I've searched the whole forum...Still????

[5corpi9]

I know there are tons of questions on jetting...And someone suggested that I do rejet it...

I looked at every forum here for someone that has the similar set up and lives in Southern Califonia as me, but no luck. I've saved all the forums that tell you how to jet. Thanks for those!

I plan on jetting it myself and I am asking for your help...And many thanks in advance to those that reply.

I am going to order the jet kit from JetsRus and not sure what Pilot Jet(s) to get along with the Main Jet Kit???

I live in San Diego, California and the elevation I usually ride (as it states on thier website) is "from sea level up to 500 ft", temps can range from 60 deg to 100 plus deg in the summer.

My 07 TRX400EX has:
-Lexx MXe S/O exhaust with silencer/spark arrestor in.
-Uni Air Filter with lid on.

My questions are:
What do I need to rejet?
What size main jet and/or pilot jet should I start with?

I plan on doing the spark plug check to get it as close as I can.

Any tips/what to avoid or try is greatly appreciated!

Thanks again and this forum ROCKS!

[Wheelie]

Stock pilot, 150 main and A/F screw at 2.5 turns is a good start.

[5corpi9]

Originally posted by Wheelie
Stock pilot, 150 main and A/F screw at 2.5 turns is a good start.

Does the type of brand matter? Keihin/Mikuni/FMF Power Kit?

The jet kit I want to get from JetsRus does not come with a 150 Main Jet so I might have to go with another website.

Any recommendations?

Thanks!

[Wheelie]

Go to your local dealer and buy a Keihin 150 main jet for about $5.

[tx07400ex]

I have an 07 w/ trinity full system everything else stock lid on stock filter and i run kiehen or however u spell it 155 main and 40 pilot and i didnt touch my a/f screw, i ride in tx but the airport down the road is supposed to be at 327ft. and temp i ride in is also usually 60-100+ however im thinking about going up to a 42 pilot it is too **** cold natured

[5corpi9]

Originally posted by tx07400ex
I have an 07 w/ trinity full system everything else stock lid on stock filter and i run kiehen or however u spell it 155 main and 40 pilot and i didnt touch my a/f screw, i ride in tx but the airport down the road is supposed to be at 327ft. and temp i ride in is also usually 60-100+ however im thinking about going up to a 42 pilot it is too **** cold natured

Your riding is very similar to mine, with the exception of your full exhaust. I might try starting with a 150 main & 40 Pilot, but will still be looking for the replies here.

Thanks for your info! Really appreciated!

[tx07400ex]

Yeah im running a full but no filter its probably a slight difference the trinity headers arent too much bigger than stock only the mid pipe is really larger, the pic is my stock header next to the trinity, i know its muddy sorry

[400exMO]

42 pilot, help with the cold starting. 150-160 main, needle middle clip the start fine tuning. Start with the fuel screw 2- 2 1/2 turns out, then fine tune that as well.

[tx07400ex]

I never touched the a/f screw i dont have any problems except cold starts, it wont run with the choke so i have to either sit and play with the throttle to warm it up or just get it to run long enough to move and ease around for the first few min to let it warm up going down the road once it warms up i get snappy response at all rpm and no other problems

[5corpi9]

First off, what type of carb do I have? I couldn't figure it out?

Where is the Fuel Screw located on the carb?

What's the difference between the Pilot Jet going up from 40 to 42/45/Etc?

Is there a special tool I need to get these jets out?

Thanks!

[tx07400ex]

the carb is a 38mm Keihin, as for the a/f screw i think its somewhere on the bottom not really sure never messed with mine, but i think im fixing to put an 04 450r carb on mine, one of my buddies got an edelbrock for his 450 and said i could have his stocker free:D

[5corpi9]

Originally posted by tx07400ex
the carb is a 38mm Keihin, as for the a/f screw i think its somewhere on the bottom not really sure never messed with mine, but i think im fixing to put an 04 450r carb on mine, one of my buddies got an edelbrock for his 450 and said i could have his stocker free:D

Sounds sweet! A 450 carb! Let us know how is works!

[5corpi9]

Originally posted by 400exMO
42 pilot, help with the cold starting. 150-160 main, needle middle clip the start fine tuning. Start with the fuel screw 2- 2 1/2 turns out, then fine tune that as well.

Is the middle needle clip adjustable on my model?

Thanks!

[tx07400ex]

does your bullhorn bumper stick out past the front tires, i want one but i dont want it to stick out much i like not having to worry about the front of my bed or my back glass getting dented/broken

[5corpi9]

Originally posted by tx07400ex
does your bullhorn bumper stick out past the front tires, i want one but i dont want it to stick out much i like not having to worry about the front of my bed or my back glass getting dented/broken

Here's a pic of my bumper...It actually doesn't stick out farther than the front tires. If you haul your quad in your truck, the tires would hit before the bumper.

[5corpi9]

Front view...

[priesty]

Originally posted by 5corpi9
Is the middle needle clip adjustable on my model?

Thanks!

No, 05 & later models have a fixed needle with only 1 groove. You can fit the needle from <04 model. I'm running Big gun full system
with air lid off, my jets: pilot =42, main =155, needle clip moved down one notch, idle screw 2.5 turns out, starts & runs great.
BTW be careful if you use a dynojet kit cos thier sizing is completely different from the keihin jet sizes.
cheers.......

[5corpi9]

Would this be a good starting purchase?

1. Pilot - 40 & 42
2. Main - 150, 152 & 155

When I do get the jets in,
I want to start with the 40 Pilot & 150 Main correct???

Then if the spark plug is a whiteish color, it's still lean, which means to move up to the next size main jet 152 or next Pilot 42???

How do I know which one (main or pilot) to change out after the first rejet?

Or do I keep the 40 pilot and just change out the main?
Very confused at this part...

Thanks!

[priesty]

Originally posted by 5corpi9
Would this be a good starting purchase?

1. Pilot - 40 & 42
2. Main - 150, 152 & 155

When I do get the jets in,
I want to start with the 40 Pilot & 150 Main correct???

Then if the spark plug is a whiteish color, it's still lean, which means to move up to the next size main jet 152 or next Pilot 42???

How do I know which one (main or pilot) to change out after the first rejet?

Or do I keep the 40 pilot and just change out the main?
Very confused at this part...

Thanks!
Start with one jet size up on both, have a test ride & then read the plug. You also need to note when riding if it splutters or bogs at any point in the rev range. As a general rule the pilot jet controls 1/4 - 3/4 throttle opening & the main controls 3/4 - full. The idle mixture screw controls idle - 1/4 & the needle controls the transition between these points in throttle opening. Just be patient & methodical & you'll eventually dial it in. It also helps to have a couple of spare clean plugs, so you can do half throttle runs & WOT runs on different plugs making it easier to read the results.
Have fun....

[400exMO]

I would research more about jetting. There are great articles written everywhere that will answer you questions very thoroughly. Jetting can be very simple and very complicated, just depends on how close you wish to get to perfect.

Also many people swear that on four strokes you can not determine precisly lean or rich from a plug check.

[5corpi9]

Originally posted by 400exMO
I would research more about jetting. There are great articles written everywhere that will answer you questions very thoroughly. Jetting can be very simple and very complicated, just depends on how close you wish to get to perfect.

Also many people swear that on four strokes you can not determine precisly lean or rich from a plug check.

400exMO,

Research has been done on this whole forum (searching and going through all 400ex topics) and other websites also, I did find good instructions on the JetsRus website, saved them.


Thanks again for the input and suggestions.

[400exMO]

Originally posted by 5corpi9
400exMO,

Research has been done on this whole forum (searching and going through all 400ex topics) and other websites also, I did find good instructions on the JetsRus website, saved them.


Thanks again for the input and suggestions.
I did not only suggest this website only, there are sites with HUGE amounts of information. when I get to the home computer i'll try to get my articles.