08 needs some grunt


19 replies to this topic
  • Yamahajoe292

Posted April 27, 2016 - 06:37 AM

#1

What is a way I can give my 08 it's balls, everytime I get on this bike I feel like I'm hoping on my old 07 yz250f, this bike never surprises me like I thought it would. It feels like the power is there but just needs to be unleashed. And I have a hard time believing a slip-on and a 51t rear sprocket is going to wake it up that much.

Edited by Hondajoe27, April 27, 2016 - 06:38 AM.


  • toten

Posted April 27, 2016 - 07:42 AM

#2

Did you buy it new or used? 

 

Double check cam timing (and valve clearances while you're in there), make sure the air filter isn't all clogged up, replace the plug, nothing else I can think of if it's running ok, just low on power. Cams are a way of getting more power, of course there's no free lunch.



  • grayracer513

Posted April 27, 2016 - 08:34 AM

#3

The '08, and to a lesser degree, the '09, were both "soft" on the low-mid range power delivery.  There are two fairly easy cures for this, and they work best together.  The two items that cause this problem are the exhaust and the timing map embedded in the CDI box. 

 

1) (biggest boost) Change the CDI to one from an '06, an '09, or an '04, in that order of preference.  The '06 will give you the best combination of increased bottom end without compromising the top end power.  The '09 will also improve things, but not as much down low as the '06.  The '04 will produce at least as much low-mid as the '06 (maybe a bit more), but will reduce the free revving top end a little, and the engine will sign off earlier.  An aftermarket CDI that offers multiple maps will fix this, too.

 

2) If it still has the factory stock original "shorty" muffler, ditch it.  The exhaust is so bad that almost any slip-on will add 5 hp to the mid range at 500 RPM or so.  The header is also oversized as a compensation for the muffler, and you'll be better off switching to an earlier factory stock system, or a decent after market full exhaust.



  • Yamahajoe292

Posted April 27, 2016 - 09:18 AM

#4

The '08, and to a lesser degree, the '09, were both "soft" on the low-mid range power delivery. There are two fairly easy cures for this, and they work best together. The two items that cause this problem are the exhaust and the timing map embedded in the CDI box.

1) (biggest boost) Change the CDI to one from an '06, an '09, or an '04, in that order of preference. The '06 will give you the best combination of increased bottom end without compromising the top end power. The '09 will also improve things, but not as much down low as the '06. The '04 will produce at least as much low-mid as the '06 (maybe a bit more), but will reduce the free revving top end a little, and the engine will sign off earlier. An aftermarket CDI that offers multiple maps will fix this, too.

2) If it still has the factory stock original "shorty" muffler, ditch it. The exhaust is so bad that almost any slip-on will add 5 hp to the mid range at 500 RPM or so. The header is also oversized as a compensation for the muffler, and you'll be better off switching to an earlier factory stock system, or a decent after market full exhaust.


The bike ran fine and all just not the kind of snap I was looking for, I kind of liked it at first until I went to go climb hills and I really need the bottom end power. Will the 06 CDI plug straight in? And I'm looking at getting a full fmf or yoshi exhaust.

  • grayracer513

Posted April 27, 2016 - 10:03 AM

#5

 Will the 06 CDI plug straight in?

 

Directly. 

 

There is no fault with the engine hardware on the '08, and it is potentially all around more powerful than any previous stock YZ450F (it actually has more peak power).   It's simply a matter of how the ignition was mapped; a decision made in an effort to suit a certain segment of the market.  IMO, and most other folks, it was a screwup, not unlike the same thing they did to the '05 to "tame the aggressive hit".  Made it a bit tamer than they should have, is all, and it's easily reversible.



  • Yamahajoe292

Posted April 27, 2016 - 10:27 AM

#6

Directly.

There is no fault with the engine hardware on the '08, and it is potentially all around more powerful than any previous stock YZ450F (it actually has more peak power). It's simply a matter of how the ignition was mapped; a decision made in an effort to suit a certain segment of the market. IMO, and most other folks, it was a screwup, not unlike the same thing they did to the '05 to "tame the aggressive hit". Made it a bit tamer than they should have, is all, and it's easily reversible.


Alright just got one off eBay for $100, any recommendations on exhaust for this bike? I had a lexx mxe on my crf and I loved the way it sounded

  • grayracer513

Posted April 27, 2016 - 10:35 AM

#7

The DRD stainless system is one of the best values on all points that you can buy for the bike. 



  • cowboyona426

Posted April 27, 2016 - 11:16 AM

#8

The DRD stainless system is one of the best values on all points that you can buy for the bike. 

 

Agreed 100%.  Really liked the full DRD exhaust I had on my 06.



  • jz125

Posted April 27, 2016 - 12:48 PM

#9

I have an 09 with a Powercore 4 and 50 tooth in the rear and am very happy with it.

 

If you want more meat in the middle 05-06 camshafts have tighter LSA and really wake these motors in the middle.

 

But if you honestly feel like you are riding a 250F you might have some issues that need addressed.



  • RockerYZWR

Posted April 27, 2016 - 01:37 PM

#10

Alright just got one off eBay for $100, any recommendations on exhaust for this bike? I had a lexx mxe on my crf and I loved the way it sounded

Dang, too late. I have an 04 YZ450 CDI I have but don't need that I was going to offer up for cheap.

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  • Yamahajoe292

Posted April 27, 2016 - 02:14 PM

#11

I have an 09 with a Powercore 4 and 50 tooth in the rear and am very happy with it.

If you want more meat in the middle 05-06 camshafts have tighter LSA and really wake these motors in the middle.

But if you honestly feel like you are riding a 250F you might have some issues that need addressed.


It only feels that way I guess cause the last bike I really rode was my cousins crf with fully ported head, pro circuit cam and 14:1 piston with full yoshi exhaust

  • Yamahajoe292

Posted April 27, 2016 - 02:44 PM

#12

Dang, too late. I have an 04 YZ450 CDI I have but don't need that I was going to offer up for cheap.


How much you want? I wouldn't mind having both to see what I like better.

  • RockerYZWR

Posted April 27, 2016 - 05:29 PM

#13

How much you want? I wouldn't mind having both to see what I like better.

PM sent.

  • Yamahajoe292

Posted May 05, 2016 - 06:55 PM

#14

Ok just got my bike put back together and rode it with the 08 cdi still hooked up, stock exhaust, then with the new fmf powercore 4 and megabomb, then with the 06 cdi and stock exhaust and again with the fmf exhaust and I gotta honestly say I like the aftermarket exhaust and 08 cdi, that exhaust made a HUGE difference. Plus went with my 13/52 gearing that I've ran on all my bikes.

  • grayracer513

Posted May 05, 2016 - 07:34 PM

#15

I told you the stock exhaust was junk.  Have you tried the new pipe with the '06 box?



  • Yamahajoe292

Posted May 05, 2016 - 08:24 PM

#16

I told you the stock exhaust was junk. Have you tried the new pipe with the '06 box?

.
Yes I actually liked the 08 box better. I never thought a pipe would open one up this much. It was like I hoped on a completely different bike.

  • grayracer513

Posted May 06, 2016 - 08:05 AM

#17

On any YZF other than an '08-'09 it wouldn't have.  Your original exhaust is the worst one they ever used by a huge margin, and an obviously poor design, if you examine it. 



  • Yamahajoe292

Posted May 06, 2016 - 11:17 AM

#18

On any YZF other than an '08-'09 it wouldn't have. Your original exhaust is the worst one they ever used by a huge margin, and an obviously poor design, if you examine it.


True but I do like the look of the stock 08 exhaust. But I'll never put it back on.

  • grayracer513

Posted May 06, 2016 - 11:22 AM

#19

Everybody likes the look of it.  But there's a lot of pretty garbage in the world.



  • Yamahajoe292

Posted May 06, 2016 - 12:04 PM

#20

Everybody likes the look of it. But there's a lot of pretty garbage in the world.


I know that shits right.





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