carb preferance

[sburton1]

what carb is a better up grade a 39mm fcr carb or a 450r carb? just curious seems to be a little contoversy here!

[GPracer2500]

Controversy? I haven't noticed that.

My opinion is that the 04/05 450r carb (42mm piston valve) is probably the best bang for the buck out there for upgrading the EX's stock carb. But the performance of an FCR39 will be difficult to match with anything else that's available. Take your pick.

38mm piston valve (stock) = adequate performance, best value (free!)
42mm piston valve = good performance, good value
FCR39 = great performance, expensive

[sburton1]

ya not contoversy on this web site just trying to hear a little from the pros thanks for the info!

cole

[krt400ex]

the fcr is easier to work on too. and its easier to fine tune

[hondaexryda]

What about tuning a YFZ FCR39 on a 400ex, will the 400ex boot work with the YFZ FCR

[krt400ex]

Originally posted by hondaexryda
What about tuning a YFZ FCR39 on a 400ex, will the 400ex boot work with the YFZ FCR


the carb will work, but i don't know 'bout the boot

[XCRacerwanab29]

well as far as the yfz fcr working on a 400ex you have to bore the engine boot out a little and change up a few other things to make it work but right now I'm having issues getting jetted right b/c I'm not running an airbox so if anybody knows where to start any help would be appreciated

[CHEVYZ]

450r carb is the best bang for the buck, the FCR is (Arguably) the best in simply making power. Deonds on what road you want to go down, really. I know people using both right now, and to be honest, we all can agree that each perform very well. It is really simply personal opinion as to whether it is worth it in your eyes to get the 450r carb as compared to the FCR.

[krt400ex]

Originally posted by XCRacerwanab29
well as far as the yfz fcr working on a 400ex you have to bore the engine boot out a little and change up a few other things to make it work but right now I'm having issues getting jetted right b/c I'm not running an airbox so if anybody knows where to start any help would be appreciated


r u talking about ur yfz or ex. ur sig says that u sold the ex, so i'm a little confused

[XCRacerwanab29]

I'm talking about putting a yfz carb on a 400ex I sold my ex but a friend of mine has one and we just put a yfz carb on his and it woke it up alot I don't know how the 450r carb works but the fcr 39 is nice the only thing I can see that's going to be a problem so far is the gas tank sometimes hits the top of the carb and makes me think that its not gonna seal right with the motor and the air box setup would be an issue but we dont have one so we don't have to worry about that

[krt400ex]

Originally posted by XCRacerwanab29
I'm talking about putting a yfz carb on a 400ex I sold my ex but a friend of mine has one and we just put a yfz carb on his and it woke it up alot I don't know how the 450r carb works but the fcr 39 is nice the only thing I can see that's going to be a problem so far is the gas tank sometimes hits the top of the carb and makes me think that its not gonna seal right with the motor and the air box setup would be an issue but we dont have one so we don't have to worry about that


ok. what was ur jetting before u put on the FCR and removed the airbox?? did u have the lid on or off before u removed the airbox, and what mods r on the ex that ur working on

[XCRacerwanab29]

well we put the fcr on at the same time as pulling the airbox but I think we pretty much got the jetting now after searching on here for a little while but its a 426 with the 11:1 wiseco, k&n, and slip on hmf but I've got the jetting close just have to fine tune it now to get it perfect but I'm running a 50 pilot, 155 main, and 2 turns out on the fuel screw seems to be kinda close but like I said I'm gonna play with it here soon

[krt400ex]

Originally posted by XCRacerwanab29
well we put the fcr on at the same time as pulling the airbox but I think we pretty much got the jetting now after searching on here for a little while but its a 426 with the 11:1 wiseco, k&n, and slip on hmf but I've got the jetting close just have to fine tune it now to get it perfect but I'm running a 50 pilot, 155 main, and 2 turns out on the fuel screw seems to be kinda close but like I said I'm gonna play with it here soon


r those Keihin jets? because if they r a 155 main sound way too lean for a 426.

[XCRacerwanab29]

yeah they are and I might go to the 160 but we were running a 165 with the stock carb and a 42 pilot but with the bigger carb it was rich with the 165 so I dropped it to what I had on hand the 155 so I might go higher just have to determine if we're lean or rich just haven't had the time to work with it

[krt400ex]

Originally posted by XCRacerwanab29
yeah they are and I might go to the 160 but we were running a 165 with the stock carb and a 42 pilot but with the bigger carb it was rich with the 165 so I dropped it to what I had on hand the 155 so I might go higher just have to determine if we're lean or rich just haven't had the time to work with it


ya, i would def. go with the 160.....at least a 157, but that's still a little lean

[XCRacerwanab29]

its easy to say that but according to the bike its not the plug is a dark dark brown almost black color and when I finally do decide to rejet perfectly I'll put a new plug in and go from there