I went to a size 50 pilot jet and 1 and 1/2 turns out of the pilot air screw and it has resolved my cold starting problem. See instructions at http://get.to/quads

 

I have seen on here where people are changing the pilot jet on there 400's. What does that do for powerband, does it improve low end or top end? Where is the pilot jet at?

 

BG400,
The pilot jet controls the fuel mix from idle to approx.1/4 throttle. If you have no problem in that range, you have no need to change the jet, which is located behind the pilot jet adjustment screw. I'm not too familiar with Keihin, but I believe it is on the front lower side of the carb.If you're getting a slight hesitation off idle you can sometimes correct it with an adjustment of the pilot screw.The nominal setting is generally around 1 1/2 to two turns out from seated, depending on make of quad. On my Warrior, for example, it's an even 2 turns out. Turning it out in 1/4 turn increments will give you a fatter mix at idle to 1/4 throttle. After that, you're off the pilot and onto the needle or main, so unless you run primarily at 1/4 throttle changing the size of the pilot is rather pointless, IMHO

------------------
THE AZ HARD PACKER, calmiller@kachina.net

save the public land FOR you, not FROM you..join the Blue Ribbon Coalition online @ www.sharetrails.org



[This message has been edited by hot_shoe_cv (edited 12-21-1999).]

 

The pilot jet controls the idle circuit of the fuel's flow. It works from idle up to 1/4 throttle. Most people are changing their pilots from the factory number (#38) to a #40. This helps starting and improves low-end power as the factory jetting is lean off the bottom. As for it's location--well you need to purchase a manual. Hope this was helpful. :~)

[This message has been edited by mindcrime (edited 12-21-1999).]

 

What is with this, "http://get.to/quads".

It came up-"page cannot be found".

Ten I clicked "link" then it came up Redirect-url.

Now what??????????????

 

Try refreshing your browser a couple times and the page should load. Just in case, the tech tip from the site is paster here:
The tip to make the beast run even better

ON 400EX Jetting, The pilot jet is exactly why you are having problems with,
Cold Starting & Low end throttle Response, to name a few. When our quads run
sluggish, we want to assume that it's to rich, TRUST ME, that's not the case
here!

We have the world's largest dyno. All our research on the 4X gave us the
following extremly accurate jetting specs.

First, Remove, don't vent, air box lid. this will allow better air flow,
vents get cloged and still let water in. The 4X responds much better and you
still have a GOOD WATER TIGHT LID for the winter. Here are the specs.
Main Jet= 152 (150 over 5000' elev)
Pilot Jet= 50
Needle= Stock in the 3rd clip (stk position)
Air Screw= 1 1/2 turns out,

Now, a word on exaust, Don't waste your money on big Dollar systems. We've
tested them all. Guess what? Slip on silencers only add 2 1/2 Hp and only if
you have the right jetting. A full system, including head pipe will give you
4-5 Hp under the very best conditions!! Again, We've tested them all on our
Dyno with consistant results.
I'll give you a few good tips for the 4X:

White Bro's High Rev Kit,
Changes the timing curve and gives you 1000 more RPM
this gives you way way faster, throttle response and lets your 4X take full
advantage of any futher Mods you might make. Oh, and it doesn't make it run
hot or less reliable, I was extremly impressed.
Big Gun, Good system,
Central "Q" Great system, Chrome, Even has threaded holes in the back to
mount super trap disks should you need to be "USFS" approved. Around $300

Warren, The War man
General Manager, Head of R&D for a mail order
Co. named "Quad Central" Quadcentral@lvcm.com

 

What is the procedure for replacing the pilot jet? where is it located? I'm going to replace the pilot jet and the main jet and want to do them at the same time, but not sure on location. I know the main jet has an access nut on the bottom of carb. also what is the difference on the 3 settings on the needle, you said the stock is on the 3rd. so are one and two better or worse?

ps i'm tring to gather as much info as possible so i can hurry up and ordr the jets the slip-on exhaust and outerwears around my K&N. thanks for all the help.

also i plan to do this myself because of labor cost: for example my cousin has a stock 400ex and went to have the oil changed and valves adjusted and the bill was $150. no way man.

Jera '00 400ex

 

400exinfl-
I think I was just "Grammer-ly duped"

Jeaner-The pilot and I believe needle are pluged from the factory with pressed in plugs.And must be removed in order to alter their settings.
While the main jet is inside the carb itself.
In other words,Remove the carb from the bike, And work on it on a nice clean table.



[This message has been edited by trx430ex (edited 12-23-1999).]

 

trx430ex,
I don't have a dyno ... the post above is from a web page I found on the internet

jeaner,
you will have to disconnect the carb and flip it upside down (at the minimum) to rejet ... I agree it should be removed and done on a clean workbench

 

400exinfl, where is the pilot jet located? is it very hard to change?