Xr 250 1981 - lots of smoke

[skinny]

Hi Guys,

Can anyone shed somelight on why my bike would be smoking heaps!!

Its got compression and power but blows lots of smoke and sprays oil out the exhaust. Its been sitting for 12 months unused.

Im not if the previous person using over filled the oil or if the rings are on there way out.

I pulled off the exhaust manifold it is ful of black carbon build up and looks like a little bit of shiny oil comming down one of the valves. Is this just seals gone in the valve and entering in from the top?

[disorderly]

It sounds like the valve guide seals to me which is a piss easy job to do you can buy aftermarket complete top end gasket sets which include the seals on trade me ( I all ways see them for sale ) for something like $40 for the early xr250's but only one way to find out and thats take the rocker cover off and inspect the inside first if so whip the head off but with the early models gettin on in years you may find other things that may need doing and then before you know..................

[Katman]

It sounds like the valve guide seals to me which is a piss easy job to do

Sounds a bit more major than that to me.

[White trash]

I'm no four stroke expert but it sounds like more than the stem seals if it's blowing oil out the pipe.

Running and compression means bugger all. My GSX motor has the most amazing groves and holes in the bore from the rings being rusted to the bore then running it. Ran mint, didn't blow any smoke but litterally pumped 100cc of engine oil into the airbox through the breather, then blocked all the air jets in the carbs so it wouldn't idle.

If I had to guess (and once again, I know nothing) I'd point my finger at a broken oil ring.

[Teflon]

Was it running well 12 months ago? If it was, i would give it a good run and see if the smoke clears.

[disorderly]

like I said only way to find out is to take rocker cover off and work your way down how would oil leak down the valve stem? that why I said with the early model dirt bikes nearly 30 plus years old your bound to find more things that need doing as you work on them

[neels]

Was it running well 12 months ago? If it was, i would give it a good run and see if the smoke clears.
Wot he said.

If it's been sitting for a year, it may have the rings stuck in the grooves, try getting it hot and letting it cool a couple of times to see if it comes right by itself.

Of course, the reference to a previous person suggests that you've just got the bike, in which case the reason it was parked for 12 months could be that it's shagged.

A rebore, new piston and rings and some valve stem seals won't cost you the earth if it does need doing though...

[skinny]

Thanks guys,

Ive decided i wont risk it and will return it to the previous owner. I have only had it a little while so lucky he has agreed to take it back.

It was only going to be a hack anyway but there no point having a bike that i cant get rid of one day without a half / full rebuild.