Blue smoke

[Trolleywire]

Hello,

A friend of mine just bought a '81 GS 550T. It says it has 7,500kms on it. It is blowing blue smoke out of the left side exhaust... if this bike has such low k's on it then what would cause this? valves? rings? can he ride like this for long? and would this be a task to remedy? cheers.

P.S he is looking for used 4-into 1 if ya have one kicking around.

[arveejay]

Sounds like the petcock is letting fuel into carb no. 2. check it for gas leaking in vacuum line to no. 2 carb.

[Trolleywire]

Sounds like the petcock is letting fuel into carb no. 2. check it for gas leaking in vacuum line to no. 2 carb.

Ok, thanks.. I will take a look today.

[focus frenzy]

blue smoke is oil burning!!

had the bike sat a long time before he got it??
if it had, he might just have a stuck ring and it might loosen up on its own with some running, keep a close eye on the oil level.

on bikes that sit alot (very low mile GS's) they can get rust on the cylinder liner from a valve sitting open, the rust eats little pit holes in the iron cylinder and those hold oil that isnt wiped off by the oil ring as the piston goes down.

[flyingace]

Put the bike on the centerstand overnight then start it. If the smoke is blue, there's a problem.

If you have a little too much oil and the sidestand leans a little too far, you can get smoke at startup. The left side indicates this might be the problem.

[Trolleywire]

blue smoke is oil burning!!

had the bike sat a long time before he got it??
if it had, he might just have a stuck ring and it might loosen up on its own with some running, keep a close eye on the oil level.

on bikes that sit alot (very low mile GS's) they can get rust on the cylinder liner from a valve sitting open, the rust eats little pit holes in the iron cylinder and those hold oil that isnt wiped off by the oil ring as the piston goes down.

The bike sat for some time.... It was on the center stand all night and still is blowing blue. I did a compresion test and and discovered that #2 cylinder is down. Now, because the bike has low k's will it maybe unstick? or do I need new rings? The bike belongs to a friend of mine and I went with him to buy it and I feel bad that it is burning oil because I told him it would be a good buy due to the low k's? would just be putting in new rings do the trick? is this a difficult undertaking? I have never pulled the head off of a 4-stroke before...I have only worked on 2-strokes. Any help would be greatly appreciated as my friend is a little upset with me. Cheers.

P.S what are the compresion numbers for a '81 550T?

[Ions001]

The bike sat for some time.... It was on the center stand all night and still is blowing blue. I did a compresion test and and discovered that #2 cylinder is down. Now, because the bike has low k's will it maybe unstick? or do I need new rings? The bike belongs to a friend of mine and I went with him to buy it and I feel bad that it is burning oil because I told him it would be a good buy due to the low k's? would just be putting in new rings do the trick? is this a difficult undertaking? I have never pulled the head off of a 4-stroke before...I have only worked on 2-strokes. Any help would be greatly appreciated as my friend is a little upset with me. Cheers.

P.S what are the compresion numbers for a '81 550T?

I can't help you with the compression numbers, but I have something that might work for you. (If nothing else, it'll make Scotty roll his eyes. )

Take the spark plug out and put about two tablespoons of Marvels Mystery Oil into the cylinder. Let it sit that way overnight. In the morning, place a towel over the spark plug hole (don't stuff it in, just lay it over the top) and turn it over a few times with the starter. This should expell the oil. Replace the plugs, and run it for a few and see if that helps.

I had a similar problem with mine, and since I did this it hasn't smoked at all. Of course it's not running right now, but that's due to something else. :-D:-D

[flyingace]

A lack of compression can come from worn rings or leaky/misadjusted valves. The standard procedure is to put about a tablespoon of motor oil down the plug hole and retest the compression. If #2 improves, it is rings. If not, maybe it just needs a valve adjustment.