HELP-Why is my 250 slow?

[motox4eva]

Hi, (I hope this is the correct forum)

I recently bought a 2001 KX250 about a month ago or so. It was raced. It has a FMF Gnarly Pipe w/ FMF silencer, FMF AOF Power Ignition, and a UNI air filter. That's it for performance.

This is the first 250 2-stroke I've ever ridden in my life and my dad thought I was going to die on it (going from a KX80) because he remembers my brother's stock '93 CR250 throwing his 280 lbs into wheelies lol. Anyway I'm doing really good on it, maybe too good :think: , like because it isn't as fast as it's supposed to be. I even expected it to throw me off, or close to it. IT DOESN"T EVEN WHEELIE! Well if I pop the occasional clutch it does sometimes, but it seems the "powerbands" are really weak. BTW I think I weigh around 150 lbs. An older guy at the track told me that his '98 KX250 would want to pull away from him and all, do wheelies by itself, etc. But mine doesn't, I try to do wheelies in 2nd and 3rd and I get nowhere (well except for straight forward of course with the front wheel glued to the ground). :( :ugg: :think:

Anyway-what could be wrong with it? I'm thinking maybe the compression is low or something... Ask me questions if I need to explain it more...!! (I didn't want to make the first post too long so it would be a turnoff to reading it :nener: )

thanks,
Drew

 

[GhostRider32]

Do a compression check. New, a KX250 has around 180 to 200 psi if I'm not mistaken. If it was raced and has been a while since the last top end (if it ever even had 1), it may be time for a new top end. Severly low compression will definately cause power loss. I find it hard to think that going from a 80 to a 250 would seem to slow unless there is some form of mechanical issue.

 

[cr2504life]

Yeah even with a severly worn top end the thing would likely still scare the crap out of you. My money is on the power valve.

 

[motox4eva]

I find it hard to think that going from a 80 to a 250 would seem to slow unless there is some form of mechanical issue.

thanks for the reply- i didn't mean it like that, of course it's still faster than the 80-- it's just that my dad was making it seem like it would kill me--and i think it's more like a baby--

lol cr250, you're here too

 

[Bullwinkle58]

250's are easier to ride than small bores. To me at least. Really, it just sounds like your Dad over-promised, and the bike under-delivered, so it wasn't what you expected.

Is the bike hard to start? If your compression is low enough to cause a dramatic decrease in power, normally the bike will be hard to start.

It also could be that your gearing is tall. What size sprockets are you running?

 

[motox4eva]

250's are easier to ride than small bores. To me at least. Really, it just sounds like your Dad over-promised, and the bike under-delivered, so it wasn't what you expected.

Is the bike hard to start? If your compression is low enough to cause a dramatic decrease in power, normally the bike will be hard to start.

It also could be that your gearing is tall. What size sprockets are you running?

It definitely is easier to ride, especially throgh sand, mud, etc bc of the larger tires and all, and it fits me better.

I'm not totally sure bc like I said I never had a 250 before... but, I can start it with one kick sometimes...

I don't know what size sprockets are on there now. I just ordered a chain/sprocket kit. The front is same as stock size, and the back is one tooth bigger, so a little more accel.

I got a lot of responses on another forum saying there's a good chance it's the powervalve, it's clogged shut or something--not working properly, carbon build up or something. One guy said it happened to him when he first got his bike. What do you think about it being the powervalve?

 

[bclapham]

your clutch might be slipping.

 

[motox4eva]

your clutch might be slipping.

Damn, I totally forgot about that! That was the first thing I thought of when I was at the track.

thanks

 

[VB Racing]

As a fellow rider of an 01 KX 250, I know the reeds fray VERY quickly. Remove the reed cage and look for chipping and fraying at the corners. My reeds only lasted around 10 hours brfore they were frayed, and performance decreases rapidly. If they are frayed, stick in Boyesen proseries reeds. They work EXTREMELY well in that particular bike. The 01 motor is more of a mid motor, but the 2 stage reeds really wake up the bottom.
All in all the bike should run very strong, the 99 to 01 KX's are very strong motor wise. Make sure and check all our basics.
If you need any advise or have any questions feel free to PM me, I have owned 2 01 KX's now and I have to say thes bikes are my favorites.

Dave

 

[showtime586]

I'm thinking that the 99 KX was voted 250 of the year before Yamaha started their run with the YZ.
He did not say what year his 80 was, but a weak 250 should be a more powerful bike.

 

[2smoke]

I say the power valve is not working properly.....makes it like a 125 until you get wound out a bit then it goes like a 250 .

 

[motox4eva]

As a fellow rider of an 01 KX 250, I know the reeds fray VERY quickly. Remove the reed cage and look for chipping and fraying at the corners. My reeds only lasted around 10 hours brfore they were frayed, and performance decreases rapidly. If they are frayed, stick in Boyesen proseries reeds. They work EXTREMELY well in that particular bike. The 01 motor is more of a mid motor, but the 2 stage reeds really wake up the bottom.
All in all the bike should run very strong, the 99 to 01 KX's are very strong motor wise. Make sure and check all our basics.
If you need any advise or have any questions feel free to PM me, I have owned 2 01 KX's now and I have to say thes bikes are my favorites.

Dave

Ohh cool I found someone with the same bike!

Wow wtf only ten hours the reeds last!? OK thanks for the advice. How long will the Boyesen Pro Series reeds last? Would it be better to just get like a VForce 3 valve and those reeds would last long right and it would be a lot faster..? I'm mentioning this because the Pro Series reeds are $40 plus shipping. So roughly 30 hours of replacing reeds and I could have bought myself a whole new valve w/ even better reeds. Does my reasoning seem logical to you or no?

btw just curious- what do you think about it being the powervalve?

thanks

I'm thinking that the 99 KX was voted 250 of the year before Yamaha started their run with the YZ.
He did not say what year his 80 was, but a weak 250 should be a more powerful bike.

My 80's a '97. lol I didn't mean it like my 80 is slower! Of course the 250 is faster!

 

[91kx]

Have you ridden or raced against any other 250's to see how it compares?

 

[motox4eva]

Have you ridden or raced against any other 250's to see how it compares?

Nope, that's a pretty good idea though, next time I'm at the track I'll look for another 250.

 

[va_yzrider]

Clean your powervalve (after all, it's free) and check the compression. My vote is power valve also, however, the reeds are certainly worth a check. The 250 should make you feel cautious about how you open up the throttle, so something is wrong. Ride someone else's 250 and compare.

 

[VB Racing]

The boyesen reeds last much longer, I usually change them every spring, whether they are worn or not. I have no experience with the v force reed block, If I were you I would research them well before plunking down alot. It seems that an aftermarket reed block will work on some bikes better than others.
I would also check your powrvalve operation, and check that the powervalve cover isn't leaking.If somebody had the powervalve assembly apart and assembled it improperly, it will not operate.

Good Luck!!

Dave

 

[Kawapilot]

I ride an 01 KX250 as well. I don't know enough to help you mechanically, but I can tell you the bike should easily be capable of wheelieing you off the back. It's happened to me in 2nd, and if I ride in good traction, it will try in 3rd as well.

 

[motox4eva]

Well yesterday I went to pick up the owner's manual I ordered and they ordered the wrong one! :bang: So now I have to wait until the right one comes in--just because I don't want to mess anything up.

 

[motox4eva]

ok

I say the power valve is not working properly.....makes it like a 125 until you get wound out a bit then it goes like a 250 .

ok thanks everybody--ill post after i check/clean the powervalve and test ride