need help with 400 ex top end rebuild

[lanes400ex]

i am in the process of rebuilding the top end on my 2001 400 ex i started this project not really knowing exactly what to do i have just been searching on here for info i really need help with retiming it i dont know how to tell if its on the compression stroke because the whole top end is off does anyone know how to find it without the top end on any help would be greatly appreciated

[killer454]

when sitting on the atv you will see two plugs in the left side case cover remove these plugs (allen wrench needed)and turn the flywheel (17mm socket)till you see a T mark. line that T up with the line in the upper plug hole.

in order to make sure you are at top-dead-center you can remove the plug and poke a peice of steel tie wire in the hole to make sure the piston is at the top of the cylinder.

when putting the cam in make sure the lobes on the cam face down while in the head and your cam marks lineup with the top of the head rail.

i whent to my yahoo search and typed in free 400ex manual and found a free download on their so now i have a free manual YOU SHOULD DO THIS TO.

i dont know if this helped you but this was how i did it on my 2000 400ex

[lanes400ex]

thanks that helps out . im still not sure if it needs to be on the compression stroke to set the timing if so im wondering how to get it on the compression stroke everyone has said to look at the intake valves but the valves are all closed because i have the cam out so obviously thats out of the question in determining the compression stroke

[killer454]

i know what you are talking about when i went through school on auto machanics we where tought top dead center was this-turn engine till you see the intake valves open and close on #1 cylinder(piston on downward stroke)now when piston starts comeing up that would be top-dead center when piston reaches the top of the cylinder after intake valve closes.

i tryed this on my 400ex but could not get it to come out right.so i just linedup the T mark and made sure all the cam lobes where faceing down when the cam was installed.after i got it set i slowly turned the engine over and checked to make sure their was no binding with the valves and piston.

i put a 11-1 piston in mine so checking for binding was a good idea,i did not feel any binding so after all together i crossed my fingers and hit the starter and bam it fired to life and was running fine.

on this engine i think it is mostly the cam that determines tdc thats why you lineup the mark on the crank to T.and then install the cam with all lobes faceing downward in the head this gives you the setting.

i hope this helps you i ran into the same thing when i did my rebuild.

[lanes400ex]

yeah that looks like what im going to have to do i have worked on alot of v8 engines and a couple complete builds but this four wheeler is confusing me thanks for the info

[Dobber]

the motor dosent know what stroke its on line up the t mark on the side put cam in lobes down line up marks on sprocket with the top of the head dont forget to release the tensioner and she will fire up

[lanes400ex]

about the chain tensioner is that self adjusting or do i have to set that myself if so how do i go about that

[CJM]

Originally posted by lanes400ex
about the chain tensioner is that self adjusting or do i have to set that myself if so how do i go about that

self adjusting.

[killer454]

on the timeing chain tensioner becarfull not to mess it up,mine was bad when i did my 400ex.

1.remove the center philips head screw
2.now find a small streight blade screw driver and put it in the hole where you removed the philips head.there is a slot in there put the flat screwdriver in that slot.
3.now when you turn that little screwdriver clockwise it will pull the tensioner into the body of the tensioner.
if you remove the screwdriver when its pulled in or retracted all the way it should spring out as soon as you remove the little screwdriver.
IF IT DOSNT SRING OUT THE SPRING IN IT IS BAD AND YOU NEED A NEW ONE.this was mine when i got this 400ex.

follow these instructions
find a way to retract the tentioner all the way and at the same time mount it to the cylinder,once you have it mounted up remove the screwdriver it will spring out and keep tenstion on the chain.this is how i did it when i got the new tensioner.

hope this helps you