400ex Top End Rebuild

[atvhonda-rider]

Hey guys my question is how difficult a rebuild would be, and dont give vague answers please i know my basics on rebuilding. :D I have the piston, cam, and top end gasket kit, but i dont want to take it to a shop and pay $300 for them to install everything.. so im simpyl asking, how hard would it be to rebuild it myself? Head torqueing specs? Timing chain issues? Rings installation and etc. etc... any information is helpful im just looking at my options to better my knowledge... thanks!

[garthedavidson]

I did mine for the first time it was easy. if you have a manual thats the key. dont over hone the cylinder 4 strokes dont need as much as a two stroke just take it down till it is not shiny and so you dont see score marks. and mark the camshaft and chain and sprocket tdc possission before you dissemble it will make it a lot easier. be carefull of the decompression spring and plunger under the camshaft it is small and you dont want it to fall down into the crankcase.

[JOEX]

Yep, a repair manual will be very helpful. The less expensive Clymer version is sufficient.

Be sure to check the ring end gap...

Are you putting in a larger piston?

[AZ440ex]

I have done mine a few times now. The manual is a must. Also buy or borrow a TQ wrench. I was lazy one time and didn't use one to do the head bolts. This can cause gaskets to blow or even warp a head.

A ring depresser is also pretty handy.

You might also look at having the head decarbonized depending how much build up there is.

[atvhonda-rider]

ok good advice guys thanks, those were all tools i was taking into consideration.. i have the ring decompressor handy from a friend, but will maybe rent or buy a tq wrench... also, i havnt decided truely on what piston to run.. it'll either be a stk. bore 10.5:1 JE or a 12:1 415cc piston but im not for sure yet.. if i were to get a bore i'd feel bad not p&p and i really dont have the cash available to do that at this time.. what should i mark the cam and timing chain with? as in what works the best.. silver sharpie?? thanks again guys