i have an 08 z400 and i was going to gut the exhaust but i wasnt sure if i would need rejetting

what do you guys think?
do i need to rejet?
if so what size main and pilot?

 

This is one of the more popular questions asked. Unfortunately it is impossible for me or anybody else to answer. It all depends on factory jetting. If it is rich from the factory, then more than likely no, you will not have to rejet...........if you get lucky.

If you are spot on or even a little lean from the factory, then yes, you will have to rejet.
You will not need to rejet the pilot with just a gut job on the can. Just give it a little more on the screws.

 

cant say i know of any one that has had any serious hp claims from gutting the muffler. but then why not, you will have to rejet,145 or 150 should do it.

 

i wasnt relly tryin to get hp i just want it to sound better and i dont want it to lose power in any of the rpm range or anything like that but thanks guys

 

If the Z is anything like my V you will loose a ton of bottom end. It felt like I lost 10 HP on the bottom when I "reconfigured" my can. I just tried it out gutted and that is what happened. It moved the torque band so far up in the RPM range that I don't think I ever got it back on the top end.
I put my own reconfigured guts in the can and the bottom came back along with a good gain on top.

 

did you jet it to???

cuz i know when i had a 250ex i gutted it but didnt jet and it felt the same way

 

No I didn't. But the jetting was pretty close. I didn't ride it around enough to do a plug check. It didn't lean pop or bog or anything like that, so it was pretty close.
You will loose bottom end. How much? I just don't know? I just told you the story of my V because I was shocked at how much bottom end I lost. You can always gut the can and then weld some baffles in to pick up the bottom end a bit. Just a thought?

 

i aint what you call a welder i like riding more then welding so ill keep my can stuffed until i can get the shop to order my new yoshi pipe but thanks alot for the info but i know this is off the topic but what do you think of the polaris predator?

how does it compete with the 450s?

 

i aint what you call a welder i like riding more then welding so ill keep my can stuffed until i can get the shop to order my new yoshi pipe but thanks alot for the info but i know this is off the topic but what do you think of the polaris predator?

how does it compete with the 450s?

 

Sorry, never rode a predator, or even seen one on a trail around my parts. Good luck with your Z. It's a fun ride and well rounded quad.