Help needed refreshing my '75 R60/6

Discussion in 'Airheads' started by motocyco, Oct 22, 2012.

  1. motocyco

    motocyco nOOb

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    Recent events have caused me to rethink selling the Airhead; primarily getting out for a 130 mile ride Saturday. The important thing is that I am going to keep it. And with that decision I need to do some work.

    First issue is a possible valve spring/seat issue, at least that is what a friend recommended. Why? Well, the first symptom is that after about half a mile at 80 mph it starts sputtering and losing power, he said I was floating valves. The engine is slow to rev, but this may just be normal for a small engine and heavy flywheel. It also seems that I really have to push the bike to get it past 55-60 mph, even 65 seems like a struggle. I also get some smoke out the left tailpipe if the bike sits on the side stand for a couple of hours. Valve clearance is correct, I set that about 1,000 miles ago and have had the problem as long as I've owned the bike. I do get the nice little sewing machine tapping so clearance should be good. Carbs are balanced.

    Finally, I get pinging at lower rpms and big throttle openings. As far as I can tell the timing is correct. I'm not sure is this is connected to the first issue or another problem entirely. I do have a timing light with tachometer. If I understand the process correctly, the timing is set properly.

    Any work I've done I reference a Clymer manual for the /6 models. And for what it's worth, the odometer show 43,099 miles.

    After this we will move on to suspension issues.
    #1
  2. disston

    disston ShadeTreeExpert

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    The R60s ping under heavy acceleration, normal.

    The R60s are slow to rev up, heavy flywheel, normal.

    Smoking out the left pipe after parked on side stand can be avoided some by leaning the bike over to the right side for 10 seconds, or so, after turning off engine. See there's some oil on the cylinder walls when you shut off the engine and then by leaning the bike over to the left immediately some of this oil would then seep past the rings. If 10 seconds doesn't seem to help try longer but I think it's only ten seconds or less that works. I just let mine smoke. Let's the neighbors know not to mess with my monster machine.

    Floating valves? You're not running the rpms past the red line are you? It is common for some Jap Bike affectinadoes to run engines past the red line. This is not allowed with a stock Airhead.

    I do think you have something wrong though no idea at this point what. That bike should easily go past 65 mph. Not sure what top speed is on an R60 though, I have a much bigger Airhead,

    Good Luck. I'll leave you to the guys who know more about the smaller bikes.
    #2
  3. motocyco

    motocyco nOOb

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    Thanks for the info. No, I'm not running past redline. I checked the tach against the rev counter on the timing light and found that the tach is about 1000 rpms high and the tach reads about 6K at 80 (if I recall correctly). I'm thinking of adding a tinytach to get a better handle on the actual revs.
    #3
  4. disston

    disston ShadeTreeExpert

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    I'm not familiar with a timing light with a tachometer. Dwell meters have tachs. Not sure what you have there.

    Timing is important, I guess you do know that. I recently had some ruff running and found the timing was off, retarded, about 2 or 3 degrees. This was enough to notice in the running of my R90 but the bike was still able to run at top speed.

    There should be three lines with an S mark in between the bottom two on the flywheel. The timing light should be on these at idle. With the engine revved to about 3000 rpm the timing light should be firing on the F dot. I don't think there is a difference for the flywheel marks on our bikes for this year. My bike is the same year as yours.
    #4
  5. DaveBall

    DaveBall Long timer

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    OK, reading what you have for issues.

    1. Smoke on start up after leaving bike on side stand - that is perfectly normal. The fix is to use the centre stand if leaving bike sit for any length of time, i.e. over 20 minutes then put it on the centre stand.

    2. Pinging at low RPM and heavier load - Again that is normal. The fix for this is to not run at such low RPMs. As with all airheads, they really don't like heavy load and anything under about 3000RPM. Shift to a lower gear!!!

    3. Floating valves - extremely hard to do on an airhead if you are not going well past the red line. I seriously doubt this is an issue for you.

    4. Slow acceleration on an R60 is normal compared to newer and larger airheads. But, it sounds to me like you may have some issues causing this.

    If I were you, I would start with a good tune up, replace points, condensor and plugs. I would then check your timing and make sure it is as dead on as possible. Check and balance the carbs. If you have inline fuel filters, maybe replace them as they are cheap and can cause issues at higher RPMs if partially plugged up.

    If all appears good and you don`t see any improvement, then have other issues that will have to be looked at.
    #5
  6. Cordless

    Cordless Two Wheel Addict

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    Bogging after a half mile at 80:

    1. check fuel flow--might be obstructed slightly.
    2. Make sure your float heights are correct and the same on both carbs.
    #6
  7. motocyco

    motocyco nOOb

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    Let's see if I can address every point made.

    I changed the points out for a digital ignition about two years ago. I can double check the timing, but it was correct by what the Clymer manual said (which sounds similar to what disston said). Plugs are a nice toasty tan. No inline fuel filter, good flow to the carbs, and floats are right (I think). Checking the floats seemed real difficult to me, but correct or not they are the same.

    I just might not be spinning the engine enough; I am more familiar with the Harley V-twins and my 6 cyl Bronco II, both of which are run at low rpms. An accurate tach would help tremendously, so maybe this should be first on my list. But it does seem like I'm running it hard to get revs built up. The engine idles at an indicated 700 rpms when warmed up (what I'm thinking to be more like 1500-1700 rpm), but I typically shift around an indicated 5,000 rpm (which might be closer to 6,000).

    I have never had the opportunity to ride any other airhead, so I can't compare it to newer or larger airheads. Recent experience is mostly v-twins with some thumpers a few years back and high revving inline-fours more than ten years ago. I took a friends FJR1300 out for a spin and kept short shifting it; it just didn't feel right getting that up over 6,000 rpms when I know that should be normal.

    I might need to find a local airhead expert to let me know if it's the bike or me that is not tuned properly. The bike could be fine but I'm not calibrated for airheads. Then it would be a matter of adjusting the nut that connects the handlebars to the seat. I will bring the revs up on the commute to work tomorrow.
    #7
  8. DaveBall

    DaveBall Long timer

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    These airheads do NOT have any characteristics shared by Harley V-Twins. Harley's are built for torque at low RPMs. They can "pull" from less than 1000 RPM in any gear. BMWs cannot. Low end torque for a BMW is more like 2500 RPM and up. I rarely will let any of my airheads ever rev at lower than 2500 rpm. They love to be above 3000 rpm. Shift anywhere from 4000 to 5000 for normal riding. They should pull fairly strong to red line in most gears.

    If your tach is not accurate, and you are not used to the airhead, it makes it hard to find the proper shift points. I would get it fixed asap, or find a digital one that you can strap onto the handlebars so that you can get some accurate numbers.

    As to your "digital ignition" I don't know what brand you may have, but they can crap out as well. Possibly yours only gives issues at higher RPMs. Or maybe you might have a coil going bad, or maybe the spark plug wires are going bad, again that can sometimes only rear it's head at higher RPMs or after getting truly warmed up. This is all speculation as I do not know your bike. Only giving you some places to look.

    Myself, I think your problem is a combination of at least 2 things. A very good possibility could be your floats not being bang on. Your fuel filter in the tank could be partially plugged and when you need the full flow at the higher RPMs may not be letting enough thru to feed the carbs. It does happen. That is a very good reason why the majority of us run inline filters, and usually remove whatever may be left of the original one in the tank. You might even have some junk in the bottom of the tank that gets swirled around and sucked over to the petcock and partially plugs the screen then going over a bump or somthing it moves away and you then get full flow again. There are just to many possibilities.

    Pull your float bowls and see if you have any junk in the bottom. Then check those floats. How old are they? Might be time to replace them. I have heard of nothing but bad things about the dual floats and find the single ones are much easier to setup and will work fine for a very long time.

    There are just so many possibilities that it is a little hard to diagnose without more info. We don't know the full history of your bike, nor how it has been taken care of. Start with the simple and easy stuff to eliminate and take a methodical approach to it. You can fix it. It will just take a little time.
    #8
  9. Bill Harris

    Bill Harris Confirmed Curmudgeon

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    This is an R60 with slide-valve Bings. Thank goodness that no one suggested "diaphragms". Good on y'all.

    Be sure that you float adjustments are correct, make sure the coils are good, make sure the spark plug caps are good.

    The only time I have had a major carb problem in all the years with my bike turned out to be a malfunctioning main jet carrier/accelerator on one carb. Never figured out why-- it wasn't plugged, it just didn't flow enough fuel. Ended up replacing it and the one in the other carb.

    What it was doing: the engine would not rev, just like it wasn't getting enough fuel. Tank was clean, carbs were clean, ignition was dead-on. What I ened up doing to diagnose was a cylinder balance test (done much like the plug-shorting carb synch method), which showed that at 3000-3500 one cylinder was noticeably weaker. Couldn't figure out why, until on a hunch, I swapped the main jet/pumps right-and-left. The cylinder weakness followed the jet holder.

    This may or may not be the case with this R60. "Just a thought"

    --Bill
    #9
  10. disston

    disston ShadeTreeExpert

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    You may have a plug or plug wire or coil that is crapping out at higher rpm. These electronic ignitions that are popular to replace points ignitions? When they go bad it's not always a complete failure. They get weaker and weaker. They may stop firing one side before they completely go out. But once they start to go they will get worse. Has your current problem been something that started small and it is getting worse? Eventually the bike won't start if this scenario is correct.

    You may have junk in the tank partially blocking a fuel line or petcock. If the ignition really checks out good and you want to inspect gas flow again, take the tank off and take the petcocks apart and clean everything. If there is a lot of flecks of red paint that is the OEM tank liner. Wash the tank out.

    Just stuff that others suggested. I think these are likely suspects.

    I suggest you buy some new diaphragms. Even if your bike doesn't use diaphragms. :lol3:lol3
    #10
  11. Bill Harris

    Bill Harris Confirmed Curmudgeon

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    Foo.

    :)
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  12. photorider

    photorider Been here awhile

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    I own the same bike (my first beemer) and it took me a while to get it running right so let me try and see if I can be of any help. Sounds like you've done all the preliminary stuff (timing, cleaning carbs, etc.). Now it's time to take the next step. People might tell you (like they did me) that it's just how these bikes run. I'm here to tell you that you CAN get it running right. It should rev easily and smoothly, pull strong and not ping without any major mods.

    First let's stick with the free stuff:
    As others have mentioned, the float bowl level is CRUCIAL. I neglected to mess with mine for a while because I was convinced I had them set up right and that a little thing like that could not make that big a difference. Well, the bike was not getting enough fuel and running much like you describe. To set them up, I found it easiest to remove the carbs, hold them upside down and adjust them so that when the little tang on the floats just barely makes contact with the float needle (and before it presses it down), the floats are parallel to the base of the carbs.

    Next, the mixture screw. Our carbs are different than the CV Bings most other BMW's have. Many of the resources I found said to adjust the screw for highest idle. While that works well with my R80GS, with the little carbs on the R60 that always resulted in a lean mix that caused pinging. What I found is that you need to find the sweet spot by turning the mix screw out until the revs just start to rise and then turn the screw in 1/4 of a turn.

    If that doesn't work, I would think about getting new needles and needle jets and going to a heavier spring in the advance mechanism (provided you are still using it with your ignition set-up).

    Good luck and let us know how it goes.

    PS
    Are you running premium gas? They like it!
    #12
  13. motocyco

    motocyco nOOb

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    With all that information the floats are now the prime suspects. They look original and I didn't feel real confident when I checked them.

    As I recall the ignition is one of the better ones recommended here and performance has been steady. The tank is clean and the in tank filters are in good shape.

    I kept the tach between 4 & 6K on the ride in to work and it felt better, odd but better. Looked online for a speed/rpm chart and found that for my 32/9 rear end I should be turning 4750 rpms at 70 mph and I know that by 60 mph my tach is already reading over 5K. So a tach and floats are up first.

    As soon as I can get these installed I will report back but I have to order floats.
    #13
  14. motocyco

    motocyco nOOb

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    I hadn't read this post before my last reply. Now I really suspect the floats. And no, I don't run premium but all the pinging has been at low rpm and big throttle.

    Thanks to all for input. This is my first airhead. I will keep you posted.
    #14
  15. TINK

    TINK Been here awhile

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    One other area of suspect for your 80 mph bogging would be the gas cap vent. If it is plugged (or partly plugged) the bike will lean out as the gasoline flow slows under such high fuel demand speed runs.

    TINK
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  16. Bill Harris

    Bill Harris Confirmed Curmudgeon

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    And remember, the mixture screw is actually an air screw in that it regulates the air into the idle mixture with the fuel being set by the idle jet, and it works oppositely compared to a fuel mixture screw-- turn-in= richer turn-out=leaner

    That is where pinging is supposed to occur--low rpm/big throttle.

    You need to run Premium-- the bike was designed for that grade of gas. If you want/need to run regular, you need to install low-tes base gaskets to lower the compression ratio.

    --Bill
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  17. motocyco

    motocyco nOOb

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    I need to fill up on the way home. Guess I it's a good time to switch to premium.
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  18. motocyco

    motocyco nOOb

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    Parts finally arrived today. Hopefully I can get some time over the holiday weekend to wrench on the R60.
    #18
  19. motocyco

    motocyco nOOb

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    Today I got a chance to work on the bike. Changed and adjusted the floats, changed the needles, re-balanced the carbs, and played with the idle mixture screw again. I think the floats were too low. Not sure the mixture is right, I should probably re-read the procedure and try again. :shog

    I only got out for a short test ride, so I won't get a better idea how much it has changed until I can get in a longer ride. Maybe on the ride to work tomorrow. However, my seat-of-the-pants dyno says it runs better. I ran 75 for about half a mile without any trouble, but it still seems like it's screaming it's heart out. Acceleration felt a little better; faster than an XT225 but definitely slower than an 883.
    #19
  20. disston

    disston ShadeTreeExpert

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    I didn't know the Mix Screw on an R60/6 was actually an Air Screw. I have no experience with the smaller motors but I have a Bing manual. I thought I would give you some of the info in their manual. You may at some future date wish to change things but it is helpful to know what Bing says.

    The carb numbers on an R60/6 are......1/26/123 & 124

    They are type... 53 carbs

    Main Jet is...140

    Needle Jet is...2.68

    Idle Jet is...40

    Jet Needle is...234

    Clip position is...2

    Idle Mix Setting is...1

    Good Luck with it.
    #20