My question is, if I dont have any after market porting done but do have an xr 400 cam and a 10.5:1 piston could I still benifit from using a 39mm carb or would I better off going with a 36mm or should I jsut stay with the stock one until I can get a port job done? THanks-
Eddie

 

The 400EX head really needs very little work. It flows well right from the factory.

Yes, the FCR 39 would be a significant improvement over stock with your setup.

 

THanks Gabe,
I finnaly re joined your email group. The last company that I worked for closed my email account the day that they layed me off. Anyway, thanks for your input. I am hopeing that I dont have to do any port work to my motor. WOuld a 36mm still give me a noticeable difference?
thanks
eddie

 

Probably not, the stocker is a 35.5

An FCR 37 may do a little, but for the cost you might as well go with the 39...

 

I beg to differ, I have a 36mm lectron and it made a very noticable difference. About 5-8 Mph on topend and 5-6 bike lengths in a 100yrd run. Yes, I do realize that the carb is much more dificult to fit when compared to a FCR and it is not the most refined carb, but it does perform well.

 

Are fcr41's overkill, in your opinion, for a 440 alky? The reason I'm asking is because I'm considering this option. My goal is to squeeze the most out of the 440 with normal aspiration.

 

If your engine is wild enough, it will probably like the 41. Don't have any experience with it myself, but I believe GT Thunder has done quite a few - I'd talk with him.....

 

WOW! that is a very nice improvement! If you dont mind me asking, where did you get that andhow much was it? ANd what did oyu mean by "difficult to fit?" thanks-
Eddie

 

also, do you have any porting done?-
Eddie

 

Ya, I just dont want to go to over board. WHat I mean by this is I have heard to get the full use out of a 39mm FCR you need to have a port job done. I dont really want to do any porting or big boreing to this bike. I do how ever enjoy being able to go fast so I was hopeing that I could still be benefiting from this larger carb.-
Eddie