alright i just bought a 2002 400ex for 400 bucks the guy said it was ideling one day and just died .. wouldnt start after that

so i got it home checked the valve lash, ripped the rocker cover off and checked the timing

the tapets had no lash what so ever and were holding the valves open at tdc

timing was dead on, checked compression and i got 180psi (after adjusting lash)

cleaned the carb cranked it over started right up and went to an idle

it smokes badd, but has 180psi of compression

and heres the question:

should i hone the cylinder and slap a new set of rings and valve seals in it (being it couldnt be too worn out to have that high of compression)

or should i go with a new pistion rings over bore ect

im leaning towards the first one, i was just wondering if anyone seen a problem with it, any opinions pleasee

oh and how the heck can a tapet tighten at an idle, nuts were tight .. ?

 

9 times out of 10 seals go bad on the 400ex causing it to smoke. You can hone the cylinder and might as well slap new rings on it while in there. Use a micrometer to measure your piston. If it's out of spec get the 416 kit and bore it. It was only like 30 bucks to bore and hone at a small engine shop for me.

 

I agree Koopa, when they smoke it is usually the the seals go bad. Sometimes after they get hot or warm up some of the smoking wil clear up.