i recently put a complete exhaust on my z-400 and put in the jet that came with the exhaust package much larger then stock as for the rest of the quad stock with unifilter so in doing this i removed the airbox lid and the quad run like crap i thought it was do to somthing i did in the carb and looked into the problem after much time wasted i put the lid back on and the machine woke up and ran great so my ? is do i stay the way i am or can i get more power by removing lid and jetting more what should i do looking for some experiance here i know nothing when it comes to carbs.

 

That engine responds dramatically to an increase in air intake! Yes, take the lid off, and I highly recommend you replace it with an EHS Racing lid with Outerwears cover. You will need to rejet!

I hope you didn't run it long with the lid off and the old jetting, because you would be running lean....which means you could have damaged the engine!

 

thanx on adverage how much bigger do you go on a jet when removing lid i know this is always different but it might give me a good start

 

Jetting is more art than science! It is done more by riding it and seeing what the changes do, than by the numbers....so I can't just give you a jet size and send you on your way. Plus, besides the main jet you have the needle, air screw, and other jets to consider as well.

If you want to learn jetting and have lots of time, then maybe you can mess with it. If you are in a hurry to get riding, then have it jetted by a pro.....

 

I ride and 02 raptor 660. I recently added a full Big Gun Evo. I got rid of the stock air box completly. I bought a custom box off of ebay from CFM. I had the carb's rejetted by a pro at D&C motors in Jacksonville, Fla. It ran shitty with the lid on. I took off the lid and the silenceer in the pipe. The bike really came alive. I have been clocked at 92mph. Look into a custom air box.

 

i have to ask what number jet did you put in? was it a DJ jet, or mikuni? i dare say that what you've done a 165 mikuni should be about right,as well it would be a good idea to install a bigger pilot as well ,a # 25 is what most are going to.

 

i will hafe to check can not remember right now on the size however i beleave it was a 172 or a 17somthing pretty sure on it i contacted lte (luney tuned racing) today they are checking into my elevation and ect. they say the jet they usually send is to be with air lid removed but when i remove air lid it runs like crap i put lid on and it runs great.

 

runs like crap on the top end or when ?

 

mostly under acceleration it would stutter but it was thru the whole power range really but mostly 2-4 th gear under acceleration however that was how i was riding too. i choked it and it ran better for a few seconds than dropped i found i had to half choke it but when i put the lid on it ran better

 

its telling me that its lean, i would like you to get 2 things ,a 165 mikuni main and a number 25 pilot jet. do you have an adjustable needle ?,i would start on the 3ed clip.
and as well you will have to turn the fuel screw out , 2-3 turns . let us know what happens