WR250 Problem Revving suspect Power Valve

Well I did up my WR250 cosmetically and a couple of issues internally in the engine and now it won't rev out. Previously to the work the engine performed really strong except I was getting water in the gearbox.

Externally I changed the chamber from an gnarly to a stocker I got off ebay for a 2006 engine.

Internally I had a replace the waterpump seal and had a little help from a friend with a 360. Unfortunately he jumped the gun a little and started removing the left cover assembly as he was under the impression he needed to install the waterpump seal from the other side. To do this he took the left power valve cover and pulled the ball joint off the lever and counter shaft. After trying for a while to release the cover we realised it didn't need to come off we bolted the cover back up and replaced the seal from the outside. Then we bolted everything back up. To our knowledge nothing had chenged in terms of the counter shaft from the governor to the power valve. Everything went back together easily

Now when I rev the bike it revs kinda slow and then stops about half thru the usual revs band. About same engine speed everytime it stutters and won't rev out. Riding it and the low end is fine but it doesn't transition to the peaky band it used to have. Just bogs.

I've replaced the fuel with fresh, checked the plug. Am I looking in the right place? Also if theleft cover is going to have to come off why does it come most of the way and then just stop?

After i did my top end i noticed the power valve was sticky from pulling the bushings out, if the power valve won't move before it moves the spring, then something is tight. Also check to make sure you have the alignment dots lined up on the gears between the main and the two outside valves.

I ended up putting an old screw into the the outside valves and using my drill and spining them to create some play so they would move freely.

If you were too ham fisted with the little plastic connecting rod you may have cracked it. Did you you run the engine with the power valve cover off to watch the powervalve engage?


Try taking the stock pipe off and make sure the one you purchased does not have a restrictor in it. Try the old pipe and see if it revs out. I have seen some Euro Stock pipes have a baffle right where it goes to the cylinder. I think this was on a 125 pipe but check it.

Took the right side cover off and the Power Valve seems to be working fine. As the revs climb the valve goes from all the way shut to fully open based on the adjustment on the right side. I put a fresh plug in and gave it a run but still something holding it back. I'll pull the carb off tomorrow to verify I have no problems in there.

I was aware of the restrictor that is in some pipes but this one doesn;t seem to have anything on it. I suppose I'll try the old gnarly to see if it runs.

raisrx251 was on the money. Pipe seems to have some sort of honeycomb like a cat. converter in the bend nearest the radiator pipes. Even jetted to suit the pipe it runs like a dog up high. I have no idea how they would sell them like this is the markets where it is needed.

WOOHOO..I got one right!! There was a guy on here who had a 125 that would not run right and kept fouling plugs. I swore that the problem was it was flooded so bad that he should tip the bike up and spin the back wheel in 5th gear. Well I was wrong and felt like a fool..

Do you think there is a way to cut it out of there, the one I saw looked like a factory worker just tacked it in there right where it goes into the cylinder. It is a shame to as the stock pipe is a excellent pipe. If you are looking for a low end pipe a U.S. pipe like the FMF fatty. I think HGS, CRD are more top end pipes.

Have a mate at work planning to attack it this weekend with a dremel and then oxy-weld or mig it back together. Studying the weld burn pattern on the pipe it seems you might be right about it just being tacked in place. He'll just have to cut that whole section along the factory seams to get at it.

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