Posted May 18, 2012 - 12:06 PM
So, I told my buddy I'd try to get his 99 yz400 tuned up, and it's turning out to be a bit of a head ache. He left it sitting outside under a deck all winter(lake tahoe) long with gas in it. Obviously, I started with a full tear down and cleaning of the carb, jets, new spark plug, etc, and got rid of the old gas. It was jetted for sea-level, and we are at 5500ft. so I leaned out the main jet and clip position. The pilot seemed fine at 45, about what I run up here. Also, the fuel screw was stuck big time, the little screw tabs broke off when I tried to back it out. I soaked the shit out it with carb cleaner, and it still wont budge with pliers. So, I don't know where it's set at. The accelerator pump diaphram was totally corroded, so I replaced it with a slightly used one from my 08 yz450's carb. Not an exact match, but fit well(bad idea?). I checked his valves... the intake were spot on, but the exhuast were .05mm tight. Didn't adjust them yet thinking it didn't matter much. Other then that, the muffler is toast, sounds like there is no packing whatsoever, and it's leaking a bit of oil(not sure where yet, that's next of the list). I just want to get it running and idling well for now. It will fire with the choke on no problem, and runs at a high idle with the choke on, but as soon as I start to put the choke in it coughs and dies. Tried turning the idle screw in all the way, and it still dies without the choke.
I'm looking for suggestions as to where to go next..... Thanks!