Airhead "Tips and Tricks"

Here's more than you wanted to know about coils:

http://www.advrider.com/forums/showthread.php?t=202925


And here's some starter info:

http://www.advrider.com/forums/showthread.php?t=193226

A cheap helmet lock can be found anywhere they sell guns. Ask the counterman for the cable lock that is shipped with every new gun. They'll usually give them away. Thread it through something on the bike and the d ring or face plate of the helmet. They're usually plastic covered so no scratching.

This is a handy method to set ignition timing on pre-beancan Airheads that can be done anywhere in about 5 minutes. Even on the side of the road.

1. Remove both spark plugs and lay them on the cylinder heads attached to the high tension leads.

2. Remove the front engine/timing cover.

3. Use something pliable to stick in and splay the ignition advance weights in their maximum fully advanced position (piece of old fuel line, pencil eraser, twig, whatever).

4. With the ignition turned on and turning the engine slowly over by hand in a clockwise direction using a 6mm allen key in the nose of the crank:
A) watch for the fully advanced timing mark (F) on the flywheel through the timing hole in the motor's bell housing
B) while you listen for the crackle of the firing spark plugs.

5. Adjust the trigger plate/points plate until you achieve a perfect straight-on F mark plug crackle.

6. Continue riding on to Bangalore or Santiago or Chengdu or wherever you were going on your cool, old, self-sufficient /5/6 or /7.

You're welcome,
Lornce

Fixed!

G'day Lornce, why would you want that rubbish, it is just that. Do you want to appraise it for a survey? I'll take a pic of it, I still have it in the shed to show other people after fifteen years, if you really want?

To answer the question on Dyna coil, the answer is a definetly yes.

Buy it from Rick at Motterad Electrik and he supplies a bracket that mounts in the stock location, and the correct terminals so the coil fits and the wires push straight on, no drilling , grinding or new terminals needed.

According to the English ignition maker Boyer , the Dyna coils are the best they have tested .

I fitted one at the weekend to replace the 14 year old OEM on my R100GS which I suspected was on the way out, and was rewarded with an immediate improvement in starting , it has also smoothed out a rough spot I had between 2900 -3300RPM in top gear and the engine feels livelier throughout the rev range - excatly the same as when I fitted one to a R75/7 a few years ago.

Nowt wrong wi K&N's maite.

Prop'ly cleaned an oiled they'll stop whatevah's comin yah motah's why.

Bin usin'em fer'revah wi no plans ta stop now.

cheers,
Lornce

I may be buying a low mileage R100RS, it has been inside all its life, it's been serviced every year but hasn't been ridden much. Am I insane to buy this bike, it looks good runs well but I'm concerned I'll be buying a headache. What should I check out before I buy it, splines, carbs, rubber, etc., etc. HELP!!!

I have several airheads, and yes they require love and attention once in awhile, but so does everything else I've ridden. Advil is available at your local pharmacy.

Woodgrain

Who "serviced" it every year? R100RS is a very desireable bike, considered by many to be one of the best sport-tourers. If it runs well, the carbs should be ok, you can look at the rubber and check it for cracks, etc., and if it is low mileage the splines will likely be fine. I'd take some pics and post them in a separate thread here. You'll get more responses that way.

You should be prepared for regular maintenance anyway, parts are readily available both new and used (although the prices for parts are steadily increasing), and the bike should last a long, long time.

A low mile '84 R100RS is a pretty safe bet.

Nikasil bores mean that all those years of storage haven't corroded the iron bores (there aren't any).

Low mileage should mean rear wheel drive splines are in very good repair. In fact, post '81 twin shock airheads use a cush dampened driveshaft that all but eliminates drive spline wear/damage if they're kept properly lubed. IF properly lubed.

Change all the fluids (forks, motor, trans, driveshaft, rear drive housing) and go through the bike cleaning all the electrical connector contact points (the cause of MOST of the service issues you'll have with a bike like this). Dissassemble and clean the carburetors and inspect the rubber diaphrams.

Think aobut fitting modern shocks: Works Performance work well and are priced reasonably. A Corbin seat is a nice addition, too.

With a clean bill of health the bike should be good for some travel. These are great motorcycles for serious distance riding/traveling. Smooth, effeicient, comfortable, quiet and fast.

bon voyage,
Lornce

Here's one I had forgotten: I drop the main jet holders every other oil change (~6-8K) and blow out all the oil/gas mix that accumulates there as a result of the crankcase breather. It keeps the mix even on both sides and seems to eliminate those pesky vibrations that seem to come from nowhere. Way easier than the endless carb synch drill.

You can reach this area by blowing carb cleaner down the larger of the two holes that run parralel to the intake - the cleaner should come out freely round the neele jet.
If you spray in the smaller hole ir should come out of one of the pinpricks downstream of the butterfly.

FWIW there are a lot of 'right' ways to substitute the standard BMW
soft rivets, but more wrong ways I suspect. The way I've documented here works, but so do many other methods. Aircraft quality high strength rivets are plenty strong in shear for example, and could be used successfully...if you have a riveter that can handle them....:) Make sure your joint is tight in shear, and you are probably good to go.

Here is what I did, and why.

Thought you'd all be interested, and others I've sent this too thought
I should post it....so here goes. I've done a lot of work on this.

First of all, the rivets are mild steel. The steel rivets used in our
wheels work under shear, what I mean by that is they stop the hub from
rotating because of the tight fit they have to the holes in the hub
and female spline. These rivets are 'cold' upset, i.e. the heads are
peened over with a cold rivet. They don't really clamp the hub to the
spline as bolts are normally used to do, or as 'hot' rivets do on say
an old bridge.

Both the holes in the spline and the holes in the hub should be almost
exactly .250 inches. I have a rivet from my drive in front of me and
it measures 0.249" for the part that was in the aluminum to 0.247 for
the part that was in the steel hub.

If you are going to bolt the hub you can get the best of both worlds;
i.e. a tight shear load fit of bolt to hole, and a good clamping
force. Most people use socket head screws and 'clamp' the 2 parts
together. The friction between the 2 parts is what stops them
slipping, not the tight fit of the sheer load.

Now, some people just use Stainless Allen bolts instead of close
tolerance ones and they claim this is foolproof. I bet it does work
fine as they are adding a clamping force to compensate for a possible
(if the shank diameter is at the small end of the tolerance) lower
sheer loading ability. If the fit is tight they would work fine.

But I figure the original BMW designer used shear loading for their
design so I know it works, and using a shear loaded fastener of equal
or better strength and adding a clamping force only makes the joint
stronger. The problem with standard fasteners is that the shank
tolerance is 0.242-0.249 usually.....a big tolerance for a sheer fit
fastener and generally not acceptable when at the low range. We want
a very tight fit of the fastener to the hole for a proper sheer
fastener. If you are lucky you may find 0.249 standard
fasteners...but I couldn't find any. So the fit was loose. I went to
MIL spec...see below.

Basically you want a 'close tolerance' bolt, or one that has an
unthreaded portion of the shank at 0.2485-0.2495 in diameter. You
don't want any of the threaded portion of the bolt in the holes. If
threads are in contact with the aluminum it will act like a saw and
machine its way through your hub....ouch.
- Use hardened washers under the nut.
- machine(I needed to use a carbide cutter in a lathe, any machine
shop can do this for you)/file the new spline hub so that the surface
where the nut is going is parallel to the mating surface of the hub.
There should be enough clearance for the nut to rotate on the bolt.
Failure to do this will cause the bolt to fatigue and loosen as the
surface is curved right now. Also the carbide cutters leave a radiused
'corner' so as to minimize stress concentrations. Don't remove any
more material than you have to.
- degrease/clean the mating surfaces, remove all oils etc.
- bolt the hubs together. You may have to ream a few holes out with a
0.25" hand reamer to get everything lined up, but I did not. I did
have to use a soft faced mallet to tap some bolts in place as they
were a tight fit. This is good and ensures a good sheer fit. The
bolts come from the outside of the hub. I had to very lightly chamfer
the hole on the outside of the aluminum hub so as to give clearance
for the radiused portion of the bolt head where it joins the shank.
Failure to do so will leave a gap between the head and hub potentially
and could cause the hub to become loose eventually. Make sure there
are no gaps.
- torque and I would also use loctite red or blue...your choice (The
nuts are self locking though). I torqued to 13ft/lbs. I would have
used 15 ft/lbs but as the threads are wet from loctite I reduced it a
bit.
- I then used a small diamond wheel in a Dremel tool to cut off the
protruding threads of the bolt so they did not interfere with the rear
drive.

Now, if your holes are elongated, all is not lost. You could most
likely move up to the next size fastener and drill and ream the holes
in the hub and splines to match. A lot cheaper than a new hub.

I had to very lightly chamfer the hole on the outside of the aluminum
hub so as to give clearance for the radiused portion of the bolt head
where it joins the shank. Failure to do so will leave a gap between
the head and hub potentially and could cause the hub to become loose
eventually. Make sure there are no gaps.

As mentioned earlier, for the bolt you need unthreaded shank in the
holes, + the thickness of a washer under the nut. The unthreaded
portion or shank length should be ~.675" + 1x the washer thickness
(I'd measure your own hub and driven spline cup to compare). You can
always stack washers as spacers if you want. Basically you want no
threads in the hub or spline cup.

I used MIL spec bolts, nuts and washers.

Here are the part numbers I used:

MS21250-04012 (12 point close tolerance bolts, cad plated)
MS20002C4 (washers, countersunk on one side as the bolts are
radiused under the heads, you will also need to grind one side so as
to fit this under the nut on the spline cup.)
MS21042-04 (self locking nuts)

All of this stuff is for 1/4-28 thread size.

I have my hub together, so if you want I can take some pics for you.
I haven't used it though, but it is properly designed and I believe
this is better than original. BMW couldn't afford to do this as these
fasteners cost me ~$3 each.

Just so you know, there are other options. Aircraft AN-174-12 will
probably work as will NAS 6204-13 for bolts. If you have an aircraft
supply place they can help you out. Check head diameters and
clearances on the hub though.....

Also, if you know anyone that manufactures aircraft, there are some
VERY strong blind rivets out there, that equal or exceed that of the
steel rivet (it's about ~2,000lbs shear I think, my data is at home).

BTW, I can back all of this up with engineering books. Carroll Smith
has a great one on fasteners for racing. I'm a techno geek so I love
books like this...(my wife thinks I'm crazy)

NOTE: ALL FASTENERS ARE NOT EQUAL. I hate using bold typeface, but
if you substitute full thread fasteners, loose fasteners, ungraded
fasteners, etc. there is a good chance that your hub will fail! Clean
the mating surfaces, torque everything properly, machine the hub
surfaces and everything will be done in a proper way. Fasteners
differ in many regards, not only in strength or corrosion resistance.

MrLuftkoph

Good advice

1. My personal tip/trick for all the Bing carb issues that show up in every airhead forum is Mikuni. Instant throttle response, set-em-and-forget-em reliability and at least a small boost in gas mileage. Rocky Point Cycle has them. Pricey, but absolute reliability.
2. As to the K&N issue, I bought one 9 years ago, I follow the cleaning/oiling procedure, I got no complaints.
3. Batteries? I got one of those Omega(?) batteries on ebay($50?) about 6 years ago, never had to charge it, it gets washed off twice a year whether it needs it or not.
TIP TO NEW GUYS: Use GL-4 rated synthetic gear oil in your tranny. The transmission is the weakest point in these otherwise bulletproof motorcycles. Personally, I use Royal Purple 75w140 MaxGear.

Ride Long, Ride Safe

The 83 and 84 model years are notorious for valve recession issues. You'll wind up doing a top end on it, unless someone has already done them.

Watch for rapidly shrinking valve clearances as the indicator it's time to pull the heads and get them done.

Had a strange "chuffing" noise while idling. Thought it was a bad vacuum hose and decided to just get rid of all the emissions plumbing. Maybe old news to some folks but a revelation to me, the ports in the engine for the emissions plumbing are 16mm x 2 = Universal auto oilpan drain plug for $1.50 . Had to saw the plug shorter but it is the right thread to get the job done. Probly spent <$5 all together. Not to mention the newly acquired '89R100GS sounds MUCH better and runs smoother-stronger!

I wrap that boot with electrical tape even if it is brand new. Why take chances? And you dont even realy see the electrical tape if you do a neat job.

I remove it at the battery and if I need to keep cutting power, I use my vice grips to clip it on and off the battery terminal as needed. Of course you wouldn't clamp down hard on it, just enough (since battery terminals can break)