where is oil going? is this normal?

[KHEEREMA129911]

I just found my r90/6 to be 3/4 a quart low, and I haven't even put enough mileage on the bike to warrant an oil change.

I'm pretty good at keeping the level almost full and not overfilled. I am not noticing any smoke out of the exhaust at all, except for a very small bit upon start up when cold, but I attribute that to the rich mixture when choked. After that very brief cold start up, I'm not getting any visable smoke/blow by at all or while running. i also keep the bike on the center stand (learned that after week one!)

I'm not getting any oil leaks anywhere at all on the bike, I'm really anal about that. I recently had the tranny out to replace the rear main seal and clutch and lube the splines. (All work done by competant former airhead dealer mechanic.) I don't think I'm getting any engine oil seepage into the tranny (I will check filler level on the tranny this weekend to double check.)

I haven't checked compression because bike only has 36k miles and "butt dyno" guestimate tells me compression is within range.

Should I be concerned?
Is this normal? i.e., do these bikes just burn a wee bit oil in normal course of riding?

 

[20774]

Kevin -

No way can engine oil get into the tranny...major magic for that to happen! Some oils burn off their additives faster than oils...maybe it's your oil. As a general rule, the better the brand of oil, the less they'll do that. Also, too much oil will create more of a misting/windage situation inside the engine case due to frothing, etc. That mist will go out the breather valve and be burned in small increments. Once the oil gets to a certain level, it should stop. I've heard that full is probably not good but that about half on the dipstick is about right. Maybe your bike likes 3/4 down on the dipstick??

You could check your plugs and see if the right one is more black and sooty than the right. It's possible that your valve guides are a little worn and oil is getting sucked into the chamber that way. I've heard of ways to check for worn valve guides. I think it's get on a pretty good down hill section at a moderate speed and then close the throttle for 5-10 seconds. If you see smoke, it'll be the valves or guides. To check for rings, drive along at a moderate speed and open the throttle quickly...smoke means rings.

Other than that, maybe just watch the current situation...although I would be a little concerned about running around with only a little more than 1 quart of oil in the bike. I would say using 1 quart of oil in 1000 miles would be marginal...more miles than that, don't worry about it; less miles than that, probably something to check.

 

[EASTER85]

1,000 miles per quart is pretty normal.

I have had a 1978 R80/7 since new. It always used about a quart every 1,000 miles until I switched to Mobil 1 Synthetic 20/50 Air Cooled Motorcycle Oil. I now go somewhere between 2,000 and 2,500 before adding a quart. My theory is that sythetic oil doesn't vaporise until a much higher temperature. Might be worth a try.

 

[na cl k9]

BMW technical bulletin

I've heard that full is probably not good but that about half on the dipstick is about right. Maybe your bike likes 3/4 down on the dipstick??.

I have a copy of a BMW factory service bulletin from around 1975 that addresses the issue of the 900cc engineÔÇÖs propensity for setting itÔÇÖs own oil level. The suggested fix for the ÔÇÿproblemÔÇÖ was to monitor the oil level after each change and watch to see where the initial consumption stopped. Then, scribe a new line at that point on the dipstick and use that as the new ÔÇ£fullÔÇØ mark. IÔÇÖm serious, that is what the notice really said to do. Most of the 900cc machines I've owned that were in good condition have settled at about a quarter or just a little more below full and not more than half way between.

I think it's get on a pretty good down hill section at a moderate speed and then close the throttle for 5-10 seconds. If you see smoke, it'll be the valves or guides. To check for rings, drive along at a moderate speed and open the throttle quickly...smoke means rings.

You are correct. Rule of thumb: If it smokes getting on the throttle itÔÇÖs oil getting past the rings. Smoke when getting off throttle, its oil being drawn in to the combustion chamber through the guides.

 

[Rod Sheridan]

As previously stated, the engine oil will normally settle to a level that is correct for that bike.

Both of my 900's do that, the level settles at aproximately 13mm below the high mark. (That's with the dipstick not screwed into the engine).

Attempting to raise the level causes it to be consumed at a high rate until the level settles.

Regards, Rod.

 

[26667]

huh?

I always thought the oil level was to be checked w the dipstick NOT screwed in, but resting on the top thread.

Tho' mine's a 1000 cc '78, it had been using a qt in 1000mi. So I've changed to synth. too early to compare yet, but many think it could help the consumption rate.

 

[Rod Sheridan]

I always thought the oil level was to be checked w the dipstick NOT screwed in, but resting on the top thread.


That's correct, dipstick not screwed into the engine................Rod.

 

[26667]

oops

Sorry, Rod, sometimes I'm dyslexic. My bad.

 

[Rod Sheridan]

Me too, however as I get older I can always use the "seniors moment" excuse.

 

[tuber1]

My R90 always would settle down to a certain place, never on full mark, thats outstanding mileage only 36k??

 

[FRANKT]

I recall that when the R90's came out, a lot of owners had issue with oil consumption. Seems that the larger crankshaft counterweights were slinging the oil out the breather after which it gets burned in combustion without actually looking like a smoking engine. A common fix was to install the aftermarket 3 qt. oil pan and only put in 2.5 qts.

 

[Ray1505]

The R90/6 and the R100/7 I had used enough oil that I had to add some every two to three tanks of fuel. The R100RT (91) uses very little oil ( less than a quart on a trip to Alaska and back). The oil never quit being consumed.
I would be very concerned about running a quart low. The oil is part of the cooling system and my bikes quit pumping oil at anything more than a quart low.
90+ % of the time I ran synthetic oils.
Figure out how often you need to add oil, do it, and then ride forever!

Ray

 

[TGHSMITH]

when bmw increased to 900cc and then to 1000cc they did not increace the air verses oil ratio of the crankcase too make up for the larger displacement. my high comp. 78 r100rs never needed oil added, I ran the level at 1/8 inch above the add mark and it would stay there for 3000mi, if I ran it higher it would run crappy until it blew the oil down to that level and then stay there and run much better!. a twin relies on oil flow and not amount(you don't have a large amount to start with and an extra half pint isn't going to help!) yes adding an sump spacer and or a later model sump wil help as long as you still don't overfill. add means add, max means to much. much of this info I learned from the late keith patchett, as I was a neophyte in the early 80s and he new many secrets and was glad to share them

 

[na cl k9]

when BMW increased to 900cc and then to 1000cc they did not increase the air verses oil ratio of the crankcase too make up for the larger displacement.

Well, actually BMW _did_ increase the volume of the crankcase by making a slightly deeper oil pan starting with the 77 R100 series in late 76. As you said, "...adding a sump spacer and/or a [later model sump] will help..."
The 1980 on oil pans increased volume once again and later a baffle was added which makes that one the pan to have in my opinion. One interesting aside to all this is that there are a number of different dipsticks out there. It's as if the factory had embarked on a little social engineering after the tirade from owners over the 'oil consumption' of the R90. There are subtle changes to the stick length and the position of the marks indicating low and full or max - Nicht Uber "max" Stand auffullen y'all ! - (southern German)

 

[KHEEREMA129911]

My R90 always would settle down to a certain place, never on full mark, thats outstanding mileage only 36k??

Yup, the odometer/speedometer is in working order so I believe it to be true!

 

[KHEEREMA129911]

Thanks for the info everyone, I"m pretty sure its just the "settling" that going on here. I'm not getting any oil past the valve guides or rings. I had no idea about the "level setting" that these bikes are prone to.

I guess I could find an oil pan from a 1980+ 100RT to perform the oil pan swap? Would this match up to my R90? It gets hot down here, and i'm in stop and go traffic frequently on this bike...probably would be wise to increase the oil capacity as was mentioned in this thread...