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Camshafts, broken cam tips, cam sprockets,
lifters (followers), alternator & cam seals,
crank nose bearing, etc.
Sports-cams installations.
Assembly lubricants.


copyright, 2013, R. Fleischer

Article 60
sub-section 7
http://bmwmotorcycletech.info/cams.htm


This article is meant to be used with the following articles:

http://bmwmotorcycletech.info/timingchain.htm  comprehensive on the crank, timing chest seals, oil pump, etc.

http://bmwmotorcycletech.info/flywheelremovalwarning.htm


Preface...The importance of proper engine oil:
Most any engine oil will work reasonably well for the engine, but there are specific areas of the engine that WILL BE damaged, and perhaps expensively, if the oil is not of proper quality and that means proper additives that are blended by the oil makers.  The author's website, http://bmwmotorcycletech.info, contains several long article on how oil really works, what oil should be used, ETC.    Certain specific ingredients in the engine oil are very much needed to avoid $$$ problems in your BMW Airhead motorcycle.  THREE are critical.  One of them is ZDDP (or ZDP).  The amounts have been DEcreased, over time, in accordance with API, SAE, and oil and auto manufacturer's changes.  Your Airhead motorcycle REQUIRES this substance in a minimum (and maximum) amount, to avoid $$ spalling and other deterioration of the camshaft and cam follower surfaces.   Another ingredient is needed to be sure that under storage conditions, the cam and followers (and other items in the engine) do not have the oil dripping off and leaving the metal unprotected at engine startup.  The final ingredient (of major importance) is that the amount of detergents (Increasingly higher in modern car oils) should not be excessive, as that defeats BOTH long term storage metal protection AND defeats the protection of ZDDP.
Here's a few photos of cam and follower damage:
  
 


Terminology

Base Circle

The base circle is the round portion of the cam lobe where the valve lash adjustments are made. A slight high spot on the base circle is called base circle runout.

Cam Lift

This is the maximum distance that the cam lobe pushes the lifter. Because the rocker arm ratio will multiply the overall valve lift, this should not to be confused with valve lift.

Cam Profile

The cam profile is the actual shape of the camshaft lobe. A flat tappet camshaft is slightly more pointed on the nose of the lobe, while a roller lift camshaft has a more rounded profile on the nose of the lobe.

Degreeing the Camshaft

This is a process that synchronizes the camshaft with the crankshaft. For best engine performance, builders use a degree wheel to dial in this measurement. Most manufacturers will list the exact specifications for each cam on the cam card.

Duration

The length of time the valve is held off the valve seat from the cam lobe. This is measured in degrees of crankshaft rotation.

Duration at .050-inch Lift

This is the distance measured in degrees of crankshaft rotation from when the valve is open at .050-inches until it’s .050-inches from closing.

Gross Lift (Valve Lift)

Typically camshaft manufacturers list this measurement by multiplying the cam lobe lift by the stock rocker arm ratio, usually 1.5:1. For example, if your cam lobe lift is .319 and you're using a 1.5:1 rocker arm ratio, you can take .319 x 1.5, which is .479 inches of overall valve lift.

Lobe Separation Angle

This is the angle in degrees between the centerlines of the intake and exhaust lobes. A 112-degree lobe separation angle means that the peak opening points of the intake and exhaust lobes are 112 degrees apart. This measurement is another way of expressing valve overlap, which is the amount of time that both valves are open on the same cylinder. If the lobe separation angle were 0 degrees, both the intake and exhaust valve would open and close at the same time. Measurements typically range between 104 and 115 degrees.

Tight Angle (104 degrees)
  • Lower rpm torque range
  • Increases maximum torque
  • Higher cylinder pressure
  • Lower idle vacuum
  • Rough idle quality
  • Valve overlap increases
Wide Angle (115 degrees)
  • Higher rpm torque range
  • Decreases max torque
  • Lower cylinder pressure
  • Higher idle vacuum
  • Smooth idle quality
  • Valve overlap decreases

Broken tip on pre-1979 Airhead camshaft:

This relatively serious problem is seen now & then.  The cause is typically from over-torquing the nut holding the automatic advance unit to the camshaft tip.  It could have been abused long before you got the bike, weakened, then it was YOUR unlucky day to snap off the tip ....even using proper torque.   Officially the nut torque, at least in one BMW manual, is .6-.7 Mkp.  0.7 Mkp is 6.86 Nm or 5.1 ftlbs.  I would not go that high.  4 footpounds is, I think, more than plenty high enough.  MOST torque wrenches that read, perhaps, to a maximum of 75 foot-pounds are NOT accurate at low settings of 4 or 5, even if they can be set that low at all.   If you must use a torque wrench, use an INCH-pound wrench at maximum 48...or some other lower torque type of wrench (inch-ounces??), with appropriate conversion of values...there is plenty of information on torque, torque values, etc., using the torque wrench, conversions, etc., on this website, see articles 71A, 71B, 71C.

I personally tighten these nuts by feel, and I use the original type of washer or a waverly locking washer. I do NOT use a split-type of washer.  Nuts need NOT be overly snug, but must be snug enough so the nut does not back off!  I NEVER over-tighten these nuts!  DO NOT use Loctite on these nuts.
 

What to do if the tip does snap off:

A Boyer ignition will likely fit, but you can likely fix the tip, if you do the following very carefully:

1.  File the cam nose smooth & flat and as square as you can.  Do NOT remove any of the D shaped boss area.

2.  Center-punch the EXACT center of the cam tip, with a SHARP centerpunch.  You need to make up something or use the proper centering tool, to
BE SURE that it is dead-centered.  I cannot emphasize that enough.   A machinist can do that for you, or, contact one of the Airheads LIST guru's.  You also NEED a drilling guide AND tap guide made up.

3.  Using your drilling guide, drill the cam tip, very slowly, very carefully, to a depth of 7/8", using small sized increments of drills, ending with a diameter of 11/64".  Use a GUIDE for the drill bit!  Do NOT break the drill bit!
   Clean out the chips often.  Use tapping oil & tap for 5 x 0.8 thread (see next paragraph regarding the thread size), to a depth of 3/4"....carefully!   DO NOT break the tap!  Use a GUIDE for the TAP.

HINTS:   USE a brand-new tap of the taper tip 'starting tap' type, do a thread or two, then back out & repeat.  BE ABSOLUTELY SURE that you select a thread pitch that you can purchase screws for at the same time!   5 x .7 and 5 x .8, etc., are metric sizes, but you may find that the .7 is not common for tap & screw. Yes, I know that many of you will use American size taps and screws and not Metric.   Do it right, use metric.   BE SURE to pay attention to my remarks about centering, and using drilling and tapping guides. 
You MUST have a proper drill guide, etc.  Here is a contact for information:   "Paul Tavenier" repairhead@sbcglobal.net

HOLD the advance unit counter-clockwise while snugging the screw you install;...against the D-flat, ....to remove any slop & prevent shifting movement.  


STOCK, original equipment camshafts:

For the stock cams, at .0787" valve lift (2 mm), the timings are as follows, keep in mind that TWO types of these cams available, the 3 advanced one & the NOT advanced one.  
 

R50/5, R60/5, and R60/6 to 1975:
BMW issued a SI on that camshaft, saying that some published information was NOT correct.  BMW said the correct figures are: 
Intake Opens TDC; Intake Closes 40 ABDC; Exhaust Opens 40 BBDC; Ex Closes was illegible, but I am sure it said 40 BTDC. If you were to look up the sprocket and camshaft in the present parts fiche, it would be 11 31 1 250 253, sprocket.
284 camshaft, used UP TO 09/1975, 11 31 1 259 262.

UNfortunately, BMW is confusing itself.  You will find that other manuals say Intake Opens 40ATDC....all the numbers are 40; that INCLUDES the intake opening at 40 ATDC.

Maybe the confusion came about as the R60/6 for 1976 and the R60/7 for 1977 had the following timing:
INtake opens TDC; closes 40 ABDC.   EXhaust opens 40 BBDC; closes TDC.  
If you were to look up the sprocket and camshaft in the present parts fiche:
/7 to 09/1977, sprocket 11 31 1 250 253, camshaft 284 11 31 1 262 999.
From 07/1976 to 11/1977,  sprocket 11 31 1 335 588,  camshaft 284 11 31 1 336 374.

If you look carefully, you will see there is an overlap, not-explained, on the manufacturing dates, and the parts associated.  NOTE that the SAME sprocket was used to September 1977, yet the last item, above, shows a 588 used earlier.

Some of this confusion has to do with the changes for the bikes actually shipped to the USA.  January 1, 1978 was the absolute start date for the emissions bikes for the USA. There is more to all this, including changes for associated things...such as that cam seal.  The whole camshaft, oil pump rotor, etc., needs to be carefully looked at depending on what your bike actually has.  This is one of those instances that a look-see is needed, as well as using the serial number of the engine, when looking into the fiche.  Even then, could be anomalies. Be Cautious!   Read this entire article several times!  If you are into your engine in depth, ask about seals, camshafts, pump rotors, ETC, on the Airheads LIST, if you have the slightest confusion.


R60/7 1978: 
INtake opens 6 BTDC; closes 34 ABDC.  EXhaust opens 46 BBDC; closes 6 BTDC.   Note that these figures are 6 different, due to the change in the keyway placement of the camshaft sprocket.   This camshaft, or the engine, or, however folks tend to describe it, is the first "emissions" engine.

One of the confusing things is that BMW's literature, or some of it, showed the R60 models having the exact same horsepower & torque at the exact same rpm, no matter what year!


R75 (all) and R90; R100/7; R100S; 1977 R100RS: 
INtake opens 10 BTDC; closes 50 ABDC.  EXhaust opens 50 BBDC; closes 10 BTDC. 


DURATION CHART (Duration versus CAM LIFT ITSELF):
http://bmwmotorcycletech.info/CAM-DURATION-R75.pdf

R80/7, R100/7, R100S, R100RS (1978): 
INtake opens 16 BTDC; closes 44 ABDC.  EXhaust opens 56 BBDC; closes 4 ATDC.  

After 1978, U.S. models (R80/7 & larger): 
INtake opening 10 BTDC; closing 44 ABDC. EXhaust opening 56 BBDC; closing 4 ATDC.  

I am NOT sure about the R45/R65.


Note that sometimes cams are spoken about as the total degrees, and the 1978 would be 308.  Note well above, the description of 284 earlier camshafts.

What is total degrees?   How is total degrees calculated?:
Total degrees means the difference between closing and opening angles.  The number of degrees is given in crankshaft degrees, and is the number of degrees that valves
are off their seats.  
This can be exceptionally confusing because different camshaft makers, difference engine manufacturer's, etc., can and do specify such degrees at varying amounts of valve lift.  Also, the same manufacturer may specify the 'degree' of any camshaft, as for a quite different valve lift, than for the TIMING of the individual cam events.   You may want to read this paragraph over and over!

BMW uses 2 mm (.0787") valve setting lift as the reference point for cam events timing; tolerance on timing is + or - 2.5. 
If you are measuring at the CAM lobe itself, the R60/7 had a 0.2417" lift; and the later larger bore engines had 0.2634" lift.  The rocker arm ratio on the engines is 1.39, so for valve lift you multiply the cam lobe lift by that 1.39 factor.  If you are doing measurements, a quite small change in valve lift can mean a fairly substantial change in the TIMING of opening or closing of a valve.  Be very careful!


For NERDY folks only: 
http://www.tildentechnologies.com/Cams/Tip_DegreeCam.html
http://www.tildentechnologies.com/Cams/CamBasics.html
http://www.tildentechnologies.com/Cams/CamDesign.html

see:  http://W6rec.com/
also see Clymers, Haynes, the BMW books, etc.


If you are changing to a NON-stock camshaft, this article does NOT cover all the possible problems you may run into.  This can include such as spacing rocker blocks, modifying piston valve pocket areas, valve sizes, compression ratio problems with pistons & valves, non-compatible drives to the oil pump inner rotor, 0 and 3 degree types, and a LOT MORE.   Do your homework.  I am not able to supply all the information you could possibly need in this article, although I will try to incorporate most everything.


Changing camshafts....to stock or to Sportier:
Because of the large amount of confusion & various parts numbers & combinations from BMW, I recommend that those wanting to change camshafts should purchase the cam & sprocket, using the information about them (& the oil pump drive and the seal size), from these folks: http://www.motoren-israel.com/

Sometimes someone has to replace a worn-out stock cam with another stock one, or they decide to go to a sportier cam.  Whatever the reason, you may or may not be able to get the exact original camshaft like your old one, from your BMW dealership.  You will have to look into that.   Be VERY careful about details. 

BMW NEVER installed the "336" Sport Cam in a stock motorcycle. The so-called "336" sport cam will NOT perform well in the lower rpm ranges, nor at idle, due to the timing of the camshaft lobes.  I am not going to get into the background of this cam as originally designed, nor all the details of how to make it work for you.  The 336 cam will NOT work well, unless you run the RPM up considerably higher than normal.   If the rest of the engine is mostly stock, performance will SUFFER below the mid-range.  The cam detracts so much from the bottom end of the RPM range, that you MUST have high compression, and it will have to come nearly entirely from the PISTON selected, not by shaving the head or cylinder; ....although those are some of the part-of-the-story options.

To use the Sport Cam where it truly helps, you must do all the other things that serious engine builders of hot rods know about.  You MUST be sure the piston & valves never touch; nor, with big valves, that the valves never touch (remember, the valve timing is changed).  You will HAVE TO modify the heads for large carburetors unless you already have 40 mm carburetors.  Changes on the R100 engines will be more than the smaller engines.  You must be sure the cam aft end fits the oil pump rotor...or, change yours...I noted the number for that part change below.

It is possible that BMW's classic division, whatever they are calling it now, will have some parts you need, if going to all-BMW items. 

The complications are considerable.  POSSIBLY the better approach is to either get into it deeply on the Airheads LIST; or, contact an aftermarket supplier of the camshafts, like Motoren-Israel, etc.....who have the experience to give you solid advice.  You will want to know every detail!

The valve pockets in the pistons might have to be modified if you change camshafts.   You may have to modify not only the piston valve pocket, you may have to sink the valves deeper into the head and relieve the area.

The 284 camshaft has 8.62mm lift (0.339"); the 308 camshaft has 9.40 mm lift (0.370"), for some reference points here. Yes, you multiply by the rocker arm ratio, to get actual valve lift.  Yes, these figures may disagree by a FEW thousandths. Yes, it seems to disagree with the following.  But, keep in mind the variables in how lift is measured!  

Numbers on cams are likely to be CASTING numbers, not the part ordering number.
 

 

336 degree camshafts, the so-called Sport Cams, are the ones ending in part number 053, 412,  848 and 393.  Note that the last batch of the 336 cams was for the square drive oil pump; the cams came with the oil pump parts. The 336 cam has about a .424"  lift, rather mild soft rise ramps, & runs strongly between 5700-7700 rpm, with roughly 8000 max rpm.

If you seriously take into consideration the performance of the various camshafts that are available from BMW and from aftermarket sources, & you delve deeply enough into all details, you MAY decide that the BMW factory '336' cam IS THE ONE TO GET...PROVIDING you do much more than just change the camshaft.  It really performs WELL, if you raise the compression ratio to a minimum of 9.5, and it is entirely possible to use up to 10.2 or even a bit more (even on 91 octane fuel at sea level, and maybe 89 at altitude).  I highly suggest dual-plugging with Accel coils and using electronic ignition (the stock ignition, but used with twin tower Accel coils is FINE for 1981 & later.   You can also retrofit the canister ignition from 1979-1980).  Modify the advance in accordance with the RESTRICTED advance RANGE, as one of the two choices shown in my dual-plugging article.  Use 40 mm Bing carburetors or the Del Orto's from the R90S, and use the 40 mm exhaust system.  The stock BMW mufflers will work fine.

DURATION CHART (Duration versus CAM LIFT ITSELF):
http://bmwmotorcycletech.info/CAM-DURATION-336.pdf


NOTE:  There is a 320 camshaft available, 11 31 1 338 498, that I have no further specifications on, at least not yet.  BMW installed it in some ECE delivered countries for many R80 engine'd models.  It is a simplex drive, that is, the nose is flat, for use with canister ignition and simplex chain.  I suspect it was used for Authorities bikes. 
 


Alternator and camshaft seals used in the the inner cover: 
All models use 11 14 1 255 011 alternator seals, probably 28 x 47 x 7 mm.

One of the changes was due to the camshaft SEAL, the early one being 12 x 25 x 8 mm.  The seals are often talked about as the Small Seal, and the Large Seal.  see the timing chain article:  http://bmwmotorcycletech.info/timingchain.htm

Obviously, the larger seal requires a larger cam diameter at that point. Another point is the oil pump; the rotor was changed.

The camshaft seal up to models built in 9/1975 was 11 14 1 261 193.   It must not be used in later models, or there will be leaks.  The later cam seal is 11 14 1 262 977, is 20 x 32 x 7 mm.  From 09/1975.  To change any of these seals, if leaking, you do not have to remove the casting.  Remove carefully.  Clean off old seal residues; that can be done by moistening a rag or paper towel with a slow drying solvent, such as WD40 or even kerosene, pushing it into the seal area, letting it sit overnight; after which you can wipe away the residues. Before installing the new seal(s), use a VERY fine grit paper to clean any sharp seal entrance area.  HEAT the case, then OIL the seal; PUSH it into place.

Centering the cover, at the camshaft seal:
Tom Cutter suggested the following method, which is somewhat different from what I do, but it is good.  NOTE that I do not use BMW's centering tool (there are two of them, old and later seal sizes).

Try installing the cover (heat); snug the bolts finger tight. Wait ten minutes for the cover to cool. Now LOOSEN all the bolts 1/4 turn.  Then shift the bottom of the cover left-to-right-to-left, etc., at the cam. You will see that you can move the cover over a millimeter each way. The seal does not center the cover. Instead, if the seal lip deforms to the off-center cover position, IT WILL LEAK. Use a caliper to measure from each side of the cam to the points plate bore; lightly tap on the cover to match the left & right measurements. That will give the seal the best chance for survival.

Cams/Seals/Pump Rotors:
11 31 1 338 302:   this is the 308 camshaft.   The 412 cam is for the large seal.

11 31 1 258 053:   has a small cam seal, used on /5 to R90S (to 1976 model year); was replaced by the 337 848 cam.   Officially up to 9/1975...but in some instances a year later, & now used only with the oil pump rotor 11 41 1 335 194.

11 31 1 263 412:   has a large cam seal, used on R60/6-R100/7 (to 1979 model year); replaced by the 11 31 1 337 848 for both /5 and /6.   Officially up to 9/1975...but in some instances a year later; now used only with the oil pump rotor 11 41 1 335 194.

11 31 1 336 393:   used on
canister ignition models.  Cam was available in TWO styles.  Both have a slot on the front face (flat nose) for use with the canister ignition; the large seal is the difference.   The cam is only available in the advanced timing version.  The cam is likely stamped 336 on the end.  The actual sport camshaft, often referred to as the 336 cam, if sold for the early models, is for the large seal.  If you have an early bike, with the engine cover that has a small seal, you need to get a later large seal cover; they are available with & without the tach cable hole area. 

CAM SPROCKETS:  There are THREE:
11 31 1 335 588 is likely in the literature as for 09/78 to 09/84, and you may see it then continued, date-wise use for flat nose camshafts (canister ignition models).
11 31 1 250 253 is for up to 09/77.
11 31 1 335 241 is from 09/77 to 09/78 in the literature.

 


SOME explanations:

By the time you get into all the above, you probably will find all sorts of problems with cam availability, your dealership may be able to supply just the last cam, creating problems for you.  At the end of this section is a reference to Motoren-Israel.  You  might want to contact them.

Repeated, plus MORE:  BMW presently sells a 336 cam to fit early models; but it is for the large seal, see above.  If you have an early bike, with the engine cover that has a small seal, you need to get a later large seal cover...and you can get them with or without the tach cable hole area.   If you order that 336 cam, it comes with a oil pump rotor.  The cam end that drives the pump has two flats, while the original rotor was keyed.  

Do NOT use the BMW Airhead one-piece pushrods with non-stock camshafts!!
Do NOT try to use the 1 piece pushrods with a 336 camshaft.

To further confuse the issue, there were TWO versions of the -053 and -412 camshafts.  The difference is the KEYWAY for the gear.  The later version is advanced 3, so the valve timing versus the crankshaft is changed 6.   The -393 flat nose cam is available ONLY in the advanced version.   The cams are not easily identified by appearance, and must be measured. If an old cam is installed in a 1979+ engine, the slot is retarded 3 degrees.

Some of the part numbers (last dash number) will seem to disagree with information on what BMW sold, is in present fiche, etc.  Sorry, but things changed over the years!

Here is a link to the BMW factory information on the "336" camshaft.  It includes installation information, camshaft TIMING, things you need to know...etc.  LOTS OF INFORMATION.  Rather than put many of these things into the article you are reading, they are in this hyperlink.  http://bmwmotorcycletech.info/336-cam-factory-literature.pdf

A bit of background on how this .PDF came about ...and some additional information:
In 2006 John Falconer came across a German language document on the "336" camshaft.  John did some preliminary translation, & a bit later, David Paulus finished the document, making it a pdf.  While the document seems to reference just the  053 & 393 part numbers, you can see equivalents/changes, by going to any BMW dealership's on-line fiche.  I believe there is an error in that pdf.  The second cam listed should be 11 31 1 263 412, which is the cam for the /6 & some later, using the large cam seal.  The 1 mm R69S washer is fibre, part 11 34 0 026 186, & fits.  You are unlikely (OK TO TRY!) to find the correct size washer, other than that one.   This washer is fiber, & has the additional benefit of reducing spring temperature. 

You will still probably find old & new part numbers confusing.  Keep in mind the type of nose on the camshaft & the type of oil pump drive, & if the proposed camshaft is a 0, or a 3 (well, sprocket...).   Once those things are decided, then it is 'just' a matter of fitting things properly, & paying attention to the various things about spacers, rocker arms, pushrods, valve pockets, etc., that I have mentioned.

If you are purchasing a camshaft from such as Motoren-Israel, they can certainly supply you with INDIVIDUAL ADVICE.

UNconfirmed data for the sport cams,  where P=(inches):
4000 rpm, 3 cam, P= 46.    For 6000 rpm P=30.  For 7000 rpm, P= 25.  for the zero degree cam, add about 2 to the P figures above. If you don't know what P is, well, too bad, & I am going to leave you UNinformed.

BMW does not have many of the old camshafts available, & only had one, the so-called 336, for most bikes.  BMW never supplied R65/R45 special camshafts, AFAIK.   One company that I know of that has a LARGE assortment of camshafts, even 'modernized' versions of the "336", even R45/65 cams, & even cams for the Krauser 4 valve heads, ETC...is Motoren-Israel    http://www.motoren-israel.com/
They probably can supply a camshaft to fit any Airhead, for any purpose, & they probably have enough models to reduce changes you need to make, such as on the oil pump or simples/duplex, sprockets, and so on.  


Explaining the 3 and 6:
In 1977-78 BMW made changes that amounted to a 6 difference in crankshaft to valves timing.  This was done by changing the tooth-to keyway in the camshaft and sprocket by 3.   Engines/bikes SOLD in the U.S. from January 1st of 1978 HAD to have the advanced timing, to meet the 1978 emissions rules.  Many just before this date did NOT.   Thus some "1978"  might not have the emissions camshaft.    If you are interested in another way of describing all this, see http://bmwmotorcycletech.info/timingchain.htm   

BMW had a bulletin on this more than once, and in at least one of them, it said you remark the flywheel.


Here is a interesting way of determining which type of camshaft (symmetrical or not, that is, the advanced timing cam or not).  This is an edited by Snowbum version of something passed on by Tom Cutter, long ago:
Remove the spark plugs & valve covers.  Put bike in 5th gear & rotate the rear wheel in the forward direction until the EXHAUST valve rocker arm pushes the valve inwards & then JUST returns ALMOST all the way outwards.  As you rotate the wheel (jerks work fine on the system backlash for that purpose) and the exhaust valve starts to come back out, the intake will start to go in.  This is the overlap phase.  Lay a straight edge across the adjustment LOCKnuts, from the exhaust to intake rockers.  Looking straight down on the rockers, and on the straight edge from above, the straight edge will change angle relative to the valve cover gasket, as you turn the rear wheel. STOP when it is parallel
.  At this point, if OT mark is lining up in the window, the cam is symmetrical.  If it is about 3/8" below the window, it is the advanced timing cam.

NOTE the following from Tom Cutter; a posting from him in 2017, it is another way of saying the above; but these comments were pointed towards an Airlist query about whether or not the owner could have gotten the timing sprockets off by a tooth, when doing a chain job::

It is WAY easier to check cam timing on any pre-78 Airhead, all of which had symmetrical cam timing. That being the case, you simply put the motor at OT, and put a straightedge across the ends of the valve adjuster bolts. If the ruler is parallel to the valve cover, the cam is timed right. Takes SECONDS to check with nothing but a metal ruler.

On the 1978 and later Airheads, the cam timing is advanced 6 degrees, so just put the motor 6 degrees BEFORE OT ( the OT mark will be barely visible if you peer way DOWN in the hole. Do the ruler test there and if the ruler is parallel to the valve cover gasket surface, the cam is in time. 


MISCL:

When working on Airheads, you may occasionally need to know the spacing between markings on the flywheel (or clutch carrier).  You may need to know the distance per degree on the circumference. The diameter of the larger engine flywheels are all the same, and there is 2 mm between each degree.  For the R45/R65, it is 1.5 mm between each degree.

Chain size:   3/8 x 7/32, both SIMPLEX and DUPLEX.

Crankshaft bearing:   For many years, this was number 07 11 9 981 722, and is 35 x 62 x 9 mm. The bearing number has been changed to  07 11 1 468 882.   It is a common bearing, but you must get the correct GRADE.  Here is the FAG part number for it:    FAG16007-C3

Changing the front main bearing?...and confused about its holder/carrier?  Pay attention to the information in the BMW factory literature about properly positioning things, & the oil holes being vertical & about the drilling needed on the two holes through the bearing...0.124"...right through the existing front bearing carrier, & then the bearing area.  A new locating pin hole....taper hole, partial at 0.156", & full at 0.148"....there is a special ream...etc.  ... all this is being mentioned for you, & not put in exacting detail.... so you will be extra cautious in not just willy-nilly changing things.  MORE on this subject is here in a very comprehensive article dealing with everything about the crankshaft and what is attached, etc: http://bmwmotorcycletech.info/flywheelremovalwarning.htm

Aftermarket rockers are...or were...available with roller tips. Installation and use are not covered in this CAMS article; nor is information on the Krauser 4 valve heads, etc.  I have a separate article on the Krauser's:
http://bmwmotorcycletech.info/krauser-heads.htm
 



LIFTERS (Followers), ZDDP, Break-in, Rotation of lifters (and valves), ETC.

There is an article on this website specifically devoted to assembly and break-in: 
http://bmwmotorcycletech.info/break-in.htm


The lifters are properly FOLLOWERS (I use the two words interchangeably in this article); these break-in to the camshaft lobe, & the camshaft lobe breaks-in to the lifter as well.   I HIGHLY RECOMMEND that if you remove the lifters that you do NOT MIX THEM UP... always replace them into the SAME engine case hole.  Your lifters/followers ARE NOT centered with regards to the camshaft lobes. That is done on-purpose in your engine.  On some BMW vehicles, they use a slight convex crown on the lifter face, & the mentioned, just below, cam lobe.    This convex crown is usually impossible to see with the naked-eye; on some engines can be as little as 0.0009", to as much as 0.015" (can seen with a straight-edge).   BMW does not use that method in our Airheads, instead BMW uses OFFSET followers.

The purpose of the offset, etc., is to ROTATE the follower, reducing over-all wear.  This same offset idea is used at the valves, to rotate them, by offsetting the rocker to stem.   NOTE:  some uninformed folks that do BMW Airhead HEAD work do NOT understand things as well as they should ....and they FILE or GRIND the valve keepers to prevent valve rotation. This is usually done with SS one-piece valves. See the article for detailed information:  http://bmwmotorcycletech.info/valves.htm

It is common for "flat tappet" engines (meaning the lifter/follower, here) to REQUIRE special lubricant additives to ensure low wear.  The type of cam lobe shape, & how the lifter comes in contact with the camshaft lobe, causes SCUFFING.  You can think of this as a wiping motion of the cam lobes to the lifter face.  The best additive is known by its shortened name as ZDDP (ZDTP is used in synthetics) & is almost an absolute necessity; other additives for the purpose are not as successful.  It is my belief that when the ZDDP concentration falls below around 900 ppm, excessive wear can occur.  Modern car oils have very little ZDDP (IF ANY!).  The oil essay & other oil articles on this website explain oil additives & properties in much more depth.  Do not take oil base stock & additives lightly, they are IMPORTANT for Airheads.  Note also that the heat-hardened characteristics of some BMW items has varied, that is why some have used car oils in the past & gotten away with it.  I highly suggest you DO NOT use car oils.

Wear, scuffing, & actual DAMAGE, is highly variable, depending on oil compounding, the factory hardening process & quality of such hardening, etc.  Some owners may get away with common low or no ZDDP car oils.  Others may have cam and follower failures. Yes, I HAVE SEEN IT.   BREAK-IN IS OR CAN BE CRITICAL, ESPECIALLY SO WITH HIGHER LIFT CAMS AND/OR HIGHER SPRING PRESSURES .... WORSE YET WITH HIGHER RPM.

On most all more-modern flat tappet engines the cam lobe is ANGLED, in one direction or the other, towards the camshaft.   This ANGLE plus followers OFFSET, cause exceptionally good reliability of rotation of the follower.  The angle is almost impossible to see with your eye....it may be a degree or two....and sometimes can be seen with the camshaft removed from the engine and a straight edge carefully used.

Brand-new lifters/followers should be coated with a special high pressure cam assembly lubricant when assembling the engine. Most fail to do this.   If you do not use such a camshaft assembly lubricant, at least use a reasonably high ZDDP oil for break-in.   You can use 10W40 or 20W50 Golden Spectro 4 for break-in and everyday use.....these are not car-rated (forget what the container seems to say or imply), but have relatively high old-fashioned ZDDP additive levels.  There are other brands, and some with very high levels of ZDDP (NOT recommended), etc.   See my oil articles for information.   DO NOT USE CAR OILS, nor break in a top end on full synthetics, is my basic advice.   I assemble camshafts & followers using a
break-in "assembly lubricant".  This is not a moly-type oil.  It is a special anti-scuffing oil and the ones I use generally came from manufacturers or re-grinders of camshafts.  Some of the products I use are no longer available.  Auto-parts stores that specialize in racing items usually carry these types of assembly lubricants. 

One that is OK, and relatively common, is from the Royal Purple folks, their product called Max-Tuff.

My oil articles point out why certain viscosity grades of oils are not considered to be car oils, by SAE, API, and industry in general.  A bit complicated. The articles explain the problems with understanding the MESS industry, car makers, SAE, API etc., got us all into....and why engines like early Corvettes, Porsches (and Airheads....) must have ZDDP, in reasonable concentration.

I am not about to get into arguments about these things.  You can read my oil articles on this website.  Disagree if you want to, just do not bug ME about it. 
 


There may be errors in the above article by me, regarding part numbers and details.  Double check...no, triple check! with other information-knowledgeable sources; and dealerships; ETC ....before purchasing parts, doing modifications of any sort, especially machining work!  I suggest you just post the inquiry to the Airheads LIST.


rev.:
NEW.  Released 01/26/2008
04/26/2010:  remove bad hyperlink
05/03/2010:  fix two errors where valve clearance should have been valve lift.
05/21/2011:  Minor cleanup
11/06/2011:  explain cam sprockets and cam numbers here and there, a bit better.  Add note about timingchain.htm article.
11/08/2012:  Fix typo on new bearing number for the crank.
04/25/2013:  re-work entire article.    Include pdf ON THIS SITE, eliminating hyperlink to outside sources where the hyperlinks were dead.
05/02/2013:  Add two .pdf's on R75 and 336 cam lift versus duration, courtesy Stoner.
09/24/2013:  Expand, slightly, the information on replacing the seals
10/20/2013:  Add section on lifters, zddp, rotation, etc...and modify other areas of the text slightly.
08/05/2014:  Add BMW note/SI, on the /5 camshafts timing.
09/28/2014:  Clean up article, fix a couple of MINOR typos too.  Noticed that article will hang up in some browsers or in Preview mode; determined that the old language scripting was not removed in 2013 like it should have been.  Fixed that.
05/28/2015:  Forgot to upload 2014 update on Motoren Israel, so did so.
01/26/2016:  Update Metacode. Font size increase.  H. Lines adjusted.  Clean up article. Expand information.
05/20/2016:  Final updating of metacode, scripts, H.L., layout, improve clarity, ETC. 
04/17/2017:  Expand comments by Tom Cutter.
06/03.2017:  Adjust fonts and colors and minor layout improvements.
07/25/2017:  Add preface and photos of cam and follower damage.
07/28/2017:  Add Terminology section, copied from another article.
                             

Copyright, 2013, R. Fleischer

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Last check/edit: Friday, November 03, 2017