Hey, I have a 2000 Honda 400ex with an Fmf Megamaxx II Pipe, and a K & N airfilter. I consider it to be fast, but when my friend (on a modded banshee) and I drag race, well it really isn't much contest, he eats me alive. Anyway, my quesiton is should i buy the big bore kit for some extra power. I have been told by many that it alone does great things, but when i called the dealer, he said that a big bore kit alone only increases 1/2 of a hp. He also said if I went to a different size cam, it would make that biggest difference. He said that if I bought the big bore kit and a different cam, i could maybe squeeze out 35 ponies. But I have aa couple of questions to you:

What is a cam? (I really dont know!)
Do you think the dealer is just trying to rip me off with the cam?
Do any of you have a 440ex or know someone who does and could give me some info cause im really considering it?
Would it be worth $400 for the extra horsepower?

Thanks alot guys, help!

 

If you want to beat your friends piped banshee I would suggest a web cam, 10:8:1 piston bored to a 416 or a 426, and race porting, that would put you pretty close to him and only cost about $650.

 

Cams are what open your valves. The cam has lobes that dictate valve lift and duration. HP can be gained by changing your stock cam for a race cam and will cost you $150-$200.

I'm installing a IMS 440, web race cam, port job, K&N, rev box, WB R-4 slip-on, and hardened rockers on my '99 400EX. I figured that I should see a 10-12 hp gain from these mods.

 

ldj, why would you say only bore it to a 416 or 1 426 instead of a 440.

also, if I have a fmf pipe, k and n filter, white brothers revkit, bored (?) over and the race cams, would that be extremely fast for a 400ex?

and if i would go ahead and add the cam and kit, would that make my engion alot more tempremental?

thanks

 

The reason I told you to get a 416 or a 426, is that the 440 does not rev as quick as either of those kits, and in a straight out drag those other kits would do better than the 440 because they make your 400 rev like a two stroke. If I were you I would get your sleeve bored 2mm over to make it a 416, then get a 10:8:1 JE piston, get any drop in cam and if you have the money port it, you will love the power. Before I put in my 426 piston, I had a 10:5:1 piston and web cam, it felt like a new bike, I could beat a lot of bikes, you don't need a race cam, then you would need new valve springs and that's not worth the money.

 

ok, but overall, which kit would add the most power? 416? 440? 426?

 

On the dyno, I think the 440 would put out the most horsepower, but the quickest would be the 426 or the 416, I think the 426 might be quicker than the 416.

 

I agree with LDJ, I would go with the 416 or 426 kit. I would try to get a piston with around 11:1 compression, don't get a Wiseco piston though, they aren't that good. A 440 piston will give the bike more torque for like hillclimbing, and the 416 or 426 will be a revver. you have to get a cam though if you want to even come close to that Banshee. It will allow the bike to "pull" harder in the midrange and top-end without running out of power. i would get a Web-Cam 450-451 grind for the 400EX, because you don't need heavy-duty valve springs or hard-faced rockers. I put in the stock sized piston in mine with 11.25:1 compression and the web-cam along with my other goodies, and i can beat a piped Banshee from start to finish. This is the truth, even though the guys in the Yamadog forum think there is no way i would be able to touch a piped Banshee.

 

alright, I have another question then, if i were to get the 440 kit, how much would i have to bore it out, or would i even have too? You guys are helping me out alot, keep the answers coming!!

 

A 440 kit comes with a sleeve. The IMS does not require a bore to the new sleeve, Sparks sleeve requires a bore. I don't know if you have to bore to get the new sleeve to fit. The 440 sleeve costs around $100 or so.