This started with an ear infection, which meant I couldn’t wear ear plugs like I normally do when I’m riding. I was out on my Basic which was running ok, but…….I noticed a light pinking noise when I was accelerating under full throttle. I haven’t heard this before because I always wear ear plugs.
Being mechanically OCD I thought I’d better check the ignition timing. I remembered that last year I’d had problems with the idle hanging but I’d managed to sort it out with a carb rebuild, careful adjustment of the idle mixture settings, and some juggling with the ignition timing, but I couldn’t remember exactly what I’d done with the latter.
Anyway, long story short I put the timing light on the bike and found that at 1000rpm tick over, the static S mark was central in the timing hole, but the Z mark was coming up at about 2000 rpm (which I think means that the ignition is too far advance). By the way the ’bean can’ isn’t a bean can, it’s the new electronic ‘tuna can’ that BMW now supply. The instructions that come with this say that when it’s set correctly you should see the S mark at 1000rpm and the Z mark at 3500rpm.
So, thinking that the pinking could be being caused by the ignition being too advanced, I adjusted the timing so that the Z was coming up at 3500rpm. When I did this though S mark is no longer visible (its below the timing window) and the bike would not tick over without turning in the throttle stop screws by 1 turn. When I rode the bike in this condition the pinking had gone away but the power felt a little flat and the idle revs were hanging badly.
I then had another go and tried to find a setting somewhere in the middle. This allowed the bike to idle with the throttle stop screws about half way back to where they were originally, but now I’ve got hanging idle (not as bad as last time though) and some pinking, but not as bad as it was before I started messing around with the settings.
aaaaargh! where do I go from here? I can’t seem to get the S mark and the Z mark to where they should be, I can get either one or the other, but not both together. Any suggestions?
BTW, valve clearances done recently, idle mixture correct, carbs balanced spot on with twinmax.
Being mechanically OCD I thought I’d better check the ignition timing. I remembered that last year I’d had problems with the idle hanging but I’d managed to sort it out with a carb rebuild, careful adjustment of the idle mixture settings, and some juggling with the ignition timing, but I couldn’t remember exactly what I’d done with the latter.
Anyway, long story short I put the timing light on the bike and found that at 1000rpm tick over, the static S mark was central in the timing hole, but the Z mark was coming up at about 2000 rpm (which I think means that the ignition is too far advance). By the way the ’bean can’ isn’t a bean can, it’s the new electronic ‘tuna can’ that BMW now supply. The instructions that come with this say that when it’s set correctly you should see the S mark at 1000rpm and the Z mark at 3500rpm.
So, thinking that the pinking could be being caused by the ignition being too advanced, I adjusted the timing so that the Z was coming up at 3500rpm. When I did this though S mark is no longer visible (its below the timing window) and the bike would not tick over without turning in the throttle stop screws by 1 turn. When I rode the bike in this condition the pinking had gone away but the power felt a little flat and the idle revs were hanging badly.
I then had another go and tried to find a setting somewhere in the middle. This allowed the bike to idle with the throttle stop screws about half way back to where they were originally, but now I’ve got hanging idle (not as bad as last time though) and some pinking, but not as bad as it was before I started messing around with the settings.
aaaaargh! where do I go from here? I can’t seem to get the S mark and the Z mark to where they should be, I can get either one or the other, but not both together. Any suggestions?
BTW, valve clearances done recently, idle mixture correct, carbs balanced spot on with twinmax.
