I'm laid up with a busted hand and trying to find things to "fix" on my Raptor while I can't ride. Yeah, I got the itch something fierce!!:-) I put FCRs on shortly before I screwed up my hand and haven't had a chance to do any plug checks. 142/148 and needles on the 2nd groove was a little rich at the very top end, I couldn't feel it but heard it when another guy was riding my Raptor. I talked to Sparks and they said to try 142/148. I changed the jets and didn't notice any top end stutter but when I raced my buddies Banshee, I didn't smoke him quite as bad as I did with stock carbs and 190/195 mikuni needles/jets. I suspect I am still a little rich on the top end. My mods are:

full Yoshi comp
Craycraft P&P
JE 12:1
Hotcams Stage II w/Kibblewhite springs
K&N w/14mins adapter and no lid
UPP carb boots ported to match head
Straight VP C12 fuel
35mm FCRs 142/148 2nd groove

Anyone else running a similar build? What are your FCR specs? Thanks!

 

bump

 

im running 145 mains in both, third clip from the top in both. Unocal 110. Uni Pod clamp ons w/ outerwears. 12:1 JE. Megacycle 280x4, trinity headwork,graydon pipe with 18 disks. OCGMR needle, 170 main air jets.

 

not to be rude, but if you didn't beat him as bad as with the stockers, sounds like there should be lots of room for improvement!!!! if the fcr's didn't give a good top end boost, then they are a waste of time and money.

 

The more I think about it, it runs like it did with 195/200 in the stock carbs, strong but not screaming. With 190/195 in the stock carbs, the top end was unreal and I would just blow by my buddies piped Bansee. I REALLY want to try 142/145 but I'll do a plug chop first with 142/148 to be safe. FWIW, I spent the money for FCRs to get consistency, any extra power is just icing on the cake. Besides, I don't know if I can handle any more power than this thing produces on a MX track:-)

I just re-read my first post - I meant to say that they shipped with 145/148 and Sparks told me to try 142/148. Sorry for any confusion.

 

are those mikuni jets, dyno jets or different jets all together that are used in the FCR's?

142 to 148 seems small for dynojets in a 35mm carb

 

They are Keihin (sp?) jets, not the same as anything that fit in the stock carbs.

 

This probably will not help you at all but I had it and it might.
FCR tuning...but for bikes
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I have a simular set up and I am using 140-142 mains, 200 air jet, gmp needles on 4th notch with Ultimate 4 and I'm still a little rich.