400ex wont run!!!!!!!!!!!!

[400exboy]

i sure hope some of you guys can help me! i blew the whole back of the case out on my 400ex and once i got a new case and put it all back together i figured since it was apart and had a bad bore job that fit really loose i would put a new piston in it well i decided to put a 11:1 compression piston it it and did and got all of the timim figures back to normal but it wont run it just spits and sputters like the timing is off but i moved it one tooth in each direction and it only does the same thing. Is there sumthing i could have missed? plz help me

thanks
josh

[4TraxRider]

Did you have the engine at TDC when you put the timing chain back on. The marks on the sprocket should line up with the top of the cylinder. Are you sure you have all the little things ironed out, like a stuck choke, fuel valve off/out of gas, good sparkplug and most iportant of all your jetting? Did you put an airbox lid on or off, or install anything that would affect it?

[mojoe2878]

besure when you take it up to top dead center that the timing mark on the "T "and not one of the other marks, and make sure that your cam sprocket is right side up with the center cam bolt index mark facing up.

when you put the cam back in did you put it in with the lobes facing down?

[JDiablo]

well when i got my frame pc'd and then put everything back toghter i couldn't get it started,i had to pop the clutch to get it started,and then it ran fine,i think that cause it hasn't been started in awhile that it is hard to get started,idk JMO

[MELVIN20]

mine did the same thing one time and i had screwed up my pistion some how and had to replace it. so u should take it apart and inspect it all.

[400exboy]

i dont know what to say guys she still wont start. i made sure before i even said any thing on here that the flywheel timing mark was on the one with the t cuz i figured it meant top dead center and i even checked to make sure by doing that before i put the head back on. I tried the cam in both ways but still on fire (making sure the valves wouldnt hit first by turning the motor over by hand) but i still didnt get anything out of it. i sprayed starting fluid in it but it just spits and sputters and still dont do a thing so idk. I even thought it could be the plug since it was a restrictor plug cuz i hate those, they never work right from new but that wasnt the problem. my friends keep telling me it could be from the valves being set wrong but wouldnt that just make the motor rattle?

hope to hear back soon
Josh

[400exboy]

also since there is two timing marks on the cam gear should it point up or down on top dead center?

Josh

[400exboy]

the lobes are pointing up for the time being so idk

[4TraxRider]

The middle hashmark points up.

[400exboy]

does that mean the point of the lobe or what? im young and stupid yet so idk i mean im only 16 so i dont know a whole lot yet so hook me up lol

[mojoe2878]

the mark by the sproket bolt has to face up when you line the other 2 marks up with the head when its on tdc . if you take the cam back out be sure when you put it back in that the lobes are facing down. i wouldnt spray too much starting fluid in there, about 13 years ago i did that to a bike engine and it melted the piston:( .. just dont want that happening to yours if it does decide to catch when you turn it over.

pull the plug out and ground it to the engine and turn it over to make sure you are gettin a strong spark, a weak half a** one wont do it. is the cam chain good and tight?

get a compression tester( about $20) and do a test, with the new piston and rings it should be 120psi or better.

does the engine actually crank up and run like crap or does it not crank and run at all?

a engine really only needs 3 things to run=good compression, fuel, and a strong spark at the right time.

if all the timing marks are lined up right and you are sure you are getting a strong spark and fuel, then you need to check the compression. hope some of this helps and good luck man.

[400exboy]

it has a lot of compression cuz i checked it with a good set of snap on screw in type compression tester it has around 150 lbs. any how it does have the lobes pointing down cuz otherwise it would push on the rockers pushing the valves in the piston at tdc. that was kinda dumb. duh lol any how it does have spark that was one of the first things i checked when i tried to get it running cuz i thought maybe the plug was junk which is typical of a restrictor plug but it was ok even though it could have been stronger but its gotta be alright cuz it will spark enough to make the motor spit and sputter. it shouldnt have a bad stator or coil though should it? i mean it was fine a couple of weeks ago when i pulled it out?

thanks again for all of your help guys

Josh

[nakomis0]

Is it the stock cam? If it is does it have the decomression spring installed on it?

My buddy had a 400ex sit for about 9 months because we couldn't figure out that spring problem.

I wouldn't worry about lobes up or down. Just line the marks up for the timing correctly.

its something like get the motor to TFC then at the cam sprocket the marks should be level with the case and 1 mark at the very top.

.. go spend $15 and get a manual

[400exboy]

when u say about the spring is that the really messed up thing that flops around on the cam beside where the catch is to keep the motor from turning over backwards. If not i need sum more details but thanks

thanks again guys
later

Josh

[400exboy]

when u say about the decompression spring by any odd miracle does that mean that sum of the new exs have compression releases on or sumthin

[eric400ex]

i had the same problem that you had just a few weeks ago. what it ended up being was the rocker arms were screwed up on the right exhaust valve so it wouldnt open to let it start, it would just sputter. also make sure your decompressor is working ok because if its not it wont open the exhaust valve either.

[400exboy]

i got it figured out u mean the little metal thing and spring that sticks out and hits the thing on the cam to retard the timing when trying to start? either way i pulled the cam out again and that is now gone. Does anyone know where i can get one so i can avoid my local honda shop because i dont really like the person who owns it its one of those deals where if u pay for something you dont know if ur ever gonna get it u know?

well thanks again guys
Later
Josh

[440exnacsracer]

how long was it apart? sounds like it could be bad gas....the spring/ metal pin is an oil port to shoot oil on the cam, so this wont have anything to do with it, i left mine out on accident once and it ran fine

[400exboy]

according to my book it says that you have to have the pin and spring in there or else it will not run unless ur not running a stock cam. If you arent running the stock cam you dont need it. also according to the book it does retard the timing to start easier. I also just went to my friends cuz he also has and ex we rode it a while then pulled the valve cover off pulled the cam out and pulled the plunger and spring out and it wont run.

Later
Josh

[Toadz400]

Originally posted by 440exnacsracer
the spring/ metal pin is an oil port to shoot oil on the cam, so this wont have anything to do with it, i left mine out on accident once and it ran fine

If it was something that shoots oil onto your cam, wouldn't you WANT to have that in there even if it does run without it. If you left a part out that lubricates your cam, don't expect it to hold up much longer...

[400exboy]

Originally posted by Toadz400
If it was something that shoots oil onto your cam, wouldn't you WANT to have that in there even if it does run without it. If you left a part out that lubricates your cam, don't expect it to hold up much longer...

Finally sumone is on my side, thanks a lot man even though im only 16 i new it wasnt for oil because the hole doesnt go any where.
later
Josh

[Toadz400]

I would check out Honda's service parts website and check to see which part you need. You can order it from Honda or else order it from your local shop, but it sounds like you don't like dealing with your local shop so I would try ordering it through Honda or maybe C&D might carry it?

Good luck, I know that I definately wouldn't want to run my 400ex when I knew something internally wasn't there...

Also, I don't remember if you clarified this yet, but did you check your jetting, filter, carb, and intake yet? It sounds like it could also be a jetting issue if it just spits and sputters, sounds like it could be very rich. Your filter could be clogged or your carb could be dirty, I'd check all those and make sure EVERYTHING is clean.