I'm having trouble getting my jetting spot on. It seems to be in the pilot cicuit. If I let the machine idle for a bit it wants to die when I try to throttle up. I feel like it's a bit rich and is loading up, but when I lean it out with the fuel screw I get the same results. I'm a bit stumped.

 

Have you jetted your quad before? because it might be the wrong jet...your jet might be altitude specific...but if you look on the side of your carb there should be an idle screw...might just be a quick fix but just turn it clockwise till it idles the way you like

 

According to HMF and the guys on the 400EX forum, my jetting should be good; and it is good, but not perfect.

I would think that I'm close enough to get it with a fuel screw adjustment, but I have been unsuccessful thus far. I've tried moving the needle and adjusting the fuel screw everywhere from nearly all the way in to about 4 turns out with similar results. I just can't quite seem to get it just right and it's haunting me, lol.

 

have you tried dropping the pilot jet size down to next lowest? you could prolly tune it in after that, seems like the pilot is to rich to be able to make a good change with the idle or fuel screw, getting jetting like 100% perfect is a BEOTCH on pretty much anything...it takes so much tinkering...lol

 

Buy a wideband O2, sensor and gauge. Weld the bung on then tune it.

I used the plug reading thing for years and years until I broke down and bought a wideband. You will NOT find me tuning ANYthing with out welding on a bung first!

Its turns a tedious and time consuming job into mere minutes! and you know EXACTLY! what your mixture is through out the RPM range.

Some of my buddies who "think" they know how to tune a bike are now coming to me Again for a retune after they jack their stuff all up trying to milk every last bit of HP from their bikes..

I can pull more power from a bike now than ever before.

 

Anybody ever change the needle and seat on that carb, you know it could be worn out and alowing more fuel at idle then you need making it really hard to adjust. But again ezdaar is rite and it is really hard to adjust to 100% perfect fuel to air mixture if you don't have a special tuner. Good luck.

 

All carbs need to be adjusted from the factory. Take to bowl cover off and tip the carb upside down. The float should be level with the bowl. If not bent slightly until flush. Now put bowl cove back on and put carb back on. Turn fuel adjustment all the way to the rt and the back off a turn and a half. Start the machine. You may have to adjust the fuel adjustment a little more until you half to play with the choke to keep it running. Once its staying running manually by playing with choke. Time to adust the air screw. Start with a half a turn either was if it gets worst try oppisite direction until engin runs itself usually works. Dont worry about jet until taking for ride if you bog at half throttle change jet