Yamaha Dirt Bikes Forum

I got a great deal on a leftover 2006 YZ450.  I'll never sell my old 2 stroke YZ250 though!  Since this is my first 4 stroke, I'd like to hear any suggestions on how to set up and care for this beast that I bought to use for motocross racing and trail riding.  Now that I'm over 40, I think the 4 stroke power will be better suited for my riding style, especially when racing.  
2006 YZ450
2000 YZ250
sons:
2005 CR85
2008 TTR110
2001 KX65
1996 CR80

The jetting that year was too lean.  Switch to a 48 pilot (stock was 42) and a 168 main (stock was 165).  That will give it much better response, and will help it keep from overheating and stalling.  While you are at it, put an aftermarket fuel screw on it - getting to the stock one is a pain, and you have to adjust it frequently.

That bike is a beast - you won't need any more HP out of it, unless you happen to have a cape and a serious distaste for kryptonite!

The valves on the 450's - especially the Yamaha - hold up very well!  Check them after the first 5 hours, and then again every 25-30 hours of runtime.  SPeaking of which, install an hour meter - it will help you know when to perform the various services.
Change the oil and filter after the engine has 5 hours on it.  Run regular (not synthetic) Yamalube for the next 15 hours, and then change the oil and filter again (this time switching to synthetic). This will allow the rings to seat.  From there on in, change the oil every 10-15 hours (trailriding) or 5 hours (racing), and change the filter every OTHER time you change the oil.

If you do the 5 hour oil/filter change, and valve check, and then change the oil regularly and check the valve clearances a couple times a year this thing will treat you well and last a long time.  

Final thoughts:

1. Keep your air filter clean and serviced regularly
2. Don't trust the oil window or check bolt - always measure the right amount of oil and put it in

Enjoy!  
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Here we go again!

Thanks, Skip!  That does bring up some more important questions though.  Who makes the best hour meter and fuel adjuster screw?  Where can I buy them?  Thanks, again!  
2006 YZ450
2000 YZ250
sons:
2005 CR85
2008 TTR110
2001 KX65
1996 CR80

No one makes the best hour meter.  Or, if you are an optimist, everyone does!  

They are all made by the same company, and just have different labels on them.

I use the Yamaha meter/tach and my local dealer sells them for about $45

As for the fuel screw, I use Zipty, but again - all of them work well.  Yamaha also makes one (GYTR) that is good to use.  I'd say your local Yamaha shop can get you squared away with both for around $60.

When you install the fuel screw make ABSOLUTELY SURE not to lose the little o-ring, washer, and screw.  When you put the new screw in, the spring goes on first, followed by the tiny washer, and then the o-ring.  Tighten it until you barely feel it bottom, then back it off 1.5 turns to start off.  
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Here we go again!

The jets are on order.  My only gripe with the bike is a stiff clutch.  Moose Racing makes a clutch lever assy. that has different ratios.  I'm also thinking about extending the lever at the engine.  It seems quite short.  Any ideas?  Thanks again!  
2006 YZ450
2000 YZ250
sons:
2005 CR85
2008 TTR110
2001 KX65
1996 CR80

You use a clutch on a 450??!!

Just put it in 3rd and leave it there!  

All kidding aside - lube the cable.  If that doesn't help, then look into a Maguro hydraulic clutch.  
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Here we go again!

I've been looking at the Moose Racing Ultimate Clutch Lever System.  It has a clutch lever with 2 different positions for leverage.  Has anybody tried one?  
2006 YZ450
2000 YZ250
sons:
2005 CR85
2008 TTR110
2001 KX65
1996 CR80

ive used similar and to tell you the truth, if you dont like the clutch the way it is, change the springs...

its the easiest and cheapest way i have ever majorly adjusted a clutch. it only takes about 20 minutes to do and you will love it...

if you dont want to get into that, i would listen to skip and look into a magura hydraulic clutch system  

Im 40+ and have an 06 450, you will love it,i said id never sell my 2 stroke too but it got sold,heres lots of info for you.

http://www.thumpertalk.com/forum/archive/index.php/t-447989.html  

I RECENTALLY PURCHASED A YZ450 ALSO, I HAD A 250 AND IT JUST WASNT ENOUGH BIKE.  I'M 38 6'4 AND ABOUT 220 I USUALLY TRAIL RIDE BUT MY SON IS STARTING TO GET IN MOTOCROSS SO HE IS KINDA DRAGGING ME IN.  THE 450 IS A BEAST BUT IT'S A PERFECT FIT EVERYONE OF MY FREINDS THAT RIDE IT SAYS IT'S AN ANIMAL.  THE ADD ONS THAT I DID THAT WERE AMUST AND THAT I GOT THE BIGGEST RESULTS WERE A REKLUSE CLUTCH, GPR DAMPENER, 120 REAR TIRE(MAXXIS IT) AND 51 REAR SPROCKET AND A PRO CIRCUIT T4, IT HAD A FMF WHICH I HAD TO REPLACE TO REAR ENDER. I AM FROM FLORIDA SO MOST OF MY RIDING IS SAND, PALMETTO STUMPS AND MUD. I AM REALLY NOT TO FAMILAR WITH THE TWO STROKES BUT I RIDE WITH GUYS THAT DO AND TO ME THE FOUR STROKE WAS THE WAY TO GO.