I recently asked a local dealer which mods would provide me with the most bang for the buck and I purchased exactly what they told me to. Now im wondering if they led me in the wrong direction. On their advice I purchased an FMF pipe and Silencer, some sort of K&N kit for $150 that came with jets and a needle aswell as the filter. They advised me to install all the bolt ons and go 3 sizes larger on my main jet. They also told me to remove my airbox lid. These are all mods I frequently read about here but I have never heard anyone mention anything about the FMF pipes or silencers that my dealer regards as the best for my paticular bike... Oh by the way its a KFX 400.

 

I would disagree. I believe the Black Driven Spring from EPI is the best $35 I could have spent on my 650. It wakes the machine up like you wouldn't believe. The gain in low end is VERY noticeable. Why Kawasaki doesn't retro their stock spring is beyond me.

 

i would make sure that your jetting is right. it seems to me you would need to be more than 3 sizes bigger than stock. u are probably going to need at least a 155 maybe a 160 main jet try a 25 pilot jet and around 3 turns out on your fuel screw. the fmf pipe should be just about as good as any other.

 

Thanks for the tip. I will start with the largest jet and work my way down untill it runs right. What about the needle? As I understand it jets can only let so much fuel in. The true regulator of fuel delivery is the needle? If so why isn't there much mention of that in this forum?

 

I dont think they mislead you. This site will tell you different things on different brands. But a pipe, filter, and rejet should make a noticeable difference is the jetting is right.


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86 trx250r
97 warrior

 

try putting the needle on the third or fourth clip from the top. this should help.

 

If you run with your air box lid on, remember to remove the constricting snorkle connected to the air box lid.