Exhaust isses on 08 yz450

Is anyone having any issues with their after market exhaust on their 08's? I talked to both Dr. D and yosh and they said they were very happy with the 06-07 pipe on the 08 so they were not developing a new one. White bros said they thought it sucked so they were developing a new one. I got tired of waiting on White Bros since it was back ordered to many times and ordered a yoshimura. But the header is smaller in diamater then the stock and I am not sure after bolting it up if it is sealing or if its leaking or what. Everything else installed just fine. I called yosh and they said it would be fine, but then asked me to send pics of the header and the manifold, why would they want these if they are so sure of their product and testing? I am not sure if I should take it off and return it, or try to ride it first, but I am concerned they wont take it back after i ride it. I would imagine, Dr. D's pipe would have this same issue if they are using the smaller 07 header as well. Anyone, anyone? Bueller, Bueller?

Dr.D pipes might have similar problems if not for the fact that they are complete systems, and use their own header.

It should be fine. I don't think Yamaha changed the diameter of the exhaust port so it should bolt up fine. On my yz250f you had to remove the gasket material that went between the stock headpipe and where it mounted up to the motor but it fits and works great. I'm sure you'll be happy with that pipe if you got the full RS-2 system. It ripped on the 07 yz450

Hmm, thats what is strange. The 08 manifold and the stock pipe are a larger diamater, I would say maybe a millimeter, maybe mil and a half more. The yosh pipe is the one for the 07, it bolted up perfectly, I imagine the part that bolts to the head would center the pipe, but I am still concerned that its not sealing the way it should be since its smaller in diamater, or maybe it is and its all in my head. I am learning a lesson with buying a new bike that is issued so quickly, no one has parts lists, or any info available on it. Hell, yesterday I learned they have been selling me 07 oil filters hoping they would work, god I hope so!!!

My Dr D works great on my 08 that I pulled off 06 really helped power also. I used full system. 08 Head pipe is larger

So matt, since you did the same thing, obviously your Dr D had a smaller header, but it sealed up fine and worked great? That is my only concern that the yosh header is smaller in diamater then the stock one.

So matt, since you did the same thing, obviously your Dr D had a smaller header, but it sealed up fine and worked great? That is my only concern that the yosh header is smaller in diamater then the stock one.

Yes its going to be smaller but will seal fine. And will run like a scalded dog.:confused:

I hope it runs great, I dont know how to jet myself so if it needs better jetting after the yosh I am sort of hosed till my friend can ride with me, he is pretty good with that stuff. My other complaint is the allen screws on that yosh are hard to get out of the back so I can remove the spark arrester. One is so stuck I rounded the darn head out yesterday!!! Now I gotta find a way to get it off and on again.

I hope it runs great, I dont know how to jet myself so if it needs better jetting after the yosh I am sort of hosed till my friend can ride with me, he is pretty good with that stuff. My other complaint is the allen screws on that yosh are hard to get out of the back so I can remove the spark arrester. One is so stuck I rounded the darn head out yesterday!!! Now I gotta find a way to get it off and on again.

Jetting is very easy. Look at your manual and do a search on here and it will be alot of things that will make it easier. A year ago I had no idea how to do crap on my nike now Chad Reed wants me as a mechanic, well not really but I have learned alot:applause:

My 08 Dr. D fits and runs perfect on my 08 yz450f. 48 pilot and two out on the fuel screw is the only change.

What is the stock jetting on the 08 yz450? I am in Colorado and it ran okay but was REALLY hard to start and they jetted it for free to fix it, put a 155 main and a 48 pilot in. It ran really strong even with the stock exhaust after the re-jet. So far I have only been able to go up and down the street with the new yosh on. Oh, I took the sparky arrestor / cone silencer thingy out and it runs dam strong!! This thing has a hit now and some HUGE balls. Cannot wait to hit the track Saturday and see how it does.

What is the stock jetting on the 08 yz450? I am in Colorado and it ran okay but was REALLY hard to start and they jetted it for free to fix it, put a 155 main and a 48 pilot in. It ran really strong even with the stock exhaust after the re-jet. So far I have only been able to go up and down the street with the new yosh on. Oh, I took the sparky arrestor / cone silencer thingy out and it runs dam strong!! This thing has a hit now and some HUGE balls. Cannot wait to hit the track Saturday and see how it does.

They should have given you back the standard jets.

No, they didnt, but they also didnt charge, they made it part of the sale to make sure I am happy. they also explained how they live and die by the survery that comes from yamaha and since I gave them a bad one last time they wanted to make sure I was extra happy and to state that cause apparently yamaha comes down on them and to many bad surveys could lead to a loss of the yami line I guess. So they really went out of their way for me and continue to make me happy. They have deffinatley earned my business back between the great parts manager and the service I recived when I buying this new 08. Heck, I got my 08 for 6700 OTD including everything, spent the savings on new gear to match my new ride!!!

I think the jetting is okay actually, havnt track tested it yet, but it sure fired right up and ran great in my neighborhood. I cant believe what a difference the pipe made. Its night and day on the 08, it's almost crap that Yamaha put that stupid stock pipe on there. I will tell you all more after we ride Saturday at Watkins here in Colorado.

Racer808. You are right about yamaha and the stock exhaust, they basically did all the marketing for all the aftermarket exhaust companies out there for them! Any exhaust is better than that stocker from what we have heard so far. And to be honest, this is great news (would have been better if they had a good stock exhaust but such is life), it shows that the stock motor is good and the exhaust simply has it plugged up.

A tip when installing new pipes/headers

install the header first....but do not tighten it

install the rear cannister do not tighten

- I use high temp gasket sealer on the header where it meets the rear cannister for a airtight seal

Tighten up header first - make sure the flange is even on both bolt sides

then push rear cannister forward while tightening subframe bolt then tighten both up

this helps to seal the connection better

Once the new pipe heats up it will set up correctly:thumbsup:

What is the stock jetting on the 08 yz450? I am in Colorado and it ran okay but was REALLY hard to start and they jetted it for free to fix it, put a 155 main and a 48 pilot in. It ran really strong even with the stock exhaust after the re-jet. So far I have only been able to go up and down the street with the new yosh on. Oh, I took the sparky arrestor / cone silencer thingy out and it runs dam strong!! This thing has a hit now and some HUGE balls. Cannot wait to hit the track Saturday and see how it does.

Stock jetting:

45 pilot

55 leak jet

160 main

needle: #NFLR

So are jetting specs from the pipe manufactureres worth a crap since they test at sea level? I am in colorado and it seems every bike is different no matter what.

So are jetting specs from the pipe manufactureres worth a crap since they test at sea level? I am in colorado and it seems every bike is different no matter what.
If you correct for your altitude, yes they are.

Hi guys,

I have 07 wr450f and am waiting on delivery of my new 08 yz450f. will my akropovic carbon fibre exhuast and header system bolt straight on to the 08 yz450 (coming off the wr450)?

any one runnin same system? and if so jetting specs? hope it does what it did for the wr!!!:crazy:

thanx

That will depend on how closely the mount points on the WR subframe match those on the YZF. My guess is that it will fit.

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