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Trikotic
11-03-2002, 03:45 PM
i got an 85 250sx and when i start'er up when she's cold she smokes real bad when the choke is on, then i turn the choke off and she still blows some blue smoke but then it clears up after a little warm up but it doesn't go completely clear i don't think. i'm hoping this is normal.... it started doing this after i changed the oil a few weeks ago. any opinions? rings maybe? allegedly the motor was rebuilt last year so i don't know what the deal is.
Trikotic
11-03-2002, 04:40 PM
so i warmed it up, after about 2 minutes of riding around it stopped smoking and after about 5 minutes there were no signs of smoke or any oil being burned. any ideas?
dads
11-03-2002, 05:54 PM
What color is the soot in the tail pipe. if it is black powder from over fueling you my have sticking rings do to carbon build up.
Mr. Richard
11-03-2002, 06:09 PM
blue smoke is oil,,,,,, maybe your valve seals are gettin a little worn.. when it sets around the oil left in the head seeps down the valve stem ,,,,after a couple of minutes its all gone till next time,,,,,, maybe
ATCRYDER
11-03-2002, 08:16 PM
Everything should smoke a bit in a 4 stroke from gas & oil sitting inside the cylinder before a startup but that blue smoke is not noraml.
dads
11-03-2002, 08:40 PM
Originally posted by kasey
blue smoke is oil,,,,,, maybe your valve seals are gettin a little worn.. when it sets around the oil left in the head seeps down the valve stem ,,,,after a couple of minutes its all gone till next time,,,,,, maybe


Kasey is right about the vavle guides. but that should clear up in less than 5 min. if guides are bad. unless you have a cloged oil return from your valves.
Trikotic
11-03-2002, 09:56 PM
it clears up in less than 5 minutes. no power loss or loss in starting reliability or any reliability for that matter. so i'm just wondering how concerned i should be.
Mr. Richard
11-03-2002, 10:08 PM
if you don't hear any strange noises then i wouldn't worry to much. until the smoke gets to anoying,,,,,,,,,
dads
11-03-2002, 10:13 PM
Just watch your oil consumption, and start planing on a valve job in the future.
dads
11-03-2002, 10:26 PM
There is a quick fix that buys you time when the smoke starts geting bad. You can replace the ruber valve stem seals under the springs with out pulling the head.
Mr. Richard
11-03-2002, 10:44 PM
man dads your right on top of this one!!! i was going to say that too, take some 1/4" nylon rope pull the spark plug out and fill the cylinder up roll it around to hold the valves in tight ,,,, presto you can change the seals!!
dads
11-03-2002, 11:14 PM
The rope is inturesting.
I pressurize the cylinder to hole the valves closed with air.
a cuple PSI over max compression will work.
Quick screw in divice. nock seramice out of old plug, insert a 2 inch tube braze in ,put air hose fitting on other end and braze.
use tank regulator to set psi.