Allright gentleman, got a question for ya`ll.

I laid off my Banshee for a day or two to help a newcomer to the ATV world get his bike dialed in. I`m a 2-stroke guy at heart...but jetting carbs IS NOT new to me. But rather than start from absolute scratch to dial this bike in, I thought I may call upon you all for a nice baseline to start off with. I understand each bike is different as well as geography. Just a general concensus is really all I`m after.

Mods:
`04 YFZ 450
K&N in the box but without the lid attached to Pro-flo.
Full Trinity exhaust.
Stock pilot and needle (3rd clip) 180 Main-jet <--- Genuine OEM jet (99% sure its not DJ)
Dyna digital ignition, CURRENTLY set in the stock setting for baseline jetting purposes.
The rest...IS STOCK.
800 ft above sea level
93 octane.
General/Play --> intended usage.

The bike hauls out nicely in the 4K to 10K RPM range and only shows signs of needing a pilot change and/or needle adjustment due to a hiccup/hesitation in the idle to 1/3 throttle range. If I stab the throttle as quick as I can off idle.....it stalls and sometimes can be a bitch to get to fire again....cranks and cranks then reluctantly fires up again. I`m thinking lean because when I pull the chike to 1/2 throttle it doesn`t stall and only hesitates a little. Fuel screw adjustment does not correct the situation.

I`m leaning towards a 45 <-----> 48 pilot. WHAT DO YA`LL THINK?

I also ordered the NCVQ needle and it`ll be here by Friday. What clip position? 3rd or 4th? (and this kinda sounds silly but, when you reference needle clip position it is "3rd" from the TOP or the BOTTOM?) [img]i/expressions/face-icon-small-blush.gif[/img] [img]i/expressions/face-icon-small-smile.gif[/img]

While we are on the subject...what Main do you think would be a good starting point at 800ft say... 70 deg for these mods?

Secondly, (as if that wasn`t enough) for those of you whom have changed the cam timing to match that of the dirtbike....what did you feel after the mod was completed? Was it worth doing? Did it shift some of the power in the RPM range around, as in robbing Peter (down low) to pay Paul (up top) ?

Thanks alot,
Chris

 

I think the main 180, may be a little big for a stock engine. 170 to 175 is about the biggest for stock. I have lte dual exhaust, K&N pro flow, lid off. and run a 48 pilot, 170 main stock needle in 5th groove (from top). there are seven grooves. you can only use the first 5 without grinding off the top of the needle. the screw on top will come into contact with the top after the 5th groove. the 3rd groove on a NCVQ is the same as 5th on stock. I had a 60 pilot to start with. way to rich. also the mix screw should be changed to a longer thumb screw type. unless you have the special tool for adjusting the stock one. mine is set at 1.5 turns out. seems to work good with these settings. I think someone else in this area. (oregon) 0-800 ft. is running 45 pilot and 168 main. they are also happy with that setup. the stock 42 pilot sucks as soon as have different exhaust on. I have not done the cam mod. bit, it does seem a little week down low.

 

Your mods go with 172main,45pilot, 4th clip ncvq, the numbering on needles are the top one is the 1, goes top to bottom. If you have cam mod bump the pilot to 48. Im running 172,45,4thclip, 200-800 (dumont), mods are ESR full exhaust, and ESR intake removed airbox.

 

I'm running 170 main, 45/48 pilot jet, 1 1/2 turns on air/fuel screw, NCVQ neddle 4th from top, K&N pro flow with EHS air box lid, HMF full exhaust with quite core, CAM MOD
This set-up works very good on my 450 and it pulls hard from bottom RPM to top RPM, no problems at all.......

 

Wow...Thank you all for your quick replies...they will DEFINITELY help. [img]i/expressions/face-icon-small-happy.gif[/img] And now that I have seen just how EASY the feul adj. screw is to get to...I`ll be sure to get the extension thumb type replacement unit. Best place to pick one of them up?

BigDaddy660R......you have the cam mod.....what...exactly, did you feel with the change in cam timing? Was it a seat-o-pants change/improvement? If so how/where in the RPM range was it most noticeable?Or...just something that you "think" you can tell the difference in? LOL Kinda like putting one of those"Tornado" product into the intake tract of a 200K mile `87 Ford Escort ! [img]i/expressions/face-icon-small-wink.gif[/img] [img]i/expressions/face-icon-small-happy.gif[/img]

Thanks guys.

 

picked my adj/mix screw up at the local yamaha shop. I have seen them on ebay also. the one I saw on ebay is kinda cool looking. anidized blue aluminum. mine is brass and has a small roll pin through the knurled part for better grip and referencing.

somebody posted this earlier. it has some videos that I found helpfull.

 

Do you have the part number for the air screw, or the manufacturer. Went to get one from the shop here and all they told me is that they only have the stock screw and don't know of any others.

 

There was a big difference in the bottom end performance. It's a very simple mod to perform go to the DADOG link that is posted and they walk you thru with videos and instructions.

 

I am pretty close to what some of these other guys are running. For reference, here is my jetting:

DR. D slip on
Air box lid removed
172 main
45 pilot
stock needle 5th clip position
fuel screw 2 1/2 turns out

Hope this helps[img]i/expressions/face-icon-small-wink.gif[/img]

 

Ditto for me except I have the GYT-R jet/ needle and running Elf Race Fuel