Jump to content
Sign in to follow this  

CRF450X JD Jetting issues

Recommended Posts

Hi All,

 

I realise that this subject has been widely discussed and I have read through heaps of posts on various forums but I cant get my JD jetting kit to run properly.  I have emailed JD but not had a response.

 

I have a 2009 CRF450X with DEP S7 powerbomb exhaust.  As far as I know the rest is stock (I'm the 3rd owner).  In saying that, the main jet is a 155 which I don't believe is standard...

 

I followed the JD instructions as per my elevation (sea level) and warm climate, which meant putting in the RED needle and a 165 MAIN jet.  The instructions say nothing about the PILOT jet at all so I assume they expect you to leave it stock.  Unfortunately when I tried to get it out to check it, it was tight as &%$#@! and wouldn't budge.  I was seriously scared of snapping it off in the carby.

 

With the RED needle and 165 MAIN jet, fuel screw 1 & 1/8 turns out as per the JD instructions, it ran like crap, spluttering constantly and generally not happy.  It ran a bit better with the fuel screw wound further in so I guess it was way too rich.  It wouldn't run properly with any fuel screw adjustments so I tried smaller MAIN jets (160 and 155), no good.  In the end I pulled the JD kit out and went back to my previous setup because I needed it to run decently to get to work.

 

Is it simply that I need a smaller PILOT jet?  What is best way to get it out? or at least read the size?  What is the stock size?  I'm thinking I need to completely remove the carby so I can have a better crack at getting the PILOT out.

 

Any advice would be great,

 

Cheers

Share this post


Link to post
Share on other sites

  You have some blockage above the pilot jet, it sounds like. Use a piece of large dia fishing line and spray cleaner.

 

You have to service the carb at least once a year, cleaning and lubing the hot start and choke plungers and cavities, inspecting the apump system, checking for apump squirt quality, replacing the slide plate seal, and replacing the fuel screw oring.

 

 

With a non stock pipe and snorkle removed, it should run well with:

 

165 

Red 3rd

45 pilot (if you have not personally installed a brand new pilot, what ever size, it will NOT run well, as it is undoubtedly corroded)

    - we know it is corroded because you have stated that it is 'stuck' in the carb. So the pilot is you main problem right now.

    - DO NOT try and force it out. Spray some PB Blaster on it, and wait till the next day to try and break it loose. Then throw it away.

45 or 50 0r 55 leak

2008 apump upgrade kit from crfsonly.com

apump linkage spring upgrade from Tokyo mods or Merge racing

 

You adjust your fuel screw by idle speed.

You want the fuel screw to raise your idle to 1850/2000 rpm

It is goes too high, you lower it with the idle screw, and repeat.

Share this post


Link to post
Share on other sites

Thanks so much for your advice.  I'll hopefully have a shot at it this weekend. With the leak jets you mention, which size is standard? Should I be buying the other sizes ready or just see how it goes with the stock one first?

Share this post


Link to post
Share on other sites

Thanks so much for your advice.  I'll hopefully have a shot at it this weekend. With the leak jets you mention, which size is standard? Should I be buying the other sizes ready or just see how it goes with the stock one first?

 

Technically, the leak jet is not a jet. It only feed the apump cavity. so it will not run badly if it's off a bit.

Stock is 70

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

Sign in to follow this  

×