1982 R100RS - Quite a bit of oily accumulation around air intake tubes and carbs. Assume that the breather atop the engine is the problem. Is this breather serviceable or will it need to replaced?
From my research there are 2 breather systems, a phenolic disc and the metal reed valve. A 1982 bike should have the later (better) reed valve system. Other than a good sealing of the 2 small breather covers to the engine block and replacement of cracked hoses there's not much to do there. The only reason to proceed in that direction is if you see oil coming out the drilled hole in the crankcase above the LH cylinder.
• First thing to do is replace your air filter element. The breather system is so tight that a clogged air filter will actually pull excess air from the crankcase so the engine can continue to run. Paper elements can look clean and still do this. If you are unsure of the last filter change, then do it.
• Excessive breather oil can also be a sign of pressure from the combustion chamber by-passing the piston rings and adding undue pressure to the crank case. This is commonly called "blow by". The only way to reduce this blow by is to replace the piston rings.
In other engines this could be fairly expensive and require cylinder boring and expensive new pistons. However the BMW boxer runs so cool that hardly any cylinder wear is recorded and usually piston ring replacement will suffice. This work is best done in concert with push rod tube seal replacement. So if your push rod tube seals are still holding up it may be too early ! 😛
(Top end gasketing and ring replacement is an excellent Tech Weekend job. If you decide you can't live without having this work done, then make plans to attend one.)
• Another cause could be the type oil you are using. Synthetics could be working their way into tighter spaces than normal mineral oils might venture. If you are using a synthetic, then try an oil change to Valvoline VR1 20W50 and see what happens.
• Your bike should have an oil cooler, so I doubt thinning due to higher oil temps is an issue.
Hope this helps.
Owning an old Airhead is easy.
Keeping an old Airhead running great is the true test.
All of Wobbly's points are well taken and true, but if you are trying to keep your oil level at the full line on the dipstick, it is possible that your motor is simply expelling the oil that it does not want. All the Airheads I have owned did this. The top picture is the happy level in my R75/5, and the lower is happy level in my R100RS
former Airmarshal, IL.
This "lower than normal" oil level is a continuing mystery that has reached the level of BMW folk lore. Whatever the reason, my '79 RT displays the same low reading. I finally gave up and installed a Mac deep oil pan giving me an extra ~2 quarts. Now I don't worry at all about being 1/3 quart low on the dip stick.
http://www.shop.macperformance.com/MAC-BMW-Twins-1970-1989-Large-Oil-Sump-Pan-98101.htm
Owning an old Airhead is easy.
Keeping an old Airhead running great is the true test.
This "lower than normal" oil level is a continuing mystery that has reached the level of BMW folk lore. Whatever the reason, my '79 RT displays the same low reading. I finally gave up and installed a Mac deep oil pan giving me an extra ~2 quarts. Now I don't worry at all about being 1/3 quart low on the dip stick.
http://www.shop.macperformance.com/MAC-BMW-Twins-1970-1989-Large-Oil-Sump-Pan-98101.htm
Folklore?...maybe not.... "lower than normal" is actually normal in my experience. What is normal? I took a MAC deep oil pan off my R75/5 and replaced it with an OEM pan. The churning action of 2 pistons pressurizing the sump at the same time creates the mist that gets shed off, expelled, directed back in to the intake via the breather system.
Unleaded gasoline created more trouble on my bike. In the years after I paid for a head re-build and put in a fresh set of rings, my 750 (@ around 122K miles) has been completely stable with regard to oil consumption, with the OEM oil pan, so long as I don't over fill it. But, we are discussing 2 different issues here.
The true purpose of a deep oil pan is to increase the volume of air in the sump, not necessarily to carry more oil, however more oil is better, right?
It is critical that the oil pick-up extender be installed along with a deep sump. Otherwise, a person could run a motor out of oil with extra oil in the sump. Also, a person needs to have a longer dip-stick, or a different device to indicate the level of oil relative to the oil fill hole, from which the oil level is measured.
former Airmarshal, IL.
Actually, oily intake tubes is an indication that the breather system is working properly. You can't get anything out of a system like this that is not put into said system,... see above
former Airmarshal, IL.
"Folklore" was indeed a poor choice of words. "Standard Feature" might be closer.
🙂
Owning an old Airhead is easy.
Keeping an old Airhead running great is the true test.
Have replaced air filter, even though it looked clean to me. Will check oil level.
Thanks for chiming in
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