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i have a 2001 400ex and when it's not running/not warmed up, it leaks oil really slow then when i'm running it, it drips a lot faster. it's coming from the head somewhere, it looks like it's coming from where the header comes into the engine or right beside it, and when it's running its smoking from where the oil is burning. any suggestions of how to fix it?
 

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Well the oil is leaking from the valve cover gasket. But. Thats the least of the worry. Going off what im seeing. And what sadly we see all the time on this forum. That engine has been taken apart and put back togeather by someone who mostlikley dosnt even know what a torque wrench is. That being said they used gasket maker on the valve cover which on the 400ex is a big big big no no. Many other quads require the use of honda bond on it but the 400ex is not one of them. And just going off what i see in the picture i would be very concerned. More than likely they broke many bolts in the process of what they were trying to do. And dont get me wrong the valve cover bolts are very easy to break. I have 2 heli coiled on mine. Because no way were they ever coming out without snapping. But the reason a 400ex needs a metal gasket and nothing else on the valve cover gasket is because it is a very important thickness which is a spacer for your cam shaft journals. The biggest thing you have on your side is the people on this forum and the fact its a 400ex motor. They can handle alot of abuse and alot of questionable mechanic work and turn around and come back from it. You just need to cross your fingers its not a 440 big bore kit in it. Keep the questions coming and we will do everything we can to help. Got yourself a FSM and a cometic valve cover gasket and start pulling the quad apart.
 
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Well the oil is leaking from the valve cover gasket. But. Thats the least of the worry. Going off what im seeing. And what sadly we see all the time on this forum. That engine has been taken apart and put back togeather by someone who mostlikley dosnt even know what a torque wrench is. That being said they used gasket maker on the valve cover which on the 400ex is a big big big no no. Many other quads require the use of honda bond on it but the 400ex is not one of them. And just going off what i see in the picture i would be very concerned. More than likely they broke many bolts in the process of what they were trying to do. And dont get me wrong the valve cover bolts are very easy to break. I have 2 heli coiled on mine. Because no way were they ever coming out without snapping. But the reason a 400ex needs a metal gasket and nothing else on the valve cover gasket is because it is a very important thickness which is a spacer for your cam shaft journals. The biggest thing you have on your side is the people on this forum and the fact its a 400ex motor. They can handle alot of abuse and alot of questionable mechanic work and turn around and come back from it. You just need to cross your fingers its not a 440 big bore kit in it. Keep the questions coming and we will do everything we can to help. Got yourself a FSM and a cometic valve cover gasket and start pulling the quad apart.
is it fixable? i was planning on bringing it to a shop that works on small engines and tell him to go through everything to get it perfect.
 

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That all depends on the trail of destruction left. I buy and sell 400ex's so i have seen the worst of it. The 400ex platform though is almost always able to be fixed. Very very few have i seen that there was no hope for. But the gasket maker on the valve cover is number one on my list for if it has it walk away. So im keeping my fingers crossed yours isnt as bad as it looks off the bat. But i have learned with these quads you cant always judge a book by its cover so to speak. My brother bought a 400ex for 900 bucks. We quickly nicknamed it "jenk". He blew the bottom end and we had to replace the crank and when we blew it apart found well over 3k in aftermarket in the motor and all over the place on the quad. It was a well loved quad at one point. Even had sparks racing headwork and valvetrane. We learned alot on that rebuild and built it up good as new and sold it soon after. Because it still just looked so jenk from the outside lol. Someone got a crazy fast reliable quad out if it cheap though. Good luck!
 

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Discussion Starter #5 (Edited by Moderator)
That all depends on the trail of destruction left. I buy and sell 400ex's so i have seen the worst of it. The 400ex platform though is almost always able to be fixed. Very very few have i seen that there was no hope for. But the gasket maker on the valve cover is number one on my list for if it has it walk away. So im keeping my fingers crossed yours isnt as bad as it looks off the bat. But i have learned with these quads you cant always judge a book by its cover so to speak. My brother bought a 400ex for 900 bucks. We quickly nicknamed it "jenk". He blew the bottom end and we had to replace the crank and when we blew it apart found well over 3k in aftermarket in the motor and all over the place on the quad. It was a well loved quad at one point. Even had sparks racing headwork and valvetrane. We learned alot on that rebuild and built it up good as new and sold it soon after. Because it still just looked so jenk from the outside lol. Someone got a crazy fast reliable quad out if it cheap though. Good luck!
how much do you think it'll cost to make it right and what do i need? i traded a 04 kfx400 with carb issues and probably some wiring problems for it and i still think i came out on top. since the first day i looked at the engine i always thought the gasket looked weird but in your honest opinion.. is it screwed? im not trying to put a whole lot in it to make it right again, maybe $200-300 at the most.
 

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My honest opinion i would sell it and get a way cleaner less messed with quad. Just an fyi. I know your new here. But we keep a clean family friendly forum here. I will edit your posts if i see them. But please keep it clean if you would. Thanks!
 

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My honest opinion i would sell it and get a way cleaner less messed with quad. Just an fyi. I know your new here. But we keep a clean family friendly forum here. I will edit your posts if i see them. But please keep it clean if you would. Thanks!
yeah sorry lol, thanks for letting me know!
 

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No worries! Always glad to help!
 

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Man that header bolt looks like it was CRANKED on way too hard...

I agree with Slammed about looking for a cleaner bike to start from.

Not sure if you are going to be able to fix it for $200-$300 if your having a shop look at it, although I do live in Canada where everything is twice the price so maybe you could haha.

But looking at that gasket and bolt, it's a little nerve racking.
 
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No most likely the reason the gasket is leaking is they broke one or more of the valve cover bolts. That would be why they tried to use gasket maker on it. You can use a light layer of copper spray on it but nothing more on the valve cover gasket on a 400ex. The header bolt is just way way way over tightened is what unklerara was saying. Not that it needs replaced or anything unless is breaks.
 
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