Old EC250 idle issue and power valve leaking...
 

Hey all. I have a question on a 1997 Gas Gas EC250. I'm new to 2 strokes and bought this a year and a half ago. It was super clean and well maintained. After a nooby problem with the carb it's been running fantastically since I bought.

The other day I went for a ride, maybe slightly higher elevation? Not much though. 1000' higher? It wouldn't idle. Started out just having problems idling, then got progressively worse. At the end it started feeling like it had nothing in 1st and 2nd gear up hills. I messed with the idle screw and it felt loose so I got it feeling better. It started idling better but then it was idling high unless I reved it down. Then it would idle too low. Very weird. This bike never idled amazingly well but never like this. I pulled the spark plug and it's got a lot of black deposits and looks oily. I'll replace it. Also cleaned the air filter.
Here's the thing I'm most curious about. At the same time as this idle thing started happening I noticed the power valve cover was leaking goopy oily stuff out the bottom front corner. I figure it's just oil build up from the mixed gas. Today I took the cover off and cleaned a bunch up. Is this something that should be maintenanced from time to time? And would it affect the idle and the power at lower revs climbing a hill?

I'm not up to snuff on the regular maintenance on a 2 stroke so anything else helpful would be great. I ride a few hours a month so it's not getting a ton of use but I use fresh gas with a 50:1 mix.

Pic
 

Maybe it's not cool to post a thread from another forum in here. Let me know if it's not. But I posted a pic in the thread below and I don't have it hosted anywhere so I can't post it here.

https://advrider.com/f/threads/which...#post-40903346

Sounds like an air leak.My rmx 250 would do something similar - poor idling, low power, it would idle really high, until put it in first and slipped the clutch a bit.

After lots of head scratching, it turned out to be a slight leak in the base gasket and a decent one in the flywheel side oil seal.

Neither of those were detectable with carb cleaner, nor did the flywheel side seal leak oil like people usually say they do.

Check your crankshaft seals.

The power valve covers should have drains both sides ,prob blocked.As for your Idle issues,Check /replace Jet Block O ring in your carb.If this is not sealing ,,the idle will be poor ,your jetting will be affected and your fuel consumption will be high.Cheap to buy on eBay .Look at you tube for fitting instructions.If the bike is older ,it will be an issue,Good luck