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It’s a problem I have not had to face in many years due to fuel injected bikes.  Since 2001, I have had Aprilia’s which are all fuel injected and my trusty YZ426 that came to me already jetted.  Now as I go through my YZ450 to get it ‘right’, its the learning process all over again.

As an avid believer in motorcycle forums for the best knowledge available, I am a member of thumpertalk.com.  It seems like everyone and their mother is running a 45 pilot jet and a 165 main jet.  The main has been on since the beginning, but the idle circuit has not.  Starting this machine has been a bitch from day one - cold or hot.

Checking the pilot jet process goes something like this:

• set the idle
• adjust the fuel screw to get maximum yet smooth rpm
• fuel screw should be between 1-3 turns out. 
• less than one means a need for a smaller idle jet
• more than three means a need for a larger jet

Not trusting the process and only trusting the TT forum left me with a 45 idle and popping at idle no matter the fuel screw setting.  Wayyy too lean.  Finally, I trusted the process and upped it to a 48 pilot jet.  4 turns out and it ran great.  Started great too for the first time ever…first kick great.

Keeping with the process, I upped it to a 50 pilot jet and got to three turn out on the fuel screw and the same result.  First kick cold or hot with no other input needed.  Finally.

I will ride it for the first time in its current condition this weekend.  I am very optimistic that the jetting is finally correct or very close.  I am expecting some small tweaks on the trail, but again hopeful that I am done with the wrenching.  I will say that I am smarter than I was before and had to go back to fueling basics 101.  I trusted others settings over the process, which in this case may have been a mistake.

Fuel injection is a great thing.  Fortunately they are already in the Suzuki off-road lineup and other manufacturers are close behind.  I don’t mind the work (I can have my carb off in about five minutes now ), but I did lose some riding time and that always sucks.  The good news is that once the jetting is dialed in, it’ll probably never have to be meesed with again for local conditions.

Woohoo!