Pilot Jet Length?

[BigThumper33]

Hello, I removed my spark plug the other day to check on it and it was white....aahh! My quad is totally apart getting powder coated so I decided I would grind the welds off the header, remove the choke, and will be adding a sparks cam, and will not be running a air box lid anymore.

My main jet size was a 144, the closest thing I have is a 145, I didnt think that would make much difference, the next size I had was a 155. With all the new mods I'm getting do you think a 155 is to big a jump?

Now to the point of this thread. I've heard that you want up your pilot to a 40-42. I took my pilot out and compared it to the others I have. The others I have are for a 250r stock crab, they are identical except that the ends(where you screw them in at) are slightly longer than the 400ex pilot. Is it okay to run these? Or do I need to get jets specifically for my ex carb? And If I do where I can order some online?

[RiPPiNiTuP7]

Originally posted by BigThumper33
Hello, I removed my spark plug the other day to check on it and it was white....aahh! My quad is totally apart getting powder coated so I decided I would grind the welds off the header, remove the choke, and will be adding a sparks cam, and will not be running a air box lid anymore.

My main jet size was a 144, the closest thing I have is a 145, I didnt think that would make much difference, the next size I had was a 155. With all the new mods I'm getting do you think a 155 is to big a jump?

Now to the point of this thread. I've heard that you want up your pilot to a 40-42. I took my pilot out and compared it to the others I have. The others I have are for a 250r stock crab, they are identical except that the ends(where you screw them in at) are slightly longer than the 400ex pilot. Is it okay to run these? Or do I need to get jets specifically for my ex carb? And If I do where I can order some online?

Well first off I think you read your main jet wrong because they don't make a 144 main jet. The increments go like this: 140, 142, 145, 148, 150, etc.. A stock 400ex comes with a 148 and most will agree thats a little lean. You can try the 155, and see how it is from there. About the pilot...yes the stock one is shorter than all the rest of the sizes, so your ok. www.magicracing.com sells jets if you need extras which most likely you will.

[BigThumper33]

Sorry the main jet was a dyno jet. I think that makes a difference?

[RiPPiNiTuP7]

Originally posted by BigThumper33
Sorry the main jet was a dyno jet. I think that makes a difference?

Yea, their different :p

[Newbie400ex]

If you have dynojets then you are going to have to use a dj160-dj170. Especially, I think, will all those mods. I have only minor mods and a dj165 @295' or so above sea level.

[BigThumper33]

I went to magic racing and their jets are for the PJ and PWK. What is the stock 400ex carb. THe only thing I can get out of the manual says QB. I'm lost.

[BigThumper33]

bump

[RiPPiNiTuP7]

Their the same.

[BigThumper33]

thanx. Just making sure.

Start witha 160 and I bet that'll get ya almost perfect on the main.. 400ex carb is a keihn carb. Go witha 42 pilot I beleive it's series II. the 42 pilot is way bigger than a stock 38..