My old 1971 started pinging a few years ago and two mechanics have not get it out. On hot days or two up, on up hill it pings. Full throttle helps, adding lead does not. Seems to be common, but whats the cure???
tweak the timing. (easy, free, may or may not help) Lowering the compression. (easy. pretty cheap or in some cases free. Check out the free option first---decarbonizing the top end. Use water.) Dual plugging. (easy, not so cheap). High test gas, it's not the lead that matters, it's the octane. (very easy, cheaper than it appears). If your mechanics didn't tell you this, find mechanics that know what they are doing. It's standard stuff. Ted Porter is far South bay (Scotts Valley, pretty ride) and knows all there is to know. Worth the drive. People at San Jose BMW pretty good too. Beware so called gurus in the city. Lotta hacks. If they have plenty ink and piercings, move on.
The Boyer ignition curve was designed with the R60 in mind, the curve is not linear, it retards the ignition between 2500-3000 revs, which in my experiance is where airheads tend to ping the most. What size cylinder to crankcase base gasket does your bike use? I thick one is avaiable to help stop pinging. I think that it is 1.5mm thick. But as Plaka says just retarding the ignition a bit should help, albeit at the expense of performance.
You can also fit the heavier advance springs. Over time two things have happened: Ca gas has gone from piss to really bad piss. Carbon has accumulated in the top end. So check the compression and inspect the piston crown through the spark plug hole. This will speak to carbon build up. It can be cleaned by running water in the right way. Hard on the rings and jugs. Or you can tear down and hot tank. Maybe try gas additives. Having to run real hi test (get it at the airport) is a pain. Messing with the timing addresses the symptom, not the problem. Sonoma has a 360 day riding season, so there is no best time to tear down---maybe the rainy spring. If you are just decarbonizing and dropping compression with the low-test base gasket, it can be a 2 day job. If you get into "oh yeah, as long as I'm here...." it can be much longer.
I'll bet it did start pinging several years ago. Mine started in 1979 when the gasoline started getting funky... Three methods of dealing with this: 1. The early R60/5's will have the Bosch "-007" advance unit (BMW part# 12 11 1 356 286). As a band-aid approach, you can replace the advance unit springs with the /6 ones (BMW part# 12 11 1 357 627) which will slow the advance curve a bit. Best way is to replace the advance unit with a /6 one, BMW part# 12 11 1 357 626, which has a slower and longer curve. 2. The factory supplies "Low Test Base Gaskets" that lower the compression from 9.5: to 8.6:1 and are meant to allow the engine to run on (1970's Regular grade gas). Use those and run (unleaded, ethanol-laced) Premium grade gas. 3. Dual plugging. An extra lower spark plug gives two flame fronts and allows a high compression engine to run on no-lead Regular. Expensive option and cannot be set up by hacks. I used Method #2 starting in the late '70's with a mid-'80's addition of #1. Ran this for 30 years, and a couple of years ago adopted #3 while still using #1. I am able ti run Regular on a 9.5:1 engine. --Bill
Thanks all for the input. Going to go with thicker cylinder base gaskets and decarbon while I'm at it.
About a year ago, I helped an inmate here with the same problem on his R60/6. He had done all the other things, so we pulled the heads off to clean out the carbon. Prior to going ahead with it, I rode the bike, and just like he had said, it pinged like the dickens. When we pulled it apart, there was some carbon, but not as much as I had thought it would be, and not as much as my R100S engine has had every time I've had it apart.We cleaned it out and put it back together, and it didn't ping. What a relief, as once we were in there, I was feeling kind of sheepish since I had recommended that we go into it, and then once in it didn't look like to me like we had solved the mystery. It only took us a few hours of leisurely work. For some reason, the R60s have a pinging problem. Good luck!
Plaka noted a way to reduce carbon buildup using water in my R60/5. I am clear on the concept but would like to know how to get it done without damage to the cylinders. Any thoughts???
"Gas additives" have been suggested above. The gas additive to employ is Seafoam. Seafoam was originally developed to attack carbon fouling on Evinrude outboards, decades ago. If you have bing carbs with a vacuum port, you can remove the screw and spray Seafoam directly into the carb (and hence the intake) while the engine is hot and running. If you don't have the vacuum ports, just add it to your fuel in the recommended dosage. While you're waiting to add the compression-lowering shims, the Seafoam can begin doing its thing. It's generally a good solvent for varnish in your carb ports while it attacks the carbon in your combustion chamber and piston crowns.
I would start with new springs as has been suggested (there are two kinds, get the heavier ones). Seafoam is wonderful stuff, try it. Just might help. Run premium fuel and set the carbs just a tad rich. Base gaskets would be my last resort. If you go that route, expect some performance losses on an engine that doesn't have that much performance to spare! Mine is single plugged and runs just fine (on premium). It would be nice to run regular but I had a hard time justifying the expense. Carbs clean and balanced? Float level set? Seems all these things affect the pinging on mine so you have to be thorough. But when you get it running right, you'll be happier than a pig in shit! I think it's a pretty sweet running motor once you get rid of the pinging. Good luck!
I had a coolant leak into the oil on my Toy truck. Thing was blowing steam like it had a blown head gasket (wasn't blown, cracked timing chain cover). When I opened it up the heads and cylinders looked like they just walked out of the factory. So I looked into this. stuff this into google: using water to decarbonize an engine Don't overdo it, you don't want any accumulation of water in the cylinders, you want it turning to steam pretty much immediately. Then a good hard run to get the oil temp up and boil off anything in the oil (and check it for milky color, indicates massively too much water) But first establish if you even have a carbon build up problem. The buildup causes detonation or pinging by raising the compression. So check the compression, is it real high? If not you don't have a carbon problem. Edit: carbon buildup can also cause preignition. Glowing bits of carbon light off the mixture prematurely. Inspect the piston crown through the spark plug hole. Get a snake light (Streamlight Reach or similar) and inspect the piston crown and valves through the spark plug hole. The carbon is never a consistent coating. Chunks flake away and you can see how thick the coating is. Ideally, you should be able to see the markings on the piston crown. A set of base gaskets will cost $10 (MAX BMW) and if you really want to go first class, add head gaskets for another $34. $44 for the whole compression lowering game. But that is your only your next move after establishing correct compression, mixture and timing---and messing with the mixture and timing some. It is also a popular mod when traveling in parts of the world where the gas is even worse than the fermented cattle urine they sell in California. As an aside, very high compression motors (turbo and supercharged) are often fitted with water injectors to control detonation. Work alongside the fuel injectors and are fed by a water tank and pump. This way you use the phase change of water to cool things rather than using extra fuel to do it. Water absorbs huge amounts of heat in it's phase changes (ice->water->steam).
A compression test wont necessarily reveal a carbon issue. Carbon causes pinging in two ways. First, it does raise compression a bit. But secondly, and more likely, carbon causes detonation by becoming incandescent (glowing hot) and pre-igniting the air fuel mixture, like a glow plug in a diesel.
