how often and how easy is it to adjust valve clearences on a 400ex

 

the maintenance schedule says after the first 20 hours 100 hours then every 100 hours after that to inspect them ie gauge them. you have to take off the gas tank to get to the intake side. I just did this for the first time and it only took me about 45 minutes and next time will be much faster you will need 6 and 10 mm allens 10 and 12 mm sockets 10mm wrench, flathead screwdriver, 10 and 12mm feeler gauges. if you have never done this the manual is helpful also [img]i/expressions/face-icon-small-smile.gif[/img]

 

I recently bored my 400ex to a 416 and I have adjusted the valves several times. Its not hard, all you have to do is remove some body plastic and gas tank. Make sure when you go to measure the gap, that you have the piston top dead center. If it's not top dead center it could throw off your gaps. This can be done by removing two caps from the side case of the motor. Theres a large cap and small cap. Turn the motor over with a socket wrench in the big hole until a little T mark lines up with a line on the case in the small hole. Make sure that you turn the crank counterclockwise. This will then tell you that the piston is top dead center when the T is in line with the slit. Now you can use your feeler guage and measure the valve gaps. Hope this helps!

 

Heres a pretty good how to article on the 400ex. Even has pictures. After reading it, youll know if you want to take it on or not.
400ex valve adjust