FCR 35 Carbs

mgentz · September 11th, 2013, 08:07 AM

Does anyone have these? thoughts? dyno results? etc.....?

quarterliter · September 11th, 2013, 03:11 PM

Well I can't tell you anything specific that you don't already know. I'm guessing the're not a CV carb so throttle response should be better. Also the larger opening will flow more air if you have accompanying head work etc. So better throttle response more power if jetted right. Only downside is cost. Are you running a non oring chain? Its an easy way to pick up a few horses.

KawiKid860 · September 11th, 2013, 03:43 PM

Everyone says the FCR carb on the DRZ400 is basically the best mod you can do to it so it may be worth it on the ninjette. CV carbs kind of suck ass, the FCR should respond to mods better, as well as have much better throttle response.

mgentz · September 11th, 2013, 05:11 PM

Yes I have a non oring chain and plenty of mods. My stock carbs are not responding cc well and I will most likely upgrade.

Many people have the cr31's but I want an accelerator pump and the extra flow.

quarterliter · September 11th, 2013, 08:38 PM

Makes sense. That would probably be a good choice for you then. I wish I could help you more with dyno charts but I haven't found any. I would be interested to see the improvement over stock carbs.

ninja250r81 · September 12th, 2013, 03:27 AM

do you mean these??

Sudco Introduces Keihin CR31 Carb Performance Kit for Kawasaki 250 Ninja
Sudco International continues to expand its extensive product line of high performance carburetors kits for street and dirt bikes with this new dual carb Keihin CR31 Kit for the latest 2008-09 model Kawasaki 250cc Ninja street bikes.

The Keihin Special CR is a pure racing carburetor featuring a larger than stock smoothbore venturi for high air flow and precise fuel meeting. This CR Kit provides for increased horsepower, particularly when combined with other engine modifications. This CR twin carb kit will work with the stock Ninja throttle cables and can run with modifications to the Stock Airbox, with separate Clamp-On Filters also available from Sudco, or with the tuned Velocity Stacks provided in the Kit.
Sudco Part No. 016-3205 for the Keihin CR31 250 Ninja

http://www.sudco.com/NewProducts02.html

mgentz · September 12th, 2013, 04:38 AM

Those are the ones people usually get. They also offer fcr 35 carbs.

I will try to get a pic and post it.

choneofakind · September 12th, 2013, 06:52 AM

Mike, I think you know more than me here, but hear me out.

35mm carbs have a larger diameter. This would let in more air, but would it not also lower the intake velocity? Even the ninja 300 (which has 34mm TB's I believe) has a secondary set of butterflies and a taper inside the TB to control intake velocity at small throttle openings. I've followed your build and theory on your engine and I know your engine is sucking in more air (think that's why the 28mm stock carbs are limiting you, not enough air volume in the given time), but would you be better to use the 31's than the 35's to keep the velocity up?

Idk, I'd have to see some math to really give any definite help on 35's vs 31's. Every idea I've got is just speculation.

Somchai · September 12th, 2013, 07:18 AM

Quote:

Originally Posted by choneofakind

Mike, I think you know more than me here, but hear me out.

35mm carbs have a larger diameter. This would let in more air, but would it not also lower the intake velocity? Even the ninja 300 (which has 34mm TB's I believe) has a secondary set of butterflies and a taper inside the TB to control intake velocity at small throttle openings. I've followed your build and theory on your engine and I know your engine is sucking in more air (think that's why the 28mm stock carbs are limiting you, not enough air volume in the given time), but would you be better to use the 31's than the 35's to keep the velocity up?

Idk, I'd have to see some math to really give any definite help on 35's vs 31's. Every idea I've got is just speculation.

Very good comment Chon

In one case please let me correct you, the Ninja 300 TB's are 32mm.
With a 35 Carb the driveability in high revs maybe would be possible but I think below 6000/7000 rpm this would not work.

choneofakind · September 12th, 2013, 07:26 AM

Ah, 32mm. For some reason I had 34mm in my head.

mgentz · September 12th, 2013, 07:37 AM

Attached are the pictures of the FCR 35's.

I believe the 35's taper and/or the boots are specially made to taper in as I have been assured that the match/align.

***this is not my bike, but instead the test bike the sudco used***

mgentz · September 12th, 2013, 07:39 AM

here are some pics of the cr31's

***this is not my bike, but instead the test bike the sudco used***

mgentz · September 12th, 2013, 08:52 AM

Here is my problem: when I slowly open my throttle now the motor coughs/bogs then accelerates. When I hold throttle steady she can studder (jetting lean). She is a b#/&* to start and only accepts choke when it is cool to cold outside...any other time kills it instantly (suggesting too much fuel). At high rpm low throttle situations she is rough getting back on the gas.

Much of this would say jetting if each piece was looked at seperately....however all together I think they point to carbs that cannot handle the motor and its dynamics.

I have gone through them a lot and I even had a trusted tuner go through them.

bruce71198 · September 12th, 2013, 10:50 AM

How did it run with the stock carbs?

mgentz · September 12th, 2013, 11:23 AM

that is how it runs with the stock cv carbs.

I am thinking that I need to upgrade. In talking with @Racer x, the tunability of these will be MUCH better. I am simply trying to see who, if anyone, has them.

bruce71198 · September 12th, 2013, 12:13 PM

Oh, I thought those pictures where of your bike. I would run the FCR's over the stock CV. Especially with the engine mods. My experience has always been positive when switching away from the CV's.

mgentz · September 12th, 2013, 01:12 PM

Not yet. Those are the test bikes that Sudco used and they show that these carbs will fit the stock airbox.

mgentz · September 13th, 2013, 01:08 PM

See poll thread:

http://www.ninjette.org/forums/showthread.php?t=149608

I assume no one has these as I have received no answer.

September 11th, 2013, 08:07 AM	#1
mgentz Board Member Name: ... Location: WI Join Date: Dec 2011 Motorcycle(s): 250R (street), 250R (dirt) Posts: A lot.	FCR 35 Carbs Does anyone have these? thoughts? dyno results? etc.....?

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September 11th, 2013, 03:11 PM	#2
quarterliter ninjette.org guru Name: Kevin Location: Madison Join Date: Apr 2013 Motorcycle(s): 2004 Ninja 250 Posts: 465	Well I can't tell you anything specific that you don't already know. I'm guessing the're not a CV carb so throttle response should be better. Also the larger opening will flow more air if you have accompanying head work etc. So better throttle response more power if jetted right. Only downside is cost. Are you running a non oring chain? Its an easy way to pick up a few horses.

September 11th, 2013, 03:43 PM	#3
KawiKid860 ninjette.org certified postwhore Name: Murphey Location: Eastern Washington Join Date: Apr 2011 Motorcycle(s): 2002 Honda 919, 2004 Ninja 500R NAKED Posts: A lot.	Everyone says the FCR carb on the DRZ400 is basically the best mod you can do to it so it may be worth it on the ninjette. CV carbs kind of suck ass, the FCR should respond to mods better, as well as have much better throttle response.

September 11th, 2013, 05:11 PM	#4
mgentz Board Member Name: ... Location: WI Join Date: Dec 2011 Motorcycle(s): 250R (street), 250R (dirt) Posts: A lot.	Yes I have a non oring chain and plenty of mods. My stock carbs are not responding cc well and I will most likely upgrade. Many people have the cr31's but I want an accelerator pump and the extra flow.

September 11th, 2013, 08:38 PM	#5
quarterliter ninjette.org guru Name: Kevin Location: Madison Join Date: Apr 2013 Motorcycle(s): 2004 Ninja 250 Posts: 465	Makes sense. That would probably be a good choice for you then. I wish I could help you more with dyno charts but I haven't found any. I would be interested to see the improvement over stock carbs.

September 12th, 2013, 04:38 AM	#7
mgentz Board Member Name: ... Location: WI Join Date: Dec 2011 Motorcycle(s): 250R (street), 250R (dirt) Posts: A lot.	Those are the ones people usually get. They also offer fcr 35 carbs. I will try to get a pic and post it.

September 12th, 2013, 06:52 AM	#8
choneofakind ninjette.org certified postwhore Name: . Location: . Join Date: Feb 2011 Motorcycle(s): . Posts: Too much. MOTM - Feb '13, Feb '14	Mike, I think you know more than me here, but hear me out. 35mm carbs have a larger diameter. This would let in more air, but would it not also lower the intake velocity? Even the ninja 300 (which has 34mm TB's I believe) has a secondary set of butterflies and a taper inside the TB to control intake velocity at small throttle openings. I've followed your build and theory on your engine and I know your engine is sucking in more air (think that's why the 28mm stock carbs are limiting you, not enough air volume in the given time), but would you be better to use the 31's than the 35's to keep the velocity up? Idk, I'd have to see some math to really give any definite help on 35's vs 31's. Every idea I've got is just speculation.

September 12th, 2013, 07:26 AM	#10
choneofakind ninjette.org certified postwhore Name: . Location: . Join Date: Feb 2011 Motorcycle(s): . Posts: Too much. MOTM - Feb '13, Feb '14	Ah, 32mm. For some reason I had 34mm in my head.

September 12th, 2013, 08:52 AM	#13
mgentz Board Member Name: ... Location: WI Join Date: Dec 2011 Motorcycle(s): 250R (street), 250R (dirt) Posts: A lot.	Here is my problem: when I slowly open my throttle now the motor coughs/bogs then accelerates. When I hold throttle steady she can studder (jetting lean). She is a b#/&* to start and only accepts choke when it is cool to cold outside...any other time kills it instantly (suggesting too much fuel). At high rpm low throttle situations she is rough getting back on the gas. Much of this would say jetting if each piece was looked at seperately....however all together I think they point to carbs that cannot handle the motor and its dynamics. I have gone through them a lot and I even had a trusted tuner go through them.

September 12th, 2013, 10:50 AM	#14
bruce71198 ninjette.org sage Name: bruce Location: northern illinois Join Date: Jan 2012 Motorcycle(s): Race bikes:08 Ninja 250,11 R6,16 ZX6,SV650.3 HD-1947,2-2003,2010. 1946 Indian and a lot of dirt bikes.2 Posts: 999	How did it run with the stock carbs?

September 12th, 2013, 11:23 AM	#15
mgentz Board Member Name: ... Location: WI Join Date: Dec 2011 Motorcycle(s): 250R (street), 250R (dirt) Posts: A lot.	that is how it runs with the stock cv carbs. I am thinking that I need to upgrade. In talking with @Racer x, the tunability of these will be MUCH better. I am simply trying to see who, if anyone, has them.

September 12th, 2013, 12:13 PM	#16
bruce71198 ninjette.org sage Name: bruce Location: northern illinois Join Date: Jan 2012 Motorcycle(s): Race bikes:08 Ninja 250,11 R6,16 ZX6,SV650.3 HD-1947,2-2003,2010. 1946 Indian and a lot of dirt bikes.2 Posts: 999	Oh, I thought those pictures where of your bike. I would run the FCR's over the stock CV. Especially with the engine mods. My experience has always been positive when switching away from the CV's.

September 12th, 2013, 01:12 PM	#17
mgentz Board Member Name: ... Location: WI Join Date: Dec 2011 Motorcycle(s): 250R (street), 250R (dirt) Posts: A lot.	Not yet. Those are the test bikes that Sudco used and they show that these carbs will fit the stock airbox.

September 13th, 2013, 01:08 PM	#18
mgentz Board Member Name: ... Location: WI Join Date: Dec 2011 Motorcycle(s): 250R (street), 250R (dirt) Posts: A lot.	See poll thread: http://www.ninjette.org/forums/showthread.php?t=149608 I assume no one has these as I have received no answer.