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View Full Version : jetting???


lilholt7
09-21-2011, 07:12 PM
i have an 03 400ex. i bought it with a jet kit and the guy said it was the highest they could go with a pipe and air box lid off. well my problem is i ride in creeks a lot so i usually ride with my lid on but it makes my four wheeler lose a lot of power. so i was wondering if i can set my carb to give the right amount of gas for the air its getting with my lid on with out rejetting it?
CJM
09-21-2011, 07:25 PM
No, you need to rejet it, 152-155 main might be close
lilholt7
09-21-2011, 07:33 PM
i dont know much about carbs and jets but how many new jets do i need and how many are there total? whats the best brand for a good price?
Stickman400
09-21-2011, 08:16 PM
Here's the site to buy your jets from: http://www.jetsrus.com/a_jet_kit_atv/honda_400_TRX400EX_1999-2008.htm

There are only 2 jets in your carb., a pilot jet and a main jet. All you need to do is replace the main jet. You only need to buy as many jets as you think you will need, or you can buy a jet kit which will contain quite a few jets for a lower price than buying them individually. If you need help taking apart the carb and replacing your jet we can help, just say so.
lilholt7
09-21-2011, 09:02 PM
I rebuilt my 300ex carb so I'm not completely lost on it. I don't plan on doing this soon but just wondering. How much power will I lose by doing this rejet?
wheelman
09-22-2011, 11:06 AM
you wont lose any power vs how you're running now (likely too rich since you're running a closed lid and jetted for an open one) It should pick up a little bit, but not much.
lilholt7
09-22-2011, 08:21 PM
Do you think it would be better to leave it jetted high and just leave lid on for creek ridding and off for everything else. Because I love the power without the lid
wheelman
09-23-2011, 06:38 AM
Depends on how bad it runs with the lid on i suppose.
lilholt7
09-23-2011, 01:43 PM
Its not bad. An pull them 3rd gear with me standing on grape bar with lid on. But is it bad on my engine to run it lean like that?
powerbomb400
09-23-2011, 02:44 PM
Its sounds like its jetted with no lid. I know Powroll had a lide that had slots in the top. You could put slots in the lid and glue a thin foam on the underside. That way you could still get plently of air but yet still offer some protection from water.