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To the tune of 1/2 qt in +/- 500 miles!

Haven't ridden it much this summer, so I've been slow to notice.

No smoke at startup, haven't been able to check on decel; one plug is more fouled than the other.

Newer reed style breather installed 4-5(?) years ago.

Rings/bore or valves (no changes in lash) first on the menu?

Normally, the right plug will be a bit more fouled than the left because the crankcase breather dumps into the right cylinder's intake snorkel. A quart every 1K sounds like a lot, but it might actually still be in spec. If you're filling the crankcase all the way up to the top line on the dipstick, some theorize that the crank will splash a lot more, causing more oil vapor that gets vented to the intake system. Letting the oil level drop to mid-way between the max and min lines reduces the churn/vapor/venting issue, reducing oil consumption. Obviously, you'll want to keep a close eue on the dipstick to make sure you don't run it too low. A leak-down compression check should be done to see how the oil is getting into the combustion chamber.

A leak-down tells you about the compression rings (and the valves), but it doesn't necessarily tell you about the oil rings.

BMW's spec that they considered normal was something like 0.8L in 1000Km which is a US quart in 735 miles. That's outrageous but a common stance from engine manufactures. They were well aware of the breather issue if oil was run too high and in a service bulletin advised that "oil should not be added until the min mark is reached on the dipstick and then add no more than 1 pint" Effectively that means running oil at no more than half mast on the dipstick was a BMW recommendation.

You didnt say how many miles are on the bike/engine.

barryh wrote:BMW's spec that they considered normal was something like 0.8L in 1000Km which is a US quart in 735 miles.

And you thought your airhead had a 4-stroke engine. My auto-injected Vespa P200 uses oil at about that rate . . .

khittner1 wrote:

barryh wrote:BMW's spec that they considered normal was something like 0.8L in 1000Km which is a US quart in 735 miles.

And you thought your airhead had a 4-stroke engine. My auto-injected Vespa P200 uses oil at about that rate . . .

Yeah, but the Airhead is using far far less per gallon of gas.

I don't think so, Major. I've had the P2 for only a couple of years, and less than 1K miles (it sat for quite awhile needing electrical work), and I haven't measured carefully, but I think I went about 75 miles on the last 1.5 gallon fill-up, so 50mpg seems pretty comparable to airhead mileage. I don't really thrash the old beastie---but maybe I will after I get a few rocker piercings and tats . . .

Whoops---thread hijack! We now return to our regularly-scheduled thread already in progress.

Yes, yes, a leakdown; just trying for a shortcut in that I have a pair of jugs and (I think) matching pistons on the shelf.

I find it difficult to believe that worn valve guides could be the sole source of this much oil usage. Yes/no?

For the record: 94,700 mi. ( sadly, only 24k are mine) and was hoping to roll the odo this year

Little to no known history...

Major Softie wrote:A leak-down tells you about the compression rings (and the valves), but it doesn't necessarily tell you about the oil rings.

This is my thought.