problems with 2001 yz426F?
- Thread starter speedymx
- Start date
Biggest problem they have is the jetting. Yamaha never got the jetting crisp on the 426s. Came close on the 02 models, but with the leak jet on the 450s things were much better!
Basically get a JD jetting kit, do the BK mod and extended fuel screw installed. Also the 450 exhaust cam or Hotcams with autodecomp will make the bike much easier to live with
Basically get a JD jetting kit, do the BK mod and extended fuel screw installed. Also the 450 exhaust cam or Hotcams with autodecomp will make the bike much easier to live with
in for a head spin.
My boss/best friend/mentor has an 01 426. we work in a bike shop and are having the damdest time. he had it stock but it didnt have much bottem end. he got a big gun exhaust package and lost the bottem end compleatly lost some mid but had great top. we ran about 60 different jets through it and finnaly got the mid back. we changed the needle to the fmf race, put hot cams, got the quick shot and are just barely better off than stock. these bike like money. i dont know how extream you want to go but my 99cr250 and my 84cr500 both blow the 426 away. unless we dont have it dialed in yet. a guy at another shop bought a new dyno, maybe his will help better. my thoughts are dont get it.
My boss/best friend/mentor has an 01 426. we work in a bike shop and are having the damdest time. he had it stock but it didnt have much bottem end. he got a big gun exhaust package and lost the bottem end compleatly lost some mid but had great top. we ran about 60 different jets through it and finnaly got the mid back. we changed the needle to the fmf race, put hot cams, got the quick shot and are just barely better off than stock. these bike like money. i dont know how extream you want to go but my 99cr250 and my 84cr500 both blow the 426 away. unless we dont have it dialed in yet. a guy at another shop bought a new dyno, maybe his will help better. my thoughts are dont get it.
nikki
Moto Junkie
- Apr 21, 2000
- 5,802
- 1
My hubby had an '01 426 for 1.5 years, bought it new... not really enough time to test the motor durability, but he didn't have any motor problems. If I remember right, he put a clutch and top end in it for general maintenance after a season, but the stock stuff was pretty good. And he did shatter a rear hub after a year, which we ended up finding out was fairly common on that bike (lots of torque, crappy hub). So take a look at the hub and rear sprocket/rear sprocket bolts for any stress fractures/egg shaped bolt holes, etc. As for the motor, really all you can do is make sure it runs good/is jetted decent now... then plan on checking the valves every 6-10 hours, or if the bike becomes hard starting.
B
biglou
No low end on a 426?! :rotfl:
Byran, your buddy must have had a hurt motor, because my 426 can throw me ass first on the ground at 1/4 throttle if I'm not careful. Biglou knows whats its all about. They are not slow, they might have a horse or two less than a 450. I have no complaints with the 426, it runs strong.
not to hi-jack the thread, but i am looking at a 2001 Yz426F , it all stock and looks alright, i think the only thing it has is a flywheel weight and some pro-taper bars.
how much should i pay for it? he just sold his 01 raptor 660 quad for 1800 so i should pay that much or less is what im thinking. since the quad cost more then the bike brand new...
thanks alot
Fred
how much should i pay for it? he just sold his 01 raptor 660 quad for 1800 so i should pay that much or less is what im thinking. since the quad cost more then the bike brand new...
thanks alot
Fred
THe only time the YZ rear hubs have problems is when the sprocket bolts come loose. After that, they take out the hub. That is an installation error and not checking your bolts as you ride.
For no bottom end, you had something really messed up. Timing, the pipe you choose is a poor one for a YZF and your jetting will be way off, especially if you use anything FMF in the carb.
For no bottom end, you had something really messed up. Timing, the pipe you choose is a poor one for a YZF and your jetting will be way off, especially if you use anything FMF in the carb.
HEre is more info to help you on the jetting:::
Okay some background on the 426F bikes. Each year was a learning experience from yamaha. They have the FCR2 carb, but there is no leak jet in the bowl. They also do NOT have the autodecompressor exhaust cam.
Here is some mods you need to do to the bike:
-install a yz450F exhaust cam. That will give you autodecomp system and make kicking the bike easier. - no starting drill
-you are going to have to jet the bike. period. Yamaha got close with the 02 model, but it is going to take some time and money. do a google search for the BK mod to the 426 bike. You have to time and modify the accelerator pump in the bike. You will also need an extended fuel screw so you can adjust it easily. Last thing is to get a JD Jetting kit. Those 3 things will make the carb run without hesitation and almost like EFI when you get it dialed in.
-suspension is dated. You can either swap some 05+ KYB twinchambers on the bike with new triple clamps. Probably the best thing you can do! Short of doing that, revalve the suspension front and rear. I ran the Racetech Gold valves front and rear in my old 426 and made a world of difference. Took a couple of times to get the front shim stack where I liked it.
-last thing is with all the older YZs when you remove the manual decompressor from the head (with the install of the 450 cam), you need to buy an aftermarket plug for the head. The stock caps tend to fall out.
Okay some background on the 426F bikes. Each year was a learning experience from yamaha. They have the FCR2 carb, but there is no leak jet in the bowl. They also do NOT have the autodecompressor exhaust cam.
Here is some mods you need to do to the bike:
-install a yz450F exhaust cam. That will give you autodecomp system and make kicking the bike easier. - no starting drill
-you are going to have to jet the bike. period. Yamaha got close with the 02 model, but it is going to take some time and money. do a google search for the BK mod to the 426 bike. You have to time and modify the accelerator pump in the bike. You will also need an extended fuel screw so you can adjust it easily. Last thing is to get a JD Jetting kit. Those 3 things will make the carb run without hesitation and almost like EFI when you get it dialed in.
-suspension is dated. You can either swap some 05+ KYB twinchambers on the bike with new triple clamps. Probably the best thing you can do! Short of doing that, revalve the suspension front and rear. I ran the Racetech Gold valves front and rear in my old 426 and made a world of difference. Took a couple of times to get the front shim stack where I liked it.
-last thing is with all the older YZs when you remove the manual decompressor from the head (with the install of the 450 cam), you need to buy an aftermarket plug for the head. The stock caps tend to fall out.
I bought my 426 about 2 years ago. No problems so far. I did fet an aftermarket mixture screw. That helps. It runs strong. I must have 40 plus hours on it and have not done valves. Starts second kick most of the time. The only flaw I didnt like is that when starting DO NOT touch the throttle. Floods easy when starting. I would reccomend it to anyone. Im 5 11" 200 pounds. Im Big. And it has an AWSOME amount of power. Im going to keep this bike for a long time
