GPX 250, 1998 Loosing power.

[Gibbo88]

G'day guys, so the story is my GPX is loosing power at about the 6k RPM mark, pretty much sounding like it was running out of puff. When there is no strain on the engine and it's revved there are no issues. I was thinking that it was the air filter that was doing the trouble. This is where the question is - what should i use to clean the filter? I got it out with only minor troubles, but when i tried to blow air through it, very little got through. Suggestions? Also open to suggestions abotu what else could be causing the problem.

Thanks, Gibbo

[Marty ZZR rider]

We are only talking about the foam element filter aren't we?
I wash them in petrol, sqeeze the petrol through it a few times and let make sure you let it dry before it goes back in.
I also apply a few drops foam filter element oil and sqeeze the filter to work it through. It helps trap the dust.

[Gazza]

i had the same problem with my gpx 250 when i first bought it. i found out that there was way to much oil in the sump .

and that was presurising the engine and intern slightly restricted the internals from running freely.
and there was oil blow back into the air box .

so i decided to drain out some oil and to my surprise i drained out nearly 2 litres of oil ontop of the recommended amount.
after i drained the oil it was like a different bike , clean power right through the revs in each gear and great acceleration as well.

hope this helps

Gazza.