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setting the carborator
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Posted by: Bdav450

i just added a hmh ironman pipe and a fmf jet kit on my 2008 yfz450. the bike has a stock 155 main jet i put in a 150 jet i live in Louisiana and when we start the bike it wont idle and the only way it will is if we sit on the gas but when we do that it back fires like crazy please help what should i do

Posted by: Bdav450

i just put it on today im like 12 feet above sea level what should i do to get my bike going good again

Posted by: mxpimp2000

start with 168 main 46 pilot and 3rd clip on needle and 2 turns out on ur fuel screw should be close and 150 main is WAY to small

take ur air box lid off also will give you alot more power with the pipe.

im 500-650ft above sea level with hmf full system i have 175 main 50 pilot, in ur case the higher u are above sea level the lower number on ur jets will be, but a 150 is super lean and ur hurting ur engine running it like that

Posted by: Ride1Rob

Pimp, you have to remember to on your setup. You can't compare his carb setup to yours in terms of what you're running and what he should be running because of the motorwork. The 168 should be a good basis to start at though.

Also, I thought the higher you go in elevation the higher the jets normally are

. Ex. Cold/Less humid air is thinner and leans the bike as opposed to Hot/More humid air. I've always seen guys North of the South East run higher jetting (High 170's, 180's, and in some cases 190's). Exspecially in the mountains.

Posted by: Bdav450

yea its really humid down here all the time but in winter we might if we lucky get in the 20's or so but u think i should go with a 168

Posted by: yfzrider690

Well for one thing you have a jet kit so your numbers are gonna be different than most people that run keihin jets. And the higher you go in elevation the thinner the air is so you would run a smaller jet. Jet kits are a waste in my opinion. Also there is no 46 pilot. Stock is a 42 and most people run a 45 or a 48. If I were you I would go get some keihin jets and the ncvq needle. The needle is only 15 bucks and the jets are about 4 bucks a piece. I would start with a 45 pilot and a 168 or 170 main and 3rd clip down from the top on the needle. It sounds like you are lean that's why your bike won't stay running. It needs a bigger pilot jet. The pilot controls idle to 1/4 throttle, needle is 1/4 to 3/4 and the main is 3/4 to wide open. Also set your a/f screw to about 1 1/2 turns.

Posted by: mxpimp2000

well mine suggestion was almost 100% although i did give him the basic starting point because that setting will get it close with some minor adjustments here and there atleast it would be terriably lean

Posted by: Bdav450

I have the fmf jet kit I got it from motosport the largest jet says 162 so I'm going to to buy a few bigger 1s but I changed the main jet adaptor so will the kilhin jets still fit that

Posted by: mxpimp2000

your best bet would be going to a dealer and buying seperate jets they are 1.99 here at my dealer. i would get 165-172 mains and 45-50 pilot just to have them when gettin it right it takes a while to get it perfect but take ur time

Posted by: Bdav450

Will these jets fit the fmf main adaptor you think

Posted by: mxpimp2000

i wouldnt use a fmf adapter if ur buyin stock jets you dont need the adapter

Posted by: Bdav450

Do you know a website I can order them from andif I ordered them would I have to get a new adaptor or would I even use one

Posted by: mxpimp2000

ive never even heard of a adapter. to me there isnt one in my carb. people tell me www.jetsrus.com but now www.rockymountainatv.com sales jets and they are pretty good company to order from i always get my items in timely manor and prices arent bad either

on jetsrus.com you want the following:

KEIHIN HEX MAIN JETS

and the pilots are KEIHIN SLOW JET N424-21

on rockymountainatv you would search for:

Pro X 99101-357 Series Keihin Hex Main Jet

Pro X N424-21 Series Keihin Pilot Jet

you will have to enter you machine brand year and model

Posted by: Bdav450

How do you know the sizes

Posted by: mxpimp2000

theres a list of jet sizes to order ill try to send u a link

http://jetsrus.com/main_page.htm

click the keihin logo on the right of the page then select the keihin hex main jet and it should bring up a list of sizes

Posted by: Bdav450

I'm going to get them from rocky mountain but the adaptor it holding the main jet into the carb

Posted by: mxpimp2000

idk what ur saying. get some pics or something

Posted by: Bdav450

Its above the main jet witch is why it sticks out further down then the piolet

Posted by: Bdav450

i ordered 165-180 main jets and 45 and 48 pilot jets i think the right combo of the two are in there just going to take some trial and error

Posted by: mxpimp2000

ok i found a fmf jet kit on ebay and yeh those jets are funky looking take that adapter out and dont use it anymore

Posted by: Bdav450

so u dont have a adaptor you just put your jet straiht in

Posted by: mxpimp2000

quote:
Originally posted by Bdav450
so u dont have a adaptor you just put your jet straiht in

yep, from the way it looked the adapter looks like a stock main with a tip that takes a smaller jet, idk why or who would wanna make something so difficult but stock jets dont need any adapters

Posted by: Bdav450

but then i took the main jet out from when it was stock it had one but with these new jets i ordered i wouldnt have to have it is that what your saying
but thanks for all the help its helped me alot

Posted by: yfzrider690

Take a look at this microfiche for your carb. It is what a stock one should look like. If you are missing any parts then i would get them ordered
http://www.yamahasportsplaza.com/pa...nd/default.aspx

Posted by: Bdav450

I'm not missing any oarts I just changed the stock main adaptor with the fmf main adoptor the kit came with

Posted by: quadboy-55

you seem a little clueless on the whole jet thingie. the stock main jet, aswell as other main jets from Keihin do not have adaptors, they will not work with an adaptor. they just go right in, they are not round, they are long and 6 sided.

the FMF jwet kit is the same as a Dynojet kit. they have an adaptor to add a jet with a screw driver instear of a 7ml socket.

so, there is no such thing as a stock main jet adaptor.

PLZ, someone draw this guy a picture or something!!!!!

in the pic you are bout to see, there is a pilot jet, needle and main, take a good look at it. thats a stock jet. no adaptor!

Posted by: Bdav450

thats all i needed to know thank u tho its my 1st time ever jetting a bike but im getting ride of the fmf jets

Posted by: quadboy-55

quote:
Originally posted by Bdav450
thats all i needed to know thank u tho its my 1st time ever jetting a bike but im getting ride of the fmf jets

nice.