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2000 Honda 400ex
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7 Posts
Discussion Starter #1
Needed some thoughts I just changed the head gasket on my 2000 400ex and on my test drive just now the motor locked up and refuses to even turn over,the noise it made sounded liked the cam chain got loose or something. I'm new to this so this was my first go at taking a motor apart. I watched a video from partzilla on YouTube showing exactly how to take it apart step by step, and when I did take it apart I noticed the little decompression pin was missing , I woke up around 2am last night and remembered I didn't set the cam chain tensioner and couldn't fall back asleep lol so I got up this morning turned it with a screwdriver and put it back I also didn't have the cam lobes facing downwards when I put the camshaft back yesterday and I'm wondering if that had something to do with it ...I'm just wondering where I went wrong at this point oh and the engine was not on top dead center when I put the tensioner back this morning but I didn't think that would really effect anything...help lol
 

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2000 Honda 400ex
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7 Posts
Discussion Starter #2
Okay so I took it apart this morning and lo and behold it is totally clapped inside,my mom always said I have a special talent for breaking things :LOL:
Take a look
149891
 

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2000 Honda 400ex
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7 Posts
Discussion Starter #4 (Edited)
I have absolutely no clue what happened , I washed my hands around the time I got to the piston ,maybe there was some water in there, or maybe since I forgot to set the cam chain tensioner something was off , I see grooves in the piston head from where the valves were beating themselves into it but im not sure what causes that to happen so at this point I'm gonna buy a new top end I guess , any suggestions where I can buy these parts ?
 

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38,518 Posts
ebay or power sports nation for used, honda for new oem, but your pockets better be deep !..lol.
 

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just guessing: you put the cam in 180 out, forgot the cam chain adjuster, it jumped time, piston stuck that valve, i would not be surprised if you bent the other 3 valves because of this.
 

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2000 Honda 400ex
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7 Posts
Discussion Starter #7
I think your right ,it's a shame I had to learn this way but I can promise you I won't do that again lol and Id hope they're deep enough for some spare parts! Lol
 

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I think your right ,it's a shame I had to learn this way but I can promise you I won't do that again lol and Id hope they're deep enough for some spare parts! Lol
some of us , like you, have taken our hard knocks through the years !..lol.
 

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2000 Honda 400ex
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7 Posts
Discussion Starter #9
Apparently Its my turn now , Its alright I like to learn and I try to learn from mistakes lol I will get it running on my own mark my words ? it was running like a champ too didn't know it had a hotcam and keihn carberator and probably alot of other modifications I'm not familiar with the guy before me had it running on 110 racing fuel and I fiddled with the carberator to get it to run on 93 ,it's a good quad I'm looking forward to fixing it
 

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Registered
2000 Honda 400ex
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7 Posts
Discussion Starter #10
some of us , like you, have taken our hard knocks through the years !..lol.
Apparently Its my turn now , Its alright I like to learn and I try to learn from mistakes lol I will get it running on my own mark my words ? it was running like a champ too didn't know it had a hotcam and keihn carberator and probably alot of other modifications I'm not familiar with the guy before me had it running on 110 racing fuel and I fiddled with the carberator to get it to run on 93 ,it's a good quad I'm looking forward to fixing it
 
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