I have a 99 400ex and my friend just bought a 00. so to be faster, so i thought, i bought a fmf powercore pipe went out to race and lost to him and his is perfectly stock. talk about embarrassing. my question is this, undoubtly someone here has made this modification and my next step is to get a k&n flter but what should i change my jetting to. I hate carb mods and guessing what it should be,so i am hoping someone here has these simple mods and can tell me exactly what it should be. thanx in advance
i am no mechanic and admit it

 

Did u beat him any where in the race like off the line or anything. Did u rejet after the pipe.00000000

 

no i never lead at all and i having done nothing more than take the stock pipe off and put the new one on

 

Thats the prob. Because the high flow exhaust needs more fuel. So you should probabley go up 2 jet sizes.

 

is he lighter then you?

 

hey now we will have none of this. what do u think i am a 400 lb lard boy. just kidding realisticly he probably has a 15 lb advantage. but remember his is completely stock not that mine is heavily modified but the only difference i have noticed on mine is that it is louder lol

 

hey now we will have none of this. what do u think i am a 400 lb lard boy. just kidding realisticly he probably has a 15 lb advantage. but remember his is completely stock not that mine is heavily modified but the only difference i have noticed on mine is that it is louder lol

 

ya the exaust is not just going to do it. It is like putting on a stock pipe. How can you get more air flow out if you don't let more air in. I have an fmf with a kan, etc and am running a 165 main and my plug comes out nice and shinny. I run the 165 during the Summer (out here in vegas 100+ and at 2200 ft) in the winter i goto a 170. Stock is 148

 

i have a powercore 4 and a K&N, i drilled 6 1.5 in. holes in my airbox lid. i re-jetted to a 152, seems to work for me. try it. and remember....muddy side down !!!!!!!!!!!!!!