Ignition Timing and Automatic Advance
Units, Single Spark Plug BMW Airhead Motorcycles. Installing and
Adjusting
Points,
Automatic Timing
Units for the Dual-Plugged Airheads as well as the Single Spark Plug Airheads,
and some information
on various coils, etc.
©
Copyright,
2012, R. Fleischer
ignitionsingleplug.htm-29
This is FIRST, so please pay attention! Everything on this long page is only PART of what you really need to know about the airhead ignition system, and all its components. PLEASE be SURE to read not only this article #29, but to read #28, 31, 32....but; especially 30!! SOME things in those articles ARE pertinent to the points models, settings, adjusting, and many other details on the various ignitions!
AGAIN...DO NOT FAIL TO READ ARTICLE #30...THERE IS A SECTION IN THAT ARTICLE JUST FOR PROBLEMS WITH HIGH IDLE RPM DUE TO ATU STICKINESS, ETC.
Section I: POINTS removal/replacement/adjustment & maintenance. Amplifiers/boosters.
It is extremely common to hear about a poor running engine, and
often a hard-starting engine.....the cause being nearly completely closed-up points.
When I install brand-new points, I set them a tad wide, about 0.019" for
all models, and I am VERY careful to lubricate (sparingly!!) the cam and the felt
(no felt on canister models). Since
I have to remove the ATU (on models through 1978) to replace the points, I also lube the
shaft, and inspect the ATU. If you do NOT lubricate the cam, the points rubbing block will wear rapidly, closing the points.
On the 1979-1980 models, the points are in the canister, and things are a bit
different, but you still must have a faint trace of lubricant on the points
cam. I've even heard those rubbing blocks (especially models up
through 1978) make squeaking noises. You can sometimes hear
this even with the outer engine cover in place. Bosch has several lubricants for use at the points
cam, and at the shaft. I prefer to use the original specified lubricants, but
I WILL use almost anything in a field repair....you can use any good high temperature grease.....even something like BMW #10 red grease will help. I still have
the same tubes of my original Bosch grease, that I probably purchased 35 or more years ago...and I used those tubes a lot!
FYI, the Bosch numbers are: Ft 1 v4 for the felt; Ft 1 v22 (or 26) for the ATU.
DO NOT over-lubricate the cam nor felt! You do NOT
want the lubricant to fling off and contaminate the points.
That can cause burning and misfiring.
In the canister the ATU is not 'available' for lubrication, it is buried at the bottom
of that canister...and the canister is generally taken totally apart to work on
that portion. It is possible to remove the side oval metal plate, and
spray lubricant inside, for a temporary fix for some problems, such as sticking
ATU, which results in high idle speed, usually after warmup.
You can NOT measure, nor adjust, the points on a canister model,
withOUT the front bearing being IN PLACE.
NOTE! Regarding
the ignition
points for 1970-1979 Airheads: BMW has been shipping
wrongly made points sets, made in China. The rubbing block
is too long, and you cannot get proper timing, etc. I
suggest the Norris points from such as Beemershop, etc.
NOTE: NON-canister points:
Rotating the points plate Clockwise will
retard the spark.
****NOTE!! The NON-canister Airheads have
points located on the end of the camshaft in a small engine cavity. The
lower points screw heat is very close to the points spring, and if a wrong screw
or washer is use, the screw can contact the spring and the points are
effectively shorted, and you get no ignition. This is seen now and then
right after someone replaces the points and can't understand why the engine will
not start.
****NOTE!! The ignition points wire that leads from the points cavity to
the rest of the motorcycle fits through a rubber protection grommet, and this
grommet often gets displaced when working in the area. DO NOT replace the
cover until the wire and grommet are in proper place, or you can cut the wire
when replacing the cover.
Caution!!!....The nut on the
BMW Airhead motorcycle camshaft tip
(through 1978) must NOT be
over-tightened! I do it with a short 4 inch wrench, and by feel. I would guess that
I don't use more than 4 foot-pounds (at the most). Specifications are
4.3-5.1, and I don't use quite that much. A waverly spring washer belongs
under the nut. Be careful here. The previous owner or
maintenance person could have over-tightened that nut, and the
threads ready to give you a real problem.
If you break off the tip of the camshaft, all is
NOT lost. With a proper drill guide and information, you
can fix it. Contact: "Paul Tavenier" <repairhead@sbcglobal.net>
When setting the timing, the points gap MUST be set FIRST.
Rotate the points plate CCW to advance the timing. For the
canister, that means the canister. Points wear is almost
entirely that of the rubbing block, and the points themselves.
Do NOT ever 'file' the points, unless it is more or less an
emergency in the field problem;....the points have a rather
thin layer of something like tungsten (?) on them, and the filing
can remove that hard layer. I'd not hesitate in the field.
Just file squarely. Don't open the points quite wide with your fingers when installing,
etc....you can take some of the tempering spring action out of the points leaf spring....and then the points may 'bounce' at high rpm,
causing misfiring of the ignition.
If the capacitor fails (not all that common, actually), the ignition can either quit, or the points starting burning up at a fast rate.
Points will last about 12,000 to 25,000 miles withOUT an
amplifier or booster; and MUCH longer with one of those. Most
plain points setups will last 15,000, but you DO have to maintain a slight lubrication on the cam.
You MIGHT have to file the points very lightly.
Contrary to my own above advice, on a few of my touring airheads that had points, what I actually did was to, yes, very LIGHTLY file
the points with a very thin diamond coated blade (300 grit) every 5000 miles when I set the valves ( I did the valves first,
on cold engine, before
the points, so I did not have to wait for the engine to cool after setting
timing). I checked the cam lube, checked the gap, checked the timing at high rpm....rode the bike, and synch'd
the carbs.....this was standard at every 5000 mile interval.
I don't really recommend filing points. I have
gotten some big mileages off a set, but don't recommend trying for
that. Points amplifiers or boosters are a very nice addition to the
motorcycle, as points can last for many tens of thousands of miles with just cam
lubrication, and a booster. SO....you can eliminate wear of the points themselves (you still have to replace them eventually, for rubbing block and other wear, but they
will last a LONG time, if you keep the cam lubed) by using some sort of points amplifier. Keep the
capacitor in its normal place, and you can, if the amplifier fails, convert to the stock system in a FEW minutes!
Dyna still makes points amplifiers, and are probably others, including Boyer,
and there is a Velleman (spelling?) kit, and others. There are full electronic ignitions available too,
from such as Boyer-Brandsen and Dyna....but if one fails
on a tour, you are less likely to fix it as easily as with the simple points
amplifier equipped bike. If you install a Dyna pickup unit, in place of
the stock points, follow Dyna's advice about a drain hole.
NOTE that occasionally a capacitor will partially open, or,
otherwise does not match the points and coil. That
causes the points, after many miles, to develop a hill and valley
appearance. Usually this looks like a relatively sharp tit
on one point with the other having a sharp corresponding
depression. This type of thing is actually normal, but if
extreme, a judgment call, install a new set of points AND new
condenser (capacitor). Rarely a condenser will
short completely. You have to remove the wire to test for
that, or, use some sort of test light, etc. A shorted
condenser will not allow the engine to start and run.
It is probably a good idea to carry a spare
condenser in your bike's tool tray. All
condensers are NOT the same, and I do not mean the physical
mounting nor wire lead. Condensers have a value, in
fraction of a microfarad of capacity. most ignition condensers
are sold to match the system, and may not have the microfarad
value on them. However, in any emergency, almost any small
condenser used on any car's ignition (or even for noise
suppression) will likely work temporarily. Values of 0.25 to 0.50
microfarad will work.
If you use a points amplifier, it is even more important than with the stock
setup to never let the points get dirty/oily/greasy; as the current through the
points is vastly lessened with the amplifier. When stock, the larger current helped keep
the points in usable electrical contact when closed.....although allowing pits and valleys and burning to occur.
1979-1980: The
canister used POINTS in 1979 and 1980. The 1979 and 1980 canisters
with points did NOT have a felt pad to help keep the points cam lubricated,
hence, if the lubrication on the cam dries out, the rubbing block and the cam,
together, can make a very loud chirping noise, sometimes audible
with the outer engine cover in place. In that case, remove
the outer lid (2 screws) and lubricate the cam very sparingly with a high temperature grease. Put one drop of a
decent oil on the outrigger bearing. NOTE that the points can NOT be
adjusted withOUT the outrigger bearing in place. I think BMW's idea was
that there was enough oil vapor in the canister to keep the cam lubed. I
am not convinced.
HINT: Some Porsche points, with stiffer springs, will
fit the canister, and provide better performance
near red-line rpm, in SOME
instances. DO NOT willy-nilly install those points.
PRE-1979: The automatic advance unit is INDEXED by the D shaped flat on
the nose of the camshaft, where it fits precisely the same D shape on the
automatic advance. These D shaped areas wear, often due to
improper assembly and tightening.
ATU units are very expensive, if you
must purchase one because the D has gotten very sloppy.
Fixing a worn D is possible.
There is an aftermarket sleeve tool available, that some folks like, it allows the ATU to be removed and the points adjusted without the fun of small feeler gauges in cramped places.
Section II: Everything else::
BMW modified the automatic ignition advance unit around the end of 1972 on its motorcycles when not far into the early production of the /5 airheads. Other changes were in the early years too, to the mechanical advance unit; and, to the flywheel markings. The stamped part number on your automatic advance is a Bosch number. Not only was the cam profile of that automatic advance unit that bumps the points changed from 110° to 78° dwell with a sharper shape, but the springs were changed, and not all these things at the same time. So, you have the DWELL changed, also the RATE of advance, and also the RPM at which the advance stopped advancing. Going along with this was a change in the flywheel markings a bit later (coinciding with a change in the camshaft sprocket timing)...for the transition between 1977 and 1978 for the beginning of emissions reduction bikes.
What follows, before I get into anything else, is the technical story on the automatic advance units used on the NON-canister bikes (prior to 1979). Keep in mind that it is possible that someone has changed the springs on your automatic advance, or even otherwise modified it...you might have any of the ATU models in your bike.
In late 1972 BMW made changes to the automatic advance
(centrifugal advance unit, automatic timing unit, ATU). This was done
in TWO stages:
To
the R50/5 after chassis 2901787 with the second change as of
chassis 2905857; to the R60/5 after chassis 2932689 with the
second change as of chassis 2946096; to the R75/5 after
chassis 2973307 with the second change as of chassis 2996220.
The first Service Information bulletin came from Munich, dated
Nov. 1972, and the bulletin was numbered as 4/72 (041 M)e.
The second bulletin was also from Munich, numbered 1/73 (056 M)e.
Both referred to SI 284e, Group 13, page 2., which is unimportant
HERE.
Don't be overwhelmed...I'll get deeper, but will explain it all.
((Parts shown below described as 'fully suppressed' mean
the Authorities (police) models))
From November Bulletin:
Earliest ATU mechanism: Bosch 023 202 005 BMW
12-11-1-351-571 15°30' timing. Note that this early
mechanism had a 110° dwell. The updated mechanism: Bosch 023 202 007 BMW
12-11-1-353-639 12°30' timing.
NOTE that some
were 110° dwell, some were 78° dwell, same part number. The 78°
ones were also more abrupt on the cam lobe shape of the ATU. Updated mechanism, but with the breaker plate fully electrically
noise suppressed,
complete assembly, Bosch 023 202 008; BMW 12-11-1-354-404. 12°30'
timing.
What is DWELL? One revolution of the cam timing unit is obviously 360°. Dwell is the time the points dwell (touch) with each other. It is that fraction of 360 degrees, the relationship between amount of time, per ATU one rotation, that the points are open versus closed. It is relatively easy to measure mechanically as well as electrically. The longer the time, the more time for current to flow. BMW changed the dwell initially because the Authorities (Police) motorcycles, which had metal shields over the coils (and retained more heat), let the coils overheat....and later BMW found that the 78° dwell was more than enough for coil saturation at any reasonable RPM, so all units were changed to 78 dwell (until the canister models).
BMW made some initial changes as the cleaner emissions models were contemplated. One change was the BMW changed the CAMSHAFT sprocket by THREE degrees; this is same as SIX degrees measured at the crankshaft, as far as valve timing is concerned. BMW changed ONE flywheel marking, by repositioning it, when the three degree change in camshaft timing was done. The NEW timing point was placed 6° BEFORE the original marking, as seen in the direction of the moving flywheel. That was 12.5 mm on the flywheel, in the direction OF THE TDC (OT) MARK. NOTE that the STATIC ignition timing (also called idle timing, or the S mark) was NOT changed, it remained at 9° BTDC. Obviously, OT, top dead center marking, also was not changed. Think about the differences of no-change at S, and a 6° change at the maximum advance point. ((For the super nerdy, yes, if you have a wrong flywheel, or just want to know, you can measure the S mark and see which flywheel you have)).
When BMW made the changes to the camshaft timing, BMW suggested those "upgrading" the ATU should repaint the timing marks. This was because if one put a 007 unit into a 005 bike, the F mark would not swing far enough. If one timed at the S, it was OK...but you would have to ignore the F mark....but, S is not the REAL place to time a bike, the F mark is THE important one, leaving S to fall in the window someplace. The S mark continued at 9° BTDC until 1978 mid-year production. After Jan 1, 1978, bikes were officially 'emissions controlled' and the S mark was moved 6° BTDC, and; thereafter. The engine camshaft (not talking about advance cam here) was changed during 1978 production too. All these changes in the automatic advance unit, and the flywheels, is a bit confusing. Those playing with any sort of changes to the engines, including compression ratios, camshafts, timing, gasoline octane's, and lots more, may well be trying things such as adding a bit of ignition advance beyond the F or Z marks, and various types and combinations of ATU parts. ETC (lots of ETC).
Please take
note that it is possible for you to purchase a bike with wrong
components, done by the previous owner (or?). It is also
possible for you to install the wrong components, particularly
the ATU and MOST particularly the camshaft sprocket when doing a
timing chain job. Be careful!
You may be interested in reading this article:
timingchain.htm
That article contains some more insights about the camshaft and
ATU, well worth reading at this point.
The BMW engine combustion chamber characteristics and sound radiation from the fins is very good at telling you, by noticeable pinging (pinking), of an over-advanced or poor gasoline octane condition. Hence, it is usually acceptable to advance the timing until pinging at mid-rpm is heard, then back off a bit. I don't recommend it.
If you use a dwell meter with the BMW points, you probably do not have a 2 cylinder dwell position, that is rare. If you have a 78° dwell timing cam, and set the dwell meter on the 4 cylinder 4 stroke position, the dwell meter should read 39°. In the same manner, the 110° timing cam will read 55°.
Restating, again: The reason for the change from 110° to 78° was that the Police models, with their heat retaining metal shielding around the ignition coils, were having coil failures. 78° is PLENTY-enough dwell for coil saturation, at Airhead engine speeds. Racers using extreme rpm might get a wee bit more out of the early 110° cam, but the points don't like super-high rpm, and racers are likely to be using other ignition means, such as electronic triggering from Hall element or light sensitive devices.
CONFUSING THE ISSUE FURTHER (??), IS THE FOLLOWING:
Only a bit later than the above BMW's phasing-in of the above first changes, BMW was finding a lot of pinging (pinking), in countries where the gasoline had a relatively low octane. BMW again changed the automatic advance, so that the prior maximum advance which was obtained at about 2200 rpm, was now 3000 or 3200 rpm (depending on which literature you are reading). The previous 'new' mechanism, 12-11-1-353-639 retained that same BMW part number. BUT the Bosch number on the automatic advance changed, and the ONLY ACTUAL change was the two springs. Do see later, below, NOTE #1
0232 002 007 Bosch, BMW 12-11-1-353-639, was now 0232 002 010
The fully suppressed assembly was 0232 002 008, was now 0232 002 011
The early springs were BMW 12-11-1-356-142, the newer, very slightly stiffer springs, were 12-11-1-356-546. So, by simply changing those springs, the ATU got a new number from Bosch, and not BMW, and the maximum advance point went up roughly 1000 rpm higher. That is, the maximum advance point was no longer ~2000 rpm, but ~3000 or ~3200 rpm.
NOTE that Performance bikes, with good gas, will perform better with the early springs giving the faster advance and one might consider using the 110° dwell unit, which helps SLIGHTLY at very high rpm (only).
NOTE that an even later automatic advance unit was made, carrying the Bosch number ending in -012, and was used on the late /6 and /7 to 1978, still with 78° Dwell. Units ending in Bosch numbers -007-012 had advance limited to 34° BTDC. Only the 005 unit had 39° BTDC. The early advance looks the same but the holes in the cross plate allow the advance to swing a bit more open. Those hotting-up their bikes should know about this.
In 1979 BMW went to the canister system, and the
1979 and 1980 had 120°
dwell, using POINTS. With the later coils, and the canister
points ignition, the ignition was considerably better than before, although previously good.
Improvements included the new flat outer portion of the camshaft,
with a slot, and a matching tang on the canister. The old
problem with slightly wobbly cam tips was gone; the points were
no longer exposed to dirt, etc. that was possible with the old
style method of 'sealing' the points area, there was lessened
chance of oil contamination, and the entire ignition system had
higher output and more precise timing, especially comparing one
cylinder to the other.
In 1981 BMW kept the canister but went to full electronic
ignition (except for the ATU which remained mechanical).
The Dwell was now 104°, and the ignition output increased, and
became even more dangerous, in the instance of electrical shock
hazard.
**************************************************************************************
The important timing point for all single
spark plug BMW's, is
NOT the "S" static (idle) marking, but the MAXIMUM advance point.
The maximum advance marking on the flywheel of early models is a F-marked dot depression. Later models use a
LINE next to a Z marking.
There is also an OT marking on the flywheel for top dead center of the pistons,
used mostly by owners for setting valves.
Some bikes have two lines, they are 6° separated, the limits
for double images using a strobe lamp, and have other uses, not important to this article.
I am well aware that there may be conflicts here with SOME publications that talk about setting the timing at the S mark. Many
years ago, the idle (or often called STATIC) timing mark (S) was used, on points machines, even the /2 magneto models, by setting the
(engine off) points opening
position, with an ohmmeter, or voltmeter, or test light, or even some thin paper like
cigarette rolling paper. Strobes were not plentiful nor overly cheap, and the
above methods sufficed. It was always a compromise, as the range of advance and the maximum advance
point are
far more important. PROPER METHOD is to set at
maximum advance point (F or Z) and let the S mark fall wherever
it does.
All BMW airheads use a very similar mechanical ignition advance
assembly. The ears and timing weights hole on the timing unit tend to wear, although VERY slowly, and this tends to
INcrease the amount of TOTAL timing advance
available...which is usually just fine.....but
may be marginal on some older BMW's, such as the R60 models, which tend to need super
premium fuel, especially with much carbon in the combustion
chamber. VERY especially if one has 39°
advance unit. In fact, some of the old models are fitted with compression lowering
plates, to allow use of lower octane fuels. The very mild valve timing of the
R60 tends to make it more sensitive than other models. That is because
quite mild valve timing ACTS as if the cylinder pressure is higher (which it is,
briefly). The best cure for pinging, after
all else has been tried, including de-coking, is conversion to dual plugging, which offers
many other advantages, and FEW disadvantages...cost being just about the only one.
Using the more restricted advance unit, and slightly stiffer
springs, to raise the maximum advance to about 3500 rpm may work
well.
The following, as in all of this article, is for single plugs, NOT DUAL-PLUGGED
MACHINES!!:
Time the engine using a strobe light, clamp it over either plug wire, the left is more convenient
as the timing hole is on the left.
From idle rpm up to around 1500 rpm (maybe 1200 on the early /5), the S mark
will be and remain at approximately centered, and as you increase RPM the S mark begins to move upwards, and eventually you should see the Z or F
mark appear at the bottom of the window, and move upwards. At some rpm it will stop rising, and
THAT is the rpm of full advance. It should occur at about 3000 rpm. If that occurs around
2000 or so, you
have a /5 machine with the very early advance unit, or someone put one on your
bike, or changed your springs to the lighter pull types or ground
down a timing unit weight(s). On RARE occasions
springs have been known to get slack, or stretch.
In some instances, the engine may exhibit pinging (pinking), especially if a high compression
model, unless you have 98+- octane
gasoline. A machine that can handle the faster advance, will
accelerate slightly faster from low rpm. Having the wider
advance plate (pre -012) can help sometimes with lower rpm power
output. Generally speaking, BMW airhead engines give
plenty of warning about pinging, and in many instances a small,
perhaps 3° more advance (sometimes a bit more) is
advantageous...this is especially so at higher elevations, where
pinging may not show up even on 87 or even 85 octane grade
gasoline.
Move the Z or F markings to the upper half of the window, and see. Pinging, if
it occurs, will usually show up first on poorer gasoline's, at near sea level,
on a hot day, under moderate to heavy throttle, typically well under 4000 rpm.
For STOCK setting: If, at the rpm of maximum advance, the Z LINE mark (F
or F dot on earlier machines) is not centered, then make a small adjustment to the timing...by adjusting the points plate
position on early models...or rotating the canister on canister models. Points MUST be
in good condition and the gap set FIRST,
before attempting to do anything
about timing. If you have a points-in-canister model, such as a 1979-1980, be aware that the outer bearing holder MUST be
in position when checking the points gap. You should lubricate the
CAM (and the FELT on pre 1979 models) with the proper greases, sparingly, and the inside of the
automatic advance also has a grease type assigned to it. I like a very
TINY droplet of good oil on the weights pivots.
With the maximum advance properly set, now check the S, idle timing. It should be
approximately correct. At
this point you know you have approximately the correct RANGE of advance, and if you want to,
move the timing such that the Z line or F or F dot is a SMALL amount above the center of the little timing window,
at high rpm (something above the maximum advance rpm, so you are sure the
automatic advance unit has quit advancing). Going beyond 3/4 up the window is likely to result
in pinging,,,,especially with regular low octane gas and at sea level on a hot day. Those having high compression
motors using premium gas should be cautious about advancing timing.
HOWEVER, the BMW airhead combustion chamber is such that it tends NOT to hide
pinging from your ears. Sometimes, depending on the motor model, year,
modifications, gasoline, timing unit, ETC., one can move the mark fairly close
to the very top of the window. Be cautious. You may find a bit more
performance, and fuel mileage....particularly if you ride all the time at high
altitudes.
OT: when this mark is centered, both pistons are fully
out. The typical use is for setting valves, but one must rotate the engine
360° from one cylinder ON COMPRESSION STROKE, to the other cylinder, when
setting valves. 1981+: LINE next to OT is TDC.
S: Static timing, lines, if present, are 3° from S, for maximum limits for split images.
F: Full advance, at rpm for that or above. For 1970-1980, is a machined dot.
Z: 1981 and later, full advance, if a line is present, Z is that line.
NOTES:
(1) The timing advance should BEGIN on the later machines at approximately 1500
rpm, and quit at about 3000. Some books specify 1550 for the beginning of
the advance. The early /5 advance started, per SOME literature, at 1200 rpm,
but some books will say advance began at 800.
Racers might be interested in that, as the advance starts right from,
essentially, idle rpm. Note that the /5 advance quits at about 2000 in
some books, 2200 in others, and one factory
manual even shows it quitting at
2500 rpm. With today's poor octane gasoline, having the
advance quit at the higher rpm is better, although performance suffers some.
(2) 2 mm (.08") on the flywheel is ONE degree. The 1980's and later
flywheels are called clutch carriers, and are not a continuous metal part showing in the window, but the information is same.
The R65/R45 models have a different flywheel, and the markings are deeper inside
and harder to see.
(3) Later models may have two lines, one above, one below a timing character letter, these are spaced at 3 degrees from the timing mark, and are there for reference to factory spec limits. These lines are 6 mm separated (.236 inch).
(4) If your strobe light shows double timing images:
that can be due to one or a combination of the following: worn timing chain,
bent cam tip (on NON-canister models), worn automatic advance unit, unequal
timing bumps of the two
bumps on the cam of the automatic advance unit, worn
chain sprockets, worn chain guides.
(5) 1979 and later models have either points (1979-1980) or a
Hall Element (1981+) (a type of transistor that is magnetically sensitive) in a canister,
driven by a new style nose of the camshaft: flat, with OFFSET
keyway. CONTRARY TO
SOME INFORMATION in some
aftermarket books like Clymers and Haynes, you can NOT put the canister
into the engine with the keyway wrongly engaged
due to the keyway offset. This type of drive is more stable, and cam tip
irregularities are a thing of the past.
The automatic advance units in these canisters is known to get gummy or otherwise stick in an advanced
position, usually this happens after FULL engine warm-up, and the engine will
idle way too fast.
You may be able to remove the small oval plate on
the side and spray in some oil (NEVER WD40), and fix the problem,
MAYBE for
awhile. A full disassembly and cleaning is the proper answer, sometimes
with some minor metal burnishing.
The effect is provable by slowing
the engine using a stop like a brick wall in front of the front wheel
(or use the brake), and
easing the clutch to slow the engine to normal rpm....if the strobe shows
advanced timing, you found your problem.
An article on the canister and
electronics will be found here at:
Ignition.htm
(6) Ignition cutout problems after some miles down the road on
1981 and later models is quite often due to a failure to clean off, and replace,
the transistor-type heat sink grease, located beneath the ignition module, which
is under the fuel tank.
Every year or three is probably OK.
Allowing this cutting-out from excessive heating to continue too often will
result in module failure. Radio Shack has heat sink grease.
Riveted later modules are exempt.
(7) COILS:
Be sure to read article #30:
IGNITION.htm
(a) The airheads before 1979 had an extended
nose camshaft, points in their own 'cavity' (which needs to have
its rubber intact!). Those bikes used TWO EACH 6 volt coils, primaries connected in series,
for a total of 3 ohms.
If you use coils with lesser
resistance then the points will be burned and not last long. You can
use a points amplifier, and the points last a VERY long time if
you regularly (~5,000 miles) faintly lubricate the advance cam.
(b) In 1979 and 1980, the points in a
canister was used
(c) In 1981 to 1984, all models EXCEPT
the G/S and ST, used 2 each 6 volt coils, but they are higher
performance coils, draw more current, as they have 0.7 ohm
primaries, and they have a lightning
bolt
symbol on the coils. These do NOT work reliably with points
amplifiers unless the amplifiers are capable of handling the
extra current. There were some coils made that are
0.5 ohm. See article #30.
(d) From 1983 (with a few exceptions, like the
ST and GS when introduced earlier) a single coil was used,
originally gray in body color (and they cracked and were UNreliable); these were 1.5 ohm.
The Bosch
number on those bad coils was 0 221 500 200. They can
be upgraded with the Oilhead coil, or, BMW has a
replacement for the airhead.... 12-13-1-244-426, it looks a
bit different, but fits just fine. The Bosch number
on
that coil is 0.221.500.203. Lots of ignition problems
from those old failing gray coils, including the acting up of the
electronic tachometer. BE SURE to read article
#30!!!!
(e) Around 1990, BMW went to a BLACK coil, the
Bosch number on the coil is 0 221 500 203. These have a low
primary
resistance, ~0.5 ohm, and the module was changed to handle the
increased current and with
some internal changes to shorten what is called
the time-out period. The lettering on the module was
changed to turquoise or pink. Not a great idea to use the
old module
with this coil, but has been done. There is extensive
information on these coils and modules in my
ignition article. There is also
a low ohm RED coil.
(f) The last change to the module was to a
INTEGRAL, RIVETED module on its heat sink. It
supposedly never needs heat sink paste renewal.
Be sure to use the proper coil; they are different for points versus electronic module models.
There is often confusion about the coils used on early
models. Some of the literature is wrong.....or misleading.
BMW coil 12-13-1-243-452 was used on the POINTS MODELS, TWO EACH
OF THESE 6 VOLT COILS WAS USED.
BMW coil 12-13-1-244-142 was used on the electronics ignition
models. The electronic ignition models began with
MODEL YEAR 1981.
Because the MODEL year begins in September, some literature might
show the -142 coil being used in 1980, or even on R65 models as
late as 1982. Very confusing, and WRONG!
***NOTE!.....the old black Bosch coils, with the lightning bolt
on the side, can be used with ANY of the ignition modules!
These old black
Bosch coils, with the lightning-bolt on the side, which are BMW 12-13-1-244-142
(these coils are NOT marked 6 volt), are the best old coils to use with the
electronic module ignition.
In all cases of using two separate
single tower coils, terminal 15 on one coil goes to terminal 1 on the other
coil. That leaves one terminal 15, which is for the
GREEN
lead; and the remaining terminal 1 lead goes to the BLACK
lead.
If you are replacing a dual output stock coil with two separate
lightning-bolt coils, you will have to fashion
mounting...one can go where the original coil was, the other to the
rear....under the relay bracketry. Have the rear coil fire the right
plug.
NOTE: a common reason to install the lightning-bolt coils
is that a stock grey-bodied early twin tower coil has cracked, and started to
fail, usually with moisture conditions. If you can dry out the coil, you
can epoxy or otherwise seal the crack....but this is a very temporary fix....and
sometimes will not work. Even if the coil has OPENED its secondary winding,
this still may work to get you home.
Do not use the coils marked 6 volt, nor the Bosch blue coils, for the module ignition.
Coil secondary's are about 4000 ohms for the two separate coil models, and 8000 for the twin tower single coil model. For any coil, clean the top now and then, maintain a good rubber boot fit and condition, and inspect the metal contact at the bottom of the tower after removing the boot (inspect wire clip too)...clean out any internal tower corrosion, use a bit of silicon grease to help prevent that after the internal metal is clean and shiny.
(8) Early spark plug caps were about 1000 ohms, and are fine for any POINTS ignition bike. ELECTRONIC module/Hall element bikes MUST use 5000 ohm caps. Appropriate NGK caps are fine. For the 5000 ohm caps, caps that measure 4000-8000 ohms are OK, 8000-12000 is questionable, over 12000 definitely faulty. NEVER use resistor plugs!!!!
(9) It is perfectly acceptable, on ANY airhead, to
short-circuit a spark plug wire
CAP at its inside metal fitment, to a cylinder,
to ground out the ignition. Do it securely; and simply install the cap to
the plug, lay the plug metal onto the cylinder/head, and SECURE it there. NEVER, on ANY
airhead, allow the spark plug cap to be off the spark plug or be ungrounded,
with the ignition ON....you can ruin a coil, and the problems may
not appear for months or years later. One of the better
methods of securing a spark plug metal body to a
cylinder head is to use a long spring sold at hardware stores as
a Sash Rod spring. A screen door long spring will also
work.
(10) There is a detailed article on the canister
electronic ignitions elsewhere's: Ignition
...but here are a few hints on troubleshooting:
The Control Unit (module) under the tank, if non-riveted type,
needs fresh heat sink grease every year or three, otherwise it overheats. Power
is supplied to this module at pin 2 (ground or -, negative 12 volts) and pin 4
(+12 volts). Note that the ON-Run switch on the bar and the key
switch must be on and in RUN position. If voltage is present, try
measuring between pins 5 (+) and pin 3 (-). This is the trigger assembly
output (from the canister). There should be at least 5 volts, if not, the
fault could be EITHER ignition unit.
If you do not have that
voltage: Disconnect the plug from under the tank, at the module where
you are taking these measurements. In order to remove the plug you MUST
remove the very thin rectangular steel bale-wire first....it simply clips around
the plug assembly, there IS an opening in it, it is not a complete sealed loop.
With the plug removed, withdraw pin #5 from the plug (you will need a very thin
tool to press the hidden release point tab) and then reconnect the plug.
Connect a milliampmeter, between the removed wire and
the module pin 4. If the reading is 3-20 milliamperes, the control unit is
faulty, if more or less than that value range, the trigger (Hall) is
faulty.
If the testing is not conclusive, or you wish to do this anyway
or instead,
here is another thing to do, and this is a nice test:
Remove the battery negative wire at the battery or transmission as
appropriate, then remove the front timing chest cover, then reinstall the
battery wire. Disconnect the three pin plug assembly coming from the
canister (key is off). Same sort of bale clip. Remove one spark
plug, and with it still securely pushed into the spark plug cap, tie the spark
plug metal to the cylinder head securely. Turn on the
key. Momentarily and repeatedly short the center terminal of the 3 pin
plug (not the canister side) to engine ground, with a jumper lead. A
strong spark should occur. If it DOES, then the problem is definitely the
trigger Hall device. Be sure your bike's kill switch is centered, or
this test doesn't work. Another test is to not bother with the
canister plug, but to still have the spark plug as described. Turn on the
ignition, and move the kill switch repeatedly from center to one side....should
be a spark each time.
(11) To retard the spark, turn a canister clockwise; and to
advance the spark, turn it CCW.
(12): Points amplifiers, sometimes
call points boosters, are made by a number of
manufacturer's. They will GREATLY increase points life.
Numerous makers.
Accell and Dyna are
two of the popular makers.
NOTE: http://www.qkits.com/ www.apogeekits.com
and maybe others...
Velleman is probably the
actual maker of a number of kits sold by others, using the model
number K2543, this is a kit.
It it is rated at 4 amperes, but with the heat sink that
comes with it, I think it will handle MORE, if placed in a
relatively cool place
on the motorcycle.
http://www.vellemanusa.com
A problem can occur if you have coils that draw more amperes than
the points boosters/amplifiers are rated for. Many have used them
in this somewhat overloaded condition, if they are kept
reasonably cool. The Velleman seems to hold up to this.
Revisions:
02-03-2003: complete information added on the automatic
advance numbers and specifications, and some revisions made to accommodate
those, and other changes to match and clarifications.
04-14-2003: add .htm title; edit for clarity extensively.
06/29/2003: Extensive incorporation of information moved from elsewhere's
on this site. Clarify and update that information as required.
07/13/2003: expand #7
07/23/2003: add #11
09/07/2003: Expand NOTES (1)
04/09/2005: add beginning of article note
10/07/2006: Updated
11/28/2006: add paragraph on points amplifiers
01/11/2009: Clarify some details
02/06/2010: Again, more clarifications
02/16/2011: Add information on faulty early points sets
06/12/2011: EXTENSIVE clarifications and additional
information in some areas.
07/29/2011: minor clarification on coils
08/30/2011: Fix typo error on R60/5 chassis number
changeover on the advance unit
01/11/2012: add some cautionary notes on installing points and cover
© Copyright, 2012, R. Fleischer
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