I was skeptical about the carb swap, but then I found one for a good price on ebay, so i figured i give it a try (FCR40). I finished the conversion, and even though I'm quite rich on my main and pilot jets, I have found the carb to be even more responsive than the stock carb, which i thought was going to be impossible to do. I can't see it being better in all out drag race, but I can see how guys on the mx tracks might like it. It seems as if it has more torque, and revs a bit quicker and maybe a slight gain up top. Its not worth the $800 baldwin or others charge, but it is a very responsive carb. I would normally figure that stock 42 makes better top end, but this carb definately seem comparable if not better on top. I did notice that i was downshifting quite a bit less than normal, which i was attributing to the added torque and throttle response which was helping lug out of the improper or too high gear. I like it!the stock carb is larger than the fcr so even accuonting for slight volume loss by the choke and low speed butterflies it should at least be a match for the fcr.
in zillions (that's a lie it's probably only millions) of dyno runs i have always found that the least amount of power gain comes from the carb upsizing. and unless you have done ALL the other mods, especially porting and cam, the gain is almost nothing in most cases. a notable exception is replacing the ltz400 dismal stocker with a fcr.
usually it tops the list of most spent for least gained. unless of course you are using a fcr for the easily obtainable jets to run on alcohol vs the stock carb. is that what all the interest is about?[/b]
call Sudco at sudco.com. That's where I got my 39mm FCR carb. It comes with a billet ring that go's right to the stock air box with not having to do a thing to it. The only bad thing is between the carb and the ring it was $600!Originally posted by 04450r@Sep 7 2004, 09:40 AM
is there a company out there that makes an adaptor to run the stock 450r air boot with the fcr carb?
Here's what I have. Of course, altitude, climate and everything else matters but here's what I have. I have the same setup as you except for the ESR!! Hope this helps!Originally posted by Holeshot13@Sep 12 2004, 11:29 PM
My carb just came in and I was wondering if anyone could get me in the ball park with the jetting. I have HRC cam, Yoshi pipe and an ESR intake