Just installed my FCRs today with whatever Sparks installed for jetting. I need some suggestions as to jets I should pick up and take along for a dune trip to get it dialed in. In my short back yard run I could tell it was gonna be a MF off the bottom, way better than stock. Of course not much you can see in a 20ft run. Just dont want to drive 2 hours to the dunes and have a quad that runs crappy on top or mid without being able to rejet and fix it. Thanks.

 

Sparks shipped mine with 145/148 and the needles on the middle groove. I couldn't get past mid-throttle until I moved the clips to the 2nd groove from the top. It ran great but still had a little break up at the very top end so I called Sparks for some advice. They said that they should have shipped with 142/148. I installed a 142 and didn't hear/feel any top end break up. I think I might still be a little rich though, it doesn't have the insane top end power it had with the stock carbs and 190/195, feels like it did with 195/200. I am running straight C12 in a 12:1, Craycraft P&P, full Yoshi, K&N no lid, ported UPP boots, and Hotcams Stage 2. If your setup is similar, I'd make sure I had a 140, 142, 145, and 148 with me and be prepared to make some needle adjustments. Yes, the bottom end of the FCRs is unreal:-) Did you have any install problems?

 

Can you get it to pull on the top better than the stockers? I see the bottom end all the time,some bikes i race that had fcr's take off out of the hole really quick. too quick...

 

Install was easy, I used 2 washers on the motor mount to clear the linkage and had a helluva time stretching the stock boots but other than that no clearance issues. I run a P&P head, hotcams stage 2 and 12:1 JE piston. In the quick short rev I had in my back yard I did hear break up in the top end but that was NOT under load. I didnt get much info from Sparks on the carbs current setup as I was told Curtis sets them up himself and he was out when I called. I'll pick up a few mains from my dealer and see how it goes.

 

Ran it for the first time today, not at sea level as I'd hoped but near it in the woods. I noticed that under load in 2nd or third if I gave it a little throttle and lugged it it was gurgling a bit. A very little thumb throttle input there, and it would clear up immediately if I punched it. WAY more bottom end than EVER before. Overall I'd give the carbs an A+ I know there's work to be done dialing them in but I can see the improvement already. I havent had a top end run yet but I'm hoping for the same amount of improvement there too. Also interesting is that without any chokes the FCR's seem to light right up every time without stumbling....I wonder why other carbs need the choke but the FCRs dont???

 

FCR's are pumper carbs right? Maybe that is the wrong term. But when you give it the throttle, motor not running or running, it squirts gas. That would be the reason if they do... I think anyway.

 

Yea they are a pumper and will squirt fuel 15' when they're off the quad. Immediate throttle response with my FCR41 on a 465EX.

JMiller