82 550 now using oil

Hi all,

82 550 LTD. Quick update: I burnt a hole in #2 piston few years back. Replaced the piston and rings (for just #2). Had valve job done (on just #2). Everything put back together and running ok now, but I'm using oil. It was near the top of the site glass, and after about 200 miles, it's at the bottom third. Plugs don't look horrible. After a hard hr long ride at 65 mph, I notice a little smoke from the right tail pipe (which I thought was a bit weird because I thought it would be from the left because #2 would be the most suspicious).

Oh, compression is 150, 138, 154, 160 (from 1 to 4). Have about 300-400 miles on the bike after rebuilding #2. Now, I'm thinking maybe my #2 cylinder got beat up a bit from melting the piston...It looked ok and measured up ok though. Then I was thinking maybe it's a valve seal on any of the valves...then I started thinking that maybe I should have replaced all 4 pistons rings instead of just #2, but at the time the rings only had 400 miles or so on them, so they went back in.

Any ideas how I can diagnose the problem other than reading the plugs? (which I said before didn't look bad at all). Maybe I should just ride it as is and keep an eye on the oil level. It isn't a hod roddin' machine, just my daily commuter and screwing around bike...

You really need to do a leakdown test on it(requires gauge assembly) This will tell you what percentage you have leaking in each cylinder
I used to set my leakdown tester at 50lbs air instead of 100lbs and simply double the leak percentage. This allows you to lock crank at TDC on that cylinder and connect air to it from the sparkplug hole.(when you put air to TDC you better have a good hold on that crank with breaker bar or lock it in place somehow that compression will try to spin the motor if its not 100% on TDC. Then I'd remove the oil cap and carbs. If its leaking, you see the percentage and most likely will hear excessive air coming from oil filer cap(rings cyl) or youll hear air passing the valves, you can put your hand over the exhaust to feel for exhaust valve leak and over intake for intake leak. This might be more than you want to get into. Maybe you know someone who can do that for you?

I will try this method this weekend. However, how does one figure out if a valve seal is leaking? (Other than a fouled plug with no signs of ring leakage)

Generally a valve seal or seals leaking will be more visible on start up and then quit smoking. When the motor is turned off a slight amount of oil runs down its stem and when you start it, that little bit of oil burns off and smoking quits. Its not common for a valve seal to cause a big loss of oil. I'm more likely to suspect ring damage/cyl before I would really suspect a valve seal.

Hi guys,

Finally got around to working on my 550. I put 130 psi into each cylinder at TDC. Each cylinder hissed, but #4 was very little and 1 and 3 were a little more. #2, being the cylinder I smoked, was leaking more. Now, 1,3,4 I had to really listen to hear where it was coming from, so it wasn't terrible, but I'm not sure really how much is too much without a leakdown tester. At least I know now the valves don't leak at all!

Anyway, as I pulled the plugs, I really became bummed out. One would think that the plug in #2 would be blacker than the others because the rings seemed to leak more. Well, as you can see, #4 is actually the darkest one. #4 also has the highest compression and leaked the least. So, I really have no idea which one could be burning. Also, if the oil was at the top of the sight glass and now is at the bottom third after about 200 miles of county highway driving, wouldn't you expect MUCH darker plugs? In the photo, plugs go from 1 to 4, left to right. The #4 plug looks wet, but it was dry when it came out, I managed to get some oil on it...long story...

rem....leaks are not just rings...gasket, valves and possible crack in head. dont get tunnel vision on rings....check all.

smoke and oil use is a good clue oil is being burned....your prob right.

I just thought of something.... I mentioned that all four cylinders passed air, with #2 being the worst. Well, I wasn't sure how much passing of air is acceptable, but then I realized I did this with the bike stone cold, which probably would cause more air leakage, right?

Apbling,
A couple of things about trying a leak down test. For one a cylinder can show almost no leakage and still have an Oil Ring Issue. As the compression rings will seal. Also you could have a Valve Stem Oil seal issue, and that won't show up either. So to me I see #4 plug with the oil on it. Now did you replace the stem seals when you had it apart before? I don't remember. You could still have an issue with either the guide being worn in the bore, or the guide lose in the head. Maybe the stem seal is damaged or came lose where it fits on? Other wise it would be back to the rings, oil ring has ends lined up and not staggered. Or possibly got bent during install, as thats easy to have happen the are pretty fragile. Or the expander, behind the two oil rings have either the ends not butted, or one end has broken off.
You can pull the carbs, and the exhaust looking for a build up of junk on the valve in each port. If the whole EX port is wet with oil, and not just around the guide, I would say rings.
Good luck sir.

Thanks Motorhead. I did purchase a complete top end gasket kit, but only replaced the #2 seals (the one I smoked). I was flat broke at the time and couldn't afford to pay the shop much more than what they did.

A fiend of mine helped me install the cylinders and he's done it tons of times, so I would *think* we didn't damage it, but you never know...

So, if I take a peak into the ex port and see oil just on the guide, you're thinking it could be the seal, but if it's all over, then rings? Forgive me, but if it was leaking down the seal, wouldn't it still end up all over in the port?

Are these seals known to go out, or are they pretty much trouble free for the most part? Like, do they have a history for leaking, such as the base gasket on my bike?

So you only replaced the Valve stem oil seals on the #2 cylinder that had the hole in the piston?
If the Stem seal is leaking the oil residue will tend to be from the guide, flowing out toward the end of the port, on the Exhaust. Intake port there will oil from the guide into the engine. If the rings are causing the problem, the intake will be clean, the whole exhaust port loaded with black slime. In order for it to be on the plug, #4, it has to be either the Intake valve stem seal, or the rings. If it was EX it would smoke and burn outside of the combustion chamber. So piston and plug would not have residue. Intake seal will suck oil through under vacuum from the engine.
Yes the seals are Known to fail.

yep, it was one of those "I'm broke and can't afford the proper fix (and who knows if it is fixable after burning #2 piston) so lets short cut it and regret it later."

So, since I have all the seals yet...is this job doable with the head on, or is it much easier to pull the head and valves? I think a buddy of mine did it on a 900 by putting air into the cylinder to hold the valve shut...

You can do it with the head on, if that is what it needs, Stem seals. Cams out of course, either Air to hold the valves or some soft rope down the plug hole just before TDC then rotate the piston up. the rope will hold the valves. Then depends on what you have for a lever and such, but you can fab a lever and a cut out piece, window, so as room to remove and re-install the keepers. It can be done for sure, but like I said it depends on the tools you have or can fab.
I just put in a set of GPZ cams and APE valve springs last Friday, head on. Pretty easy with a Lever and a piece from the regular compressor. Still not real fast though. For Flat Rate it would be faster to pull the head.