I think I have a carb problem?

5 replies to this topic
  • Stan_yz426f

Posted September 26, 2004 - 08:17 PM


I had to do some work on my carb. My AP nozzle was damaged so I made a new one. I guess I went into the part of the carb you are not suppose to. Anyways I noticed the small gasket which seperates the ap system, the pilot air jet and the main air jet was also damaged, factory problem! I had to cut a new gasket from viton and put it back together. Kiehin does not support that part of the carb & will not sell a gasket for it. Slapped it together and also replaced a the top end(Weisco piston) and went riding. Broke it in for an hour and did a hard 17 mile loop, the bike rode great. Washed my bike and took it out the next weekend and could not ride. It would start with the choke but sound terrible and when I push in the choke it would barley idle and if I gave it gas it would die. I also noticed alot of smoke from the exhaust. I tried adjusting the pilot air screw but to no avail. Oh yeah I own a YZ 426f and has a FMF Q. Took the carb apart three times after the problem and everything looks clean the one concern I have is that small gasket. I am stumped! Can anyone help.

  • SureBlue

Posted September 26, 2004 - 08:32 PM


So all this after you WASHED the bike? Did you plug the exhaust? Whatabout your airfilter, did it get wet or did you remove it and use the cover?

  • Stan_yz426f

Posted September 26, 2004 - 08:46 PM


I always plug the exhaust and side hand holds(vents) when I wash my bike. Tell you the truth the carb fix with the new AP nozzle was about 3 months ago and my bike was running great. The top end I just replaced. Had a good ride on it. I am thinking of buying an Edelbrock has anyone used one? But would rather not spend the money. My guess is an air leak somewhere but I have looked. One thing I did notice and this could be normal but when I kick it over to start a whole bunch of compression air comes from the oil vent hose which is attached to the the valve cover. Is this normal?

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  • SureBlue

Posted September 26, 2004 - 09:44 PM


I'd say there's something wrong with your intake valves, one is perhaps stuck open?

  • Bryan47

Posted September 26, 2004 - 10:14 PM


If it was an intake valve you'd get a pop back through the carburetor. Exhaust valve you get a pop noise in the exhaust. Only thing that allows compression into the crankcase is rings or piston problems. Sorry to say it.... :cry:

  • adaguy

Posted September 27, 2004 - 10:56 AM


I would change the spark plug first. From what you described it sounds like it is fouled

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