250-500cc My WR feels flat on top

[Acmesalute76]

Or is that just how they run? It's a 2010 wr250. I don't notice it much in the woods, because I am never near full throttle, but if I come out into a field during a race or whatever, I will hold it wide open and it will pull hard through the midrange but then just sign off as if I wasn't holding it wide open. Is this just the cost of having such strong low and midrange power? Every 2 stroke I've ridden pulls hard up to about a billion rpms, and the sound will get "narrower" as it gets to the top end, if that makes any sense. I guess the sound just becomes a higher note. But my bike doesn't get there. Like I said, it's not a huge deal in the woods, but I'd like to be able to rev out the gear I'm in through a short straight rather than shift up and down real fast. Anyone else notice this or is my bike broken? It is bone stock, btw.

 

[TROFFER88]

Mj

 

[dartyppyt]

Check to see if your powervalve is adjusted to the manual or see if it goes so far and sticks. My 08 250 ran great then started having a flat response. Went in and the adjustmen bolts were loose and the powervalve moved. After adjustment I think it ran even better yet. Another try, look at your reeds. If they are week and open fast you get bottom and a flatter feel up top. If they are firmer it helps the top. Are you running out of fuel up top out of your float bowl and main is not spraying as much fuel. Lower your needle clip one move or is your main jet too low? Is your timing retarded to much? Is your throttle cable frayed and letting the throttle only open so far? I've taken a carb top off and cable looked like bird nest in there. How is the packing in your silencer? Just some thoughts?

 

[utopia]

Mj

+1, stock was way too rich on my 'O9

What's your jetting?

 

[454x]

Mj

+2 go bigger on the main.

 

[lankydoug]

My 09 did that and I believe it is part pipe and part jetting. I had to go leaner than the stock 460 main. I went all the way down to a 380 and back up and settled on a 420. If you go lean on the main it will rev out but it starts hurting the upper mid pull. I have 13:52 gearing and I can still go 70mph but then it feels like the pipe signs off.

 

[Vinduro]

+2 go bigger on the main.

 

[Acmesalute76]

OK, half of you said it's too rich, half of you said go bigger on the main.

 

[TROFFER88]

Do a plug chop

 

[lankydoug]

OK, half of you said it's too rich, half of you said go bigger on the main.

I didn't say for you to go leaner I said I went leaner. What is your current jetting? You'll have to give your bike what it wants (+1 on the plug chop).

Another factor is float level and some say you can modify the well plug in the bowl to prevent fuel starvation at wide open. The plug forms a lip to trap sediment or so it's believed, you can drill small holes in the land area between the "O" ring and the threads of the plug. These holes will allow fuel to go into the well without having to go over the lip of the plug. I did the mod to mine figuring it can't hurt anything.

 

[Acmesalute76]

If what I'm describing is a symptom of jetting, it would either be due to a rich or a lean condition. It wouldn't be either. The bike runs fine everywhere with plenty of power, and it doesn't foul plugs, it just falls on its face once you get through the midrange. I wouldn't think jetting would be to blame. I'm going to look at the PV just to make sure it's ok, since it take only a minute. The only other thing I could figure would be that there is a throttle stop (and the throttle doesn't seem like it stops short, although maybe I'm wrong), or that the bike is just set up to run that way.

 

[lankydoug]

If what I'm describing is a symptom of jetting, it would either be due to a rich or a lean condition. It wouldn't be either. The bike runs fine everywhere with plenty of power, and it doesn't foul plugs, it just falls on its face once you get through the midrange. I wouldn't think jetting would be to blame. I'm going to look at the PV just to make sure it's ok, since it take only a minute. The only other thing I could figure would be that there is a throttle stop (and the throttle doesn't seem like it stops short, although maybe I'm wrong), or that the bike is just set up to run that way.

If you find something that will let it rip down low like the WR250s do and rev out like a 125 let me know because I'll be all for doing that to mine. I may go right now and look at my power valve just for grins.

 

[haulin husky7]

My PV came loose on the 00 wr and had no top end at all had awesome bottom and mid took the cover off the PV and the hand with the teeth had came off the gears not allowing it to open, put it back on and tighten the bolts and the top came back.

 

[Lincolnlock]

Change the main to the smallest in the package that came with the bike.(440?) My 2010 WR300 was exactly like you are describing. Be ready for some serious power after you make the jetting change. It's easier to check this first than pull the whole power valve out.

 

[2stroked]

Plug chop before anything, simplest and easiest to check.

 

[shawbagga]

Do a plug chop

hey troffer whered you get that case saver?

 

[TROFFER88]

hey troffer whered you get that case saver?

Bills

 

[twwinston]

Ditto what haulin husky 7 said on my 09 WR 250. Check your power valve. Mine had great low to mid but just went flat or signed off at the mid range pull. The cover has 4, 8 mm bolts on the left side of the cylinder. My pv had came loose. I put some red locktite on the threads and it's good so far. Start the bike with the cover off. As you rev the bike the pv should activate. Watch it's mechanism a few throttle twists and make sue the main bolt holding the assembly is seated correctly and tight. This happened to my bike twice until I used the locktite. Good luck.