I just bought a 07 yfz 450 and after break in i want to put a two brother pipe ,highflow air filter ,pro tec lid do think i should put the jet or not , if not will it do anything to my valves or something any advice i would greatly apprecieate thanks.

 

Yes, you WILL have to rejet. It is easy though, just buy the next three sizes up main jet and one size larger pilot jet. Loosen the carb from both sides and turn it so you can see the bottom, take a 17mm wrench and take that nut off. Pull the MJ out and go up till it feels good. These bikes are lean from the factory.

 

THANKS I APPERCIATE IT

 

Yep what he said...........
Might need to richen up the needle too............

 

I also have an 07 yfz450. When i hammer it from an idle it will just hesitate and sometimes die, i have to rev it up and then hammer it. I bought a white bros mixture screw and turned it out a bit and it still does it. What exactly is supposed to fix this? Like, is there a jet that is too small from factory or is it a different adjustment?

 

What all have you done to the quad?? Aftermarket air filter?? Aftermarket exhaust???? Anything??

 

My bike is completely stock. I hear this problem is called the "bog". Is there anything specific you have to do to eliminate this? Like a certain jet to go higher or lower on that is a sure fix? I dont want to be juggling with options.

 

I have heard of this problem before......
I believe the (Accelerator pump?? I think thats what its called) can be adjusted to help eliminate this, but its been a long time since I've read up on it.

I've also heard that bumping up the pilot may help with this also, but only if it is coming from a lean condition.

I have an 04', and it doesn't seem to have the "bog" problem, but I've got an aftermarket air filter and pipe, and it is jetted accordingly.

If I were you I'd try to go up one size on the pilot and play with the fuel screw a bit to see if you can make it better that way....

Also check your idle... if it is too low it may cause problems also.

Lastly I would check the needle setting and see if adjusting it makes any difference.

PM me if you need more info about the Accelerator pump thing..

 

my suggestion...buy an edlebrock [img]i/expressions/face-icon-small-wink.gif[/img]

 

I have an 05 yfz le and i have this bogging problem as well. I thought that it is just the way the engine runs. Once the quad get around its power band it doesnt bog at all. But anywhere around idle and if i give it WOT insantly it will usually stall. I have gotten use to it and i havent had a problem with it, When i am lugging the engine i just cant give it full throttle.