ive got a 2003 honda 400ex mainly stock except for slip on exhaust,air filter,nerf bars and front bumper...i want to make it more of a 450 without getting a 450
list of what i want to doif prices are wrong or you know a cheaper way plz tell)
power now kit~$100
aluminum airbox~$100
cdi rev box~$80
procon rectifier~$60
rear holeshot tires~$150
450r suspension(off ebay)~$300(or can i use the yfz?)
+2 a-arms~$350
possible after market carb??~$300
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now to the big one...440 kit!!!
on ebay there is a 440kit for $170 but that doesnt seem right...please check it out

http://cgi.ebay.com/ebaymotors...WQQrdZ1QQcmdZViewItem

1. i heard they blow gaskets alot,but if i got a good strong aftermarket one would i be ok?or go with a 426?

2. do i want higher or lower compression?

3. how reliable will it be?

4. do i need different hotcams?whats the diff. in stages?

5. what all do i actually have to do to make it be a 440?

6. can i do it at home or do i have to send it in to be worked on?

7. bottom line 440 cost including labor(as in being able to ride with no problems)

8. in the end how will this par with a 450?because they are totally different engines

as you can tell i know nothing about this and many others have probably wondered the same thing as boring is a very popular thing
so please answer my questions not just for me but for the sake of others
~thankyou~

 

You will not be able to wake that baby up enough to compete with the 450's, 2 totally different animals. If you do all the stuff you listed you will have one of the nicest 400's around.

 

I was thinking of the 440 kit for my Z400, I heard the Athena 440 big bore kit is pretty reliable. I have heard the sleeve kits aren't so reliable. As far as suspension if you or a friend knows how to weld and fabricate you could muont just about any suspension on your bike. Don't forget to go with a full exhaust system. I love my White Bros Pro Aluminum 2 setup.

 

My EX had been a 440 and a 426, but I went overboard with the modifications. I had the White Brothers CDI box, bigger valves, titanum springs, big Web cam, lightened fly wheel, head was ported and polished and an FCR carb. The exhaust was a GT Thunder (huge head pipe), the piston was a 11.1 compression on the 440 and I'm not sure on the 426 kit. The 440 had more torque but the 426 seemed to rev out quicker. When Yamaha came out with the 450 my causin bought one and it was a close race with the 440 motor when his was bone stock. I never raced him after he jetted it, added a aftermarket filter and exhaust but I'm sure he would have easily beat me. As far as reliability, you will loose it. I suggest not adding an aftermarket rev box if you go with a 440 or 426 kit. The cost of a big bore kit isn't that much it's the labor that cost and yes someone will have to bore the cylinder, If I remember right both kits take the same bore but different sleeves. After several hours I did have some problems with head gaskets so I added a big stud kit. An aftermarket carb does help with response but they are costly. I don't know much about the power now kits but I've heard good reviews on them. The air intake, carb and exhaust (full exhaust, maybe Sparks) is the biggest improvement you can make on a 400ex and not loose any reliability. They also make a 416 kit. Make sure you do enough research on all of the cost because it could add up to more than what you could buy a used 450r for.

 

thank you very much

 

imo send your quad to CT racing

 

I have a 1999 400ex that I race short track with and I have no problems running with 450's or out running them. I have a 416 kit on it with very high compression, infact so high that I just got it back from the shop where they had to put bigger stud bolts in cause the old ones stripped out. If you run high compression then you need to run race fuel. Stock 450's in a drag race! I play with them. I have had 426 and 440 kits and the best kit is the 416. Depends on what you are going to use it for and I could tell you what you want.

 

yeah hes right race gas will be needed i think your supposed to start race gas when you quad puts out 12:1 compression then 110 octane or somewhere around there would be good to run

 

My daughter kicked azz with the 416.
You need a reliable motor builder to answer some of your questions. TC/Sparks/Dasa.