The Airheads Beemer Club is a non-profit club reclaiming the 'Legendary Motorcycles of Germany'

Topic-icon 1982 R65 Timing Issue

  • dretek
  • dretek's Avatar Topic Author
  • Offline
  • R100 Level
  • R100 Level
3 weeks 1 day ago #4997 by dretek
1982 R65 Timing Issue was created by dretek
Fellow Airheads,

This past weekend I spent all of Saturday troubleshooting and working on my 1982 R65 at the Culpeper, VA Airhead Tech meetup. I got to meet some awesome and passionate people. The tools and resources were insane:

The main problem right now is the left cylinder is cold and not firing. Occasionally, the cylinder has pre-ignition and the ping is so violent - it knocks the carb off. The bike runs great but just on one side.

If you look closely, the pings in the video knock the carb off yet the bike still is able to run.

(sorry for the shakiness, the bike was vibing the phone)

The bike has Mikuni VM34 Round Slide Carbs jetted at:
Needle: 6DH3 | 3rd Slot
Needle Jet: 159-P0
Main Jet: AB180 -> moving to 210 (according to Bill @ Rocky Point Cycle)
Pilot Jet: 35 -> moving to 40 (according to Bill @ Rocky Point Cycle)
Slide Cut: 3.0

We have eliminated the following problems:
  • Valve clearances - set to 0.008|0.004
  • Compression - 120 psi each side
  • Leak down - no leakage
  • Spark plugs - gapped and arcing
  • Carbs - we switched LH/RH carbs and same problem occured - right side was firing and hot - left side cold
  • Checked distrubtor & cap resistance
  • Removed exhaust and checked for air flow

  • More information:
    • The bike was cranked over several times with the ungrounded and empty caps.
    • The bike was able to idle and static timing was checked (with strobe light) on the left side.
    • Is it possible to show 'S' for static timing on a side that isn't firing?
    • When running 2-3k rpm, the right side would be close to ~2x hotter than the left side.

    Near sunset, we were advancing/retarding the Motorrad Hall Sensor and it felt like the left side began to fire a bit.

    Thanks to everyone at the meetup!



    Please Log in to join the conversation.

    3 weeks 19 hours ago - 3 weeks 19 hours ago #4999 by Wobbly
    Replied by Wobbly on topic 1982 R65 Timing Issue
    Your bike isn't "pinging" at all. It's actually trying its best to run on the left cylinder. In fact it does run quite a bit. That can be plainly heard in the video, which is excellent. Thank you.

    The test of swapping the carbs is a good one, and only leaves the ignition at fault. Since the ignition unit fires both sides at the same time, the only discrete parts are the coils, plug wire, plug cap and spark plug. Next test is to swap the plug wires in the coils. That is, make the right coil fire the left cylinder. I bet you'll find something.

    Supporting evidence was the fact that you allowed the bike to turn over without plugs fitted to the plug caps. That's a BIG no-no. You'll literally burn up a coil doing it that way.

    (A new set of plugs wouldn't hurt either. I don't care if the ones in there are only 2 days old. Ethanol gas is no friend of spark plugs. )

    Hope this helps.

    Don't hide 'em, Ride 'em !!
    Last edit: 3 weeks 19 hours ago by Wobbly.

    Please Log in to join the conversation.

    • dretek
    • dretek's Avatar Topic Author
    • Offline
    • R100 Level
    • R100 Level
    1 week 6 days ago #5029 by dretek
    Replied by dretek on topic 1982 R65 Timing Issue
    So last night I jetted the carbs to recommended specs from Bill @ Rocky Point Cycle, replaced the fuel lines (with nice cloth covered ones), replaced the 3D-printed rubber boots that go on the intake/exhaust of the carbs. I was feeling confident in the bike. The next thing, I checked for spark on both plugs. Then fired her up!

    Same thing - LEFT side was colder than the right side, heard some pings.

    Then I switched spark plug caps, cooled her off, and waited. While doing so, I noticed the RIGHT side was running lean (the plug was white and extremely hot). I only ran for about 2 minutes at 2-3k rpm. LEFT side had wet spark plugs.

    Once cool, I fired her up wuith the swtiched spark caps and guess what?

    The RIGHT side was now cool and I believe there was some pinging on the right side too.

    So I have everything dialed in from a mechanical standpoint. I am getting spark, but when I switch caps, the problem switches sides (I will do a couple more trials to be 100% sure).

    Does this mean something is wrong with my ignition coil?
    It doesn't make sense that I am getting spark on both sides though.

    I am currently running the Brown 1.5 Ohm Dyna Coils and the ALPHA Ignition System V.3. from Motorrad (that comes with a Hall sensor and control unit). Is it possible my control unit is messed up?

    Thank you guys in advance.

    P.S. One thing I need to try and I'm just reminding myself:

    Switch Caps
    Pull Throttle Cable on One Side - LISTEN
    Check Plugs

    Please Log in to join the conversation.

    1 week 5 days ago #5032 by Wobbly
    Replied by Wobbly on topic 1982 R65 Timing Issue
    And did you install new plugs ?

    Look, plug wires, caps and new plugs all together total under $20. Why don't you stop all this foolishness and simply replace those items ? The bike is 35 years old, and those items will need replacing soon anyway. You're not saving any money by delaying. All you're accomplishing is to waste good riding weather.

    While [waiting on the engine to cool], I noticed the RIGHT side was running lean (the plug was white and extremely hot). I only ran for about 2 minutes at 2-3k rpm.

    A plug will not take on meaningful color in 2-3 minutes. Therefore, you do not have enough data to make a determination of lean/rich. All you know is that the side that the engine is running on is burning cleaner than the side that's not running.... Which is exactly what we would expect under those conditions.

    At one point I suggested pulling on the throttle cables independently. Was that ever tried ?

    Don't hide 'em, Ride 'em !!

    Please Log in to join the conversation.

    • dretek
    • dretek's Avatar Topic Author
    • Offline
    • R100 Level
    • R100 Level
    5 days 8 hours ago #5052 by dretek
    Replied by dretek on topic 1982 R65 Timing Issue
    I switched the caps and new plugs around and even tested them on my buddies R65. Caps are good. Spark plugs are good.

    I then switched the spark plug caps on the coil-end. The problem switched sides, meaning the left side was firing and the right was cold. Switched it again (coil end), right side was firing left was cold. During these runs - we pulled on the throttle cables. Cold side had no reaction - even spraying starter fluid down the throat of the carb had no impact.

    Does this mean the culprit lies in the coil?
    Is it possible to be in the Alpha Ignition Hall Sensor or the Module?

    Can someone please explain to me what the Hall Sensor does and what the Module does?

    How can I bench test the Brown Dynatek 1.5 Ohm Coil?

    Also, when removing the Dynatek Coil, I forgot to disconnect the battery. In general, when working with the electronics, should you have the battery disconnected?

    We're close, but I need your help!

    Please Log in to join the conversation.

    5 days 5 hours ago - 5 days 5 hours ago #5054 by 8166
    Replied by 8166 on topic 1982 R65 Timing Issue
    The Hall sensor sends a pulse to the Module (what most of us call the Ignition (or Engine) Control Unit), one pulse for every revolution of the cam, so two pulses per revolution of the engine. That's how the ECU knows when to fire the plugs.It does so by grounding the coils, causing the magnetic field in the coil primary windings to collapse and induce a current in the secondary windings that is then transmitted via the plug leads to the gap at the spark plug. The coils are wired in series, so both plugs fire every revolution of the engine, which gives rise to the name "wasted spark" system.

    As Wobbly has already pointed out, if you swap sides for the plugs, caps, cables, or coils, and the problem follows the swap, it is very likely that the swapped component is defective.In your original post you wrote "The bike was cranked over several times with the ungrounded and empty caps." Wobbly is also correct that running, or even trying to start, the engine with a spark plug lead disconnected is a very bad idea, as it can not only destroy a coil, but the Hall sensor in your Alpha ignition unit as well. Apparently you're still getting spark, so you may or may not have dodged a bullet on the Alpha. It could be damaged and still sorta work, meaning it may work for a while, then quit suddenly, perhaps due to heating, vibration, or the phase of the moon.

    To check the coil, get out your multimeter and set it to the Ohms range. Touch the probes together and verify you get something close to 0 Ohms. Then disconnect the primary side of the coil so you can test it separately. Measure across the primary terminals of the coil and you should see something in the neighborhood of 1.5 to 3 Ohms. If you go to the Dyna web site you should be able to find the value, which correlates to the color of the coil. If you see infinite resistance, the coil is bad, but since the coils are wired in series and one of them is still working, I think you'll see some sort of resistance reading. Now test with one probe on one of the primary terminals and the other probe in the hole where the spark plug lead goes. You should see a high resistance, several thousand ohms. My guess is that the secondary coil is damaged and perhaps shorted (connected) to the primary coil, and you'll see a resistance value on the meter that is much lower, or maybe even no resistance at all (0 Ohms).

    The cure is to replace the damaged coil, and since it is a twin tower coil, you'll be replacing both secondary windings. That's a good thing because even though the other secondary winding is still producing a spark, it is very likely operating in a diminished capacity because it was subjected to the same abuse as the secondary winding that failed. It is also likely that the other secondary winding will fail at some point in the near future.

    And speaking of the future, NEVER EVER start your engine unless both spark plugs are connected to their respective leads and those leads are firmly connected to the coil, AND the spark plugs are grounded to the engine by either being screwed into the spark plug holes, or held down to the engine with a bungee cord or other type of clamp. Failure to heed this warning will (not may) result in a damaged coil or Hall device, if not immediately, then sometime in the not too distant future.

    8166 Scot Marburger, This email address is being protected from spambots. You need JavaScript enabled to view it.
    Check out the Yankee Hill AirTech Weekend, April 20-21, 2019
    Last edit: 5 days 5 hours ago by 8166.

    Please Log in to join the conversation.

    Moderators: 8166Wobbly
    Time to create page: 1.364 seconds