Xr 250 is still
Blowing smoke after new valve seals it only blows smoke on engine break
Help xr250 r still blowing smoke :-(
Started by
Mcintyre101
, Jul 21 2012 04:42 AM
28 replies to this topic
Posted 21 July 2012 - 04:46 AM
Im lost I bought it about 3 months ago and I noticed a slight amount of blue smoke out of the exhaust even though it was very slight it annoyed me I took
The time and put brand new vinton valves seals on started it up thinking you beauty no more smoke behind me then it just started pouring then stopped and now is the same as it was but a little worse, I believe I took all the correct methods with the valve seals I made sure there were no sharp edges so they didn't get cut I was very carefully please help as to what it may be would be very appreciated :-) also I'm
New sorry if this is in the wrong part or something?
The time and put brand new vinton valves seals on started it up thinking you beauty no more smoke behind me then it just started pouring then stopped and now is the same as it was but a little worse, I believe I took all the correct methods with the valve seals I made sure there were no sharp edges so they didn't get cut I was very carefully please help as to what it may be would be very appreciated :-) also I'm
New sorry if this is in the wrong part or something?
Posted 21 July 2012 - 07:47 AM
Does it smoke bad on just start up? Or does it smoke all the time getting worse with revs?
If the latter you need to check the piston rings unfortunately..
2 reasons for blue smoke, bad valve seals (which you did) or a bad oil control ring and or compression rings, or mating surfaces.
If the latter you need to check the piston rings unfortunately..
2 reasons for blue smoke, bad valve seals (which you did) or a bad oil control ring and or compression rings, or mating surfaces.
Posted 21 July 2012 - 03:20 PM
It only smokes after engine break and when you give open the throttle I thorte it might be rings aswell but it's weird it's only done 5 thousand kms and being a xr it should hold up to more and if it was rings it would smoke constantly could it be valve guides? Also could it smoke if the valve clearances were wrong they havent been done in about 1500 kms
Posted 21 July 2012 - 03:22 PM
And when its first starts there's no smoke at all untill you start reving it but only blows smoke after you shut the throttle
Posted 21 July 2012 - 05:13 PM
then your clearances are bad or its the oil you are using.
try usinf different oilk. did you put your rings ar 180 degrees to each other when installing?
try usinf different oilk. did you put your rings ar 180 degrees to each other when installing?
Posted 21 July 2012 - 06:42 PM
Il do clearances now and I didn't take the head off. I didn't install the piston as far as Its still the original
Piston and never been taken apart I only took rocker cover off
Piston and never been taken apart I only took rocker cover off
Posted 21 July 2012 - 08:55 PM
No worries mate! Older dirt bikes smoke a little on startup. Check your oil level before you ride and enjoy.
Posted 21 July 2012 - 10:20 PM
That's the thing though it doesn't anime on start up but then as soon as you start revving it it atarts
Posted 22 July 2012 - 05:30 AM
Sounds like it needs a piston and rings to me. It's smoke caused by the rings no sealing properly. It could have a stuck ring also.
Posted 22 July 2012 - 03:34 PM
It doesn't smoke on power though
It's only when you
Back off the throttle and go to get back
On the power and a puff comes out then it's gone if it was rings it would smoke all the time yeah? And when it starts up cold start there's no smoke untill you rev it a few times then it comes then goes away then rev it up again it comes again then goes away it all points to valves
It's only when you
Back off the throttle and go to get back
On the power and a puff comes out then it's gone if it was rings it would smoke all the time yeah? And when it starts up cold start there's no smoke untill you rev it a few times then it comes then goes away then rev it up again it comes again then goes away it all points to valves
Posted 22 July 2012 - 10:02 PM
RINGS!!!!!!!!!!!!!!!!!!
cant believe you took the head off and didnt do the piston or rings while you were there?
let me guess, you didnt lap the valves in either?
cant believe you took the head off and didnt do the piston or rings while you were there?
let me guess, you didnt lap the valves in either?
Posted 23 July 2012 - 01:29 AM
please understand ^^ i never took the head off and it cant be rings cause it doesnt blow smoke constantly its gotta be something to do with valves and there were no need to lap the valves as i only did seals
Posted 23 July 2012 - 01:31 AM
and i dont see how clearences would make a motor smoke? it only adjust when the valves open and shut it can only result in burn out valves and alot of noise
Posted 24 July 2012 - 03:36 PM
wow.
usually, when you replace the valve seals. you decarbon the valves and lap them in for good seal while your there.
its the first thing i do when i get a xr. the valves.
and if your tolerances are out, then your new seals will leak anyhow due to excess (sideways) movement.
and worn rings will smoke on deceleration because of the vaccume caused when throttle is shut off, sucks oil into the combustion chamber due to negative pressure.
look, change the rings (and piston if necessary). make sure your valves and guides are not excessively worn, decarbon your head/valves, lap the valves in, and your engine will run smooth and smoke free for years.
usually, when you replace the valve seals. you decarbon the valves and lap them in for good seal while your there.
its the first thing i do when i get a xr. the valves.
and if your tolerances are out, then your new seals will leak anyhow due to excess (sideways) movement.
and worn rings will smoke on deceleration because of the vaccume caused when throttle is shut off, sucks oil into the combustion chamber due to negative pressure.
look, change the rings (and piston if necessary). make sure your valves and guides are not excessively worn, decarbon your head/valves, lap the valves in, and your engine will run smooth and smoke free for years.
Posted 24 July 2012 - 05:54 PM
thestuz, on 24 July 2012 - 03:36 PM, said:
wow.
usually, when you replace the valve seals. you decarbon the valves and lap them in for good seal while your there.
its the first thing i do when i get a xr. the valves.
and if your tolerances are out, then your new seals will leak anyhow due to excess (sideways) movement.
and worn rings will smoke on deceleration because of the vaccume caused when throttle is shut off, sucks oil into the combustion chamber due to negative pressure.
look, change the rings (and piston if necessary). make sure your valves and guides are not excessively worn, decarbon your head/valves, lap the valves in, and your engine will run smooth and smoke free for years.
usually, when you replace the valve seals. you decarbon the valves and lap them in for good seal while your there.
its the first thing i do when i get a xr. the valves.
and if your tolerances are out, then your new seals will leak anyhow due to excess (sideways) movement.
and worn rings will smoke on deceleration because of the vaccume caused when throttle is shut off, sucks oil into the combustion chamber due to negative pressure.
look, change the rings (and piston if necessary). make sure your valves and guides are not excessively worn, decarbon your head/valves, lap the valves in, and your engine will run smooth and smoke free for years.
What he said...
Posted 25 July 2012 - 12:58 AM
There's no need for that it's only got 5 thou on the clock rings smoke constantly I've ridden bikes with worn rings there's a huge difference as for the decade band lapping valves my opinion
No need if I had the head I would off but I did it without the head off using air pressure to hold the valves up I believe it's just valve guides
No need if I had the head I would off but I did it without the head off using air pressure to hold the valves up I believe it's just valve guides
Posted 25 July 2012 - 01:02 AM
Decarben*
My expiriance with worn rings is constant smoke not just on decel. I know it's not rings cause the spark plug still looks like a heathy running engine and there's no change in compression and I did the crankcase breather test and it was perfect its not rings however thanks for your input
My expiriance with worn rings is constant smoke not just on decel. I know it's not rings cause the spark plug still looks like a heathy running engine and there's no change in compression and I did the crankcase breather test and it was perfect its not rings however thanks for your input
Posted 25 July 2012 - 07:31 AM
Mcintyre101, on 25 July 2012 - 12:58 AM, said:
. . . . I did it without the head off using air pressure to hold the valves up . . . .
I know you're in a different time zone down under.
Would you be kind enough to explain the process of using air pressure to lap the valves with the head on?
Edited by BajaRmblr, 25 July 2012 - 07:42 AM.
