wont start

[hondamxerd]

i have a 400 ex that will not start, i need some help, i have checked everything i know, i have done as suggested and ran a compression test, spark test, timing check, fuel, wiring, air, and exhaust. it will crank but sounds like the kill switch is on, when attempting to roll start i here a noticable clicking noise that almost sounds like valves, a metal on metal sound, not real loud but noticable, i have check valve clearance and to see if they are bent and sticking, everything i have done has turned out ok, so should'nt it start, whats the prob?, please help, when it shut down the guy riding it was accellerating in 4th gear and heard a loud clicking noise then it died. nothing since. this is my cousins ex mine still runs fine and i have not had this prob with, i changed out the coil and nothing, any pointers or info would help greatly thanks

[hondamxerd]

ANYONE? ANY IDEAS, ANYTHING I CAN CHECK, ANY IDEAS ARE GREATLY APPRECIATED, EVEN THE FAR FETCHED ONES

[mojoe2878]

how much compression did you have when you did the check, did it build up pressure quickly or did it take it a while? the compression test should have shown around 120psi or better dependint on what ratio piston you have and should have built up quickly. is the spark strong?if a ignition pulse generator or control module is bad you could be gettin the spark at the wrong time. let me know what the compression test is showing and try to count about how many times the engine turned over to get to that reading and then maybe i can tell what else to check for.

as far as the clicking sound you hear when tryin to push start it, it is probably just the chain making that noise, my 400ex and all my bikes make that clicking noise when i push them, the faster you roll them the louder it is. hope this helps some and good luck

[hondamxerd]

ok, my compression did not check out as good as i thought it would, i used a mac tools digital compression tester and its highest was 33 psi, i know i know, not good..... i did put some oil down the spark plug hole and try again, i was told this would tell me if the rings were bad, i tested the same 33 psi, so, what now bad valves? bent, stuck, how do i go about checking this properly, i thought i checked it but may have not been correctly, learn something new everyday i guess, your help is greatly appreciated, thanx

[mojoe2878]

it doesnt sound like the rings, when rings go you still usally have a little more compression than that. next thing i would do is pull the head off and check for a valve problem, if one is bent then it wont be seated all the way, if they look good then pour some kinda solvent in the intake and exhaust chambers and see if it leaks out ,if it leaks out then either the valves arent seated or the head is cracked, check to see if the head gasket has blown and check the underside of the head for any unusual marks that would indicate that the piston has slapped it and damaged it. also make sure your timing chain is still in one piece and on the cam.

[hondamxerd]

thanks so much for guiding me through it, he is really missing his 400ex, and i am getting kinda disgusted with it, i am also in the process of tearing mine down, wanting to clean it up, make it look a little better, would have loved to had raced it at the mountaineer, but it was not ready, so i raced my rincon, didnt do to bad, but mostly i had fun, it was a great experience

[hondamxerd]

I WILL TRY TO TAKE THAT APART THIS EVENING AFTER WORK, BUT I WAS JUST WANDERING IF ONE OF THE VALVES ARE BENT, WHAT WOULD CAUSE SUCH A THINK?

[mojoe2878]

engine timing not being right would open a valve at the wrong time and letting the piston hit it, may have jumped timing. detonation from being out of time or too lean of a fuel mixture would also cause it, if a piece of the aluminum part of the intake broke off around where the rubber gromet goes where its real thin and got sucked up in the engine that would cause it too. if the keeper on the valve stem spring broke it would let the valve drop down into the cylinder. sometimes the valve stem gets weak and breaks, the stock 400ex valves can be bad about that sometimes, thats why some people when they build there engines will go back with titanium valves instead of stock ones. but it may be something as simple as a blown gasket. if the head got slapped by the piston and it wasnt a valve related issue (should be able to tell by the condition of the valves) then you will have a crank, crank bearing or rod problem that caused the damage. if the engine is turning over easily when you hit the start button and isnt binding or making a knocking sound when you do that then you probably just have a blown head gasket.

[hondamxerd]

:eek: :confused:
this does'nt look good, not good at all, i just took the upper part of the head off, and was looking at the top of the piston, looked a little carboned up, but nothing real unusual, so i pressed on it to see if i could see the cylinder wall,
:eek:
little droplets of water on the front of the wall toward the exhaust side, well first i know water in an engine is bad, but then even worse i see on the intake side a white looking film, so i feel it to see if it will come off, nope, feels rough, so what now, rings, valves, or complete engine rebuild, what ever it is that does not look good at all, wish i could take some pics, have'nt even took the chance to look at the valves, how do i get them apart, or do i need to just take this thing to a shop, i would love to do the work myself but if this is that serious then here i come

[mojoe2878]

where exactly is the white film? is it on the cylinder sleeve where the piston bore is ? does the underside of the head have any marks on it, like the piston slapped it anywhere. does the head gasket look good, any marks on it ? wish you could take pics so i could see the cylinder and piston, and underside of the head.
sounds like your cylinder bore is glazed over, but its usually like that all the way around it, not in just one spot. did you wash the bike off any since this happened or has it gotten wet for there to be water in there, like it got through a gasket?

as far as the valves, you need a valve compressor to take them out,if you have never done it before i would get someone else to do it because you need to keep all the parts in order and put them back in the same hole they came out of. if they dont look damaged like something hit them or dont look burned then they are probably o.k.

[hondamxerd]

i will try to get some pics so i can show ya, no indication that the piston touched any thing, the white film is directly on the side that would be intake, the white film is mostly directed on that side sleeve, just some moisture on the front, and yes it has been sprayed off, so that is probably it, sprayed off with pressure washer, i work at a toyota dealership so my tech should be able to look at the valves for me and compress them, but they dont know a whole lot about quads, head gasket looks good, no burnt or discolored spots, valves on bottom look ok, just carboned up, look to be evenly seated, none sticking out farther than another, i will defenately try to get some pics tomarrow, i think we have a digital camera at work...also you are smart on these things, do you work in a shop, race, own a shop?......:D and again i appreciate your help, that film we are talking about, it actually feels like it is raised out from the sleeve, not smooth, rough kinda spreads like
I
III
IIIII
IIIIIII
spread out like that sort of , hmmmmmmmm, i really need to get some pics

[hondamxerd]

i got some pics but it will be tomarrow b4 i can put them on, i borrowed a buddy's camera but they forgot the usb cable needed to hook it up to the computer

[quadrider400]

If you still have the stock rev limiter try it .... I could not get mine to start with a whites rev limiter to save my life...

Went to a BIG GUN and starts first time every time.... :rolleyes: