Smoke and Low Compression

[facepants]

I'm getting a lot of smoking coming out of my bike, oil is being burned in the engine

Compression on right side is normal, compression on left side is 50-something

If I stop giving spark to the left side and only run on the right, smoking goes away.

What could possibly be causing this?

[NiceGuysFinishLast]

smoke + no compression = bad rings.. no?

[Egaeus]

Either rings or valve guides.  Check the compression again in the left cylinder but this time put a tablespoon or so of oil in the spark plug hole first.  If it goes back up to normal, then you have worn piston rings.  If it stays about the same, then you have worn valve guides.  Either way, it's somewhat major engine work, but it's not impossible for the mechanically inclined.

[facepants]

Is there any possibility that a stuck valve would be the cause of the problem?  *cross fingers*

[Egaeus]

Yes.  The lack of compression could lead to incomplete combustion and also cause it to smoke.  What color is the smoke?  What does it smell like?

[Mandres]

Could also be a bent or stuck valve, or a shim that's waaaay too thick holding the valve slightly open.  Do the oil-in-the-spark-plug hole check to help narrow down the problem.  Either way you'll probably end up having to pull the head to find out exactly what's wrong. 

[Egaeus]

Either way you'll probably end up having to pull the head to find out exactly what's wrong. 

Yeah, that's what I was thinking.  Unless it's a way too thick shim (unlikely that it would go that far without being fixed), it's major work.  Worn valve guides or a stuck valve are going to be about the same amount of work. 

[facepants]

Yes.  The lack of compression could lead to incomplete combustion and also cause it to smoke.  What color is the smoke?  What does it smell like?

Smoke is blue and smells like burnt oil.

[facepants]

I had a shop do a leakdown test and they said that the valves are sealing properly.  What does that leave me with?

Bad rings and/or cracks/holes in the piston?

[Jughead]

Bad Rings.May Also look into replacing the Valve Seals.

[Egaeus]

Well, if they did a leakdown test, then they should have been able to tell you exactly where it was leaking. 

If it's blue and smells like burnt oil, it's not a stuck valve.  It's rings or valve guides.

[facepants]

Well, if they did a leakdown test, then they should have been able to tell you exactly where it was leaking. 

If it's blue and smells like burnt oil, it's not a stuck valve.  It's rings or valve guides.

Yeah.. I'll check with them tomorrow morning.  What they told me was that I'd "basically need a top end rebuild". 

I've already dumped 450$ on them to fix other problems... and the bike isn't worth what they're charging for a rebuild.

It's a 96 with 9k miles on it... I was reading around on the boards and saw another post where someone said that theres no possible way that an engine with 9k on it would need a top end rebuild.  Is this true?

[GeeP]

Well, if they did a leakdown test, then they should have been able to tell you exactly where it was leaking. 

If it's blue and smells like burnt oil, it's not a stuck valve.  It's rings or valve guides.

It's a 96 with 9k miles on it... I was reading around on the boards and saw another post where someone said that theres no possible way that an engine with 9k on it would need a top end rebuild.  Is this true?

If they did a leakdown test they should know what the issue is.  Basically, a leakdown test involves pressurizing the cylinder with the valves closed through a calibrated orifice.  The differential pressure between the supply side and the cylinder side of the orifice is the leak spread.  The test is normally done at 80 PSI.  If the valves were the trouble they should have heard loud hissing from the exhaust or intake.  If the rings/piston/cylinder the loud hissing should be coming from the crankcase breather.

Ask them to clarify their findings on the leakdown test.  This is crucial to determining what is wrong with your engine without being there to inspect it.

In answer to your question about lifespan, anything is possible.  Although it's a little less likely that it should require major repair, it by no means rules it out.

It sounds like this bike has been in the corner under a cover for a number of years.   9,000 miles is nothing for a 10 year old bike.  One thing that can happen is the valves will seize in the valve guides due to dry valve seals allowing the intake valves to coke up.  What is the history on the bike?  Did the owner say it suddenly started running poorly one cold morning?  Was it stuffed in a dark corner when you bought it?  This will help shed light on what is going on.

Let's hear what they have to say about the leakdown test, then go from there.  Until then anything I say is conjecture.

[facepants]

What is the history on the bike?  Did the owner say it suddenly started running poorly one cold morning?  Was it stuffed in a dark corner when you bought it?

The seller was a certified motorcycle mechanic.  Her friend was the owner and she hadn't ridden it for a while.  The mechanic "repaired" it and assured me that it was in perfect condition.

It's had problems since the first time I rode it.

I'll update tomorrow after I talk to the shop.

[Jughead]

Could be a stuck rings due to Carbon build up (Leaky Valve Seals) in the Ring Grooves.When you get it home find some Seafoam and fill that cylinder completely full and let it soak as long as you can.The seafoam is a great Decarbonizer and may free the rings up.After it Soaks for a week leave the Spark plug out and Blow what is left of the Seafoam out of the Hole.If it all makes it's way past the rings into the Oil thats OK since it works as an Oil Additive.Just add more to make sure the rings stay saturated.
If you run it much and it is a Stuck or Even Broken ring you will ruin your bore by either egg Shaping it with stuck ring or Scratching or Gouging with Broken rings.If you ruin the Bore your SOL because Suzuki Doesn't have Oversize pistons anymore.

[Egaeus]

I had a shop do a leakdown test and they said that the valves are sealing properly. 

What they told me was that I'd "basically need a top end rebuild". 

Unless I'm reading it wrong, they said that your rings aren't sealing.  Possibly honing and new rings will work, but possibly need to bore it out and get oversize pistons and rings. 

The seller was a certified motorcycle mechanic.  Her friend was the owner and she hadn't ridden it for a while.  The mechanic "repaired" it and assured me that it was in perfect condition.

It's had problems since the first time I rode it.

I'll update tomorrow after I talk to the shop.

If she told you that, then I wouldn't trust that it only has 9000 miles on it either. 

[GeeP]

I had a shop do a leakdown test and they said that the valves are sealing properly. 

What they told me was that I'd "basically need a top end rebuild". 

Unless I'm reading it wrong, they said that your rings aren't sealing.  Possibly honing and new rings will work, but possibly need to bore it out and get oversize pistons and rings. 

This is what I don't follow.  "Top end" generally refers to everything above the cylinder head/cylinder parting line ie valve gear.  "Bottom end" refers to everything below the cylinder head/cylinder parting line ie pistons, rods, crankshaft.

Did you get in writing that this thing was in operable condition?   I would see about getting your money back.  Especially if it turns out to be a bottom end problem.

[Egaeus]

I think they meant top end as in pistons and cylinders as opposed to crank and rods.

[facepants]

I got the bike back yesterday.  The mechanic said it's either the rings, cylinders, or pistons.

I'm going to have to take it apart when I have some free time and find out.

I bought the bike "as is", even though she assured me through email that it was in good condition.  Even said that in the craigslist ad.  I emailed her right after I rode it for the first time (already had problems) and she said that it was fine when she delivered it.  I don't see how that would be possible.

I don't think I'll be able to get the money back, so I'll just have to work on it myself.

[GeeP]

Let us know when you get the head off.