Just bought a YZ426 w/444 kit, need some advice

1 reply to this topic
  • cRaZy8118

Posted October 12, 2012 - 08:05 PM


Hey guys. Been reading up on these bikes for some time now. Always looking for a nice YZ to ride on the street.
Couldnt pass this one up.

2000 YZ426
Wiseco 444 big bore 12.5:1
Excel wheels/hubs
Street tires
Upgraded front brakes

Top end is fresh, less than 1hr on it.

I just finished reading (last three/four nights) a bunch of posts.
I saw the how-to-start vids as well.

The bike does not start/idle well without the choke.
I am pulling the carb tmrw to clean it, inspect, change jets/needles if needed.

Whats a good baseline for the carb with these mods?
I couldnt find someone that posted in the jetting FAQ with a similar setup.
Not sure what it has in it yet.
But assuming it needs choke to run, I am guessing it has a dirty/restricted pilot jet/circuit or the wrong jetting/needle height.

Bike is in pretty good shape for its age.
Came with a ton of extra parts- jets, plastics, clutch, levers, etc etc.
Im pumped to get this thing running well and registered.

I plan to pull the carb tmrw, put it in my ultra sonic cleaner, drain the fuel tank, replace the fuel line, change the filter, etc.
Any tips would be great!!!!

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Posted October 13, 2012 - 06:30 AM


I recently built a 2000 YZ426/444 for my Hybrid ATV and after much research on this site I went with the following mods right off the bat.

Hot cams for the auto decompression and easier starting

Port work

Combustion chamber reshape (this does wonders)

JE 13.5 comp piston (runs on pump gas, less cylinder pressure after CC reshape)

07 CRF450 FCR carb

It seems that alot of guys ungraded to a newer 450 carb and have nothing but great things to say about it. I also have had no problems with the 450 carb but I never used the 426 carb so I have no comparison.

All I can say is this is how I built mine and it fires right up and runs real strong,

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