increase topend power on 400ex

[montyjcm]

Hey,
What increases the topend power of a 400ex? Do the bigger bore kits, or are they all low to mid range? I hope this is not a common topics because I looked and couldn't find anything. Thanks!

[cals400ex]

a good pipe, cam, piston, carb, and some gearing changes will get you more top speed. you don't need a big bore. i am running a 406 and i noticed a nice increase in top end power.

[montyjcm]

That is good. The reason I was asking is because I am looking for an ex for desert riding, and I wanted to know what to look for. Would a 440ex have more topend?

[Quadfather]

Does the pope wear a funny hat?

[montyjcm]

Haha:D It depends on who you ask. I am guessing that means yes.

[H_W]

Originally posted by montyjcm
Would a 440ex have more topend?

If it has just a 440 kit (which means just resleeved with a bigger piston), then probably not. You need a cam, pipe, and a carb. You could also get an aftermarket rev limiter. I noticed a huge increase in mid range and top end with my mods.

[montyjcm]

Well, the quad I was checking out was had a ims 440, I don't really know what it has in it.

[montyjcm]

Would the 440 kit with a cam, pipe, and carb keep up with my brother's lt250r with a pipe?

[H_W]

Originally posted by montyjcm
Would the 440 kit with a cam, pipe, and carb keep up with my brother's lt250r with a pipe?

If all he has is a pipe, then a fully built 440ex would smoke it.

[montyjcm]

Hey H_W, is your quad considered fully built? How does it compare to 250rs? Thanks for the help

[K_Fulk]

Don't fprget about porting and oversized intake valves. :cool:

[H_W]

Originally posted by montyjcm
Hey H_W, is your quad considered fully built? How does it compare to 250rs? Thanks for the help

I don't know if it would be considered "fully" built, but it has about everything I can think of without boring it out. I have only raced one 250r, and we were about dead even. We raced about 3 times, with the same result each time. The guy on the 250r is the lighter rider by about 50 pounds. I don't know what the 250r had done to it besides a pipe, but it was setup for racing as far as suspension. I think it had a 265 kit in it. That's what someone else told me. I would like a 416 or 426 kit, but I am planing on buying a 450r in a couple of months anyway.

[montyjcm]

That is pretty good considering that most people say 250rs smoke 400exs. If you don't mind me asking, how much did you spend on your engine mods (not including pipe). thanks

[H_W]

It has been over a year since I did all the engine work, but I will try. I think I paid $125 for the piston, $140 for the cam, $275 for the port work and 3 angle valve job, $440 for the carb, $110 for the rev box, and $29 for the rear sprocket. A friend of mine helped me put it all together. I actually have a 16 tooth sprocket for the front, but I did not like it so I took it back off. I have enough top speed without it. I cut my front fenders, some say that helps performance. I don't know, I just think it looks cool.

[montyjcm]

I think it is more the looks cool, thing:D .

So, one of the bikes I was looking at had a edlebrock carb, a cam, and rev box. Would it be close, if it was in good condition, to your quad, or does the piston make most of the extra power? Thanks for your help!

[montyjcm]

Man, something is messed up with my pc, just read the next post.:confused:

[montyjcm]

What do you guys think that the relative hp gain would be of an ex with the mods stated above? Also, the other quad I am looking at is a cannondale. I will be doing desert and dune riding. Do you guys think I should go for the dale? thanks

[montyjcm]

I hope the above posts show, but sometimes I can't see them. Weird. Can anyone answer the last question I asked?

[H_W]

Originally posted by montyjcm
I think it is more the looks cool, thing:D .

So, one of the bikes I was looking at had a edlebrock carb, a cam, and rev box. Would it be close, if it was in good condition, to your quad, or does the piston make most of the extra power? Thanks for your help!

It would probably be close, but the porting and polishing of the head on mine makes a good difference in mid range. The piston would help with bottom end power.