wanting to rebuild my honda trx400ex 2003

[MYTRX400EX]

hi im from australia, im new to this forum. i was thinking about rebuilding my bike to 416cc. i want it to be reliable with more power, i dont want to spend a fortune, i was thinking just a new piston and sleeve is this possible?? my bike is already jetted, i have a white bros exhaust aswell, would i need a new clutch?? feed back would be great,aswell as a list of parts recommended, please be as specific as possible,im not overly knowelidgable, performance rebuilds are new to me. i want to run normal pump fuel wich is 98% octane, and still want reliabilty, any feed back would be great, thanks all.:macho

[REDRIDDER]

Welcome to the site.

[ben_400ex]

Hey mate!
welcome to the site!
good to see another aussie ex rider on here...
you'll love this site, theres a lot of really good blokes that are willing to help out and some top bikes to check out.
good luck

[sodbuster]

Make it a 440 with heavy duty studs if you are going to sleeve it. And add a hrc cam or hotcams stage 1.

[MYTRX400EX]

im told that a 440 will be to unreliable,and bigger oil coolers will need to be installed, i dont want to spend heaps of money, just simple but noticably more power, thanks all. keep the feed back coming.

[rideracelivemx7]

if you want a new sleeve and top end its going to ring you up a few bills anyhow. i figure 130 for topend kit and 100 for the sleeve, it still has to be bored and honed at the shop, thats around 150-200 anyhow. a 416cc kit will giv eyou a little bit of boost in power. you must think, its not a 2stroke your not going to notice a huge increase in power. bigbore applications on a 4 stroke will finally be noticed rather than small increase in cc's. but if you match the 416 with a cam and high compression piston. say, 10 or 11:1 to one. you can still use your pump gas, preferably 93, you shall notice a nice couple extra ponnies under your seat. 416 is safe of the stock sleeve,426 is taht much more off the stock sleeve. 440 is the ebst bang for the buck. if you know what your doing and watch how you do it, a whole knew sleeve and new top end is a good match. but it all depends on how much you want to dump into the engine. if you give us some numbers to work with, im sure plenty of us can help you pickout the best kit for you. i gota 440 kit, cam and all for 350. and it was 200at the machine shop. so for 550, itwasa great addition in power.

[MYTRX400EX]

the first addition of money isnt so much an issue, just everyone ive spoken to in oz says that the 440cc kit is unreliable. could you put together a suggested package for me that you think will be a good reliable power gain, i realise you said a 416cc kit will not be a huge power gain but id like to stick with a 416cc kit, so any suggestions on a 416cc package will be great. thanks alot.

[Balaz_73*00]

Theres really no need to resleve if you only want a 416. I'd say get your cylinder bored out to 88mm (426)...je has one with 11:1 compression so should be able to run 93, throw a cam in there (hotcam stage 2), maybe install heavy duty studs just to be safe(i would) and you'd be good to go. Of course if your pulling the motor apart youre gonna need new gaskets. While apart id make sure your cam chain is ok and replace if needed. Always run good gas and oil and you should have a strong reliable motor for awhile. Im goo goo gaa gaa about klotz oil thats all i run