top end tear down

[dustybalz]

Just had a few questions and I was wondering if anyone could help. do I have to put the motor in the compression stroke before I take the head cover off? the manual has that as one of the steps. also, after I take the 12 bolts out, how do I get the cover off without damaging the goods? I dont have a rubber mallet. any tips would be greatly appreciated.

[methyman]

The motor needs to be Top Dead Center, meaning the piston has to be at the top. This is done rotating the motor counter clockwise till you see the "T" mark in the inspection hole on the left side cover (sitting on the bike). Wiggle the rockers after you removed the 4 cap covers. If all 4 wiggle then your at TDC, if not rotate the motor one more revolution again to the T mark. Make sure you remove the center bolt that has the 12 mm size socket. The valve cover should come off very easy. If it doesn't lightly tap the vavle cover with the wooden part of the hammer and it will come off. Good luck with you overhaul!:D

[CranMan]

By the way don't be surprised if one of the 12 small 6 (?)mm bolts breaks off in the head. I've heard that is not uncommon, it happened to me. I don't know if there's anything you can do to try not to break them either, they are small and if they get seized they snap off easily:(

[BadA$$440]

ya, i broke 2 of the in my head.

Just take your time and follow the manual. And when you rotate he crank DONT rotate it to the right ( clockwise ), you have to rotate it to the left ( counterclockwise).

[RED121572]

I managed to strip one out last winter with a torque wrench.:confused:

[dustybalz]

I got the head cover and head off, no problem. The whole reason I am tearing my engine down is because the spark plug , I guess, melted to the head. I got it out and it is really messed up. Has any one ever heard of this happening on 400ex's? Everthig else looks great. Does anyone know who has the cheapest price on a head? So far service honda is the cheapest at $300

[danney f]

Your spark plug melted to the head? If you can explain a little better I might be able to help.

[dustybalz]

well, it all started a couple weeks ago. I went to change my spark plug with the sparkplug tool that comes in the tool kit. It was stuck. I tried warming it up, still stuck! The tool was starting to bend. As you know there is not a socket made that will fit down in the head on a 400ex, so I bought a 18 mm deep socket and ground the walls down so it would fit. When I went to pull it out I could feel that something was very wrong. An hour later I had the head off and the plug out of the head. The threads around the end of the plug look like they're melted together. Thats why it was "stuck"

[danney f]

May of been over tighten. You can take the head to your local mechanic and they can replace the threads with a heli-core. I had this done on my kids little atc70 cost about $25, don't buy a new one. Try useing some antiseize on the threads and a tourqe wrench the next time.

[dustybalz]

I used anti-seize and I know how to install a spark plug. The threads are melted together. If I can get my buddies digital camera I will post pics. Thanks for the advice on the heli-core though

[danney f]

My bad, I didn't mean to make it sound like you didn't know how. Surely if you can take the top end off you can change a plug. Its just easy to mess up the soft thread.