Jetting Help !!

[liljhall09]

I have an 04' 450r with a full sparks big core , uni filter , no air box lid. The quad back fires when letting off the gas. I checked the jets. It has a 118 main and 52 pilot. What should i do ?

[post450r]

118 sounds small i have a 04 same mods pretty much and i have a 185 main

[Sjorge450R]

holy chit! 118 with that setup!!!! thats a stock main jet. Get a 185 in there. Your motor will thank you!

[liljhall09]

alright ill try it. i was told to get a sparks jet kit or hrc kit. or could i just use stock needle with 185 main ?

[maticus]

im from ohio too so mine will be pretty close. im running a 185 dynojet main, not sure on the pilot but i know that you can run a stock needle but my buddies with a sparks still pops with the stock needle. i think its too fat, a dynojet needle is thinner so more fuel gets through. when you put the bigger main in you might have to put a smaller pilot in cause the pilot runs the whole time and the main just feeds the top, so when you fatten up the main on top of the pilots fuel flow it might be rich on top ( if that makes any sense)

[liljhall09]

so should i just get a sparks jet kit or hrc or dynojet ?

[maticus]

dont get the hrc kit cause i dont think it will have that many jets. and i think the sparks kit is the same as the dyno jet kit. i bought the dyno jet kit and it had needle pilots and a bunch of mains. get the higher stage kit though. mine had a couple that i couldnt even use cause they were too small.

[hendershot106]

just get the full sparks jet kit if your not familiar with jetting.... you will save yourself trouble in the long run...

[maticus]

hendershot are you stalking me:devil:

[hendershot106]

no dude i swear!!! you must be bored in an office like me!!!!! :( :D

[liljhall09]

so sparks jet kit ?

[maticus]

yeah you go wrong with the sparks

[Sjorge450R]

the sparks kits is the HRC kit i think. All the HRC kit is the 185 main, the needle and maybe the 50 pilot.

I ran a 185 with a open box, stock needel and stock pilot and my header changed colors(too lean). Polished my pipe back to where it should have been, but the HRC needle in and its good to go. Nice and gold color.

[post450r]

pick up the hrc carb setting kit part #16020-NLZ-651 it comes with hrc needle and 185 main you can pick it up at yamaha of troy for $24.01 just installed one on my 04

[liljhall09]

well i tried a 185 main and 50 pilot and its worse. so im gonna pick up the hrc kit tomorrow

[hendershot106]

u dont need either kit if you already have a 185 main and a 50 pilot...... just buy the hrc needle or the 05 crf450r needle and clip designated NCVQ (thats the sparks jet package needle) u can look it up on www.motosport.com

[liljhall09]

if i buy the hrc needle what clip do i want it on

[hendershot106]

3rd or 4th clip from the top when installed....

[Ody]

06 450R PUT HRC PRO-KIT EVERYTHING IS FINE, BUT THE HEADER IS GLOWEING RED BY THE HEAD
NOW IN MY RACECAR WE WOULD SAY THIS IS LEAN RIGHT?
BUT A FEW LOCAL MECHANICS TOLD ME THAT THIS WAS NORMAL THAT WHEN I RIDE IT THE AIR WOULD COOL THE HEADER OFF
WHICH JET ON THE 450R CONTROLLS THE RICH AND LEAN AT IDOL
THANK FOR ANY REPLIES.

[liljhall09]

Took it the atv shop to put in the hrc needle with 185 main and 50 pilot. Still backfires when letting of the throttle. Any ideas what it could be ? air leak ? timing ?

[liljhall09]

any help ?

[Ody]

timing.http://webpages.shepherd.edu/ghott01/valveadjustment/valveadjustment.html

[liljhall09]

well i think we have an idea. we checked the valves and the intake is way to tight, so the intake is staying open and sucking in air , we believe thats the problem, let u know tomorrow

[speedracer350X]

Did you by any chance replace the exhaust gasket at the header ( it's actually a copper crush type gasket) it's only about $2.45 or so, just look under your model year anywhere they sell OEM parts for your machine on the internet. Could be leaking at that point.