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Exhaust / jetting question

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So I have changed my mind so many times on exhaust systems, but I have made up my mind on the FMF.                      (2004 CRF230f)

 

I am getting the:

FMF PowerBomb Header 

 

and

 

FMF Powercore 4 Muffler 

 

Does anyone know the proper jetting that would be required for this combo?

 

Right now I am running a 120 main, 45 pilot. Would I have to increase or decrease jetting size?

 

I have been doing research but I can't find any info on the 2 combined. So please leave a comment with any info you have on the subject!

 

Thanks!

Edited by -CRF-

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As long as the air box restrictor under the seat is removed, That will work fine at seal level 70d air temp.

Adjust the idle mixture screw for fastest idle speed then set your base idle where you like it best.

You can go to a 118main above 2500 ft elevation

Needle clip4th from top or 2nd up from the bottom at sea level.

Middle above 3,- 3,500 feet

This should be really close but make sure your float level is correct and engine valves are properly adjusted with a cold engine.

Edited by adnohguy
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You need to contact FMF for proper jetting.  brojas - at - fmfracing.com

 

Some systems, like Frank Nye's Outlaw, require a smaller main.  The EO Outlaw system uses a 110 main in lieu of the stock's 120 main.

 

Before you spend all that cash on an FMF muffler talk to Frank Nye about a PoweRing.

Edited by VortecCPI

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You need to contact FMF for proper jetting.  brojas - at - fmfracing.com

 

Some systems, like Frank Nye's Outlaw, require a smaller main.  The EO Outlaw system uses a 110 main in lieu of the stock's 120 main.

 

Before you spend all that cash on an FMF muffler talk to Frank Nye about a PoweRing.

I emailed him and he said put everything to stock. So thanks for the email!

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I emailed him and he said put everything to stock. So thanks for the email!

 

Please, please, please take some pictures and share them with us.  Some dimensional data would also be nice.

 

 

And then to be sure use Mikuni's Roll-Off Method:  http://www.mikuni.com/tg_main_jet_size.html

 

"The Roll-Off technique is the quickest and is almost as accurate as the Roll-On method. First, one gets the engine warm on the way to a safe roadway. If there is room, use fourth gear as this allows more time to assess the result.

Now, get the engine rpm high enough that it is on the cam and in its power band. This may need to be as high as 4000 rpm with some cam choices. Apply full throttle. Let the engine accelerate for a couple of seconds until it has settled in and is pulling hard. Quickly roll the throttle off to about the 7/8ths position. When you do this, the mixture richens slightly for a second or so.

If the engine gains power as you roll the throttle off, then the main jet is too small and you need to fit a larger one.

If the engine staggers slightly or has a hard hesitation, then the main jet is too large and you need to fit a smaller one."

Edited by VortecCPI
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I emailed him and he said put everything to stock. So thanks for the email!

So like don't touch the jetting, air box or the exhaust system, all completely stock....

Boring

Edited by adnohguy

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