I have a 2006 KFX 400 and wondering what are the best mods and what mods should be done together?
I would like to get more power out of it and found these big bore kits from Athena. They come with a complete new cylinder, piston and gaskets. They even have a kit that makes it a 454cc?
1. Are they worth the money?
2. When you do a Big Bore Kit, do you run the stock cams?
3. What benneifit do hot cams give you on a stock motor?
4. Are Hot Cams worth the money?
5. What other mods are you guys running?
Thanks for the help.
Crazyotto

real power is not made with displacement. I would have it ported cammed piped and jetted. thats your best recipie for power

I totally agree with Fulltiltrider when you start doing the other stuff with the big bore kits it simply isnt worth it!

I quess Fultilt forgot the basics of almost all engines... Hard to find a situation where more cc's wasn't the faster anything...Never forget power to weight (that's the real deal). Here's reality, if your going to get into the motor just do it all at the same time (save some dimes). If you really like running with your hair on fire a simple cam here and a pipe there Oh and don't forget the filter...Won't do crap for you after a few rides...Add you CC's, cams (not hot cams, those are toy) Crower cams or other, mild head work..... Now start throwing in fuel and air (in mass) It's a friggin engine, they havn't really changed that much in fifty years....And don't forget to increase compression to at least 12:1.. And of course run a quality fuel (minimum 105 oct or vp C-12)

how do you get your hands on 105 octane or vp c-12? Also could i run that in a stock bike?

Running the high octane gas in a stock motor is just throwing away money. It can, in some cases, actually take away performance.

Thanks man

<div class="FTQUOTE"><begin quote>Originally posted by: 1128633636

I quess Fultilt forgot the basics of almost all engines... Hard to find a situation where more cc's wasn't the faster anything...Never forget power to weight (that's the real deal). Here's reality, if your going to get into the motor just do it all at the same time (save some dimes). If you really like running with your hair on fire a simple cam here and a pipe there Oh and don't forget the filter...Won't do crap for you after a few rides...Add you CC's, cams (not hot cams, those are toy) Crower cams or other, mild head work..... Now start throwing in fuel and air (in mass) It's a friggin engine, they havn't really changed that much in fifty years....And don't forget to increase compression to at least 12:1.. And of course run a quality fuel (minimum 105 oct or vp C-12)</end quote></div>

Ok you say i forgot the basics, but everything you mentioned is exactly what I said!! I have a 250r with alot of internals done to it, but I am only running a .30 over piston. My friend has a lt500 just piped and jetted and Ill get him by 5 lengths. We dont live in the 60's anymore where engine size was out of control. Now you have Civics out there smoking v8's. Obviously you never built a motor before. The key is NOT displacement, Its air in,and air out.

hard to find a situation where more cc's are not faster apperently you have been sleeping for the last 3yrs since the 450's came out.

what is the best way for more air in and air out!