way to tone down a 426??

I really want to get a 426 for my next bike, but my dad doesn't think I am ready for one yet. is there any way(free or not) that I could really tone down the power of a YZ426 for a while, and then when I'm ready, I could redo it. Their is a guy that has one for sale for super cheap, and I want to keep this bike for a long time.

Listen to your dad! Talk with him and find out what he thinks you are ready for. Somewhere in there is a compromise. Don't buy a size 12 shoe if your foot measures a 10 with the thought that you will grow into it. Get something you can handle now and work your way up as you skills progress. You can get over your head in a hurry and create more frustration for yourself than pleasure. Riding should be fun and relaxing without the constant fear of getting hurt.

Trust me, if your dad is satisified that you are on the right bike, he will feel better and so will you.


If it's that much to big get the 250F. If you really want a 426, then get something like a PMB Quiet Insert for the exhaust and plug half of the holes, that should tame it down nicely. Then to uncork it just remove the insert.

i went straight to a '2000 YZ426. id ridden 250 2's and a 250f but wanted the power. im 19, only about 150lbs. ive been riding for about 5-6yrs but i finally got MY first bike this year. im a quick learner and i can handle my bike pretty good. if you think you have the skills required to ride a 426 then talk to your dad about it. maybe he will change his mind. but if you dont think that you arent ready then dont get it, it will only be a P.I.T.A.

I know that I am ready to ride it, but my dad doesn't. It will be a lot cheaper to tone the bike down(to keep my dad happy), instead of buying a 250F, and selling it, and buying a 426 or 450. would I have to rejet it if I got the quiet insert, and if I plugged up half of the holes??? and about how much power would be reduced???

The more holes you plug the more power you loose, tune it to your liking. Can't say on the jetting, I woudn't be surprised if it could use some tweaking after being corked up.

If you think you'll outgrow the power of a 250F then just look at Bubba, he can fly on a little bittly 125 2-stroke. If your'e riding MX then a 250F would be sweet!

flywheel weight tones down the hit doesen't take power away but makes it more useable and tractable and makes it less prone to stall. :cry:

thanks for the replies. does anyone have an estimate to how much HP a quiet insert with half of the holes plugged would reduce??? 2HP?? 5HP??? more??? and also, what would I use to plug the holes? sir thump a lot, I will be riding a lot of open fields, so the extra power would be nice. also the 426 will be more reliable for me because I won't be riding it nearly as hard as I would ride a 250F

If you want the 426 then that is what I would get. Then change the cam to the WR timing and throw a 12 oz flywheel weight on it. That will tame it down CONSIDERABLY. Then start plugging holes. Besides if it is that good of a deal why pass it up. Another option is to put a throttle stop on it like the WR's come :cry:.

Dont change a thing on it, if you want to go slower twist the throttle less. The WR timing would weaken it some but probably pick up some bottom end. The flywheel weight would just smooth the hit and make it less likely to stall. If you are responsible rider regardless of your age, it could be a great bike but it does pull hard!, anytime! :cry:

get a stock WR muffler! I just fitted one to my YZ timed WR426 and that killed the hit altogether. Still had good usable power, but it was very tame. Needless to say, the YZ pipe went back on the next day. :cry:

Just out of curiosity, how old are you and what is your size and weight?

I am 15 and a half, 5'8, and 130 pounds. and don't say you are way to small for a 426, because I could manhandle my XR250, which weighed more, just fine. would I have to buy a header and WR muffler, or would I just need to buy the muffler?? also how much HP, do you think the WR muffler would reduce?, and would you have to rejet it after doing that??? thanks a lot for your responses

The Xr 250 and the 426 share nothing in common except they both have 2 wheels. I am not knocking you or the bike but I do think you are too worried about the horsepower, just look at it as being quicker not necessarily faster. The 250 would go plenty fast to hurt you. Enjoy what ever you buy. Quit trying to detune it. The rest of us are paying a fortune to keep them running right or modify them. Not that they are expensive to maintain. Have you ridden a 426? I know there is one for sale, I was just wondering if you have ridden it or one like it?

Easiest way to kill some power is go to the dealer and buy a WR426 throttle stop screw.

Replace the YZ unit with the WR.

I started my 15 year old off on a YZ 400 and then after a year put him on the 426. For his riding ability (which was pretty darn good) the 400 was perfect. By the time he launched the 426 he was ready for the torque of the beast.

Bonzai :cry:

I agree with you 100% fastest1, and I've been trying to tell my dad that, but he doesn't believe me.

Easiest way to kill some power is go to the dealer and buy a WR426 throttle stop screw.

Replace the YZ unit with the WR.

my vote goes to the throttle stop also,having bought my wr new i can tell you that it ran like a xr250 when i got it! neat thing is you could file it down an 1/8" every couple weeks until you got used to it. after a month and a half you should be about where it belongs. :cry:

Fit a big front and littel rear sprocket. It will still chug out the turns, but it wont rip your arms out!

How old are you and what build etc? If you in your teens a 426 should be manageable. I mean you can easily hurt yourself real bad on much less than a 426 anyway! Just be careful with it!

Kid the bike will constantly remind you that it is probably too big for ya, which in turn will "tone it down" because your gonna be scared. :cry:

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