I am looking at getting a 400EX from a friend at a really good price. My problem is that I have an LT250R and have ridden a 400EX and felt like I needed to stick my leg off and kick to get it to go faster. The bike handled and felt great but tops out in 5th trying to keep up with me in 4th. I was wondering if a Duncan Fatboy 4 exhaust, K&N filter and jet kit, and Edelbrock carb will add enough off a power gain to not get left by the two strokes. Or is the only way to keep up and not get roosted to go all out with a 440, cam, springs, and port.

 

I dont know if those mods will gain enough top speed to beat the lt250. You might want to check out something like the duncan national kit.

 

If you just want to go fast, put a 16 tooth front sprocket on it, an LRD pipe, and a drop in wb race cam, k&n filter and rejet the carb, don't buy a carb it won't make it faster, I have an FCR 39mm Carb I don't use. I run a stock carb with a dynojet kit. If you want to go into the motor throw a high compression .030 over piston in it. Other than that a high rev cdi box. Don't do a big motor kit. You will save money this way and be as fast, by the way the 400 isnt going to FEEL fast after riding a 250 but it doesn't mean it isn't as fast.

 

I was looking to get the most performance I could without going into the motor. I had a 300EX and I put a TC upgrade kit with cam, piston, springs, CDI, filter, pipe, and jet in it. It was horrible, we never go it right, the timing would look perfect but some how would turn just enough when we tightend the tensioner to get off. The head ended up like swiss cheese after we got done taking the valve cover off and on so many times, almost every hole stripped out of the soft aluminum. No matter how many times we tried to have it fixed it still spit oil. So I am kinda scared of a repeat with going into the motor. The carb really won't do anything? I race motocross and need something that will explode out of the corners and fly down the straights, and still be very reliable.

 

I had the same problem as you a little while ago. I had a 91 lt250r moded to the max and thought a 400ex wouldn't be enough for me. I was wrong, the 400ex is great. It worked out so good for me because i ride mostly trails and the lt was too fast.(is that possible) All i did to my 400 was a HMF slip-on, moded header, moded airbox, and UNI filter and this thing really woke. Plus all i spent was 110. Get the 400.

 

Yeah it looks like I will be getting the 400. I love the bike and will probably come to love its power delivery, I have a little money to spend on it to make like I want it. It's handling ability should make it a great modified MX'er. Guess I'm gonna have to change my screen name now.

 

I put these mods on and it was a big improvement. My buddy Chapy has a Zilla and he rode my quad and was ery impressed with the power gain. I can hang with a raptor until 4th gear then he pulls away. If I got the Edelbrock and the 440 national kit from Duncan it might be a different story. I think the whole 440 national kit with everything is around $2200. If I had he money I'd get the rest of the kit.

 

I've got to say that you should Get a White Brothers pro Meg, and a K&N Filter, That should get you close to what you need.

 

Ive been racing 2 stroke dirt bikes and got bored so i switched 2 quads. ive got a 01 400ex, ive got dg nerfs, powermad guards,moose skids, and thats about it. i dont have a bunch of money 2 spend on it. i was trying 2 buy a little at a time. i would like 2 add some power gain what could i get that isnt going 2 cost me a fortune...