2001 YZ 250 Won't Hit Powerband

What is up beauties!

 

I'm having an issue with my recently traded for yz 250. When i traded for it, i was aware of the problem. It has strong bottom end but as soon as it tries to go mid-top end it just.. doesn't. Sounds kind of like a sorta deep bwahhhhhhhhhhhhhhh, with a constant pitch, not hitting the band. You can feel the lack of power. So here is a list of what i have done to it so far. I haven't tested it yet, but let me know of any other suggestions.

 

-Cleaned carb, was a little dirty. 

-Found out the main jet was a 175 instead of what should be a 172, going to buy a 172 tomorrow.

-Cleaned powervalve out. It was pretty sticky in there, but i'm not sure if it was sticky enough to stop it from opening.

-Ordered a new silencer, pro circuit r304 shorty. 

-Took a look at the FMF fatty already on the bike. It has a slight bend to it, but nothing extreme enough to effect performance THIS bad. I made sure to clean it out as well.

-Cleaned air filter/box

-Checked compression, was in a good range.

-Changed Plug

-Put new gas in, new fuel line on.

-Adjusted Clutch cable

-Checked piston for scores, it was pretty damn clean.

 

As far as i can remember, that is all i have done. I couldn't think of much else to check out. I guess reeds would be a good idea, but it doesn't seem like that kind of issue. Let me know if you guys have any more suggestions for me! thanks

 

I just realized this is a lean condition, not rich! I will buy a 178 main and a 180 main. Still open to ideas

ehh from my experience with my yz85 which was doing the same exact thing, it is a rich condition.

What is up beauties!

 

I'm having an issue with my recently traded for yz 250. When i traded for it, i was aware of the problem. It has strong bottom end but as soon as it tries to go mid-top end it just.. doesn't. Sounds kind of like a sorta deep bwahhhhhhhhhhhhhhh, with a constant pitch, not hitting the band. You can feel the lack of power. So here is a list of what i have done to it so far. I haven't tested it yet, but let me know of any other suggestions.

 

-Cleaned carb, was a little dirty. 

-Found out the main jet was a 175 instead of what should be a 172, going to buy a 172 tomorrow.

-Cleaned powervalve out. It was pretty sticky in there, but i'm not sure if it was sticky enough to stop it from opening.

-Ordered a new silencer, pro circuit r304 shorty. 

-Took a look at the FMF fatty already on the bike. It has a slight bend to it, but nothing extreme enough to effect performanceicon1.png THIS bad. I made sure to clean it out as well.

-Cleaned air filter/box

-Checked compression, was in a good range.

-Changed Plug

-Put new gas in, new fuelicon1.png line on.

-Adjusted Clutch cable

-Checked piston for scores, it was pretty damn clean.

 

As far as i can remember, that is all i have done. I couldn't think of much else to check out. I guess reeds would be a good idea, but it doesn't seem like that kind of issue. Let me know if you guys have any more suggestions for me! thanks

 

This may be a lean condition now that i think about it,,,, Let me know

leave the PV cover off, ride the bike, and see if it is actually opening when you rev the bike. 

 

Doesn't sound lean to me. If anything I would think that it is too rich.

Edited by BDubb106

I said the same thing in your other thread. Leave the PV cover off, ride the bike, and see if it is even opening.

 

Your bike is showing signs of a rich condition, not a lean condition.

Got an 02 yz250 I traded for with the same problem. I did everthing you did except my jets were stock. In addition I checked the timing which had been retarded so i returned this to stock per the method in the owners manual. I also visibly verified the full function of the powervalve. The timing adjustment helped but the "hit" still just isnt there. Going to check the TPS in the next couple days and see where its set. I remember a KX250 I had having a stronger pull in the mid upper than this one has. I've had a yz450f for the last year, maybe its just numbed me a bit to the pull of the 250. If i make any progress with the TPS check I'll let you know.

Forgot to post that i checked that as well! It is functioning fully.

I have my doubts that it would be the TPS. Definitely keep me posted on that though dude. 

Electrical? Does the coil check out?

a little update.... All of the things i have listed didn't make one bit of difference. I am going to check reeds, but honestly that is all i can think of!

I can't decide if this is a rich or lean issue by the way. I did a plug chop test and it looked spotless (WOT). Was a perfect tan brown. It just seems so much like jetting or PV's! 

did you check needle position?

i changed the needle to the 3rd clip rather than the 2nd.

Borrow a different pipe and try that.  You sure you cleaned it out properly?

 

Also work out if the problem is a function of RPMs or throttle position or both.

 

There are some older threads asking the same question.

I am 90% sure it is the rpms. I would like to say it is the pipe, but my friend said he bought it with that dent and never wrecked it. It worked flawlessly for him, but he let it sit for 2 months and then this started. Therefor I have my doubts on the pipe.

It needs fuel to rip. Is it flat on top or does it sputter? If carb has vacuum slide the diaphragm may be bad.

I guess you could say it's flat, it's more of... It just won't rev any higher. The exhaust gets a deep sound and it just won't hit the band

An ignition coil breaking down will cause the bike to misfire under heavy loads.

How do I check it?

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