fcr carb help and advice

[gibson450r]

i just rebuilt my 04 450r motor did high comp piston sparks mx cams sparks exhuast valves and intake valves sparks full pipe it pulls unbelievable in low and even better in mid 2 seperate ppl have ask me why i dont run the fcr carb off the crf what r the advantages of it for mx will it really make a difference and what is needed to make the conversion thanks everyone

[d3ktrix]

Mostly just added throttle response.
Personally I've never seen a dyno sheet that proved they added much if any peak HP. Boring might change that though, not sure.

Once I finish my build I'll let you know how I like my 07 CRF carb.

To do the conversion with your stock 04 air box you will need a NOSS machines adapter.
http://www.nossmachine.com/honda_quad_parts.htm
Or something smiler.

You will also need to change the plug on the TPS to be able to plug it into your 04 harness. (Use the plug off ur stock 04 carb, they unpin pretty easy.)

Some people use 06+ air box's instead of a NOSS style adapter. I borrowed my friend 06 airbox to test the fit before I bought one, and I goda say its a horrible fit that you'd have to ghetto rig to make work. Even then it would never be perfect. I said heck with that and ordered a NOSS adapter.

[rt20ps]

I don't think the fit is as bad as you say. Here is an 04 with an 06 box and 07 CRF carb.
http://img337.imageshack.us/img337/7359/200703160001hm8.jpg (http://imageshack.us)
It almost bolts in the stock location.
http://img529.imageshack.us/img529/7001/2007021100015ci4.jpg (http://imageshack.us)
http://img529.imageshack.us/img529/7001/2007021100015ci4.e2da086752.jpg (http://g.imageshack.us/g.php?h=529&i=2007021100015ci4.jpg)

[patrickj75]

taper boring an FCR carb really helps. i had an 07 crf FCR taper bored to 43mm by Chad at DRG. that setup on a built motor can see almost a 3hp gain.

[chad502ex]

thanks patrickj75.

Everything you say is true.

The 07 CRF FCR taper bored from 41mm to 43mm is an awesome modification.

I've been doing these carbs for the 450R's for years now and now other OEM applications too. I've just started getting into the KTM scene too. The KTM is a sweet setup but the FCR is really inhibited from factory; especially, on the 525.

Its really an awesome carb and many have already felt the benefits

[patrickj75]

Originally posted by chad502ex
thanks patrickj75.

Everything you say is true.

The 07 CRF FCR taper bored from 41mm to 43mm is an awesome modification.

I've been doing these carbs for the 450R's for years now and now other OEM applications too. I've just started getting into the KTM scene too. The KTM is a sweet setup but the FCR is really inhibited from factory; especially, on the 525.

Its really an awesome carb and many have already felt the benefits

Chad,
i'm planning on sending you my KTM 450xc carb to bore to a 41mm. probably around april when i do other mods. can you do the carb spring mod to lighten the throttle?

Patrick

[chad502ex]

Originally posted by patrickj75
Chad,
i'm planning on sending you my KTM 450xc carb to bore to a 41mm. probably around april when i do other mods. can you do the carb spring mod to lighten the throttle?

Patrick

yea,... i'd like to physically inspect your carb before I machine to be absolute that the 41mm rings I have will work.

I'd have to check my supplier for softer springs.

[patrickj75]

Originally posted by chad502ex
yea,... i'd like to physically inspect your carb before I machine to be absolute that the 41mm rings I have will work.

I'd have to check my supplier for softer springs.

i know Baldwin and a couple other people are doing the spring mods now. i haven't rode mine yet so i'm just assuming i'll want it done.

[gibson450r]

hey thanks for the info k3 let me know how yours works. the motor side of the carb then bolts right on to the stock boot the adapter from noss is for the air box side is this right

[d3ktrix]

Originally posted by gibson450r
hey thanks for the info k3 let me know how yours works. the motor side of the carb then bolts right on to the stock boot the adapter from noss is for the air box side is this right

Yeah the motor side stock air boot works fine.
The NOSS adapter goes on the air box side like you said.