2000 WR400 with YZ400 head won't start
Posted September 13, 2008 - 02:14 PM
Posted September 13, 2008 - 02:44 PM
Posted September 13, 2008 - 02:48 PM
If that's not the case check your timing again, I've never had a problem timing my 426 but apparently it's easy to screw up.
If you're sure that's right try removing the header pipe and see if there is raw fuel sitting in it. I've flooded my bike before to the point where it won't start because of fuel pooling in the header. With the header off remove the spark plug and give the bike 10 or so good kicks to clear the cylinder. Put a new plug in (even plugs that seem to be fine can still cause the bike not run) and header back on and try it again.
If it's still a no go I'd start looking at the carb, pull it a part and clean all the jets and orifices thoroughly will compressed air and carb cleaner.
Posted September 13, 2008 - 09:09 PM
Posted September 15, 2008 - 02:07 AM
When my 98 WR was rebuilt I used a YZ head and also gave the mechanic the YZ cams and didn't think to tell him. He couldn't get it to run right and knew about the head being from a YZ and wanted to know if the cams were the ones from the YZ as well. He said the WR will not run properly using the YZ cams and WR ignition box. I gave him the WR cams and it ran great. I never gave it a second thought when I gave him the head and cams.
Not true. YZ cams and WR cams fromt he 400s and 426s are identical...only difference is timing. Many WR folks set up their cams to YZ timing to give a more aggresive mid range hit.
One thing to check besides cam timing...If you had the slide out of the carb, make sure it is put in in the right direction. On first look, it looks like it should go in one way, but in reality goes in the opposite way. Look at the pics in the book. if it's put in backward, the bike will pop like it wants to start, but will be so lean that it will never fire. yes, I made that mistake! As stated earlier, also be sure that the vacum nipple just below the intake is either connected for a first gen FCR carb, or capped for a second gen carb.
Posted September 15, 2008 - 05:56 PM
I'm in the procss of switching my paddle out to a knobby and then I'm going to be able to test it out!
Thanks for the help!