I was just curious if you need to rejet when you pull the air box lid off the YFZ. I'm gonna leave the baffle in for sound test reasons, but I want to pull the lid. I could read the plug, but I guess I'm too lazy at the moment!! Do you need to rejet at all if you leave the baffle in, but remove the airbox lid??

 

I don't think your gonna make enough difference to validate removing the lid if your gonna leave the pea shooter in. If you pulled both yes you'll have to rejet, w/o removing the end tip.....got me. I really don't know. I don't think your going to really notice any performance gains though from just the lid.

 

I'm sure taking the lid off will have gains, you're right, not as much as doing both. But on al my other quads you drop a K&N in and it makes a difference, not enough to rejet, but a difference. I was just wondering if I had to rejet for just taking the lid off the yfz and leaving the baffle in. If I take the baffle out, it will be too loud for my racing series.

 

Hey buddy.....open that B--itch up and make her scream! Don't worry, I'm sure it will smoke your old Pred. Let's dial it in this weekend. Get that K&N filter ordered!!

03 black and red Raptor
modded stock airbox and muffler
PRM Desert Grab Bar

 

Yes you need to rejet.. mixing more air requires additonal fuel or you will run lean.. especially on the YFZ 450

I would suggest the following jetting based on my experience

45 pilot
GYTR needle in the 3rd clip from top position
either a 162 or 165 main depending on temps and elevation
2 to 3 turns out on the fuel mixture screw.

If you pull the stock silencer.. start with the above
and use the 165 main for additonal fuel.


Don't melt a new engine due to stupidity!

 

Thanks MNRap, Does yamaha offer several sizes with their $50 jet package? Otherwise I'll just keep the lid on till I slap full aftermarket exhaust on!!

 

the GYT-R kit from Yamaha includes

main jets,, 155,160,162,165
pilot jets, 40, 45
clip
new needle with different taper


you may also want to check out JDjetting.com ... they offer a kit also for the YFZ with two different needles


I purchased the needle (YZ450) and jets seperately from Magnolia Tractor,, Search the web and call Bob. great deals on GYT-R stuff

 

Welcome Pudl,

Mate you will out grow what the kit offers once you have a new can on the back.
Save your money and buy some individual jets 165 up to 175 for now and a 45 pilot.

Have fun, Geoff.

 

Thanks for all the help and suggestions guys. You make a good point Geoff!! I was thinking that I will pocket the $50 and just get a jet kit when I decide what system to install!!