NSR 250 - 1 cylinder died

**aderino4** · 25th January 2007, 11:02

So one of the cylinder in the NSR decided it doesn't want to fire anymore.
I can smell fuel in the muffler but not spark.

Since I was in a hurry, we replaced both plugs with a used items and it fires like normal.
Brother adjust the oil pump so the mark line up and it makes the bike run smoother and more powerful than before.

However I had some free time in the weekend and decided, lets have a look under the tank.

Opened the airbox and found half of the filter element is no longer there (possible went into the cylinder and foul the plug).
Carb looks clean.

Took the spark plug and it looks like the picture (it seems to run rich and there is some oil on the thread).

At the moment the bike is semi dismantled while waiting for a new filter element and spark plug to arrive.

Question:
1. with the air filter sucked in, is it possible that it may have fouled the plug?
2. Should I be worried that there is debris inside the cylinder?
3. (Look at plug picture) Am I running too rich or is it normal for 2 stroke engine to look like that?

**insane1** · 25th January 2007, 11:43

stripthe motor down just a precaution better safe than sorry.

**Ixion** · 25th January 2007, 12:27

I imagine that the air filter element is oil sodden rotten and crumbling. I doubt that whatever of it has been sucked through the system will do much harm. I've had this happen and had no ill effects. On a two stroke there are no oil passages to block and the foam is soft enough, and rotten enough, that it is unlikely to do any damage. In a perfect world one would strip the motor to check, but I wouldn't bother unless I were racing the bike or intending to go on a long tour.

It's hard to comment on the plug since the picture doesn't show the porcelain (the important bit) but it doesn't look too good . However two stroke plugs seldom do.Fit a new set of plugs and check after 500 km.

**aderino4** · 25th January 2007, 12:42

Ixion: The filter was very damp and brittle from oil and it even breaks when we were trying to remove it from the airbox.

I've started up the motor without the filter, and it seems to be ok.

Will install a new set of plugs and filter this weekend (If the plugs arrived) and we'll see what happens.

Thanks, that was very comforting.