Does anyone Know Jack ***** about a 39FCR Carb????????

[frogburner]

My buddy HOT-ROD has been trying to get info out you all about his carb,,, It has completely confused him,,, He messes with Carbs all the time it seems like ,, but this thing has him stumped... Please help him out ,,, any advice would be helpful...

[Sandragggen]

I'm going through some jetting issues on my FCR41. I found this while searching for FCR39 Carb Tuning from Mike Wright.

Fuel Screw: 1.5 turns out
Slow Air Screw: 1.5 turns out
Slow Jet: #55
Needle Jet: OC-ELS 5th groove from top
Main Jet: #155
Main Air Jet: #200
Float Height: 9mm

Mike Wright
mwright@gss-inc.net

I don't know what other mods are done to this fellows EX but it might be a good start.

[frogburner]

thanks for the reply////// He has a DMC dual Alien exhaust, K&N filter no airbox lid... When you mat the throttle as fast as you can,, it misses pretty bad,, cant really tell if its too rich or lean... Very difficult Carb. to adjust..

[nakomis0]

I'll tell you this. If you messed with any fuel/air screw, or opened it up and messed with any screws inside... than you screwed up.

Now what you do is, call Keihn(sp) and ask them how many turns on this or that screw. They are super smart there and know the answer. You must do this, if you messed with them screws. Trust me you gonna mess with that thing for months if you don't.

After they fix that for you.. than just mess with the 3 main jets.. and more than likely you will be just messing with 2 of them 3.. the needle, and main, the stock pilot jet is correct for most apps.

those turns Sandragggen posted may be the correct turns, no clue. but like i said if them screws are off, than your screwed.

[Sandragggen]

Nakomis...how do the carb setters at Keihin know what kind of mods are in your bike. They set them up rich so you won't fry your motor. You will have to mess with the screws to optimize power output. The numbers I gave are only a starting place and like I said I don't know what kind of mods he (Mike Wright) has on his bike. All motors are different and will need different jetting to make them run right.

[nakomis0]

I think all them screws you turn an such are set at the correct setting stock. I had the problem where I was in there messing with everything. I had to call them and the guy was smart as **** and he got me fixed. He said just mess with the 3 main jets.

There was another guy on this bored with the same type of problem, he messed with it for months, He called them and got fixed right away.

You have to set the jetting up for your mods, But only use the 3 main jets. (pilot, needle & main)

I could be wrong, but that was my understanding. And they guys at Keihin are extremely knowledgeable and helpful, I was real impressed.

The problem also could be a bad carb. Mine would run rich no matter what jet I put in there. I took it to my mechanic the guy that built my bike, had to swap it with another FCR to find out something was wrong with my original.

And... its real easy to get an air leak where the intake side screws into the main body of the carb. Should use pipe tape, or lock-tite to seal it. Thats another common jetting problem with FCR.

Like I said I could be wrong, about turning the screws but that was my understanding, and it did get my mildly modded bike back in order.

[Extremeracer167]

call Johnny G at the carb parts warehouse!!!! He knows ALL about hese carbs, he had one on his race quad....b4 it got stolen!!!!!

[Sandragggen]

Eric at Sudco was the best help I've found. He backed what Nakomis said about not having to adjust the fuel screw, which is 1.25 turns out from seat. Shouldn't have to adjust the Pilot air screw or Slow air screw which is the same thing and is located under the bell on the filter side of carb; 1 out from seat. This came from the FCR41 Operating Manual.

Jay