Smoking

[bazz]

My xs650 engine is smoking
I bought it around 10 years without knowing any of its history
I made a test rig for it at the time so I could fire it up to test and I do not remember it smoking
But recently I've been running the engine a fair bit and it's smoking all the time as soon as you start it
Is it likely to be the valve guide seals gone hard?
Or more likely the piston rings?

 

[Jim]

As a general rule, smoking at idle and on decel is valve guides. Smoking all the time is rings...

 

[Jim]

Sitting for 10yrs... good chance it's stuck rings. I'd be tempted to pour a little penetrating oil down the plug holes and let it sit for a week or so.

 

[bazz]

Sitting for 10yrs... good chance it's stuck rings. I'd be tempted to pour a little penetrating oil down the plug holes and let it sit for a week or so.

I should add compression seems ok
It's 132psi both sides

 

[jetmechmarty]

There is a procedure for replacing the valve seals without pulling the engine. (If you come to that.)

 

[bosco659]

There is a procedure for replacing the valve seals without pulling the engine. (If you come to that.)

Been there, done that. A finicky process but saves pulling the motor.

 

[bazz]

I should add that after riding the bike a couple of times times the smoking has got a fair bit worse
IE when you start it it belts the smoke out immediately
I'm guessing this is more likely rings than seals or guides

 

[Its been a long time]

I should add that after riding the bike a couple of times times the smoking has got a fair bit worse
IE when you start it it belts the smoke out immediately
I'm guessing this is more likely rings than seals or guides

Sounds like might be time to open it up for a look?

 

[bazz]

Sounds like might be time to open it up for a look?

Yep I reckon so
I've no Idea of the engines history
It sounds pretty quiet and runs quite well
It starts immediately etc
It's just the smoke
I bought a spare barrel and pistons in really good order a couple of months back as a backup plan
Unfortunately I won't be able to work on it for a few weeks
I have a full gasket and engine seal set including valve stem seals
So I'll stick some photos up when I pull the engine
What's the consensus on changing the cam chain and tensioner whilst I'm in there?

 

[Its been a long time]

Yep I reckon so
I've no Idea of the engines history
It sounds pretty quiet and runs quite well
It starts immediately etc
It's just the smoke
I bought a spare barrel and pistons in really good order a couple of months back as a backup plan
Unfortunately I won't be able to work on it for a few weeks
I have a full gasket and engine seal set including valve stem seals
So I'll stick some photos up when I pull the engine
What's the consensus on changing the cam chain and tensioner whilst I'm in there?

Everyone has a different viewpoint of course. For me, on an engine with little or no known history I would be inclined to replace the known service items whilst in there. Good luck with it.

 

[jetmechmarty]

I had a smoker. I had the bike since new. Here’s the thread.
https://www.xs650.com/threads/sensible-engine-decision-now-top-end-refresh.57859/

 

[Jim]

What's the consensus on changing the cam chain and tensioner whilst I'm in there?

For me, on an engine with little or no known history I would be inclined to replace the known service items whilst in there. Good luck with it.

My rule of thumb: If you have to pull the engine to replace it, replace it while the engine is pulled. The chain and guide don't really add much cost to the rebuild in the grand scheme of things. I'd change 'em.

 

[Its been a long time]

My rule of thumb: If you have to pull the engine to replace it, replace it while the engine is pulled. The chain and guide don't really add much cost to the rebuild in the grand scheme of things. I'd change 'em.

100% agree. Small beer in the overall scheme.

 

[Grimly]

My rule of thumb: If you have to pull the engine to replace it, replace it while the engine is pulled. The chain and guide don't really add much cost to the rebuild in the grand scheme of things. I'd change 'em.

Yep, it's a pain in the arris to have to pull it apart again.