the battery charged up to 12.9V in one attempt to start today, while the motor was running I measured ~13.4V but it was moving around due to the rough running, and I doubt I was revving it much past 3000. So I don't necessarily suspect the alternator or charging system.

    I am considering new coils and electronic ignition from Rick Jones anyway, but don't want to start replacing stuff willy-nilly - harder to learn from what went wrong if you use a shotgun approach.
    #1
  2. Beemerguru

    Beemerguru Beemerguru...G/S guy

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    Without seeing the bike...have you checked compression?

    set the valves at .006 and .008

    Is the gas good?

    Are the carb spigots tight in the head?

    Rebuilt the carbs...did you replace the needles and needle jets

    and the floats are at the proper level?

    Throttle and choke cables attached to the correct levers?

    Either the EME or Rick's digital ignition works great.
    #2
  3. Plaka

    Plaka Brevis illi vita est

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    if the sparks aren't a nice fat blue in the dark (hell on an overcast day) then you have an ignition problem.

    did you put in a new condensor with the new points? if not do that. you will need it anyway.

    You said you were a noob to this forum. stick around and you will find that certain people have pet things they always say no matter how unlikely they are to the problem. maybe the F650GS forum is like this too. Dunno. I've figured out nobody gives a shit about my pet thing so it is rare I mention it.
    #3
  4. boxerboy81

    boxerboy81 Stay Horizontal

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    Valves good?
    Check the ground at the coil.
    #4
  5. Disston

    Disston ShadeTreeExpert Supporter

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    Setting the valve lash is the first step to doing a tune up or diagnosing any engine problem. It's Valves, Timing then Carbs in that order.

    If you skip steps we get lost.

    Not starting is a classic symptom of tight valves.
    #5
  6. Pokie

    Pokie Just plain Pokie.

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    You can rebuild the carbs till the cows come home, if you don't clean the gas tank as well, the carbs will need attention again almost the first time you turn on the fuel. Water and dirt like to hide in the small passages of the carburetors.

    Have you tried running the engine in a dark place to see if you have escaping spark? When you put your head down around the engine while it's running, do you hear any clicking (sound of spark escaping)?
    #6
  7. Plaka

    Plaka Brevis illi vita est

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    I can only think of two small passages in the carbs that have fuel going through them. The others handle air. What am I missing? What causes junk in the tank to do anything but stay there? Why would it be intermittent? Why would it come on suddenly? Sorry, just confused here?
    #7
  8. sizzlingbadger

    sizzlingbadger Boxer Fan

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    Work back from the points and check all the connections, especially the ground under the tank next the coils. What settings are you starting at with the mixture screw ? I start with 1 turn out on the slide carbs.
    #8
  9. Plaka

    Plaka Brevis illi vita est

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    first post.
    #9
  10. bmwrench

    bmwrench Long timer Supporter

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    I'm seeing failures of the seal on the choke piston on R60s. Did you inspect them when you rebuilt the carbs?

    Actually, we're afraid to know.
    #10
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  11. velo-hobo

    velo-hobo *_*

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    Hey all, thanks for the many replies. I appreciate the attention! I'll try to respond clearly as I can:

    Have not checked the compression but the rings are new as of a top-end rebuild in early 2020. Break-in complete by now, it was ~1000 miles ago. Before the top-end job I had vacuum leaks from my right spigot and shaky plug threads on the left side, so a proper compression/leakdown test was not possible. FYI, I have done a lot the maintenance myself but also worked with Dave Ranalli on this bike when he was still operating a business. I'll leave it at that. I think we may have conversed about him in another thread not long ago.

    I thought valve clearance spec is .004" (0.1mm) for the intake - every reference I've looked at lists this. I take the slack out of the adjuster/pushrod interface with my thumb when checking with the feeler, leaning towards slightly loose fit on the feeler rather than tight. So they are probably set .0045" and .0085"; .005" and .009" will fit if I use a little more force. Do you find .006" to be preferable for some reason?

    Gas is good, it was a pretty fresh tank when this started happening. (for those that asked, also the tank is super clean because I had to braze on a patch in late 2020 - this bike has a /6 large tank, and water got trapped behind the knee pad, causing pinholes. JB weld fix failed as expected, so steel and silver it was)

    Spigots are very tight, held in with red loctite, they are new from the top-end rebuild. Right side had been loose and causing vacuum leaks, but couldn't be sufficiently tightened, and if you tried to remove it, a burr on the vacuum port drill hole was keeping it from spinning loose. I didn't want to trash my intake threads so I bored them out on a milling machine and replaced them both.

    Carb needles and jets were inspected for wear at time of rebuild and I did not replace them. Service records from PO show a reputable shop (Ben's in Freedom, CA) sent them to Bing for a rebuild in June 2016. Bike likely has less than 5000 miles on it since, though the odo sometimes craps out.

    Floats are at proper level I believe - gas starts/stops from the float needle when the seam is approximately parallel to the carb body lower edge.

    Of course the cables are correctly attached!

    I did not, I have read some opinions they last a long time so unless it's bad, leave it alone. I do have a couple others I can try, at least one of them is "new" but I don't know how old. They were given to me by a co-worker who owned a SWB R60/5 from new in ~1971 til about 2012 or so. Having worked on tube amps/linear power supplies, I know that old capacitors can dry out. Is the condenser replacement your pet peeve? Yes indeed there are some on the Dakar thread that have their predictable leanings. It's the way of things, you know...

    As mentioned above, that tank is clean, my petcock filters are clean, and my inline filters are clean. There was no way I was taking a torch near my tank without thoroughly washing it out, and I cleaned it again after to ensure any flux or burnt liner wasn't still in there.

    I checked all the carb passages when this first cropped up because I suspected fuel delivery, not ignition. Like a piece of fuel hose downstream of the filters getting into a carb orifice or somesuch. But it seems to be affecting both sides, not just one. Hence I don't think it's fuel.

    I can't really run the engine hardly at all. But I could try later in the evening when it is dark. Where is a common place to look for HT leakage? Obviously somewhere along the path of the plug leads, yes? It would have to be between the plugs and the coil secondary, unless I'm missing something. I would have to distinguish any clicking from the points and valve gear operating.

    I suspected those too and checked them, they seemed supple and have some impressions in them from their seats but didn't seem funky/dry/cracked. The choke cables have free play so unless they are hung up or leaking, they should be fully seated. Bike actually "runs" somewhat better with the choke on (cold engine) so I don't know if that's the issue anyhow. What's the likelihood of both sides going bad at once? For example I don't see evidence of one side running rich vs. the other. Soot on the plugs since it is missing a lot/likely weak spark.

    ---

    Regarding the carb settings, those were fine before the problems started, and I didn't mess with my adjusters at that time. There are only two external adjustments for the slide carbs, idle mix and idle speed. When @Motopsychoman came over to help with this, we did have the bike idling great. He has a Katdash Harmonizer which is a sweet tool. I can check again I suppose, counting the turns.

    A couple folks suggested checking the coil grounding. That is a good point, I haven't done that, and it's easy to forget they are grounded through their casing, rather than a dedicated terminal to a ground cable. Same with the condenser. [edit: this is incorrect]

    I'm almost certain the clapped-out transmission breather bolt was the cause of some of this, or not helping, but obviously something else is going on since I've remedied the engine ground situation.
    #11
  12. sizzlingbadger

    sizzlingbadger Boxer Fan

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    The secondary uses the same terminal as the primary for its ground, you don't need to worry about the case/clamps.
    #12
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  13. Plaka

    Plaka Brevis illi vita est

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    no, vac. balancing carbs. but people don't learn. but condensers do go bad and it can be quick. once it was customary to always put in a new one with any change of points. I have heard arguments that modern parts are poor quality so if it works leave it. this line of thought has flaws. At minimum I would buy a fresh spare to carry every set of points. I used a huge Mallory condenser and it lasted forever. Rather understressed. But then I lost the points as I do on all my vehicles.

    a spark leak can have a sharp electrical snap sound, not a mechanical sound at all. suspect the cap ends of the wires. if you have the wires off the coils look into the holes in the coil towers. I have found surprises.

    collect as many correlations as you can. one bad tank of gas (water in it, check float bowls) will do interesting things.

    Use go/no-go gauges on the valves. I have an extremely good touch with feeler gauges from setting up CNC machines. I use go/no-go on the bike.
    #13
  14. velo-hobo

    velo-hobo *_*

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    OK I was mistaken then - the condenser case is grounded, but not the coils. I was imagining things.
    #14
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  15. velo-hobo

    velo-hobo *_*

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    Ok I'll try a different condenser next I have time to mess with it. I like the idea of a huge over-spec'd quality electrolytic. What spec did you use?

    I've checked and emptied the float bowls a few times since this problem sprung up. I really doubt it's water in the gas. It doesn't really rain here anymore.

    As to go/no-go, yeah I keep the spec feeler gauge in hand plus one thou on either side when checking. I also set up CNC machines, manual machines, other precision equipment. I consider my touch and sense of small adjustments to be relatively good. I'm not at the level of a tool-and-die maker but I've been doing machining work as part of my job for 17+ years.
    #15
  16. reinhardhardegen

    reinhardhardegen Been here awhile

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    how old is the gas?

    if you can see a spark in the bright daylight then your ignition system is fine

    ok, didn't see your post about the gas

    At least 20 years ago I bought a R50/5 that was in pieces. It was missing a carb, the cam and some other bits. I let it sit for about 6 years and finally started to put it back together. I bought a used carb from a beemer boneyard in Texas.

    So long story short, I got the engine back together and tried to get it running but it would start and then die. I sprayed carb cleaner into the carbs and the bike would start immediately and then die as soon as it burned all the carb cleaner I just sprayed into the carbs. That got me thinking that the fuel isn't flowing from the bowl out thru the jets so I tried blowing out any passages without any luck.

    I looked at the microfisch online and just bought new all the guts of both carbs. Everything that looked like the fuel had to flow thru (jets, needles and idle mix screws and seals). There is a part that acts like a accelerator pump, PN 13111255855 (fuel pump). I think this part was my problem. There is a spring in it and the old part was really dodgy with corrosion.

    so the new parts came and I put the carbs back together and the bike started and ran lke it should

    I still have the bike and it ready for me to take it out for a ride.
    #16
  17. velo-hobo

    velo-hobo *_*

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    i've been going on the memory that i put gas in it right before it was acting up, that would be march. but i don't have a record of purchasing gas then. trip meter has about 70 or 80 on it, that could be right for the amount of miles it's got since the problems arose, but it could have been a month earlier. there's a place nearby that has really cheap gas if you pay cash.

    that doesn't seem super old, it doesn't look weird either. i've left gas in for that long before and not had trouble. i do empty the float bowls if it's gonna sit for a while.
    #17
  18. reinhardhardegen

    reinhardhardegen Been here awhile

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    My r90s starts acting up when the tank gets low. You would think it would run normally until the tank was dry but no. It seems that the hydrostatic pressure of a full tank effects how the engine runs.
    #18
  19. Disston

    Disston ShadeTreeExpert Supporter

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    Brand new rings even on brand new pistons on properly prepared cylinders sometimes don't seal because of improper break in procedures.

    Do a compression check or leak down test if you can.
    #19
  20. velo-hobo

    velo-hobo *_*

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    @Disston it's worth doing for sure, but I don't have the tools to do compression and leakdown testing... I'll have to ask around my riding buddies to see if they have one to lend. Or if someone can recommend a set of tools that's decent but not terribly expensive, I could invest. As much as I appreciate tool-collecting, just seems like something I (hopefully) wouldn't need very often at all.

    I suppose it's possible this is a carb issue but it really doesn't seem like fuel delivery. I could try opening the air intakes and spraying starter fluid into the carbs. I want to give the electrics another once-over before I get into the carbs again. I know they are adjusted well as the bike ran and idled fine a month ago (no load, however).
    #20