250 kx 250 2 stroke

i have a kx 250 2 stroke everything new fmf exhaust, v force, new top end and cleaned everything for the exhaust valve but it still doesnt have the power that i expected what is wrong.
 

James

Staff member
Are you sure it's the motor and not your clutch slipping or maybe even a bad tire choice? BTW I'm assuming that you're talking about power to the ground?
 
i have a kx 250 2 stroke everything new fmf exhaust, v force, new top end and cleaned everything for the exhaust valve but it still doesnt have the power that i expected what is wrong

What year is the bike? Is this stock bore? When you say new FMF exhaust, are talking pipe or silencer or both? Have you cleaned the carb? What is the current jetting? Have you re jetted for the pipe and reeds? Sorry but give us as much history and info as you can so we can help you.

By the way welcome to the forum and post some pic of it and what to you ride trail or track?
 
What year is the bike? Is this stock bore? When you say new FMF exhaust, are talking pipe or silencer or both? Have you cleaned the carb? What is the current jetting? Have you re jetted for the pipe and reeds? Sorry but give us as much history and info as you can so we can help you.

By the way welcome to the forum and post some pic of it and what to you ride trail or track?
Damn, look at Jackson getting all mechanical here. :thumb: When you say "still doesnt have the power that i expected" What does that mean? I'm guessing the bike ran great and then something happened and you made all these changes?:noidea:
 
Also you state that your not getting the power that you thought you should. OK.................. Not getting power where? On the bottom end? Mid range? Top end? All of the above?

Well I think Jackson and I are on the right track. He threw a bunch of new aftermarket performance bolt ons at it that require the jetting to be changed to see the full benifit of those new parts. At a minimum the new head pipe and reeds valve set up will require atleast on main jet size smaller maybe two. That and the pilot Jet will likely need to go up (I think) one size could be down. Not to mention your jet needle setting. Jetting and the jet needle position is where I would start. That and a fresh set of Plugs. Yes Plugs I go through 3-4 of them (just how I roll) Getting a bike jetted correctly.

Oh I almost forgot. Did you repack you silencer? I only say that because you where kinda vuage on the FMF exhaust portion. New head pipe is great but will be hampered by a choked up silencer.
 
As has been stated, you need to give more information. Start with the year of the bike, and what you believe is wrong with the power.

When you re-assembled it, are you sure you timed the power valve correctly? The KIPS system is excellent, but very easy to install wrong.

The V-Force is a very poor choice for any KX250 from 1997-2004. The Rad Valve works much better. Even the stock cage with Boyesen Power Reeds or Carbon Pros works better than the V-Force.

What does the plug look like?
 
Have you checked the reed-valves... I used to have v-froces and they seemed to crack fairly easily which made my bike lose a LOT of power. Just take them off while you've the carb off. After all it's worth a shot... :thumb:
 
it could be just me

its a 2004 kx250 two stroke new head pipe and silencer i cleaned the carb last night and checked the jets and they are the correct sizes for what fmf suggested 165 main 56 pilot 2nd on the needle vforce said that i shouldnt need to rejet when i got the bike it was a terd wouldnt but half run now i have done everything but put in a new crank it checked outfine the exhaust valve and all the gear work for it was carbon stuck but it all moves smoothly now.the clucth is good barnett took care of that new mx 51 front and rear warp 9 wheels new renthal chain and sprokets 13t front 52t rear stock bore 66.4.the reason i think something is wrong because i just got rid if 2001 cr250 2 stroke and it was basically stock and it would smoke this one. it could possibly be just me but i think it should be faster, me brother has a rmz250 4stroke and we ride at the same level and for me to stay with him in the straights it is everything the bike hasand i shouldnt have to work the bike so hard. i am open to any suugestions and willing to try anything thanks 4 any and all help.
 
it runs great

me and my brother were tinkering on it today i dont know if the jets had trash it or what but i also turn the vforce over i think i might have had on upside down but it runs great now and pulls all the way threw from idle to wide open. this thing screams! but anyway thanks for all the help and advice i really appreciate it
 

SRAD97750

Moderator
Staff member
One time I cleaned the carb on a bike 5 times before it started acting normal. Everytime I hooked the fuel back up it clogged the jets with junk I thought I had already cleaned... Weird. Glad to hear you got her going!!! -BIG DAN:thumb:
 
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