YFZ450 Jetting .

[erikschmitt]

04 yfz 450
white brothers e2 slip on
everything else stock air box lid is on
where should i start with the jetting?

[liquidivide300]

I just purchased a 2007 yfz last thursday. The bike came with a full rocket exhaust, and uni air filter and a few jets. the owner i bought it from said the main jet in the carb was stock. I took the bike home and it ran like crap. It was missing in every gear and had no power. i was getting beat all day by a stock 2006 ltz 400. I changed the pipe and header back to stock and was still missing in the low gears. 3rd through 5th it ran awesome. I do a lot of fast tight woods riding about 1500 to 2200 above sea level. I would like to keep it mostly stock for now. Dose anybody know the stock pilot/main jets. Ride in 45 to 90 degree weather. Any help would really be appricated.

Thanks

[ohsobad_chevy]

Originally posted by erikschmitt
04 yfz 450
white brothers e2 slip on
everything else stock air box lid is on
where should i start with the jetting?

Start with a 45 pilot, 170 main, 3rd clip needle and 2 turns out on the screw.

Originally posted by liquidivide300
I just purchased a 2007 yfz last thursday. The bike came with a full rocket exhaust, and uni air filter and a few jets. the owner i bought it from said the main jet in the carb was stock. I took the bike home and it ran like crap. It was missing in every gear and had no power. i was getting beat all day by a stock 2006 ltz 400. I changed the pipe and header back to stock and was still missing in the low gears. 3rd through 5th it ran awesome. I do a lot of fast tight woods riding about 1500 to 2200 above sea level. I would like to keep it mostly stock for now. Dose anybody know the stock pilot/main jets. Ride in 45 to 90 degree weather. Any help would really be appricated.
Thanks

Put the pipe back on the bike and start with 170 main, 45 pilot, 3rd clip needle and 2 turns out on the screw. Should get you close.

[liquidivide300]

Matt,

got your replay however i want to keep the bike stock so when you mean pipe do you mean the rocket or the stock. stock is on it now and quiet which i like because i ride in an residential area to want to make my neighbors to mad.

thanks,
glen

[ohsobad_chevy]

Originally posted by liquidivide300
Matt,

got your replay however i want to keep the bike stock so when you mean pipe do you mean the rocket or the stock. stock is on it now and quiet which i like because i ride in an residential area to want to make my neighbors to mad.

thanks,
glen

I was thinking that you were going to put the aftermarket pipe back on. With the stock pipe, I am not for sure. Probably around a 45 pilot, 168 main and 2.5 turns out on the screw would put you pretty close.

[Backstabber]

We are going to tune my friend's YFZ this weekend. We ordered a special screw driver for reaching the A/F screw. I just wanted to double check and make sure we ordered the right tool. Your help would be much appreciated, thanks!

The tool is the "Motion Pro Pilot Screw Adjust." Its on motosport.com under tools and accessories.

[ohsobad_chevy]

Originally posted by Backstabber
We are going to tune my friend's YFZ this weekend. We ordered a special screw driver for reaching the A/F screw. I just wanted to double check and make sure we ordered the right tool. Your help would be much appreciated, thanks!

The tool is the "Motion Pro Pilot Screw Adjust." Its on motosport.com under tools and accessories.

You got the right one. I would have just ordered an adjustable screw instead of the bent screwdriver. The R&D remote fuel screw is awesome!!

[Backstabber]

Originally posted by ohsobad_chevy
You got the right one. I would have just ordered an adjustable screw instead of the bent screwdriver. The R&D remote fuel screw is awesome!!

Ok, great! Thanks for the reply!

[Pack]

Ok, I have many questions:

1: Concerning an air filter. I ride trails often. I ride in water, jump just a little, drag race, and dirt roads. What's a good one for me? Also, what's a good lid to go with? My stock one fills up with water often.

2. Should I find a jet kit somewhere to buy, or buy the jets seperately due to the price, even though I have no idea how to install them.

3. If I did buy them seperately, are they hard to install? How much would it cost to get them installed?

4. What's this "fuel screw" and where can I find it? Do I have to buy it? How's that whole thing work.

I live in Missouri, so the elevation jumps around, since there are hills everywhere. So, anything you want to add for extra advice, please feel free.

Thanks, guys.

[BrettOaktree]

i ride in similar conditions minus the water and i have a k&n with the pre filter, i like it, but i dont have my lid on so i dont have suggestions on a lid, and i think you should buy a jet kit just to get a good base, i got an fmf jet kit and it had really good instructions so it was kind of a jet kit for the average newbie like myself, and after that if u start doin more mods most of the time you only need to up your main jet so u can just buy those separately after some time, and id do it yourself its really not that hard to jet if you have good instructions and my fmf kit told me how to get to the fuel screw and how to adjust it.

But im wondering if my setup sounds alright to you guys?

Hmf sport series slip on, airbox lid off with a k&n and a prefilter, and the cam mod done

The elevation around here usually floats between 0-1000 feet depending on where i am, im looking for a good all year round setup the temps now are around 70-85 and in the winter the only time i go out is if its atleast 30. Right now im running a
48pilot
165 main
needle on the 3rd position
1 turn out on the fuel screw

feel free to leave your opinion, thanks