Jetting

[Mustangous]

I know this topic is brought up a lot, but I still have a few questions before i even attemp this. I think there should be a step by step for all the first timers like my self :confused:

I have a 400ex and going to install a jardine slip on, and an uni filter with an outerwears lid cover. I am in nj @ sea level. It seems that the 42 pilot jet is the one to use, and possibly a 155 main. I will be using jets from jetsrus to keep the numbering easy to matchup.

The questions I have is:
1. How do i know if i need to move the needle clip?
2. wheres my starting point for the screws? 1-1/2 turns out ont he pilot screw?
3. I read the"jetsRus Procedure" (http://www.jetsrus.com/FAQ_rejetting.htm) , so do i pretty much follow their sequence for tuning? idle, pilot jet, re-adjust idle to new pilot, main jet. I would have done the pilot and main jet already so would i adjust the pilot screw then and idle and see how it is?
4. What about the clip on the needle again?..lol

This is confussing... :confused: I am sure there is nothing to it, but i just want to fully understand everything so when i do this and take my 400ex out to adjust all this, i will get it and be able to have fun the rest of the day. Not be fustrated and come back home.

jets r us also has an faq on how to read plugs...it will help a lot

[Mustangous]

Originally posted by speedyquad
jets r us also has an faq on how to read plugs...it will help a lot
From what i read on different sites was that plug cutting/reading is only good for wot/main jet, and also with todays gasoline its very inaccurate anyway. Is that true or not??

How about the way jetsrus says to find your main jet? Put the biggest jet in and run WOT and keep coming down a jet size till the bogging is gone???

that is pretty close...

you def. want to start out rich and then go towards lean...without getting it too lean...lean is bad

[dbc112]

I have a 400ex carb on my modded 300ex engine. I went with all types of jet sizes...

Finally I came across a product called dial-a-jet. It is really easy to install and adds fuel by the click of a dial (only adds so jet 2-3 sizes smaller)!

I went with a 138 main (was 146) I turned the dial 1 click for more fuel and it runs AWESOME (20 degrees outside), takes 2 sec to adjust.

The instructions are easy, basically you remove the float bowl drain screw (think that what its called) replace it with the dial-a-jet screw, attache the DAJ fuel line, poke a hole in your boot and install the "jet".

it is the best mod I have ever done, I can change the fuel delivery anytime with climate change.

Check out thunder products.. I also ordered the hot wires.