Airhead "Tips and Tricks"

[homerj]

This is especially important for GSers who ride offroad frequently.
Go buy a 12mm Allen and add it to your tool kit. The inner pivot bolt near the final drive can easily vibrate loose and back out.

[Dratharr]

I like to carry some extra long flat tire irons with me. The best way I have found to store them is to cut an old 700c bicycle tube in half, slide the tire irons in the tube and fold. Then I wrap it with some 100mph tape tie a piece of wire around it and slide it up into the frame tube. Its a great use of wasted space.

[rowansride]

Thats where the slide to my .45 and my dope lives (and I'm not talking about my little brother here....)

[Cordless]

This is NOT a great bargain but when you need a battery for a g/s in a hurry, go to any Sears and get the 20L-BS. It fits the g/s box perfectly and has fine performance. No bargain at $90 but available nearly everywhere.

I ordered the BMW replacement gel battery for the g/s and it is just too big for the opening. I tried taking the frame apart and removing the rear inner fender but it still didn't fit. I could get it in sideways but couldn't secure it tightly enough. $90 + and the dealer won't take it back even though it was their parts guy who ordered it for me. (Said I could make it fit and that it's the listed replacement battery # 61.21-2 346 80 )

Anyone need a slightly large new Gel battery in the Boston area?

[woodgrain]

I've used 12N-14 (Honda CB750) replacements for my G/S with acceptable results IMHO. Available at just about any automotive place(or Wally World, K-Mart etc.) that sells juice batteries.That said, it's an R80G/S with a kickstarter. Smaller than stock dimensions, a velcro strap holds it secure. Good enough to go to Fairbanks and back. Cost was $39.95.

Woodgrain

[Motomech]

I've found that the easiest way to inspect the shaft is to pop off the final drive(bevel gear case). The rearmost U-joint can be closely inspected and the front can be checked by feel. Of course, this doesn't mean a whole lot, as a U-joint can still go within several hundred miles, as happened once to me.
To re-install the final drive, this is the method that works well for me:
Tape up the rear U-joint with masking tape to maintain the desired angle and place a piece of coat hanger across the pivot bosses for the shaft to rest on to maintain the desired elevation. Once the splines engage a bit, the wire can be pulled out and the housing pops into place. It still helps to have three hands and I've found it best to remove the shock altogether.

[Joerg]

Hi,

here's a short write-up of an almost fatal kind of "movement" that I encountered a few weeks back. May the seal be with you:

At about 143000 km on my 1990 R80GS, after a holiday trip in Italy, I was coming back from a very short ride - something like 1 km to the washing place and back. The bike was barely on the centerstand when I noticed a trace of oil behind me. This was not just a few droplets - it was a real oil leak.

First I thought it was the gearbox neutral switch, but the smell of the oil was clearly that of motor oil. I roughly wiped off the excess oil, and re-started the engine. The oil pressure warning light behaved as usual, i.e. it went dark right after starting the engine. Letting the engine idle, I carefully observed the engine block.

Oil was bubbling out at the front of the oil filter cover - !

I switched the engine off, and dropped the bike on the sidestand. I removed the oil filter cover and found all three bolts to be firmly in place, and the oil filter as such was also in good shape. The most important item, the white O-Ring (aka "the $2000 O-Ring"), also was in the correct shape: slightly compressed. What was it then that caused this leak?

The question was answered by measuring the distance between the outer edge of the oil filter tube (aka canister) and the flat surface of the engine block (since an image says more than a thousand words: http://www.hpn.de/pdf/thermostat2.pdf is a diagram at the HPN website, with annotations in German). In the past, I had always found something like 3.8 mm here, which is just the perfect distance so that the white O-Ring is compressed, but no additional shim nor seal is required. Yet ... the value that I measured now was 4.2 mm. This meant that the tube had settled, the O-Ring with its 4.0 mm diameter would not seal anymore, and oil - as well as oil pressure - was lost.

Technically, the issue could be solved quickly by inserting a suitable shim from an earlier oil change (yes, I keep those ) under the cover, just above the (new) O-Ring.

However, what strikes me is that this movement of the oil filter tube occurred "out of the blue", after more than 140 Mm and 15 years, without any warning. Would I have been on a trip, it was highly probable that the loss of oil - and of oil pressure - would have gone unnoticed until it was too late

Edit/Add-it: The oil pressure warning light was off all the time (but, yes, it definitively works ).

Thus, my recommendation: Measure the distance between the outer edge of the oil filter canister and the flat surface at the engine block every time you open the oil filter cover. And, from time to time, keep an eye on that area to see if it is still dry.

Edit: Finally an oil change where I had the camera at hand ... here's a picture that shows the crucial detail:

[Slope'r]

Originally Posted by Joerg

.....Snip...
Thus, my recommendation: Measure the distance between the outer edge of the oil filter canister and the flat surface at the engine block every time you open the oil filter cover. And, from time to time, keep an eye on that area to see if it is still dry.

Great advice...

Thank you for having a great website...your photojournalism is fantastic...

[jtwind]

For gs and g/s type folks. The odometer reset button is of a compound that does seem to fail and BMW doesn't have them any more. I've found that there are rubber covers for brake bleed nipples that work perfectly. Ask at an auto parts store or a dealer. JT

[woodgrain]

If the rubber O-ring from your '77-'84 BMW dash-mounted clock or voltmeter breaks, a quick road side repair is to place an elastic band wrapped around the clock/voltmeter so it doesn't rattle and possibly damage the dash of your BMW fairing. A better bet is a Harley oil pump O-ring, or a 50mm (2inch) O-ring, available at farm supply stores, nation wide, the thinner the better. Also, spoke nipples will work as instrument retaining nuts on the back of a BMW dash- mounted voltmeter/clock, same thread and easier to come by.

Woodgrain

[Motocicletta]

Originally Posted by Joerg

Hi,

here's a short write-up of an almost fatal kind of "movement" that I encountered a few weeks back. May the seal be with you:

At about 143000 km on my 1990 R80GS, after a holiday trip in Italy, I was coming back from a very short ride - something like 1 km to the washing place and back. The bike was barely on the centerstand when I noticed a trace of oil behind me. This was not just a few droplets - it was a real oil leak.

First I thought it was the gearbox neutral switch, but the smell of the oil was clearly that of motor oil. I roughly wiped off the excess oil, and re-started the engine. The oil pressure warning light behaved as usual, i.e. it went dark right after starting the engine. Letting the engine idle, I carefully observed the engine block.

Oil was bubbling out at the front of the oil filter cover - !

I switched the engine off, and dropped the bike on the sidestand. I removed the oil filter cover and found all three bolts to be firmly in place, and the oil filter as such was also in good shape. The most important item, the white O-Ring (aka "the $2000 O-Ring"), also was in the correct shape: slightly compressed. What was it then that caused this leak?

The question was answered by measuring the distance between the outer edge of the oil filter tube (aka canister) and the flat surface of the engine block (since an image says more than a thousand words: http://www.hpn.de/pdf/thermostat2.pdf is a diagram at the HPN website, with annotations in German). In the past, I had always found something like 3.8 mm here, which is just the perfect distance so that the white O-Ring is compressed, but no additional shim nor seal is required. Yet ... the value that I measured now was 4.2 mm. This meant that the tube had settled, the O-Ring with its 4.0 mm diameter would not seal anymore, and oil - as well as oil pressure - was lost.

Technically, the issue could be solved quickly by inserting a suitable shim from an earlier oil change (yes, I keep those ) under the cover, just above the (new) O-Ring.

However, what strikes me is that this movement of the oil filter tube occurred "out of the blue", after more than 140 Mm and 15 years, without any warning. Would I have been on a trip, it was highly probable that the loss of oil - and of oil pressure - would have gone unnoticed until it was too late

Edit/Add-it: The oil pressure warning light was off all the time (but, yes, it definitively works ).

Thus, my recommendation: Measure the distance between the outer edge of the oil filter canister and the flat surface at the engine block every time you open the oil filter cover. And, from time to time, keep an eye on that area to see if it is still dry.

when I was renting I washed the '88 GS in a carwash, post washing the oil filter caister retracted into the block and at idle I lost oil pressure. The while O ring pre wash used 1 shim now I have to use two to get it to seal. The block must have expanded when washing and let the canister recede.

[jtwind]

This is a new to you airhead points bike tune up procedure that Tom Cutter made up a while bake. I've found it pretty handy. JT

1) Change ALL oils.
2) Torque cylinder heads (25 foot pounds, loosen each nut 1/2 turn, then
torque, use crisscross pattern)., adjust rocker arm end play (zero play, no
rotational binding), adjust valve clearances (cold engine) to .006" Intake,
>.008"
Exhaust.
3) Service auto advance unit (don't snap the thread off the end of the cam,
tighten GENTLY!), grease point cam felt with a smear of grease.
4) Set points gap to 0.016" (0.40 mm) using a good feeler gauge, or better
yet a dwell meter, look for 39 degrees on the four cylinder scale (gives you
78 degrees on a two cylinder).
5) Set ignition timing static setting to S mark on flywheel.
6) Check full advance timing at 3200 RPM, the dot (or hole if the paint is
gone) above the F mark should be steady in the center of the timing hole,
aligned with the machined groove in the side of the hole.
7) Service the air filter, i.e., put a new one. DO NOT blow out air filter
with compressed air, do not leave a K&N filter in at all.
8) Drop carb float bowls and clean the tiny jet in the little well in the
corner of the bowl using a single strand of wire from a wire brush, held with
needle nose pliers. Make sure contact cleaner will spray through the jet into
the bowl.
9) Remove the main jet and jet holder (make a mental note of the depth of
engagement of the jet holder), drop down the needle jet and emulsion tube,
(keep your finger over the hole so they don't fall out and get lost.) Use some
Gumout carb cleaner spray to clean the gunk that has accumulated above the jet
holder. Spray the jets and emulsion tune clean, then reinstall the emulsion
tube, needle jet and jet holder. Visually align the jets onto the needle
carefully. As you screw the jet holder up in with your FINGERS, if it doesn't
seat
fully (remember the mental note?) then back it up about 1/32 of a turn and
wiggle it as you screw it in gently (FINGERS ONLY!) You will feel when the
emulsion tube finds its way up into the carb body hole. If you can;t get it ,
remove the air tube from the air cleaner housing and visually see that the
emulsion tube projects up into the venturi about 3-4 mm. You can wiggle the
needle to help align it as you screw it up in with your FINGERS.
10) Check the float level setting by lifting the float gently with your
fingers. When the needle seats, BEFORE the spring loaded part begins to
depress,
the seam in the float should be parallel to the float bowl gasket surface.
Reinstall the bowl carefully, making sure the gasket is fully seated in thegroove all the way around.
11) Check that the throttle cable has a tiny amount (1-2mm) free play when
the throttle grip is all the way back. Get the two sides as close to the same
free play as possible.
12) Check that the choke cable fully seats the lever on the post when the
lever is in the horizontal position. At half choke, the lever on the carb
should be halfway between the posts. At FULL choke position of the hand lever,
the
choke lever should be all the way up to the top post.
13) LIGHTLY screw the idle mixture screw IN until you feel the screw seat.
Now back the screw OUT by 3/4 turns (this setting varies for other models).
14) Turn the idle SPEED screw OUT until it does not contact the butterfly
lever at all. Now screw the screw IN until it JUST touches the lever, now turn
it IN one FULL turn.

These are the baseline settings. Now take the bike for a LONG test ride, at
least five miles, to get it to FULL operating temperature. Riding around the
block or starting and revving on the stand will NOT work.

At this point you need to synchronize the carburetors. This is accomplished
either by shorting one cylinder at a time (this takes some practice to get
right, usually you need somebody to show you once) or using a vacuum gauge on
the vacuum takeoff ports on the side of the carb. Set the idle mixture on each
carb at the point that gives best running, usually between 1/2- 1-1/4 turn
out. Balance the idle speed screws, then balance the cable pull off idle.
Recheck to be sure that you still have a tiny bit of free play of the cables.
If
not, readjust the cables.

This should get the bike running pretty well. Idle speed should be at
1000-1100 RPM. DO NOT set the idle for a super low "tickover", as this will
severely
reduce oil circulation in the engine and make the transmission rattle like a
bag of rocks.

[nick_rhinocycles]

Did you try taking off the shock? That should do the trick. Just move it out of the way...

Originally Posted by Tallerman

This is NOT a great bargain but when you need a battery for a g/s in a hurry, go to any Sears and get the 20L-BS. It fits the g/s box perfectly and has fine performance. No bargain at $90 but available nearly everywhere.

I ordered the BMW replacement gel battery for the g/s and it is just too big for the opening. I tried taking the frame apart and removing the rear inner fender but it still didn't fit. I could get it in sideways but couldn't secure it tightly enough. $90 + and the dealer won't take it back even though it was their parts guy who ordered it for me. (Said I could make it fit and that it's the listed replacement battery # 61.21-2 346 80 )

Anyone need a slightly large new Gel battery in the Boston area?

[datchew]

for my fellow tightwads:

Ignition Coil: You can use a harley coil part # 31614-83A as a replacement. I don't know the date ranges on your airheads for this. Picture is here:
http://smg.photobucket.com/albums/v1...harleycoil.jpg
(thx to Lornce)


Carburetors: Rebuild Kits http://www.eubmw.com/
and it's $27.95 for two kits (IN THE US - thx Joerg!), including shipping (thx to Solo Lobo)

[Joerg]

Originally Posted by datchew

Ignition Coil: You can use a harley coil part # 31614-83A as a replacement.

You can basically use any 12-V coil with two secondary connectors, as long as it's primary resistance does not go much below 1 Ohm ... that includes a lot from the car junkyard

Originally Posted by datchew

it's $27.95 for two kits, including shipping

Fwiw, I doubt that this includes shipping worldwide. Remember, this forum's motto is ride the world ... so I'd suggest that prices are given with reference to the country where they are valid.