FCRs aren't a pain to tweak if you buy them with the right needles, air jets, main jets, and pilots. I guess if you are starting from scratch, there are more "adjustments" than some other carbs that might make them seem tougher. I know that if you buy them from Craycraft, they are set up and ready to run. I bought my first set from Sparks because they were a little cheaper. Craycraft helped me get them dialed in while Sparks customer service left something to be desired, I bought my next set from Craycraft.

The edelbrock won't run with the FCRs on big motors and/or high rpm, it doesn't seem to flow enough.

You can adjust the FCR accelerator pump but most folks don't, it's pretty close as it comes set up for the Raptor.

If you are going to build a big motor later, suck it up and get the 39s now or buy a used set of 35s and sell them when you upgrade the motor.

 

I dont know how do it yourself you are, but the edelbrocks jetting/tuning is done witht the twist of a ****, rather than messing with a bunch of different jets. This is a very popular setup for the predators, and we are getting some good power gains.

 

My local Yam dealer just got in a Sparks X6 full stainless exhaust for the 660 Raptor, nice!!! Hmmm............
The Yoshi is a great sounding & performing exhaust but I can't see putting any bends in it for FCRs when I can just sell it.

Ubetrun, I am still on the fence about whether to get the 35's or 39s but I really appreciate the insight.....nothing like hearing it from someone with experience. Does CrayCraft make their own intakes for the FCRs?

I recently spoke to Sparks & they only offer the 35mm setup but the price is good. Their customer service for the FCRs may have been shaky in the past but they seemed to be real passionate about how to run them. They don't promote the 727 big bore due to reliability issues & thus don't promote the 39mm setup either. It sounds like you guys run it all the time with no problems though.

I guess I am leaning towards getting the 35s to improve my bottom end-mid & throwing in a S2 cam to move the power up a little. I agree I would be better off with the 39s since I absolutley love hill climbing, but unfortunatley I still have to do a lot of trail riding just to get to the hills. The trails can get pretty tight & technical & some of the locals I ride with don't want to spend all day at the hills. Personally, I like to climb every hill, ten different ways until I got nothing left, then I can accept getting back on the trails, but only to look for more hills, wooohoooo!!!!!

For those who ask, I do think the FCRs are worth $900 for a few more ponies. If you are already making good power, & you can add a few more hp, I say hell ya! You will always have the option of bigger bores & cams & etc etc. Just remember, though, a bigger bore is usually accompanied by another cam or head/valve work or resleeving or machining the cases or a new connecting rod & a total engine tear down, all of which can easily cost you $900 or more, even if you do the work yourself, so no matter what......you got to spend if you want more power!

I had good success with modifying the stockers & I still have one last mod I want to try with before throwing in the towel for the FCRs. Either way, I will let you guys know how I make out. Again thanks for the input & feel free to continue the thread, I think its a great discussion for those of us who still own an 01'...'05 Raptor.

 

Yes.

 

Ok, so I broke down & bought the HotRod +4mm stroker crank/rod & the associated 102mm CP piston. I imagine most of you will definitely recommend the 39mm FCRs now.......

I was also planning on replacing my stage I Hocam with a stage II Hotcam & some HD springs & a GYTR HD clutch setup.
Obviously the +4mm deeper stroke can benefit from the higher lift S2 cam & bigger carbs but what concerns me a little is the warning sticker that HotRods includes which recommends reducing the rev limiter from 9200rpm to 8200rpm. Its obviously a great way for them to promote Dyna ignitions but its also a good way for HotRods to cover their **** in case the whole thing flies apart whether over revving it or not.....

While looking at my 686 dyno, I made 40-45+ hp from 5k -8k rpm with a S1 cam so I can't imagine wanting to lower the rpm limit especially with a S2 cam. Add in the 39mm FCRs & this thing is definitely gonna make great mid-top end hp numbers so I can't imagine limiting the revs at all.

Thus leading to the argument; are you guys limiting your top end revs with a Dyna unit or just being careful not to over rev it yourself, or are you just revving it as though it were still stock? Anybody dyno this setup?