Where's the oil going?

Ok, so I recently checked my oil after an oil change earlier this year, and after 300 miles, it needed about 2/3 a quart. So this means I'm loosing roughly a quart ever 500 miles. This is about in line with the consumption I was seeing from last year too, so this isn't particularly new.

This seems a bit high, but I don't know for sure. For the time being, I don't mind just dealing with the consumption, but is there a way to tell exactly how/where the oil is going?

Over the winter, I took the head off due to a bent valve on #1. I replaced that valve, re-lapped the it and rest to insure tight seating, and replaced all the valve stem oil seals while I had access. For this reason, I doubt that the oil is dripping down from the top.

However, whenever I start the bike, for the first 2-3 minutes I get a nice white cloud. It comes particularly heavy out of the exhaust connected to cylinders 1-2. It gets heavier in those first few minutes if I rev up to 4k-5k. After those first few minutes and the bike is all warm, there is no noticible clouds out the exhaust anymore (perhaps I should check that more closely).

I know I could just have old rings that aren't sealing well, but the fact that the cloud is differentially different between exhausts seems odd. Is there any tests I can do without taking the head off again that I can confirm where all my oil is going?

Alright, I lied. I just went out and ran the engine for a while around the block. Yes, 1-2 exhaust is continuous spewing some white smoke. Bad rings? Can I check easily with a leakdown tester and see which cylinder is flowing to crankcase more than others?

You can probably do that, or look at your spark plugs. Normally you'll get more carbon buildup at the least and possibly even be able to detect oil on the plugs of the offending cylinder(s).

dnpurdy wrote:

Alright, I lied. I just went out and ran the engine for a while around the block. Yes, 1-2 exhaust is continuous spewing some white smoke. Bad rings? Can I check easily with a leakdown tester and see which cylinder is flowing to crankcase more than others?

Yes, rings is about the only thing that can do that. Bad valve guides will put out a bit of smoke at start up but then stop.

Check rings:

Let it cool and drain down overnight.

Pull the plugs.

Do a compression test on all cylinders cold.

Shoot some oil into the plug holes and recheck. Bad rings usually show a significant compression increase from the oil shot.

Leakdown testing is also good, not as easy to do.

Alright, here's the "sitting all day but not overnight" results. First off, I think my compresssion tester is busted, but, since I used it on all the same tests, the relative results should be about right.

Dead cold, no plugs, W.O.T., I got 170, 175, 170, 180 in order on my compression tester. With a shot of 5-10 cc oil in each cylinder, I got 240, 240, >300, >300 in same conditions. Clearly the tester is f-ed up. Nonetheless, they all got better results with oil in, which for this bike probably makes sense. Not the weird thing is that 3-4 got the big jump, but 1-2 was the smoky exhaust...

Having a wife as a professional photographer, I got her to take some pics of the plugs, all close up and all. #1 looks exactly like #3,#4 with a dusty brown. #2 Looks blacker. Is this oil fouling? (picture wise, #1 on top, #2 on bottom)

After doing the oil test, I started the bike up with a wonderful cloud that filled the street. Wait, I have a fouled all my plugs now...?

If you have a fouled plug, your engine will run terrible... been there, done that. It does sound like rings. The smoke cloud at startup was probably burning out the oil you squirted in for the test.

I would get a known "good" compression tester and check again just to make sure. So the smoke does not clear up? How did the cylinders look when you had the head off? Did this smoke show start after the head work? Just wonder if something happened during the head removal/installation? Let us know...

No, last season the oil consumption was about the same. Nothing particularly new since the head work.

The combustion chambers where pretty carbon-y when i took the head off. I cleaned the domes, but didn't touch the piston tops. I did a steam/seafoam cleanout though just after reconstruction, so hopefully that cleaned some of the piston head gunk off.

yeah, I guess I just have some shoddy rings. I'm going to get 4 new plugs and run them for a few hundred miles and see if any foul up. Other than that, i was hoping to not have to check the oil every time I go out this season, but alas. I'd rather not rip the head off again this year. rebore sounds like a nice winter job anyways.