Puff of grey smoke when you let off throtte

[SpaghettiOs]

I adjusted my valves last night and started the bike today to find this... Idles great with maybe a very faint grey puffs of smoke from the exhaust but when you give it throttle and let off it will rev with no smoke but when it comes back down it puffs a small cloud of light grey smoke. It didn't do this before and I'd rather not run it if its too lean... Thanks guys! I'll be back in about 5 hours if I don't respond right away.

 

[TwoManyXS1Bs]

Your description sounds like oil being pulled up through the rings during high intake manifold vacuum.
Might want to check the plugs and do a compression test...

 

[angus67]

Or needs valve laping

 

[chizler62]

As the motor is trying to maintain intake vacuum and you chop it off by closing the throttle the motor will for a,time pull from the intake and if seals are bad then sucking oil thru them if not thru worn rings. If after sitting awhile it smokes on initial start up its typically valve guide seals. If valve is left open when motor stops the oil will run down valve stem and puddle in seat area.

Could you explain why lapping the valves may reduce oil consumption?

Posted via Mobile

 

[XSLeo]

If it didn't do this before you adjusted the valves, then I might suggest you check the valve adjustments again.
Leo

 

[SpaghettiOs]

If it didn't do this before you adjusted the valves, then I might suggest you check the valve adjustments again.
Leo

the valves were .008 on the exhaust and .006 on the intake so out of adjustment and noisy so I put them at .004 and .002 following some videos online. curious if it is carb adjustment at all or is it just sounding like my rings are bad to everyone?

 

[chizler62]

Its your valve guide seals more so than rings. Seals are cheap. I'd say a competent shop would charge a hours labor to put them in maybe more if you have mods that make removing retainers harder. Easy to do on a XS650, tho. You don't need to remove motor or head etc.
If it still smokes its most likely then the rings/piston. But, valves seals are cheap and easy first step.

Posted via Mobile

 

[SpaghettiOs]

Its your valve guide seals more so than rings. Seals are cheap. I'd say a competent shop would charge a hours labor to put them in maybe more if you have mods that make removing retainers harder. Easy to do on a XS650, tho. You don't need to remove motor or head etc.
If it still smokes its most likely then the rings/piston. But, valves seals are cheap and easy first step.

Posted via Mobile

I did a compression test tonight and each side is reading 150, it would be lower if the seals or rings were bad right? the puff of smoke is only when the throttle returns and the plugs are wet looking, not sooted up in any way where as before they were a little black running rich. It has good and strong spark on both sides and fires right up with no backfire, stumble or any other odd running symptoms.

 

[ippytattoo]

Valve seals would not affect your compression numbers. If it were rings I would expect to see numbers much lower than that.

 

[gggGary]

Might open the covers and hit the stem with a bit of rust buster. Here's a guess the motor had been running long time with the big valve gaps, your adjusting them to "spec" is causing the valves to open further, bringing a section of valve stem that hasn't seen action for a long time into the seal. That section might have some coked on oil build up, run it for a few hundred miles, see what happens.

 

[SpaghettiOs]

Here is a video of the smoke as well as a pic of the plugs, I took it out around the block a few times and the plugs are dry. video link below.