simple timing question

[Paul]

Hello,

I have an 1983 R65, which has been down on power and not wanting to idle.  One of the things I am checking is the timing.  The BMW repair manual for the R45, R65 and R65LS has a section on timing the ignition (dynamic) for 1981 and later models.  In this section it states (if the timing is correct) that an S appears in the timing window at an idle and a Z appear in the window at ~3500 rpm.  Is this true?

On my bike at 1000 rpm an S appears right where it is supposed to be.  As the rpm is increased the S moves up (I believe) and nothing appears in the timing inspection hole at 3500rpm.

Paul

[Bob_Roller]

The advance mechanism in the ignition canister ( bean can) may be hung up not allowing the timing to advance.

[nhmaf]

One other "Easy" thing to check - your valve clearances.   If they close up to
nothing then you'll also have a difficult time with it idling properly.  If the valve
clearances are in spec, it could be the ignition advance.   I think that there is
supposed to be a "Z" in the timing window at full advance, but my memory is
a bit hazy today...

 :-?

[Chris_in_BC]

Hello,

On my bike at 1000 rpm an S appears right where it is supposed to be.  As the rpm is increased the S moves up (I believe) and nothing appears in the timing inspection hole at 3500rpm.

Paul

With the bike in 5th gear, turn the rear wheel until you get the S mark in the window (easier to do this if the spark plugs are out) Now turn the wheel so the flywheel moves approx 2 inches more. You should see the Z mark.

That is the first step, verify it is there.

Then look at Bob's suggestion re sticking advance mechanism.

[Rob Valdez 79 R65]

And when you find the mark, paint it white.

[Semper Gumby]

And when you find the mark, paint it white.

With whiteout.

Hey if you don't want to muck with the bean can just set the idle past the S mark so on full advance the Z appears.  Won't idle as well but will cruise mo' betta.

[Justin B.]

I always time all of ours at the full advance mark.  I then check so see if the "S" comes up at idle just to verify the mechanical advance mechanism is returning properly...

[Paul]

I slowly rotated the engine after removing the spark plugs.  The Z does exist.  After adjusting the exhaust valve clearances, I checked the timing and the Z does appear in the timing window at 3500 rpm or so and the S is in the window at 1000 rpm.  It is just hard to see the Z due to my timing light being flaky.  I do not know if it is a crappy timing light or if it is hard to get a trigger signal off the R65 spark plug wires.

The exhaust valve clearances was non existent for the second valve adjustment in a row.  I do not want to get new valve seats installed until winter.  Has any one tried lead additive?  As long as do run out of adjustment is it ok to just keep adjusted valves (on shorter mile intervals)?

Paul

[Rob Valdez 79 R65]

I would run it for 100 miles and check it.  If they have not closed up, run it for 250, 500, etc.

If it is closing up fast on you, you have a dangerous situation that could result in major expense and down-time.

All the lead additive will not save your valves and/or seats if they are closing up quickly (within 3000 mi).
(that is being conservative...)

[Semper Gumby]

Hey Rob,

That picture of Joan's Cylinder head scared me into the valve job.  Nathan said my exhaust valves were sharp enough to shave by.  (phew)

Bill

[Paul]

After 1,100 miles my exhaust valve had tightened from  0.008 inches down to about 0.006 inches.  It looks like the valves and/or valve seats are going to have to be replaced.  Is there anything I can do to push off the repair work for a few months?  I would like to put off the repair work until January when snow and ice may cause commuting on the motorcycle to stop, anyway.

Paul

[Justin B.]

Paul, about all you can do at this point is to be vigilant about your adjustment.  From what your indications are I would start checking every 1000 miles.  It is possible that later on in the summer you may need to do it more often depending on how many miles you ride.  Just keep 'em adjusted and get 'em done this winter unless it gets to the point where you are having to have to adjust every few hundred miles.  See Joan's pic of what a busted valve can do...

[Paul]

Actually I am having a tough time finding the picture of the busted valve and ensuing damage.  Could some one point me in the right direction.

Many thanks,

Paul

[Justin B.]

Go here, http://www.pbase.com/joanmarie/blueberry , and you will find several pics...

[Rob Valdez 79 R65]

If you need more photos, here are two very recent examples:

http://www.boxerworks.com/phorum/read.php?f=1&i=200743&t=200743

http://www.boxerworks.com/phorum/read.php?f=1&i=201675&t=201675


Justin and I have met both of these owners.  They are both good, responsible people.