I think the timing chain in my 400ex broke to day. the gears in the tranny all turn. timing chain right?? Or a dropped valve maybe?? i dont know if the piston is moving or not. it will roll easily in gear like it is in neutral, but does feel like it catches every once in a while very slightly, like no compression. i dunno HELP!!

 

ok here's what i got for you.

brace your self this may be along post

If the chain broke i would like to think that if you are cranking on it you would be hearing some fairly loud noise from that chain being thrown around the bottom of the case. Unless the chain is completely off which is again not good. If it broke odds are there maybe losing pieces running around.... fortunately i've not had to experience it but just think little metal fragments running around the bottom end... not good.
so if you are pretty sure you are not hearing the piston pump then stop cranking on it.

as long as both cam gears are good then hears that process to replace the chain.

first get an 8, 10, and 12 mm socket and wrenches....
std screwdriver
t handles... 5 6 or 7mm i think.....
a manual or at least a parts fiche at minimum.
i work slow so a few hours...


->get all of the plastic off the bike that would interfere with access to the top of the engine.
->pull the oil vent/return from the top of the valve cover.

->remove the top bolt that goes through the valve cover and attaches to the frame.
->remove the 10 or 12 bolts holding on the valve cover.
(note where these went there are different sizes...)
-> you will have to retract the cam chain tensioner on the back right of the cylinder.
-- you will have to either remove it or retract it and place a stop in it to keep it retracted.

->next you'll have to remove the cam.... depending on what you find will determine what you have to do..... well just say that you had to replace it and the old once was broke with no piece running around.

->when i replaced mine it was intact and i was able to remove the two barrel stops by the cambearings and i was able to get the cam off. ( i do have a hot cam so don't know about a stocker)

-> you will have to put the engine back in time so for now what i would do is pull the starter gear cover on the left side of the engine and pull the two gears out...this will allow the crank to spin freely.
--you will also need to remove the allen bolt that gives you access to look at the t notch timing mark.... it took me while to find mine cause it was actually on the flat side and not on the end..... you will need to rotate the crank around and make sure that notch mark is lined up with the mark on the case....now that you removed the starter gears you should be able to move it.
-> with the crank at top death center (time mark lined up with the case) you should be able to feed the new chain down in and around that lower sprocket.... DONT Drop the chain.....
->you hopefully would be able to slide the chain onto the cam and put it back in place... you may have to unbolt the two bolts that hold the cam gear on you will have to see.

->when setting that gear you want to make sure the two marks on the cam gear match up with the top of the head....

->make sure everything is bolted and the barrels are holding in the cam in.
->place the starter gears back in and put the cover on as well
->release the cam chain tensioner
->get a new valve cover gasket and bolt the cover back on and bolt it down.
->and follow with the other main bolt and oil return line.


this is the best case....

worse case it is blown the chain apart and you have to dig those metal pieces out of the engine.... you would have to at least pull the cylinder off for that and and absolutely worst case split the cases....

or its just something like a starter gear but i doubt that...... you may just want to pull the started cover off and make sure the starter is spinning and make sure the crank rotates....


w/out knowing more about when you found that your bike wouldn't fire over thats about the best i can do....



so if it is anything other than a cam chain you may want to consider a shop....
$~100 new chain.
$50 new topend gasket set
plus about 3 to 4 hours at 40 to 60 per hour for a shop to do it.

again they may want to adj valves... or have to rip deeper to find/replace/ fix issue.

hope this helps....

-->Duster

 

OK thanks for the instructions. But there is NO niose except the starting "whining" cause it is turning over so fast. NO other noise. i did take off the starter cover and it is fine,and when yiu turn it with the cover off, you can see all the gears down in side the case moving. or just roll the bike them all seem to be moving. But even when the bike is in gear, the motor with not hold it, just rolls like it is neutral, and does maybe feel like it MIGHT be catching and moving the piston but with no compression. Dropped valve maybe?? i dunno. i need help!!

 

dang thats not good..... i'll have to check on a couple things

 

When you say "the gears" do you mean the starter gears or transmission? If the starter gears spin really fast but it doesn't turn the crank, you might just need a new one way bearing.

Look at the left side of your motor.. Right below "HONDA" there is a round cover. Unscrew that cover and you will be able to see the end of your crank shaft. Press the start button and see if the starter is turning the crank. If the starter doesn't turn the crank then you have a starter gear or one way bearing problem. (around 80 bucks in parts)


If the crank does turn, take off one of the valve covers and see if the rockers move.

 

i mean the gears in the tranny. i know it aint the starter gear because like i said, it is the same weather it is in gear or not. if you try to roll start it it just rolls like it is in nuetral.