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Pinging (Pinking); Piston
Detonation; Lugging.

http://bmwmotorcycletech.info/pinging-detonation.htm
52

Copyright, 2014, R. Fleischer

Pinging/Pinking and Piston Detonation are NOT the same thing.  You can usually hear either of them, and they do not sound the same either.  Pinging/pinking is a definite sharp metallic rapping/tinging sound.  The sound has been described as a piece of metal being hit by a very small ball-peen hammer.  The sound may be just one or two such 'tings', or a rapid series.

Detonation is a very much lower frequency sound, not high pitched at all.  Sort of a dull rapping or thudding noise.

The causes are different and the descriptions are different. The results of either being excessive can be very different, or similar in some respects.  It is possible for an engine to have both pinging and piston detonation happen, typically the pinging is at fairly low rpm under acceleration; and the detonation is at high power at considerably higher rpm, and is typically harder to hear.  Both Pre-ignition (pinging/pinking) and detonation are ABNORMAL EVENTS, although an occasional ping usually does no damage, and may come from too low a fuel octane for the engine. 

Pinging/Pinking may be more accurately described as PRE-IGNITION.   Pre-ignition occurs when the fuel-air mixture begins to burn too early with regards to piston travel.     What that means is that the fuel-air mixture has been ignited by something other than the spark at the spark plug, because THAT SPARK HAS NOT HAPPENED YET.  Pre-ignition often comes from wrong mixture or hot glowing bit of carbon in the combustion chamber or too low a fuel octane.  It has also occurred in multi-cylinder engines from cross-firing due to electric sparks jumping from such as cracked ignition leads to another cylinder's lead.

Piston detonation nearly always happens at high power (high throttle setting), and moderate to higher rpm.  Detonation is a spontaneous combustion event that occurs AFTER the initial burning of the fuel-air mixture,
this means it occurs AFTER the normal spark event.  Residual unburned fuel is ignited from heat and pressure.  It is possible for combustion to begin normally, and then a second fuel ignition takes place.   When the spark ignites the fuel mixture normally, the piston has not quite reached top-dead-center in the cylinder. That is, the piston is moving up, it is close to but not at the top of the cylinder, and the spark occurs, the mixture ignites, and the mixture burns relatively slowly.  But, if the piston is rising and the additional pressure in the combustion area causes an igniting, or a second igniting after the spark, that is WAY different.  In a way, you can think of this secondary igniting as being akin to a diesel engine, which needs no spark at all.  This secondary ignition can cause a tremendous rise in pressure on the piston, etc. ...and it covers a wide area of the piston surface.

In this article are photos of what a engine piston, cylinder and head can look like if there is excessive pinging or detonation, to the point that a hole is "burned' (it is much more complicated than a 'burning") in a piston or the piston top lets go; or, an exhaust valve tulip comes off the valve stem.    

An occasional Ping is usually not serious, but there best should be none. A fast train of Pings is BAD.  Same, often much worse, for fast thudding noises from piston detonation.   Many seem to think that pinging is a tiny explosion or extremely fast burning of mixture with its fast rise in pressure, that is AT THE VALVE, and the result is a slamming of the valve back onto its seat.  Rather than blinding accepting that explanation, you should THINK:  HOW would the valve be able to slam like that, with no valve-to-seat clearance for inertia?  

Photo #1:  Piston damaged by too low octane or wrong ignition timing or glowing carbon in the combustion chamber, possibly some detonation. 

Nerdy: pinging can also be a process similar to cavitation bubbles, that hammer away at metal, which happens to boat propellers if they are at too high an RPM.



Photo #2:  Damage when a valve lets go. The rod end that fits into the piston is quite visibly damaged, through the big hole in the piston crown!  This engine will be full of metal pieces everywhere and a very thorough cleaning will be needed.  The cylinder is likely ruined.  If lucky, the crankshaft is OK.

 

Photo #3:  Head damage when things come apart.



For BOTH Pre-Ignition and Detonation, the RISE in heat and pressure is VERY FAST.  Detonation is that it covers, generally, the entire top area of the piston.

The rise in pressure causes an oscillatory ringing, or resonance as an engineer might call it; the effect is such that some have compared to cavitation effects of excessive rpm of a boat propeller.  The effects are as if millions of tiny hammers are banging away at the metal surface.   The result can be broken pistons, broken rings, pitting of piston crowns, overheating.  One area of special concern is the area of thinner metal on the side of pistons, and another is the piston crown, because it is not as close to the cylinder wall as the part of the piston just a bit further down.  For those who do not understand THAT, the piston diameter is slightly smaller at the upper ring area, so it does not radiate heat to the cylinder as well as the lower parts of the piston.  Pressures can be enormously high and affect rods and bearings.  You can have broken spark plug inside insulators.   In some instances, an excessively hot heat range of spark plug has caused problems. Detonation can be caused by overheated valves, as well as from other causes.  The combustion gases could actually reach 1800F.  The excess heat is only partially removed by the exhaust gas exiting the cylinder; the remainder, which is considerable, will overheat the piston, valves, head, etc., and tends to be additive as time goes on.

As things progress, all sorts of nastiness increases.

Both types of effects can be lessened, sometimes totally eliminated, by running rich mixtures and/or higher octane fuel.  It is actually possible for detonation to NOT occur at wide-open-throttle & rich operation, yet COULD occur when the throttle is backed off slightly ...while that is somewhat unusual, it does happen.

There are instances where an excessively too hot a heat range of a spark plug has caused problems ...with both pinging and piston detonation.  Of course, if the spark plug heat range is considerably 'too hot', the spark plug central white ceramic insulator could crack and break off, causing damage to the engine.

In strict terms pinging/Pinking/Pre-Ignition occurs BEFORE the spark occurs.  In common usage however, it can also mean the effect from much too early a spark.  This distinction is probably not important to you.  Mild pinking does not generally produce damage unless continuous.  Almost all modern cars use ping detectors, and when pinging or knocking is detected, the engine is automatically adjusted, usually the spark timing is retarded (as a minimum compensation), to reduce or eliminate the pinging. BMW Airheads and Classic K bikes do NOT use knock detectors.

Oftentimes, pinging occurs with a bit too much throttle in the rpm region where the ignition has just reached, or nearly, full advance. For the Airheads, that typically means pinging with a bit too much throttle is more likely, especially with a low octane fuel, in the area of 1500-3000 rpm.  For /5 airheads with the original ATU which reaches maximum ignition advance at about 2000 rpm and the higher compression ratio as originally shipped by the factory, and, especially, in combination with lower octane ("Regular grade") fuels........... pinging/pinking is more likely below 3,000 rpm, than the models with lower compression, & later timing unit (3000 rpm delivers max advance).

A treatment of pre-ignition and detonation with regards to automotive engines, but pertinent to our motorcycle engines,  discusses things in more depth in some areas, here:
http://www.contactmagazine.com/Issue54/EngineBasics.html


NOTE!   IMO....The writer of that article uses "Detonation" for both types of things that I (and most others) separate into two separate things; piston detonation and pinging.  The author is not specifically technically wrong in doing that, but he mixes them up, and thus his writing makes it highly confusing to those trying to REALLY understand what is going on.  The writer is also using a Cadillac NorthStar engine, which is a very modern type, and there are small ramifications not applicable in his discussion.  That does NOT negate the value of the article in describing things if you can separate them in your mind, whilst reading, the events.

The writer also is not addressing your AIRHEAD's type of combustion chamber and older engine design. Thus, when the writer claims no damage from pinging (well, detonation) events in certain areas of the article, please mostly disregard that for YOUR AIRHEAD ENGINE (or, classic K-bike).

I DO suggest you read that article.


LUGGING (of all types):

One cause for both pinging and detonation is called LUGGING.  Lugging CAN cause SERIOUS & even rather immediate damage. There is no absolutely totally agreed-upon definition of lugging.  I will give you my definitions and descriptions.

If you increase the throttle, and rpm and speed does not increase, or does so very sluggishly; or even DEcreases, that almost for sure is lugging.  Some might add to that idea a second requirement: that you cannot reach yellow or red line rpm in that gear, no matter how much throttle.   Manufacturer's almost always have gearing such that you can NOT reach redline rpm in top gear, even at sea level, on a good surfaced road.   Thus, the top gear may sometimes be thought of as 'an overdrive', as the top gear ratio was likely selected for fuel mileage, wear, noise, etc.  I think both definitions are good, but the first one is primary.  If you cannot accelerate, and must drop down to a lower gear, to raise RPM, thus raising horsepower, then you ARE lugging, but, often, this is not a problem situation when you are maintaining a reasonable speed on a highway with light to moderate throttle, and neither gaining or loosing speed.

Lugging can happen with any type of engine, no matter how modern.

An example of really bad lugging might be if you tried to ride your Airhead motorcycle up a hill at 2000 or even 4000 rpm, using moderate (or lots more) throttle.     Generally, though, lugging is thought of as a lower rpm situation, with heavy throttle, although it could happen quite high up the RPM range.  Lugging can be done on automatic transmission cars, but it is harder to do in such as "drive" mode, as if you push the throttle too far, the transmission will almost always shift into a lower gear, and will also do that under moderate+ throttle if rpm drops too much.

>>>>If you open the throttle quite a bit, and rpm and speed do not increase at a reasonable rate, you are probably lugging, no matter what the speed is.

The problem with 'lugging' is that cylinder combustion pressures go quite high, perhaps extremely high, and a lot of heat can be, and usually is, developed.   A hundred or so extra degrees of heat on an exhaust valve is actually a fair amount, and two hundred+ is A LOT.  The pressure and heat is increased, and the length of time that these two are increased is lengthened, thus the cooling provided by the exhaust valve closing and thereby transferring heat from valve to exhaust seat, is REDUCED.   The cylinder head heats up, the exhaust valve heats up, and even the intake valve heats up some.  Not only are the valves affected, but lugging is hard on the rod bearings, although this is usually not any major problem in modern engines.  NOTE:  If the lugging is done at quite low rpm, the bearings will be, in essence, starved for lubrication.  Bearings need proper rpm and oil flow for lubrication AND COOLING protection.  A treatise on how lubrication REALLY works is on this website.   http://bmwmotorcycletech.info/oilessay.htm

Another type of "lugging" needs to be discussed here.   This one is probably hardly ever described as lugging.  It is when a fair amount of throttle (usually, but sometimes only quite moderate) is being used at quite modest rpm, and one hears a metallic pinging noise from the engine. Americans call this PINGING, the Brits call it PINKING.   It is commonly the result of too low octane in the fuel for whatever the engine tuning and condition happens to be.  That can be thought of in another way, meaning that an engine that runs fine if in proper adjustment can make such noises if the engine adjustments are wrongly made or compression ratio too high for the gasoline quality, etc.   Most Airhead engines have a potential pinging "zone" from idle rpm to maybe 4,000 rpm (at the most). Pinging/pinking is ALSO quite affected by ignition timing and piston speed, and is one of the several reasons that engines generally have an automatic ignition timing device. For the Airheads, the ATU (Automatic Timing Unit) is located inside the ignition control area on the front of the engine.  Except for the earliest /5 Airheads where at 800 rpm ignition advance begins ...yes, at slow idle ...and 2000 rpm gives maximum advance), our Airheads ATU's start advancing the ignition at about 1500 rpm and quit (that is, reach maximum) at about 3000 rpm.  Occasional transient pinging/pinking is not very dangerous to the engine's health, but it DOES accumulate its effects over long periods of time. If the pinging is relatively constant, for a period of time, that is BAD for the engine, and BAD things can happen, quickly.   Keep in mind that pinking, or pinking, is really HAMMERING of some sort. Some old ways of thinking about it are tiny explosions in a small area of the combustion chamber, but these are not really correct, nor are valves hitting the seats.

A final type of lugging is very serious; generally the damage can be seen rather quickly.
This effect is called detonation, or piston detonation, and is not an explosion in the way the word detonation is typically used in life (although if the piston collapses it will look something like it).  This phenomena is caused by extreme pressures in the cylinder. It is NOT a metallic sound, but more of a slightly bright thudding.  Detonation can happen from a faulty ignition system, but that is not something overly likely, particularly not so in an Airhead.  Detonation is a sudden burning of the fuel, typically caused by the compression itself, like in a diesel engine.  It can happen so early in piston movement (well before top-center) that the pressures are ENORMOUS on the piston top and rod, and if prolonged, the piston can collapse or disintegrate.

If an exhaust valve looses its head, VERY serious engine damage is HIGHLY likely to occur in a very few seconds. BMW exhaust valves are very well made, of high quality two-piece design, and seldom fail ...but there are limits to metallurgy if one abuses the engine.    There is a mathematical formula that equates exhaust temperature versus the pressure in the cylinder, and other such stuff ...but I think I'd REALLY be getting nerdy to show and describe it here.  Most people's eyes roll up into their heads when much mathematics is involved!




PINGING (pinking) .....a bit more ...and some things about ignition, fuel, etc...

Pinging USUALLY happens MOSTLY with the R50/5, R60/5, R50/6 and R60/6 models. It CAN happen with any Airhead, particularly the early high compression engines, not just those four just mentioned.  It is far less likely to happen with the low compression engines from 1981 (esp. USA models).   The information below may be of help, no matter the model, year, etc. 

While wrongly set ignition or an ignition system failure of some type can cause pinging/pinking, more often the problem is excessive carbon deposits that raise the compression ratio; or, one has lower octane than the engine was designed for.  Pinging is a metallic PING or TINK or TING noise, one or multiple pings, typically heard on an Airhead engine below ~3,500 rpm.  The gasoline mixture is burning before it should, creating teensy localized fast-burning mixtures, especially at the exhaust valve area. If you want to think about it as the valve slamming on the seat, that's OK with me, but it is not strictly correct. The gasoline mixture may have been ignited by glowing carbon in the combustion area or from an advanced spark, or even certain combinations with slightly lean mixtures, even wrong spark plugs or weak ignition.  A somewhat lean mixture promotes pinging.  Some very interesting noises can often be heard if the mixture is too lean.  Misfiring can cause excessive richness on the next power stroke, and a large sudden rise in pressure.

Back in the seventies and considerably before, gasoline's over 95 American Rating System (R+M divided by 2) were very common.  Today, it is difficult to find over 91 octane.  Most of the early Airheads were designed for 98 octane fuel (American method).   Some Airheads came with, or were modified with, compression lowering plates under the cylinders; some had higher compression ratio pistons than others, and in 1981, for the USA, the pistons were modified for lower compression ratios.

Interestingly, if one modifies an Airhead engine for dual-plugging, one can use higher compression ratios ....conversely, dual-plugging can reduce or eliminate pinging on stock compression ratios.  There are two methods of setting a dual-plug engine ignition timing (discussed on this website in the dual-plugging article) and those have a modest effect on pinging.

Some will try to reduce pinging by retarding the spark timing.  That can work or help sometimes, but at the cost of engine performance; and in some instances the heat production can increase.  3 retarded from stock is about the limit without problems. NOTE that these comments relate to SINGLE spark plug engines ...not Dual-Plugging conversions ...well, not exactly ...you COULD use an even higher compression ratio, and retard the spark a bit .....which is NEEDED on some conversions, and does NOT increase heat ON THEM ...see the dual plugging article regarding the two methods of timing  ...stock ATU and timing at OT mark; versus limiting advance maximums and timing at stock S marks, and think what this all means.  That article explains it in much more depth, and probably easier to understand:
http://bmwmotorcycletech.info/dualplugging.htm

The need for higher octane is more pronounced at LOWER elevations, as the atmospheric pressure and the oxygen amount is higher, pressures developed in the cylinders are higher, power output can be greater, etc.  The effects of air temperature is also a factor.

Carbon buildup can cause pinging (and detonation) due to increased compression.  Carbon hot spots could be glowing red hot, which can also cause these problems. 


Details...details.......details:

The camshaft timing is very mild on all the R50 and R60 models (/5 and /6), which tends to make them want to ping below 4000 rpm (especially below 3000 rpm). The earliest of these engines had VERY mild timing, and can be even worse for pinging.  The reason all of these R50 and R60 engines had so many pinging problems with lower octane fuel (and more rarely, but has happened, when carboned-up, with higher octane fuels) is because the very mild camshaft timing causes increased dynamic pressures in the cylinders.   Additionally, at sea level atmospheric pressures, the dynamic pressures in the cylinders are higher yet.  There is a nerdy thing going on too with the smaller diameter pistons of these models, and speed of flame travel is faster, in every respect including per piston movement time, which means that some areas are increasing pressures very rapidly, before the rest of the piston area has reached peak.  Consider this as lopsided burning.  This is why dual-plugging is so very effective against pinging ...and can actually INcrease fuel mileage!

****Hint: If you have pinging with your R50/5, R60/5, R50/6, or R60/6, check the ATU (Automatic Advance unit) and be sure you do not have the 39 advance unit.  Use of the 34 advance unit will be of benefit to reduce pinging.  You can RESTRICT the advance of a 39 unit easily, which is perfectly OK, by using thin sleeves. Be sure your ATU quits advancing at a MINIMUM 3000 rpm, or, better, perhaps 3500, or even a bit higher.  DO NOT use the 2000 rpm ATU of the early /5 ...although modifying it with the later springs, and perhaps shaving the weights a bit, is totally acceptable.  Be sure the fuel level in the fuel bowl is correct, or very slightly high; and be sure the needle and needle jet are correct, main jet too, etc.  If the Bing books show the Euro bikes with slightly richer settings/jettings, try those. OR, ask on the Airlist.  De-carboning and polishing the top end is of help, sometimes a lot.  DO NOT FAIL TO REMOVE any sharp edges in the combustion area.  Be sure there are no vacuum leaks where the carburetor fits the cylinder head!   INternally insulating the airbox can help.

Assuming you have checked everything, and are sure things are properly done, and you still have pinging problems, try running the bike on the highest octane gasoline you can find on the road. Usually that means 91 pump octane in the USA.  If you can find 93+, you will likely not having any pinking or pinging, even at sea level on a hot day.    If the ignition is not timed correctly, or you have too hot a heat range of spark plugs, or there is a faulty coil or ignition wire, the engine may well ping; or worse.  If you have dual-plugged your bike, you probably will NOT be having pinging problems, but the same cautions apply.

All the Airheads before the USA models change to lower compression motors (~1981), were designed for leaded high octane fuels.   The higher the octane rating of the fuel, the less the tendency to pinging (and detonation).  UNfortunately, the use of alcohol as the almost universal USA fuel additive leans the mixture, and helps produce pinging (via lean mixture heating), unless the jetting is slightly changed (made richer).  This is so even though alcohol is well-known for cooling the mixture (in appropriate richness!!!).   If you have to, enrichen the jetting a bit.  This means for idle, mid-range, 3/4 range, and full throttle, AS NEEDED.  In general, any possible required changes from the stock settings are SMALL.  Maybe 10 numbers larger on the main jet; maybe a change in needle jet size (a needle notch is a much larger change), and an adjustment of the idle mixture screw. It can help to set the fuel level in the float bowl to the higher edge of normal.   Dual-plugging is often recommended.

Be sure the correct heat range of spark plugs are being used and that the plugs are torqued to the correct values.  Be SURE not to over-torque the spark plugs, which can damage the threads in the cylinder head, and potentially the spark plug.   I think BMW's torque settings for the spark plugs, in some BMW manuals, & in some aftermarket literature too ...is too high.  I think 15 or 16 ftlbs is plenty high enough on NON-anti-seized threads, and 14-15 max on anti-seized threads (standard 14 mm, 3/4" reach spark plugs).  If torque is too little, the spark plug may get hotter than intended, and thereby act as a 'hotter' heat range.   http://bmwmotorcycletech.info/sparkplugs.htm

Anything sharp edged in the combustion chamber is suspect.

The ignition needs to be in good condition, as a weak spark can contribute to pinging and other ills, besides wasting fuel. Be sure that the ignition coils towers are clean and shiny-bright inside at the bottom.  TEST the coils ...at the very least do an ohmmeter check.  A spark gap test is best.

Do not use resistor plugs.

Do not use resistance high voltage wire.

If the spark plug caps measure ~5000 ohms, change them to zero or 1000 ohm types.   This must NOT be done on the electronic ignition models, which MUST use 5000 ohm spark plug caps.

Set the spark plug gaps slightly wider than stock.

For single plug ignition, set the timing to stock. The important timing point is the maximum advance point, which is the F dot or Z line.  When trying to eliminate pinging, you want the idle rpm to be proper too, I suggest 1025 RPM.  You absolutely MUST have a timing light to check timing properly.   There is some leeway here:  Some have tried to set the timing a FEW degrees retarded to stop pinging, and while I am not in favor of this method, I do not object to a FEW degrees of retard.   Move the S LINE mark to the 3/4 point DOWN the window, at IDLE rpm.

After the points gap is set (points models only), the advance adjustment is made such that as you raise the rpm, the F DOT appears, and the dot reaches the center of the timing window, and if you raise the rpm any more, the dot does NOT move upwards beyond the window center.  If you have a later model, the F and F dot is not there, the markings are a Z mark & LINE. If you now let the engine return to idle rpm, the S mark should be 'reasonably close' to the center of the timing window for stock.  If it is not in the window, it is possible that the springs or weights holes are worn.  

The rpm at which the F dot or Z mark line centers and then goes no higher with rpm increase, should be ~3000 rpm or somewhat higher.   ATU's, especially the types pre-1979, are interchangeable mechanically, so no telling what one's bike actually has; ...this website has the information on the ATU's by the Bosch number printed on the front, but the springs could have been changed, weights changed or modified, etc.  The main concern here is that the ATU has the springs for the ~3000 rpm advance, not the earlier ~2000 rpm advance (as on early /5 bikes).  The ATU's also varied on DWELL angle, which is not of importance for anything but a race bike, no matter who says it is.

Assuming your maximum advance IS at ~3000, you can, if you wish, lighten the weights equally so that the maximum advance is around 3500, but not over 3800. This is generally vastly easier than trying to find slightly stiffer than stock springs.  This can be of considerable help with pinging.  91 octane fuel and 3500 advance is usually enough of a fix; although dual-plugging is always an option, if somewhat costly.

DECOKING (also called DECARBONING): 
This is best done by removing the heads for a full clean-up; the BEST decarboning requires disassembly of head from engine, and the top inside of the cylinder and often top piston ring areas need decarboning too. ....but, Chevron Techron really does work, not perfect, but helps, and can help considerably, over some goodly miles to be effective.  Using the concentrated Techron from the plastic bottle PER INSTRUCTIONS will work fairly well with one tank of fuel; but, in the long run, it is cheaper, depending on one's total mileage over time, to just purchase Chevron's Techron-containing gasoline's.  The standard Techron additive bottle is good for 3 tanks of gasoline (1/3 bottle per tankful).

Be sure to check that the carburetors are tightly mounted, and that there are no vacuum leaks between the carburetors and the heads. Do this with the engine hot from riding. Let the engine idle, and spray brake cleaner at the interface between carburetors and cylinder heads. Absolutely no change in rpm should be heard when spraying. Spray around the throttle shaft and enrichener too if you have a CV carburetor.   Any such vacuum leaks will cause various problems. Be sure the valves are set correctly.

Valves and ignition timing (if has points, gap setting first) must ALWAYS be set properly BEFORE doing ANY carburetor adjustments.

Be sure that the carburetor jetting and adjustments are correct, as a slightly lean mixture will ping much more easily.  Note what I said previously about the carburetors running too lean, particularly with gas-o-hol (10% ethanol alcohol is now STANDARD in USA fuels).

If it still pings, and you are not doing something wrong, such as using a lot of throttle below ~3500 rpm; if the ignition, plugs, wires, ETC., are ALL OK ...then you will have to remove the heads and clean out the carbon and pay attention to any sharp places that carbon will gather at. Then if still pinging, get into the carburetion and ignition as described previously in this article.  Consider dual-plugging when heads are to be removed.

As an engine wears, the crankshaft timing chain sprocket wears, as does the cam sprocket, guide/tensioner, and chain.  Such wear, which is normal, causes the valves camshaft to LAG behind the crankshaft position, compared to the original design specifications.  This means, that in regards to PISTON POSITION, the intake valves open later.   The camshaft timing, in actual effect, is lagging, and the valve timing is even MORE mild, promoting leanness, MORE heat, MORE pinging, less power, more use of throttle, etc.   Be sure not to idle the engine too slowly, as that reduces lubrication to the above parts.

I suggest the carburetors be carefully balanced and that the rpm for idle be set for a MINIMUM of 900 to 950 on heavy flywheel models. 1000 to 1100 is OK ...and better ....especially for 1981+ models, but also benefits earlier models. 

Be sure the adjustment of the throttle cables is synchronized, this is always done AFTER the idle adjustments. Do the cables at 1500 rpm.   Carburetors that are well out of synch will tend to make pinging worse.  All carburetor adjustments are done with a fully warmed-up engine from actually riding the bike at least 10 miles.

Even with all the above done, you might still get an occasional ping under medium-hard acceleration, especially at lower rpm.

I suggest a lot of throttle NOT be used below 3500 except in accelerating to higher speed and higher rpm, and if you hear pinging, back off the throttle a bit.   

There is a lot of information in my http://bmwmotorcycletech.info/timingchain.htm article on this. Try my hints above, before thinking about decarboning, dual-plugging or timing chain area repairs.


Rev:
10/13/2012:  Add QR code, add language button, update Google Ad-Sense code
02/14/2013:  Clarify some details. Remove language button
05/17/2013:  Completely revise.  ALSO: Merge old article 39C into this article, add two photos from the Valves.htm article, add information from a posting I did on Airheads LIST today.
04/05/2014:  Check article for typos.  Remove a problem language select javascript that I forgot to remove in 2013.
03/13/2016:  Update metacodes; layout; clarity; fonts.
10/03/2016:  Metas, scripts, H.L., some clarifications.  Fix excessive HTML.

Copyright, 2014, R. Fleischer

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