YZ 450F Performance upgrades?

Yamaha YZ450F 2008

37 replies to this topic
  • riderboy1961

Posted November 17, 2014 - 02:38 PM

#1

     I went ahead and bought a stock 2008 yz450f.  :)   I was reading on this site that the 2006 model had a CDI tuned for: "a more aggressive hit, bottom to mid"  than the later yz450f's. Could I direct fit an 06  CDI onto my 08 and gain That change in power?  

     I would like to keep this bike as Stock as possible but, do some Performance upgrades too. What other power upgrades could I do to this bike Without opening the motor up or buying aftermarket exhaust system?

     I ordered an aftermarket Spark Arrestor Screen that I am going to install into the stock muffler so I can ride in the Oregon areas where one is required. Just an FYI about my experience. I was heavily involved with yfz450 quads in the mid 2000's riding all the Oregon dunes and some of the other big Western US dunes. I worked on them constantly, mine and friends, but I want the challenge of two wheels. I plan to ride Dirt and Sand with this bike. Really looking forward to it!!   Thanks for any and all suggestions  :)


Edited by riderboy1961, November 17, 2014 - 03:03 PM.


  • grayracer513

Posted November 17, 2014 - 03:09 PM

#2

The two biggest things holding the '08-'09's back are the stock CDI and the exhaust.  Yes, the '06 CDI does directly plug in.  If you can't find one, try an '04.  Not the '05, though. 

 

The "shorty" muffler is a really poor design internally, and there's no fix for it that won't make the bike considerably louder than a properly done pipe will.  Even a good slip-on, which can actually add 5+horsepower in the middle of the range, doesn't fix the whole thing, because the header is larger than optimum size as a compensation for the restrictive muffler. 



  • riderboy1961

Posted November 17, 2014 - 03:21 PM

#3

grayracer513 - Can you think of a Stock Muffler off a different year yz450f that might work better than this one?



  • grayracer513

Posted November 17, 2014 - 05:04 PM

#4

All of them.  The '06 and '07 bolt directly in place of the original. 



  • Hoosier-Daddy

Posted November 17, 2014 - 06:37 PM

#5

All of them. The '06 and '07 bolt directly in place of the original.

He would have to get the header too to match right due to 06, 07, and 08-09 all being 3 different headers?

  • Hoosier-Daddy

Posted November 17, 2014 - 06:55 PM

#6

Bought my 09 used with a aftermarket R&D float bowl. I don't know how much that helps because it has Dr.D exhaust also but it is suppose to help get rid of bottom end bog.
Someone here might have some insight on that..?.
All I know is that I have no complaints at all on how it runs.

  • SAthump

Posted November 17, 2014 - 07:08 PM

#7

You can tune the leak jet on the accelerator pump, preventing lean bog

Play with it

I mean the leak jet that is

  • grayracer513

Posted November 17, 2014 - 09:43 PM

#8

He would have to get the header too to match right due to 06, 07, and 08-09 all being 3 different headers?

True.  Three completely different systems.



  • Hoosier-Daddy

Posted November 17, 2014 - 10:39 PM

#9

Unless you found a used exhaust for cheap I don't know why you would choose a different year stock over one of the after market systems for close to same price as new oem.

  • riderboy1961

Posted November 18, 2014 - 02:11 PM

#10

I will just stick with the stock muffler for now... Would a 06 or 07 "stock muffler" and "stock header" Direct Fit to my bike if I came across a system for cheap?

I haven't even ridden the bike yet, I know my 2009 yz450f ran perfect in Stock form back a few years ago. I am just trying to find fairly inexpensive power upgrades, Especially ones I can do myself like maybe modify my muffler.

Back when I had the quads I took the Stock muffler off the yfz450 and Hole Sawed that plate that is mid way down the muffler on the inside and that gave it Straight Through exhaust, I could see straight through the  muffler after I hole sawed the 2" hole down through it (don't remember the exact size hole now.) That with the Free cam mod and carb re jet Really woke that quad up and it cost me a few jets and 1 adjustable needle. Great bang for the buck.  

When I take apart this stock muffler and put in the Approved Spark Arrestor Screen I will look in there and see if I can do something similar to this muffler, if not, it will stay as is with the new screen in it.

Thanks for all the help!

 



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  • grayracer513

Posted November 18, 2014 - 02:53 PM

#11

 Would a 06 or 07 "stock muffler" and "stock header" Direct Fit to my bike if I came across a system for cheap?

 

Yes.  That, combined with the '06 CDI will give you an '06 with slightly more top end than normal (because of the'08 cams)



  • n16ht5

Posted November 18, 2014 - 03:09 PM

#12

I took a socket and punched out the inside ice cream cone when I put a PMB end cap on, it helped a lot

_MG_8911.JPG

 

_MG_8917.JPG

 

1-1/8" socket is good fit to punch it out

_MG_8918.JPG



  • riderboy1961

Posted November 18, 2014 - 04:31 PM

#13

I took a socket and punched out the inside ice cream cone when I put a PMB end cap on, it helped a lot

_MG_8911.JPG

 

_MG_8917.JPG

 

1-1/8" socket is good fit to punch it out

_MG_8918.JPG

Perfect! Thank you  -  As I have been looking at these three pictures I now have a question... Why would we need a spark arrester in a Stock muffler? It looks to me like that Ice Cream Cone ought to Act As a Spark Arrestor, no?


Edited by riderboy1961, November 18, 2014 - 04:51 PM.


  • grayracer513

Posted November 18, 2014 - 05:24 PM

#14

No.



  • n16ht5

Posted November 19, 2014 - 09:58 AM

#15

I cut that tip off and put it on there so I could wrap it with spark arrestor screen, but ended up just going with a PMB end cap. That wouldn't be an effective S/A and not legal unfortunately. If someone wants it I still have the PMB end cap and spark arrestor + quiet insert


Edited by n16ht5, November 19, 2014 - 09:59 AM.


  • riderboy1961

Posted November 19, 2014 - 02:17 PM

#16

I cut that tip off and put it on there so I could wrap it with spark arrestor screen, but ended up just going with a PMB end cap. That wouldn't be an effective S/A and not legal unfortunately. If someone wants it I still have the PMB end cap and spark arrestor + quiet insert

Could you PM me a pic and price on that combo?



  • grayracer513

Posted November 19, 2014 - 02:44 PM

#17

Could you PM me a pic and price on that combo?

 

You PM him.  No trading, buying, selling allowed in the forums.



  • riderboy1961

Posted November 19, 2014 - 05:47 PM

#18

You PM him.  No trading, buying, selling allowed in the forums.

Understood, Thank you.



  • riderboy1961

Posted November 23, 2014 - 06:27 PM

#19

I took apart my stock muffler. Drilled & then pounded out the Ice Cream Cone. Waiting to buy a used PMB endcap with quiet core & spark arrestor screen. When I get those I will put it back together but, without the insulation.

I am planning to put on an 06 CDI and then I will re-jet the carb. I will ad a Zip Ty air/fuel mixture screw for easy access out in the trails, Any suggestions for the carb jetting?

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  • ipsullivan

Posted December 02, 2014 - 06:26 PM

#20

+1 on the '06 CDI and an aftermarket exhaust system. You will be pleasantly surprised with the power gain in the bottom end.





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