I have a 07 z400 with a Pro-design air filter I'm jetted and have slip-on hmf and a big gun rev box. My ? is do i need to take the screen out of the intake tube between the carb and filter? Also any suggestions on a header pipe to upgrade the stock one. We do race this quad in motocross. [img]i/expressions/face-icon-small-confused.gif[/img][img]i/expressions/face-icon-small-happy.gif[/img]

 

I will be interested in this answer from the gurus on this site. Sorry I do not have an answer for you. I have an 07 Z that I just changed the front sprocket to a 13T and installed a uni filter. I have an ESR airbox lid cover coming as well as a HMF slip on.

Where are you now with your jets? Main, Pilot, needle?

How much of a difference did the slip on and jetting make? I am anxious to ride but my pipe will not be here for a week.

I am thinking of racing some C class harescrambles. How ccompetitive is your Z? I was assuming that most guys are running 450's. I haven't had a quad for 15 years so I am just getting back into it.

 

If you want a little more airflow, pull the screen. As far as the header goes, the gains in my opinion aren't worth it, just my opinion.

 

Hey thanks for the imformation. I was told if i ran a K&N it could be taken out. Then I heard the stories of blowing motors so K&N was out. And if I would of read this sooner I might not have ordered a FMF powerbomb head pipe. As for jets with a pipe and air box upgrade I went with a moose racing jet kit it had detailed instructions and a ajustible needle. Right now I am running a 165 main and I am in the 4th notch from the top on the needle.[counting from the top down] Keep in mind I am also running a big gun rev box. Our bike pulls real hard until 5th gear then seems to go a little flat. Also my son treyson is the driver 140lbs. all in his right thumb. So we get to eat 450's mostly on the hole shot. But if there are any long straights lookout here they come. But as everybody knows a quad is only as good as it's driver!!!!

Thanks alot Mark Cassel P.S. You gotto pin it to win it!!!!![img]i/expressions/face-icon-small-happy.gif[/img]

 

Hey I think I said alot but did not answer the? The slip on made a BIGG differance with no jet change. The jetting came with the air mod. And the big gun rev limiter they were mild compared to the exhaust. But You need to jet to save your engine!! to much fuel is better than not enough. Peformance wise the z400 is great. We raced for the first time in dec. 06 and now have 11 trophies from 1st to 3rd in beginner and open class. And in all the races there was at least 1 or 2 450s and sometimes more. We now race amuture and it is hard to keep up with the 450s so we are looking at getting one.But we will keep the Z400 as a back up. I'm old school so even in quads there is no substitute for cubic inchs. But I'm 45 yrs. old 215# and this quad is all I want I have yet to hit the new rev limiter!!! I'm sure Treyson has several times but he's 14 and has no fear. I HAVE TO WORK. We have 18in tires on the back and 19in on the front And a 15t counter might go back to 14t. Oh and my stock jet was a 130.[now a 165]. Like I said before the quad is only as fast as the driver. The z400 might not win pro races but with the right mods. it will make the 450s have to pin it to win it. Mark Cassel

 

Even with a different head pipe, leave the jetting where it's at & see how it runs. I didn't mean to come off as aftermarket headpipes being junk, it's just that you have already gotten the most bang with the muffler. The Powerbomb does help a little though, so in a MX situation like yours every little bit helps. Another little "edge" to consider is a DRZ-400 bike base gasket. It'll boost the CR up 1 point.

One of my friends has a KFX400, with a slip-on & open airbox, and he runs a 170 main, stock needle, & fuel screw out 3 turns. Now, I have the same set-up on my Z400 & a 170 main was too much, so I stuck with a 165.

 

Hey CATman thanks for the imfo. You are right every little thing we do helps give us an edge on the 450s. We rode yesterday for the first time since the rejet [155 to 165] My son said it pulled alot harder out of the corners. But he was running in alot harder also. He tries something new everytime he rides yesterday it was a heel clicker over a double. I'm proud of him as you can tell. thanks again Mark

 

alot of people dont think that little screen makes any difference. but it does, without it you get better air flow, I didnt believe it either till I removed mine a year ago, as for head pipes most slipons are made for stock head pipes and if you want to get the head pipe for the slipon sometimes you have to buy the whole system because the silencer/slipon are different sizes because of the size of the pipe, stock might be smaller than aftermarket ones.

 

Thanks for the info guys. I think I will start with a 165 main, and leave my stock pilot and needle and see how it runs.

I rerceived my quiet core and EHS airbox cover kit today. I will modify the box and install the EHS kit tomorrow. My slip on will not be in for a few days. I am really anxious to try out the new power, but will have to wait for the pipe before I rejet.