YFZ Carb Question

[bloodmoney23]

Hey guys, my bro just bought a pretty nice 05 YFZ. Its at his house so i dont have access to it right now and he is not to good with this stuff. I know the bike needs jetted, its actually pretty far off when it comes to jetting. What kinda carb is it? Mikuni or Keihin and what kinda jets does it have? I know it has a main jet, and a slow jet does it also have a leak jet and all that good stuff? Never cracked one open on a YFZ so just trying to figure it out for when i do jet it for him. And can anyone with similar mods give me a ballpark good start point on the jets to use with these mods. I know they wont be dead on but a good start would be nice. It has an ESR open alluminum airbox with UNI filter and full Alba exhaust. Thanks for any help.

try a 170-180 main jet and a 48 pilot. that should get you pretty close

[DarkRider3]

Do you suggest the GYTR jet kit? I am the YFZ owner that the original question was geared for.

i wouldnt buy the jet kit , my opinion. i can get the jets for you if you want. let me know.

[DarkRider3]

What would the cost be? I have 3 yamaha dealers within a 30 minute drive of me. I havent even pulled the carb apart yet. It sucks that its so off. My buddy just called me to go riding and I'm dying to ride the new bike. Let me know.

[#17YFZRACER]

the carb is a keihin 39mm fcr. re-jetting it is easy. i can have it done in under 1.5hours thats with taking the carb off, not bad. if you dont have a fuel screw id say get one.

you dont even have to take off the carb, loosen the allen bolt and the phillips head screw and rotate the carb. the nut on the botom i believe is a 17mm remove that and your jets are right there. dont forget to turn off the fuel. it will take you 10-20 minutes, tops

[DarkRider3]

Thanks guys... the only headache I've encountered to point is overtightened and stripped screws... I should have it motoring for this weekend.

i will let you know the cost of the jets tomorrow.i have a 170 main jet i will give you for free. it was a spare i never used

[bloodmoney23]

alright, well, is there any possibility it could hit the 180's? Cause I have the jets for 182-200 for my 05 450R and they are keihin so if anything i should just pick up 170-180 as well. We are not to worried about the main jet though. Its the needle, slow and leak. I have a 48 slow a 50 slow and a 52 slow. I dont have any leak jets and as far as i can tell it dont have an aftermarket a/f screw. The bikes at my house now and im about to rip it apart. It had a 170 main and i have to go out and rip it apart to find out the rest. Whats the stock jetting on these bikes? Cause if the guy was riding it for a while with stock jets and everything im affraid to see what the piston and valves look like. Im figuring a little black. I mean this thing shoots flames out about 2 ft on decel. That was my first guess that jetting was jacked. Anyway, if you guys could let me know stock jetting that would be great.

[bloodmoney23]

Alright so what we were working with was
Needle: Stock
Main: 170
Slow: 42
Leak: 90

That sound like its a little bit off for the leak but like ive said, never messed with the FCR yet or a YFZ. So if anyone can let me know what stock jets are that would be awesome. I know the slow will have to go to at least a 48-52 and the main possible a 175 or so. Thanks for any assistance.

the stock jets are 158 main , 42 pilot

Originally posted by bloodmoney23
Alright so what we were working with was
Needle: Stock
Main: 170
Slow: 42
Leak: 90

That sound like its a little bit off for the leak but like ive said, never messed with the FCR yet or a YFZ. So if anyone can let me know what stock jets are that would be awesome. I know the slow will have to go to at least a 48-52 and the main possible a 175 or so. Thanks for any assistance.

if you increase the pilot to a 48 and a main to about 175 you should be pretty dam close on the jetting

[bloodmoney23]

good call scrimmy. I just finished up and we finished with this setup and it runs smoothly and beautifully through bottom mid and top.

Needle: 4th clip
Main: 172
Pilot: 48
Leak: 90
A/F Screw: 2.5 turns out

Plus i just ordered him the aftermarket MSR a/f screw. Thanks for all the help man.

not a problem blood, glad i could help. if you guys need any parts i can get them about 30% OFF of cost

[bloodmoney23]

well we do need 05 stock rear black plastics mint condition. will trade for like new laker rear plastics.

[DarkRider3]

Scrimmy,

YFZ subrfame? I hear $100???? Can you get to me by Friday?