Blowing smoke and I don't know why

[GooseMan]

MY yx 160 has a smoking problem, the smoke is a whitish grey colour coming from the exhaust. I have checked the rings and valves and all is good. I have tried tuning the engine but still no change in the smoke. What could be causing this?
All I can think of is a nicotine patch,:lol_hitting:

 

[motorman]

MY yx 160 has a smoking problem, the smoke is a whitish grey colour coming from the exhaust. I have checked the rings and valves and all is good. I have tried tuning the engine but still no change in the smoke. What could be causing this?
All I can think of is a nicotine patch,:lol_hitting:

Are you sure you checked the rings right?

Sounds to me like you put one of them on upside down. Have seen it before.

 

[Bouma]

cheak the oil u mite have the wrong oil in the engine or u r runnin gthe bike to rich with fuel

 

[GooseMan]

haven't touched the rings yet, it didn't blow smoke when I got it, it only recently started happening. When i checked them I did a compression test dry first and then tipped a bit of oil in the cylinder and tried again and it only went up about 5 or 10 psi. As for the fuel mixture well I don't think its that cause it revs out fine and I even tried turning it to full lean and no difference in smoke, then just out of curiosity I tuned it to full rich and still no difference in smoke.

 

[GooseMan]

When I adjusted the valves I made the gap .003 inlet and .004 on exhaust and that was in inches, was it supposed to be metric or something

 

[rotn50]

MY yx 160 has a smoking problem, the smoke is a whitish grey colour coming from the exhaust. I have checked the rings and valves and all is good. I have tried tuning the engine but still no change in the smoke. What could be causing this?
All I can think of is a nicotine patch,:lol_hitting:

Just alongshot but at work i have had a coupla bikes with the white greyish smoke and both was due to the crankcase breather being blocked, either by the breather tube being stuck between the frame and engine or usually mud from riding or bloody hornets nests, check it out mate.

 

[GooseMan]

Will check it out today, thanks for the help.

 

[GooseMan]

ok got busy and didn't get time to check it out today but will have a look tomorrow(hopefully).
However I did have a chat with a mate today who thought it could be the valve stem seal not sealing properly, oh and I forgot to mention earlier that it is burning through the oil pretty fast.

 

[Hussey]

I have a similar problem and havnt fixed it. Everything you said I have with my lxr

 

[GooseMan]

checked the breather and it was stuck between the frame and could not breath, took the breather off and started it up but it still blew smoke. Thinking that might have caused a seal to blow or something?

 

[sean01]

compression test doesnt really tell the oil control ring condition..

if the breather was blocked and forced oil past the rings then theres a good chance the bore is now glazed..
if the engine isnt that old pull it apart rehone the cylinder and just reuse the rings.. or for the little bit of coin a set of rings will cost, replace them...

top of the piston and the combustion chamber will have signs of where the problem is too..

if around the edge of the piston or the entire piston top is washed clean then its rings, if the center of the piston is clean then its valve stem seals..

another way to tell is if its blowing smoke under acceleration then its rings, if its only when decelerating then its valve stem seals..

 

[GooseMan]

Thanks Sean your a champion, one question though, when you say the piston is washed clean does that mean it will have a shiny appearance?

 

[rotn50]

its very common for the breather to be jammed between the engine and frame and its one of the last things you would worry about until it causes something like this, i run a oil cooling tank that is attached to the dipstick and valve cover to release excess heat and would work also for a blocked breather hose. Goodluck with the repair mate.

 

[sean01]

Thanks Sean your a champion, one question though, when you say the piston is washed clean does that mean it will have a shiny appearance?

it wont have any carbon build up on the washed area..
may be shinny or just clean but still coloured

 

[Hussey]

Hey goose man any luck ????

 

[GooseMan]

just got the rings today hussey, the piston was washed clean but the biggest problem I think was the valves, both were about one mill open at top dead centre so I must have done something very wrong! lol.
there was about a teaspoon of carbon build up behind the exhaust valve! Ill admit it, I adjusted the valve gap and must have got it all wrong, lol Everyone says to adjust them to .003 etc but is that in inches or millimeters?

Any way probably for the best, the engine looks like new again after a quick sand blast and it now has new rings and the valves have been refaced and lapped in to the head, so should run well after all this.

And I will certainly make sure the engine has no sand in it before I start it haha.

 

[my67xr]

are you going to give the bore a quick hone before you fit the piston etc?

valve clearances-
.003" intake, .004" exhaust, imperial measurements
.076mm intake, .102mm metric measurements
incase you cant find it-
http://www.miniriders.com/motor-tutorials/24965-how-set-valve-clearances-horizontal-engines.html

 

[Hussey]

Ok good stuff. I will double check my valve clearances as well maybe time for an adjustment as well.

 

[GooseMan]

cylinder has some small scuff marks but shouldn't effect it greatly and it was also glazed so I used a bit of fine steel wool and took off the glaze. See how it goes, if it does not work then ill just get another cylinder.

 

[rotn50]

some factories will put a parallel slice thru the breather hose in case of a blockage, so it can still breathe, just so this doesnt happen again mate incase some mud or hornets decide to block it up