• Welcome, Guest! We hope you enjoy the excellent technical knowledge, event information and discussions that the BMW MOA forum provides. Some forum content will be hidden from you if you remain logged out. If you want to view all content, please click the 'Log in' button above and enter your BMW MOA username and password.

    If you are not an MOA member, why not take the time to join the club, so you can enjoy posting on the forum, the BMW Owners News magazine, and all of the discounts and benefits the BMW MOA offers?

R100/7 Filter Change - A Pictorial


Staff member
This should apply to all Airheads from 1977-on, non-cooler equipped bikes. For the RS/RT bikes in this category, access to the filter cover might require removal of lower sections of the fairing and/or removal of the header pipe. In some cases I've heard that the header pipe might be dented, but I think this was to allow the original long filter to be more easily removed.

BMW had a bullet-proof filter system before the /7, but decided to "rethink" things! There is one critical decision to make regarding the thin metal shims and gaskets which will become apparent as I get through this. This won't be up to Brook's quality, but I thought it might be good to show the steps and what an owner might face. Oh, and do look past the dirt "patina" I seem to have accumulated. :wave

Here's a picture of my kit and tools used for this filter change...the kit is part number #11009056145 and contains the following items:

- filter -- #11421337570 ("bendy" filter is probably less likely to collapse versus the original straight filter)
- washer/shim -- 11421336895
- o-ring -- 11421264160 (was -098 per RealOEM)
- gasket -- 11421338600
- crush washer -- 07119963300

I use an extra gasket which will be discussed later.

From the tool kit, I needed the 10mm wrench along with the 8mm allen wrench. My oil of choice for the moment is Golden Spectro 4 20w50. Refer to March 2013 Owners News for the latest test on various grades of oils for the Airhead engine.

I went for a 30 minute ride first to warm the oil up. After sufficient cooling, time to drain the oil. For my oil pan, the 8mm allen wrench is used to remove the drain plug. Once it has drained, reinstall the drain plug with new crush washer. I don't know the torque for the plug, I have a "feel" for what's tight enough. It's not under any pressure from the oil...the tightness has to be enough to "deform" the crush washer so it stays in place.

Here's a picture of the filter cavity cover on the front right side of the engine block. Prior to 1977, this plate was completely flat. With the redesigned filter, the new cover was used. If an oil cooler is installed, there will be a different cover along with oil lines. Anton has some good pictures of the various types:


Remove the three fasteners with the 10mm wrench...have a pan to catch the small amount of oil that will come out of the cavity.

With the cover removed, the red arrow points to the canister that is mounted inside the filter cavity...the filter is clearly inside that canister. Note the red circle...this shows a gap between the canister and the engine block as well as the fact that the canister is inset from the outside surface of the engine block. The large white o-ring is required to seal the gap, otherwise oil that builds up around the outside of the filter will just flow back into the sump, unfiltered.

The complication created by this filter arrangement is the sharp edge of the canister as shown here. Beginning in 1977 and to a point sometime in the mid to late 1980s, all canisters were sharp edged. This requires something to protect the large white o-ring...see following discussions. It appears that the part number for the modified canister is 11111338203 and the parts fiche says "from 9/1/1985". Anton and Snowbum mention the late 1980s when this new canister showed up. It has a rolled or swaged edge which shouldn't be as harmful to the o-ring. Personally, I would still try to protect the o-ring as it is critical to the sealing of the filter area.

This shows the order of parts from the outside cover back towards the filter. In my case, I have two gaskets, then the o-ring, then the washer/shim. The use of the gasket has to do with the inset of the canister which I'll discuss next.

It's probably not that visible in this picture, but the white o-ring has some distortion to it after being compressed for so much time and miles. This shows that the o-ring was being squeezed to do its job. No distortion, and the o-ring isn't working correctly...complete havoc or cutting of the o-ring would indicate it is being compressed too much.

So, the compression of the white o-ring is important...also not cutting it as part of the fit-up. This is where one should measure the amount of inset from the outside surface of the engine block to the edge of the canister. Use a digital caliper like I show here. Generally, there are three zones of numbers you should look for:

- less than 3.0mm -- will need to use one or more gaskets along with one washer/shim
- 3.0mm to about 3.5mm -- no gasket is needed but use a washer/shim [most common configuration]
- 3.5mm and bigger -- no gasket but use of multiple washer/shims maybe be needed

Anton has info on how to determine what arrangement you need - http://largiader.com/tech/filters/canister.html

Snowbum has his discussion here - https://bmwmotorcycletech.info/Oil.htm

I have been using what Oak published in an Airmail in September 2004. His approach was to arrange the elements to cause a range of compression on the white o-ring, from about 10 to 25%. The thicknesses of the items he offered were:

- o-ring -- 4.0mm
- washer/shim -- 0.3mm
- gasket -- 0.5mm

The computation is: sum the thickesses of the o-ring and shim, subtract the thickness of any gaskets used and then subtract the canister depth. Divide the resulting number by the o-ring thickness and finally multiply that number by 100. The result is the % compression of the white o-ring.

So, for my situation, I'm going to use 2.6mm as the canister depth. Here are some computations using the above numbers with one shim included:

- no gaskets -- 42.5%
- one gasket -- 30.0%
- two gaskets -- 17.5%

So in my situation, I need two gaskets including the washer/shim. Note that the gaskets are nothing but a spacer, moving the cover farther away from the engine case, thereby reducing the compression on the o-ring. The gaskets are not needed to seal for oil as the white o-ring does that.

Another example for when the canister depth is say 3.3mm. For no gaskets and one shim, the percent compression is 25%. Adding a gasket drops that to 12.5%. So with or without a gasket is likely OK. For the situation where the canister is say 3.8mm deep, no gasket and one shim results in compression of 12.5%...probably OK. Adding a second shim pushes the compression to 20%, again that's OK. When the canister depth is great, shims are needed to make up for that added depth.

So, you can see that knowing the depth of the canister is important as well as to keep an eye on the depth over time. Looking at the white o-ring when it's removed from service will let you know if you're doing OK or not.

So, I've settled on two gaskets for me. Here is the new filter back in place...make sure the inside grommet finds the internal pipe and slides completely home. Hard to see here, but the washer/shim has been put into place.

Here's a look at the outside cover. Two gaskets and the white o-ring...it fits nicely over the inside shoulder of the cover and stays put as well as holds the gaskets in place.

I've managed to work the cover into place and have hand threaded the three bolts. The white o-ring and two gasket edges can be seen...along with copious amounts of grime!! I hand thread each bolt until finger tight. Then I evenly snug up the bolts drawing the cover to the engine case. I don't know the torque, but I just get them to a point of a nice snug. Remember these are steel bolts into the aluminum case.

Time to fill with oil. Note that the float bowl is already resting on the ground...the right side float bowl is also off.

The last step is the reason the float bowls have been carefully removed. One thing is it provides a chance to inspect what's in the bottom of the float bowls. Secondly, and more importantly, I can crank the starter without the engine firing up. I do this until the oil pressure light goes out indicating that the system has been fully pressurized...it took about 15 seconds for the light to go out. Doing this helps reduce any additional start up friction if the engine were to fire without a full oil system...might be a minor deal, but it's an easy thing to do.

Be careful reinstalling the float bowls. Make sure the bowl fully seats into the groove on the upper part of the carb body. I could probably use a new set of bowl gaskets...so if you end up pinching the gasket, the carb will leak fuel. After securing the bales, turn on the petcock to make sure there are no fuel leaks.

That's it...time to put the bike away...and in my case, probably wash the bike! :banghead