YZ450F 2008 Mods?


16 replies to this topic
  • nicogc

Posted September 05, 2008 - 07:06 AM

#1

i would like to know if cutting or drilling the air box will help me to obtain more power, and also if the oring mod for the carb should be done to this bike.

any other recommendations to get extra power out of this bike without spending lots of money?

thanks!!!

  • xorron5

Posted September 05, 2008 - 07:39 AM

#2

-08 needs ONLY an aftermarket exhaust ,and when that is done .........................:thumbsup:
me my self been doing a lots of search to find the "ULTIMATE " strongest
exhaust in the universum...and i hope i found it...at least its on its way
DMC afterburner comp-4 exhaust system
13,5 %hp gain 11% torque gain...and since the -08 yz450f comes with an restricred pipe as stock(any exhaust gives all ready 5-6 hp)....u will get so much of power that .................................................:worthy: ..............................................................................................................................:busted: :blah:

  • grayracer513

Posted September 05, 2008 - 08:05 AM

#3

i would like to know if cutting or drilling the air box will help me to obtain more power,

No, it won't. The reason is simply that the entry to the air box is not restrictive enough to cause a reduction in air flow. In order to do that, the cross sectional area of the narrowest point in the air path would have to be 150% of the cross section of the carb throat (39mm) or smaller.

The O-ring mod only helps increase throttle response if the engine needs a stronger shot from the accelerator pump, which, frankly, they usually don't. It will not improve power per se.

The best bet on an '08 is a different pipe.

  • YZ450RDR

Posted September 05, 2008 - 08:27 AM

#4

What is the best pipe? Dr. D, FMF etc?

  • grayracer513

Posted September 05, 2008 - 08:49 AM

#5

There is no best pipe for anything, and never has been.

The question disregards all kinds of qualifiers, most importantly, "best for what kind of riding?"

SX, MX, Off-Road/Desert, Enduros, Woods and trail riding all would likely find one pipe marginally better than another.

For most of us, it doesn't really matter that much beyond the questions of, what are the sound requirements, and is a spark arrestor needed?

The DRD SS does represent an excellent value, IMO, in that it gives very good all around performance at a reasonable price, and offers a spark arrestor option. Noise levels are reasonable for a competition exhaust (~96bd), but aren't low enough for some woods or other local requirements. There is a quiet insert available, but it cuts power a little, and shortens the packing life, as do most such gadgets. The FMF Q4 is a very good choice in a quieter pipe. There are others, but no one "best".

In the case of the '08, almost anything you can get to replace the stock pipe will wake up the low/mid range very noticeably.

  • nicogc

Posted September 05, 2008 - 10:01 AM

#6

so if down here there are no issues of noise or need of a spark arrestor, would it be a good idea to open my stock muffler and try to make it less restrictive? or is the problem at the header pipe? this bike is used for MX only.
and thanks very much for all the help!!!!!!!!!!!! :thumbsup:

  • nicogc

Posted September 08, 2008 - 12:12 PM

#7

has anyone modified the stock muffler and gained power?

  • grayracer513

Posted September 08, 2008 - 12:35 PM

#8

This somewhat depends on which muffler your bike came with. Some of the bikes sent to South America had the "shorty" exhaust built for the US market. That one is a power robber, and it can be identified by the fact that it barely extends past the number plate:

Posted Image

But many of the exports to your continent were the European exhaust, which has the more conventional glasspack, straight through silencer, as far as I know, and is about 15cm longer, and not so much of a problem.

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  • nicogc

Posted September 08, 2008 - 04:06 PM

#9

i have the longer one, so i guess i will not gain anything by going inside it, correct?

  • grayracer513

Posted September 08, 2008 - 05:47 PM

#10

I don't believe there's anything in there to take out.

  • nicogc

Posted September 09, 2008 - 03:23 PM

#11

ok, thanks greyracer.

  • ewilly

Posted September 09, 2008 - 09:47 PM

#12

So are you saying that there are mods that can be done with the short style can to increase power without spending $400 plus for aftermarket? Noise??

Thanks,

  • Sprew

Posted September 09, 2008 - 09:58 PM

#13

So are you saying that there are mods that can be done with the short style can to increase power without spending $400 plus for aftermarket? Noise??

Thanks,



The answer is YES my friend. Applicable to the 09 as well.
Posted Image

  • grayracer513

Posted September 10, 2008 - 06:04 AM

#14

The two internal cones can be removed, which converts the muffler to a conventional "glasspack" type, and should fix most of the power issues. Noise is probably another matter.

It would be interesting to hear from someone who has tried it. Bear in mind two things: the cones are a permanent element of the muffler, so they have to be cut out, which would make it difficult to restore, should you want to, and the header diameter may not be optimal for the exhaust once modified. That would mean the system might not be the best that it could. The Power should be better, though.

  • ewilly

Posted September 10, 2008 - 06:51 AM

#15

I might try this - worst case is I have to buy a slip-on! I will keep you posted! I was referring to the common thread about the popping too! It was late.

If anybody has additional info PM me or post if willing.

THX,

  • mazzuca21366

Posted September 10, 2008 - 11:57 AM

#16

My bike is also a 2008 YZ450F. Its completely bone stock. I noticed a lot of decel popping and slow speed surging, in 3rd gear with light throttle. This stopped after I had approx 5 hours of running time on the bike. I ride on flat trail roads only so I put a lot of miles per say on the baffels. How many hours are on your scoot?

  • Sprew

Posted September 10, 2008 - 08:24 PM

#17

The two internal cones can be removed, which converts the muffler to a conventional "glasspack" type, and should fix most of the power issues. Noise is probably another matter.

It would be interesting to hear from someone who has tried it. Bear in mind two things: the cones are a permanent element of the muffler, so they have to be cut out, which would make it difficult to restore, should you want to, and the header diameter may not be optimal for the exhaust once modified. That would mean the system might not be the best that it could. The Power should be better, though.


Yes Gray, they can be removed and it would be a very short glass pack. Its effect as a muffler would be minimal. It would be very loud. Just to complete the thought about the cone removal, it is permanent and the exit would need a little more fabrication than just a simple cut off. The diffuser seat would introduce serious reversion / blockage and would beg for a little attention. I dont believe any benefits would be realized.

The stock system, aside from performance, is such a nice unit. The factory has built a very nice pipe, just to have it taken off and placed on a shelf in your garage. The materials, bends, welds, mounts, and craftsmanship are outstanding.

It just needs a little help. Its comming.





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