I have 400ex with a white bros exaust,rev liviter,dana jet kit and the k and n filter.The moter is pretty well beat at this time and smokes bad and lost lots of power.My question is should i go all out and do the 440 kit or should i just bore it out and put new rings in.Is this kit reliable and what is involved in changing.Where can i find the best price on the 440 kit.

 

how could your engine be beat already?
you must have not taken good care of it..

well since you have money comign out the azz, and like destroying machines, why don't you just get a raptor, and beat it for a year until it is useless.

 

Hey 400exmaster,Your about as helpfull as a kickstand on a quad.They guy simly asked what would be best for him and you you cut him down like an oversized tree.Maybe he bought the quad used and it was beat when he bought it.Maybe he ran it low on oil and now needs a rebuild.Whatever the facts are if you dont have any usefull info to give him just read the post and move on like most everyone else does.

 

x250rdude:
I believe you were the one degrading everyone when trying to defend your raptor. And all of a sudden your some "Nice guy"

As someone in this forum said before, you never satisfied with your machine, and you just keep getting new ones. You and beat400exguy fit in the same category!

PS: sorry i am not someone who has money out the anus, and just is never satisfied or destroys machines.
Sorry that i take care of what i own, and don't ask for more.

Bottom line: It must suck to not be satisfied with anything. Could it be because you can't ride? hmmm.

 

Geez, just when the posts were starting to get civilized again, you guys have to ruin it. You all must have been on vacation or something. I think the posts have been going pretty well for at least the past month.

Where'd ya go for vacation by the way?


BEAT400EXGUY:
I will start off by filling you in that I am in no way technically capable of giving you a reliable answer on your question. I know, excluding a few individuals, there are plenty of knowledgeable people qualified to give you a productive answer.

I think I've read a couple of posts leaning away from doing the 440 kit. Something to the affect of your cylinder chamber walls being too thin...I think.

Hopefully, you'll get more technical replies.

 

I've also read some negative things about the 440 kit on this forum but have yet to experience anything bad with mine. The 440 is a huge improvement from stock, I went with a setup that would give loads of torque on the bottom and am extremely satisfied. It seems I never get caught in the wrong gear anymore, I just punch the throttle and it pulls your arms off, no matter the gear it has the power to pull. It increased my top end also but I don't think as dramatically as the low end. As a side note I take very good care of my machine with frequent oil changes. The machine runs much hotter so this is a must if you want it to last for any length of time. As I said before I am quite pleased with the performance gain and would recommend this to anyone thinking about doing it. Oh yeah I had Powroll do my work for me, great company that does great work.

 

hey 400freak hat other performance mods have you doe to it ??? pipe rev kit ????? just wondering i have a 2001 400ex and im a big guy need more Motor to pull my big a$$ ..let me know

 

Hey guys. I recently read in one of the mags about a 416ex that some guys are racing in the baja 1000. They had white bros build it and like it over the 440 because the 440 is mainly a torque motor and the 416 is more of a hi-rev horsepower machine. They said it was bored 2 mm over and had a JE piston. White bros ported the head. It also had a cam and re-coated rocker arms to reduce wear. It said white brothers dyno showed 40 hp. Not bad I must say. By the way they also added a rev limiter set at 9.6 grand and said that it would run wide open all day at that rpm....

 

Its worth doing but its also worth saying that it will not rev out as high as the 400 would. The bigger sleeve will also make the engine run a little hotter than before. You will see big gains in torque and HP though. Should be up 3-5hp just from the bigger piston alone. I would go with a reputable shop (take your pick out of the Mags) and send them your complete motor. It may cost you little more but its worth it to know its done right. GT Thunder has lots of info regarding pipes, cams, carbs along with awesome dyno runs that show Torque and Horsepower. They currently have a kit that rivals the awesome YZ426 Yamaha motor. Check them out at http://www.geocities.com/~gtthunder/testbed_set.html

CT250R

 

Beat400exguy,
I have a CT440 full race and have no problems to report. I had the engine done last winter and have ridden it hard all summer. The difference in the 440 and the smaller bores is that the 440 has a tapered sleeve to allow it to fit on the bottom end. The wall on the bottom of the sleeve is thinner than the top. When Curtis Sparks installs his 440 National "kit" he machines the cases to accept a sleeve that is equal thickness the entire length of the cylinder. This has obvious durability advantages. Now I have a tapered sleeve in mine and have had as stated above zero problems. Four years from now? Who knows?
Heat issues arise when using a 440 "kit". This is what will do in the otherwise bullet-proof engine. My bike ran cooler this year at the dunes [w/440] than last year [still 400]. Here's why: #1 I installed a Pingry Oil Rez. It adds 1 QT of oil to your capacity and is vented. #2 I have a ceramic coated Curtis Sparks exhaust. It is coated both outside and inside. The outside disapates heat amazingly fast. You can touch the pipe within minutes of a hard ride. The inside is ceramic coated to provide better flow of exhaust gasses exiting the system. #3 By bumping up the compression [I'm at 11.5:1] you are forced to run race fuel or a mixture of it. I am supposed to run 100 and have run 110 at the dunes. The higher the octane, the cooler the engine will run.
Whatever you do, Don't mix and match parts. Let the race shops do the R&D. My friend has bought and sold more parts trying to figure out what works and what doesn't and mine still runs better with a stock carb. I'm not saying you have to take your engine out and ship 'em the whole thing along with your retirement fund. I'm just saying "too many cooks will spoil the meal".
Knowing what I know now, I would probably try the 416 first and see how I liked it. It's supposed to rev quicker and higher. If you are an ex-2stroke guy, you may find that appealing. You can always go bigger and you will have 3 or 4 bores left on that cylinder where as I won't bore this tapered cylinder on the 440. Good luck