I have a 98 scrambler 400 that has a FMF Gold series Gnarley pipe on it. Standard bore piston and duel stage reeds. no other mods. that I am aware of. What I am needing to know is. Do I have a good pipe? and what clutch kit do I need for it if it is ok to keep it on there. If not what stage one kit do I need. Right know I have no low end. the way this bike runs it is either all or nothing. I put a new carb on it and didn't help much,It now idles better but I cannot putt around. I have to pretty much go wide open or not at all. Can amyone help me out. also I am at 4500' elevation, I try to stay from 3400' to 4500' but would like to go to at least 7000' but it runs really bad at that altitude.

 

If you can get rid of the pipe, then get rid of it and get a HPD trail pipe with the stage one kit from Rick Ritter(RCR). Then you might want to get a full clutch kit and if you really want that thing to fly, get the trail porting done to it. I got mine Bubba ported and love it, but Rick does a great job too and as far as service, both Rick and Bubba really take their time to answer ALL questions(get Rick on the phone though). Mine had great low end even with just the stage one kit installed and now that I got it ported, V-Force reeds, and the aggressive clutch kit, it really halls booty! You didn't say what kind of carb you have on it, but after you post that info, I'm sure someone can help you with that also as I only have the stock carb and live at sealevel.

 

I have a stock carb but it is new, no adjustments at all. boyson dual stage reeds on stock reed cage

 

You might want to check in the service manual for the correct jetting for your altitude. When they sell a new carb, they may not have it jetted for the altitude you're riding at. I know mine was jetted with a 230 main jet and the manual calls for a 210 main jet at sealevel I believe(above 80 degrees F). I now have a 270 in it, but I also have a 280 and 290 I'm gonna play with although at full throttle, the plug is the right color. If you modify the air box and change the pipe(RCR Stage One kit), you will most probably need to change the main jetting(Rick will send you the one you need with the kit) and maybe adjust the clip up or down one notch too. I have a copy of a jetting article that explains the basics of jetting in plain English if you need it. I'm not sure how much you know about jetting, so don't be insulted by these comments if you are a pro. Just trying to help is all. Your stock main jet should be around 210 also if your average air temp is around +40-80 degrees F. At least that's what the manual calls for.