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Discussion Starter · #1 · (Edited)
Looking for any and all fcr info, from jetting settings and mods, to part numbers ,ect.... If you know it about fcr' s lets share it here. Any thing usefull about fcr carbs will be appreciated.... I am sure others will be able to use in the future.. lets get some good info posted in one thread, all about fcr's ,35mm or 39mm .....
 

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Looking for any and all fcr info, from jetting settings and mods, to part numbers ,ect.... If you know it about fcr' s lets share it here. Any thing usefull about fcr carbs will be appreciated.... I am sure others will be able to use in the future.. lets get some good info posted in one thread, all about fcr's ,35mm or 39mm .....
Single plughead, HV Porting, stage 3 cam, open air box with white bros exhaust, dual 39mm fcrs, 11-1 wiseco piston...................
172 - 175 main jets, OCEMR needles, 55 pilots jets................Gasoline

3 plughead, HV Porting, stage 3 cam, open air box with white bros exhaust, dual 39mm fcrs, 11-1 wiseco piston...................
148- 152 mains jets, NCVQ needles, 48 pilots................Gasoline

3 plughead, HV Porting, stage 3 cam, open air box with white bros exhaust, dual 39mm fcrs, 11-1 wiseco piston, with two shims of head gasket removed...................
Main jets 225, OCEMR sanded and modified thinnner, 85 pilots..........Methanol...........


:D :D :D
 

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Single plughead, HV Porting, stage 3 cam, open air box with white bros exhaust, dual 39mm fcrs, 11-1 wiseco piston...................
172 - 175 main jets, OCEMR needles, 55 pilots jets................Gasoline

3 plughead, HV Porting, stage 3 cam, open air box with white bros exhaust, dual 39mm fcrs, 11-1 wiseco piston...................
148- 152 mains jets, NCVQ needles, 48 pilots................Gasoline

3 plughead, HV Porting, stage 3 cam, open air box with white bros exhaust, dual 39mm fcrs, 11-1 wiseco piston, with two shims of head gasket removed...................
Main jets 225, OCEMR sanded and modified thinnner, 85 pilots..........Methanol...........


:D :D :D
Great info Willykiller.I noticed that your jetting went down alot with the 3 plug head:)
I hope to get a set of FCR'S this winter....&a few other odds & ends...
 

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Discussion Starter · #5 ·
Thanks good info, let's keep it coming!
 

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Discussion Starter · #6 ·
Thumb trottle? Twist throttle? Best intake? Best rebuild kit? Fcr carb boring? Best filter set up? Any usefull fcr info......
 

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One quick comment to make is that it is crucial in your carb build to take into consideration the choice of actuation.
Thumb Throttle needs a far lighter return spring setup than Twist throttle.
I run twist.
I ran thumb for the first 3 years of riding the quad, but it was the one thing I really struggled with, everything else about the quad I loved, but the thumb........nada!

So I finally (against all advice) converted to a twist. First ride thought "oh my god everyone was right"
Every little bump & I was chopping on & off the throttle.
It still felt more natural to me, but the throttle was too easy to turn.
I got the bike home & jumped on my road bike to shoot down the road to the shops.

& then it hit me, the bike has a far stronger return spring on the throttle than the quad did.

So I changed the springing in the stock carbs. Trippled the return spring tension.
WHAT A DIFFERENCE!!!
I have now been riding with the twist for almost 2 years, & wouldn't go back.
I have ridden other bikes with thumb since & they just feel so unnatural by comparison....

So, get your carbs set up for how you want to actuate them early in your build, then you will be a far happier camper!
 

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Discussion Starter · #8 ·
The rubber boots inbetween carb. and trinity billett intake , part number m-vm36-200. This is a part number i needed so maybe it will help someone else. Lets make this a one stop shop for fcr info. Thanks
 

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FCR 35mm on a 727, 105mm bore with trail porting, stage 3 cam, dual exhaust 3 plughead, this is on my Rhino.............
152 mains, 63 pilots, with NCVQ needles................
 

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Discussion Starter · #10 ·
I will be installing 39mm fcr on my raptor in the next week or 2. I have a 719. 11:1 trinity port and polish , stage 3 hot cam , barker dual exhaust and no air box. Any seggestions on where to start my jetting out at. It came with a bag of jetts and neddles, so i should be able to get it right, but need somewhere to start. Thanks
 

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39mm FCR - 686 12.5:1 Piston, x4 cam, HV 3 plug head, Willykiller tunes, dual exhaust, Pro-design intake with no lid and UNI pod filters. Somewhere around 150 mains 48-50 pilots and running gasoline. Pulls stong with very good top end.
 

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I ran 52 on the pilots and 155 on the mains. It was a Barker HV ported 3 plug 720 with a sparks exhaust and no airbox with a K&N filter. 11:1 CR and a X-4 cam. It was rich on the mains with this set up but I never got it dialed in perfect befor the crank let go.
 

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Discussion Starter · #14 ·

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720 running 39 fcrs, dual monster exhaust 175-178 mains,k+n open filters with outerwears
webcam 685 cam,c12 50/50 pump gas,3rd positon of needle clip,cp 12:5:1 piston, 1mm bigger valves, trinity intake
 

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Discussion Starter · #16 ·
720 running 39 fcrs, dual monster exhaust 175-178 mains,k+n open filters with outerwears
webcam 685 cam,c12 50/50 pump gas,3rd positon of needle clip,cp 12:5:1 piston, 1mm bigger valves, trinity intake
Thanks , any hp numbers on that build? It's not far off from mine. I believe your cam is a little more aggressive than mine and +1 valves...... Wonder why all the three pluggers ruin so lean? I know better fuel burn, but that should just mean you could run more fuel, fuel =power ??
 

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Discussion Starter · #17 ·
35 vs 39. ?
 

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I was running the 35mmFCRs on my 720 with my standard size valve head. I believe the last time I tuned the carbs I put in 165-168 mains with 50 pilots and the needle on 2. I'm making the switch to a 13.5:1 kenz piston and my big head with the +1 valves and throats cut to 87% so I'll let you know if that made a carburetor tuning difference.
.....As soon as I get this piston fly cut for more clearance.
 

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Thanks , any hp numbers on that build? It's not far off from mine. I believe your cam is a little more aggressive than mine and +1 valves...... Wonder why all the three pluggers ruin so lean? I know better fuel burn, but that should just mean you could run more fuel, fuel =power ??
I havent dynoed it , i dialed it in at the end of last season, ive got two rides this year,
its as far as i want to go for now ive got a 4 inch longer swing arm and it does roll on 2nd gear wheelies, pulls strong on bottom and monster duels let it pull hard on top, as soon as i can ill dyno it, i was running 12 tooth front 41 rear sprocket, but went back to 13 frt
due to excess torque
 

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Discussion Starter · #20 ·
I was running the 35mmFCRs on my 720 with my standard size valve head. I believe the last time I tuned the carbs I put in 165-168 mains with 50 pilots and the needle on 2. I'm making the switch to a 13.5:1 kenz piston and my big head with the +1 valves and throats cut to 87% so I'll let you know if that made a carburetor tuning difference.
.....As soon as I get this piston fly cut for more clearance.
How much difference would the jetting numbers be on a 39mm carb? Does carb size alter the jet size, I would think so? With the same motor set up? Thanks
 
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