CRF's Only Forums

Posted: **Tue Aug 15, 2017 2:25 am**

Hi guys

I recently bought my wife a 2011 model, but as most of you know the standard bike is really 'muted and unresponsive'.

So I have read a lot on the subject and the re-jetting that is needed when the bike is 'uncorked'. However, I got a lot of conflicting info on which main jet and what needle to use.

So is there anyone that can put me in the right direction to which main jet and what year needle to install and also what the fuel screw setting should be to allow this process?

We typically ride at altitudes of around 4,393 ft AMSL and in temperatures of between 80F - 95F.

Thanks!

Posted: **Wed Aug 16, 2017 2:12 am**

Well there are two trains of thought-
1. Use the 2003-2005 stock needle, 120 main, 45 idle
2. The power up needle, 130 main, 45 idle

Some bikes run better with the 48 idle jet

Both setups work. I have tried both and the second option suited me better.
Do yourself a favour and get the CRFs Only fuel screw.

The fact that you are above sea level, option 1 would probably work best. You may have to go down a little on the mains. There is more info in the threads on the site.
The link below has some handy info to compensate for altitude and temperature to make main jet adjustments.

viewtopic.php?t=30930&highlight=coe

Posted: **Wed Aug 16, 2017 2:37 am**

Well there are two trains of thought-
1. Use the 2003-2005 stock needle, 120 main, 45 idle
2. The power up needle, 130 main, 45 idle

Some bikes run better with the 48 idle jet

Both setups work. I have tried both and the second option suited me better.
Do yourself a favour and get the CRFs Only fuel screw.

Start with the fuel screw 2 turns out, make sure the spring goes on screw first, followed by the washer and then the oring. Make sure there is no original oring left. You will have the later none adjusting screw installed at the moment with the d head. Most use an electrical connector warmed up and pushed over the d, and unscrew when cool. Adjust for even running once engine hot. If you end up less than 1 turn out go down an idle jet size and retune. If you end up at 3 or more turns go up an idle jet size and retune. Don't leave at 3 as screw can vibrate out sometimes.

The fact that you are above sea level, option 1 would probably work best. You may have to go down a little on the mains. There is more info in the threads on the site.
The link below has some handy info to compensate for altitude and temperature to make main jet adjustments.

viewtopic.php?t=30930&highlight=coe

Have fun they are a great bike. Using a battery tender will give you long battery life. My first yuasa lasted more than 5 years.

Need any more advice just hop on the board and post.

Posted: **Wed Aug 16, 2017 9:19 am**

Thank you for the advice, I will give you feedback as soon as I have changed it

Posted: **Mon Feb 07, 2022 1:05 pm**

I finally finished the "uncorking" process on my 2007 CRF230F

120 Main Jet
45 Slow Jet
Older needle ( 2003-2005 I believe)

Removed the snorkle and baffel.

Idle and revs fine but at continuos full throttle it starts missing like it's starving for gas. Any ideas? I ride below 1'000 ft.

Posted: **Thu Feb 10, 2022 1:01 am**

I would check that aircleaner is clean and that you have good fuel flow to the carby.
It maybe the tank is not venting properly or the screen inside the tank is clogged or melting.
If that is ok then step up one size main jet.
If it is currently lean the step up of main jet should reduce or eliminate missing.
The older needle should be stamped C39A.
The C83A has 2 clip positions and was in 2006 models onwards.
If C30F you have a power up needle and will need say 130 main.

CRF's Only Forums

Uncorking the CRF230F Info Needed

Uncorking the CRF230F Info Needed

Re: Uncorking the CRF230F Info Needed

Re: Uncorking the CRF230F Info Needed

Re: Uncorking the CRF230F Info Needed

Re: Uncorking the CRF230F Info Needed

Re: Uncorking the CRF230F Info Needed