Performance mods for yz426

JPIVEY

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#1
One of my riding buddies just bought a new 426 and asked me to ask you guys about some good performance mods.

About all I can tell ya is that he desert races here in So. Cal. and is coming off a yz250. ( very modified )

Thanks
 

NVR FNSH

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#2
DO NOT MAKE IT ANY LOUDER THAN IT ALREADY IS!!!! I intended to yell to make myself heard over the roar of all the obnoxiously loud YZ4s out there. IMO the engine really doesn't need any improvement beyond jetting for your conditions.

Brian
 
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#3
Is there something specific about the stock setup that he is unhappy with, or thinks is lacking for his type of riding?
 

JPIVEY

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#4
Oh crap ,I'm in trouble now

Originally posted by Rich Rohrich
Is there something specific about the stock setup that he is unhappy with, or thinks is lacking for his type of riding?
I'm going to say no to both of those, I think he's just looking to see what other owners have done to get alittle more performance.

I know his 250yz is very modified and he likes tinker with his bike alot.

I know this is a pretty lame post but, he's a friend and he asked me to,so if I gotta wear the BUTT HAT I will , then I'll roost the snot out of him to get even:D
 
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JPIVEY

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#5
Oh NVR FNSH, I COULD BARELY HEAR YA OVER THE NOISE, DID YOU SAY JUST JETTING?;)

I don't know but I think thats true for all bikes, as long as they inhale good,chew their food good and exhale good, just ride them like they're meant to be rode........ HARD
 

NVR FNSH

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#6
JPivey,
I've seen too many people spend big $ for exhaust systems & end up with marginally more power that they don't have the need or capablilty to use AND a bike that will wake the dead. There have been some very 'heated' threads here & on Thumpertalk.com about the noise issue as it relates to the newer 4 strokes.

The club I belong to is fighting the noise issue - wasn't really a problem before the introduction of the YZ/WR400.

I ride a '99 WR400 with the stock silencer & a Thumper Racing quiet core insert. Do I need more power? NO. Can I ride the bike to it's full potential in it's current configuration? NO. I'm not a professional rider & I doubt most of the other folks here are either.

Brian
 

JPIVEY

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#7
Well, I'm not going to argue about the noise level of both 2 & 4 s they can be loud. My yz is jetted and piped and it's loud but I ride it on a track or in the desert. my trail bike on the other hand is as quite as a chruch mouse.Well a big fat 250 lb chruch mouse.
 
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#8
Originally posted by JPIVEY
Oh crap ,I'm in trouble now
:)

The problem or value of the 426 (depending on your perspective) is that, as Brian pointed out it's so good in stock form that the value of "bolt on" parts is fairly limited. To see substantial gains in torque or overall horsepower requires taking the motor apart and working INSIDE :)

That said, there are a number of oversize aftermarket pipes that can trade off some of the substantial low/mid range torque for some additional breathing on top. That combined with a Vortex programmable ignition can help him achieve a top end biased powerband that should prove useful in desert racing. The value of the ignition system in the right hands has the biggest potential payoff.
 

JPIVEY

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#9
Rich and NVR FNSH

Thank you both for the information and NVR FNSH I will mention the noise issue.

Jim
 
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#10
Rich:

Where could I obtain detailed information regarding the Vortex Ignition, and assuming it's programmable, is it possible to achieve a variety of performance results throughout the entire RPM range?

Thanks
 
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#11
Mike Tolle at MTRacing has a lot of experience with the YZFs and the Vortex ignition. He's a great source of information.
http://www.mtracing.com/