Oil Burner!

[Grdnwlknsn@aol.com]

I bought my R65 earlier this year with (allegedly) only 17,000 miles since new, having been stood unused since 2003.

It starts up fine & ticks over nicely, although the carbs could do with a balance.

However, it burns oil from the left cylinder like it's going out of fashion, producing great clouds of blue smoke & leaving oil dripping out of the exhaust balance pipes after a run.

I thought that maybe the rings were gummed up after the long stand or broken & replaced the rings in the left pot.  I should mention that I thought of the rings first because it smokes on acceleration as well as on the overrun & on all throttle openings.

The problem is, it still smokes just as badly as ever.

Am I looking at valve guides now, or something more sinister?

The right cylinder is spot on.  The plug is a good colour & the exhaust is nice & dry at the outlet.

HELP!!

[nhmaf]

Some other basic questions - just to get them out of the way -
1. Do you park the bike on the sidestand after you ride it?     This makes matters worse because the oil settles into the left cylinder.    Either leave the bike on centerstand (for at least 10 minutes) after you run it, or, while still astride the bike with engine off, tip it to the right as best you can for 10 seconds.  This lets oil from the left head drain back through pushrod tubes into crankcase.   Then you can park on left sidestand if necessary.

2. When you replaced rings, what type of rings did you use, and did you use regular dino oil (if you're otherwise using synthetic) to break/bed them in?   How many miles since you installed them, and, did you make sure the rings gaps were to spec, and the gaps were not aligned at the bottom?   If the rings didn't bed in properly yet you could have alot of oil consumption.

3.  It is possible that the valve guides are worn, but usually this is only on much higher mileage engines.   Have you done a compression test on the cylinders before changing the rings?  

4.  Just as a sanity check- make sure that you don't have a pool of oil at the bottom of your airbox.  If the crankcase breather pipe/check valve is having issues, you could be getting oil pumped up into the airbox, and I tend to find (on my bikes at least) when this happened the oil always seemed to favor dripping through to the left carb.

Mike

[tvrla]

And to add just a little -

What year is the bike?

What was the end gap in the rings you removed?

[Barry]

I should mention that I thought of the rings first because it smokes on acceleration as well as on the overrun & on all throttle openings.

I see your logic in thinking it wasn't the valve guides. You wouldn't think they'd be that worn anyway at 17000 miles.

The side stand issue is real enough but if that was the cause the smoke would be expected to subside fairly quickly and from your description it isn't.

It often seems that if an R65 is going to burn a little oil it is inexplicably always on the left pot. As has been said the breather seems to favour the left pot even though if you look at the pipe work there's no obvious reason why it should. On my bike I don't have any smoke or detectable oil consumption but my right piston top is always bone dry and the left always a little damp. One of these days I'm going to do a temporary experiment by putting a bung in the left breather tube to see if it makes any difference.

If your problem is related to the breather first thing that will help is to run the oil level no more than halfway between lower and upper dipstick marks. This allows more airspace in the crankcase giving the breather an easier time. From the pictures of your bike it's an 81- on model which should mean you have the improved reed type breather rather than the early disc type. Might still be worth looking at though. You don't have any "turkey gobble honking" noises do you ? That might indicate the rear crank seal pulling in air which even a good breather would struggle to cope with.

[MrRiden]

Reading the replies has got me wondering. Does the oil ring grove on these bikes have drain back holes in it. Reason I ask is these drain back holes become clogged notoriously on a cretin brand of car, of which I have two, and is known to contribute to oil consumption. Just a wild thought.

[steve hawkins]

Are you continually topping up your oil to the max?

These bikes like to find their level - if you keep topping them up, they will just try and blow it out.

Cheers

Rev Light.

[Barry]

My oil rings are a simple single piece u shaped ring with slots in the back. I know rings for the later bikes with nikasil bores are different at least in material of construction but I think they are the same simple design.


Just to reinforce Steve's comment about oil level. BMW issued a service bulletin about excessive oil consumption which I can post tonight when I get home from work. Back in the early 90's they were clearly aware of the need to run well below the max mark and even went as far as to say that if you had a consumption problem oil should not be added until the level reached the minimum mark. These comments were made in relation to measuring oil consumption but they went on to talk about adding no more than 1 pint (presume that's a US pint) above the minimum mark. As the Max and Min marks are 1 litre apart and a US pint is O.47 litres then they are saying no more than half way between the two.  

So there you go running oil at half mast has been official BMW practice all along.


Edit: bulletin attached