CCC Mods Question

So I have a 2012 Honda CRF 250X.  It's bone stock right now as far as mods go.  I am wanting to "Un Cork" it soon.  My question is this -

I plan to use the JD Jetting Kit, but the most expensive part of this whole process is going to be buying the FMF exhaust system, pipe & mega bomb header.

Do I need to change the exhaust the same time I re jet?  I am going to open up my air box obviously right away, but can I still use the stock exhaust for now after I open the air box?  And if I do the aftermarket exhaust later, will I need to re jet AGAIN because I changed the exhaust system?

I also plan on using the Tokyo mods smog delete kit and installing a Tusk adjustable fuel screw.

I've been searching for answers to this, but all the info I find is very dated, and as I stated my bike is a 2012.  Also, what are people doing to "modify" the internals of the current stock exhaust pipe?

 

Thanks in advance

Yes you can use the stock exhaust (I prefer it as it's quieter and doesn't require repacking)

but any 'CCC' recommended settings might be too rich. 

 

Any time you increase air flow (in/out) of the engine, you have to re-adjust the fuel metering as well.

Airbox mods will require re-jetting as will an aftermarket exhaust later on.

 

The smog delete doesn't require any changes, it simply un-clutters the chassis a bit.

 

Pretty sure I've read that the newer muffler (07+ ?) isn't as restrictive as early models were as the internal are a bit different in design.

Removing the spark arrestor will net a bit more airflow and noise but also keeping in mind if it's required to have in your riding areas.

Opening up the airbox also makes the bike more prone to water injestion when fording deep water. (reason why I've only added a few holes myself)

 

You might find that some airbox mods and re-jetting performs plenty for your usage.

Aftermarket exhausts are crazy expensive, the same amounts invested in fine tuning the suspension for you needs will net you more noticeable performance.

Edited by mlatour

My uncorked (including air box opening) 250X works great with the JD Jet kit. Great power and and no bogging. The stock exhaust works great.

Do yourself a favor and buy the R&D Flexjet instead of any other aftermarket fuel screw. It’s made of brass and allows easy fingertip adjustment. With the starter motor right beneath the carburetor, there is very little room for your fingers to adjust the “adjustable fuel screws.”

IMG_1510559284.842021.jpg

<<Do I need to change the exhaust the same time I re jet? >>

<< And if I do the aftermarket exhaust later, will I need to re jet AGAIN because I changed the exhaust system?>>

No, but you would need to re-jet again when you change the exhaust.   You will need to change the main jet, which the JD Kit will have.  For the stock exhaust, you put in a smaller main jet. 

The JD Kit has a handful of main jets to cover a number of setups.

<<I am going to open up my air box obviously right away, but can I still use the stock exhaust for now after I open the air box?>>

Yes, but I would caution that you may not want to open it up fully as the CCC mods suggest.  The CCC mods assumes ridding on a track, so taking the entire top off may be more then you need.   What I did was remove the snorkel and then poked 6 1" holes in the top of the box, as I often ride in wet areas and I've had the bike up to the tank in water.

as far as this:

<<Removing the spark arrestor will net a bit more airflow and noise but also keeping in mind if it's required to have in your riding areas.>>

 It's a very negligible difference (assuming it's clean) and there is no real reason to remove it, but many reasons not to (ditto removing the backfire screen, but at least then, it would only be the bike on fire rather than a forest).   What is done by many however is they remove the internal baffle.  That will give you a definite change, but personally I'd leave it alone if your planning on getting another exhaust.  Also (and I wish more people would realize this), there are advantages to not announcing your presence when ridding.

 Depending on the type of ridding you do, most are than happy with just a re-jet and cutting the top of the airbox if it has not been re-jetted previously.   And if your not, you can always cut the baffle out later.

Jim.

 Depending on the type of ridding you do, most are than happy with just a re-jet and cutting the top of the airbox if it has not been re-jetted previously.   And if your not, you can always cut the baffle out later.

Jim.

 

 

This is what I’ve done, and along with simple suspension mods the JD Jet kit and airbox opening really made this bike much better. It’s quiet (Tested at 87db at last week’s Hare Scramble) and has great torque for a 250. The powerband works well for off road riding, especially with effective clutch use. The JD Jet kit comes with plenty of jets and detailed instructions, including recommended jetting for specific mods. This includes aftermarket pipes, etc. Plus, they have great tech support if you feel like calling them about your specific bike setup. A little pricier than buying a few jets and trying it on your own, but I’ve always had good luck with their recommendations. Working on a 250X carb is difficult, so doing it once with a dyno tested package is well worth it to me.

 

Good luck!

 

Don't know what type of riding you will be doing but all of the previous posts pretty much cover it all. I experimented with different exhaust systems, CCC mods,  and jetting; and found for my riding terrain and riding style that stock header and muffler worked best. I have most of the CC mods ( 1" holes in air box), JD Jetting, and heaviest Steahly flywheel. 
I found that the flywheel was the biggest improvement for my type of riding. 
If you are a heavy clutch user using Dextron ATF in the tranny smooths clutch engagement, I use Valvoline syn Dextron VI. 
A big help on the very bottom end for tight technical trails is to replace the muffler insert with an aluminum ring with a 1 7/8" ID; slightly more noise but really help low end throttle response on gnarly ST; my X is now almost as good as my XR218.

Here's what I've done recently. Big difference.

I was reluctant to spend a lot on a new full exhaust, so I spent a few month hunting for a good used deal.

Found a Titanium megabomb from 04-05 250R, brand new! They don't make Ti megabombs for the X anymore, only stainless steal, so was really lucky. Snatched it for under $180, and got a second hand FMF Q4 for around $170.

If I hadn't found the Q4, I was going to get an old beat up OEM can from a 04~05 250R for $80 or so. Smaller, much less restrictive than the X, and louder (which I don't mind cause I wear earplugs). Could be an option for you.

Anyway, do get the R&D Flexjet instead of the Tusk, as motrock93b mentioned.

 

 

Here's what I've done recently. Big difference.
I was reluctant to spend a lot on a new full exhaust, so I spent a few month hunting for a good used deal.
Found a Titanium megabomb from 04-05 250R, brand new! They don't make Ti megabombs for the X anymore, only stainless steal, so was really lucky. Snatched it for under $180, and got a second hand FMF Q4 for around $170.
If I hadn't found the Q4, I was going to get an old beat up OEM can from a 04~05 250R for $80 or so. Smaller, much less restrictive than the X, and louder (which I don't mind cause I wear earplugs). Could be an option for you.
Anyway, do get the R&D Flexjet instead of the Tusk, as motrock93b mentioned.
 
 


Thank you for the info! This is great stuff!

Is there a way to tell what header pipes and cans will fit my 2012 CRF 250X? I didn’t realize we could use the R exhaust setups 🤨

All model years of the CRF250X are based on the original 2004 CRF250R

The first generation 2004 & 2005 R's had a single exhaust, their headpipe and silencer will easily transfer over to an X.

 

The R headpipe is shorter in length (less curvy) and larger in diameter which promotes upper rpm power.

At the cost of some HP's, the stock R headpipe is generally preferred for low rpm grunt.

 

Starting 2006, CRF250R had dual silencers, some aftermarket exhausts of that era converted them back to a single silencer

but without confirmation, I'm thinking the subframe mounting points are different from the OEM single exhaust 04-05 bikes.

Edited by mlatour

Remember that you are at higher altitude. I have dyno tested exhaust systems in Denver, and all you are doing is lightening your wallet and making your bike noisier.

The stock exhaust can flow about all the air that the bike can produce at sea level, and you get up over 4000 feet, where the air is 14% thinner, and you would be hard pressed to find even 1/2 HP at redline with an aftermarket exhaust.

On 11/29/2017 at 11:12 PM, mlatour said:

At the cost of some HP's, the stock R headpipe is generally preferred for low rpm grunt.

Sorry I made a typo on this,

it should have read the 'X' headpipe is preferred for low end torque.

I also experimented with aftermarket muffler and R header and for my riding stock works the best.  Since I don't race all of the CCC mods are probably overkill, so I've only done part of the mods.  What I need for my riding area is smooth tractable  power delivery rather than top end, and it has required a lot of minor tweaks, some as mundane as adjusting slack out of the throttle cables.  

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