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Keihin FCR MX 41.5 racing carburetor

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82K views 231 replies 37 participants last post by  flowpro.org 
#1 ·
Freshly rebuild Keihin FCR MX 41.5 racing carburetor for sale,

Assemblies:
- TPS (throttle position sensor)
- Cold start choke
- Hot start choke
- Oversize bowl drain plug
- Fuel mixture screw remote control
- Silicone vent lines + filter case with oiled filter insert
- Velocity stack neck size ø 63.5 mm
- SS bolts

Mods:
- Fuel atomization improving type needle
- High flow main jet
- Air flow velocity increasing plate’s intake side ¼; ½; ¾
- Air/Fuel mixture velocity increasing plate exhaust side ½
- Throttle channel overbore & surface treatment

Jetting specification:
- Needle = OBEPK 3rd middle clip
- Main jet = #175
- Idle jet = #42
- Starter jet = #70
- Leak jet = #65
- Main air jet = #200
- Idle speed air jet = #100
- Fuel mixture screw up to your needs









Price - 320 Eur - worldwide shipped

Any questions............ don't hesitate, contact to me.
 
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#46 ·
Keihin FCR 41.5 mm assembled for Honda XR big thumpers. Mint condition. 360 Eur worldwide shipped.

Assemblies:
- Cold start choke
- Oversize bowl drain plug
- Fuel mixture screw remote control
- Silicone vent lines + filter
- Velocity stack neck size ø 55 mm
- SS bolts

Mods:
- Fuel atomization improving type needle
- High flow main jet
- Air flow velocity increasing plate’s intake side ¼; ½; ¾
- Air/Fuel mixture velocity increasing plate exhaust side ½
- Throttle channel surface treatment

Jetting specification:
- Needle = OBELP 3rd middle clip
- Main jet = #180
- Idle jet = #45
- Idle air speed jet = #100
- Main air speed jet = #200
- Starter jet = #72
- AP membrane rod length 2,2 mm
- Fuel mixture screw up to your needs



 
#59 ·
This would be cool to have on my Big Red Pig . . .

Keihin FCR 41.5 mm assembled for Honda XR big thumpers.

Mint condition.

$360.00 Eur worldwide shipped.

Assemblies:
- Cold start choke
- Oversize bowl drain plug
- Fuel mixture screw remote control
- Silicone vent lines + filter
- Velocity stack neck size ø 55 mm
- SS bolts

Mods:
- Fuel atomization improving type needle
- High flow main jet
- Air flow velocity increasing plate’s intake side ¼; ½; ¾
- Air/Fuel mixture velocity increasing plate exhaust side ½
- Throttle channel surface treatment

Jetting specification:
- Needle = OBELP 3rd middle clip
- Main jet = #180
- Idle jet = #45
- Idle air speed jet = #100
- Main air speed jet = #200
- Starter jet = #72
- AP membrane rod length 2,2 mm
- Fuel mixture screw up to your needs



Would I need to get a rebuild kit & send it back to you ~ or will my local dealership stock the parts to rebuild this ?
 
#53 ·
It'll be a couple months before I do this, but figured I might ask some questions now.

I have a 2003 WR450F. Still need to pull the valve cover and check what cams are in it. Powerbomb header, still need to work out what muffler I'll run (stock right now). I've been told that TPS is better off disconnected.

What carb would be best on it? How much more hp/tq should it get me? How much would it cost me? These all seem cheaper than I'd expect, very reasonable especially for fully rebuilt carbs with nice parts.
 
#54 ·
Existing one you have on the bike will be good enough if it is Keihin FCR MX or simply FCR. To rebuild your current one will cost 265 Eur and you'll get it back the same like carbs above in thread.
It is very hard to say for me about correct power increase numbers but wilmelee4food described gains very well like it is.
 
#64 ·
From what I can tell, none of the rubbers, rings, or gaskets are any different than OEM.

There are a few tricks Andis uses to make these carbs perform. I won't give away any of the internal mods I noticed, but I have had to replace some parts and just used off the shelf Honda or KTM parts. Usually Honda since they are priced a few cents lower.

So far I've only had to replace the vacuum slide gasket due to a blown head which shot some valve/valve seat debris back into the carb. Oh and just last week, I had to swap the float valve and seat from just normal wear and tear.
 
#67 ·
Willmelee4food is absolutelly right, there are no special parts required for a normal service. The only special parts I can think of are the jet needle and main jet which are uniquely modified. But they rarely see a wear or tear so intense that would require their replacement.
One thing I would like to note is this - the fuel quality available throughout the world wildly differs from what I have here, so be careful of what kind of fuel you are using, it may cause some unexpected deposits that I have struggled to clean out from carbs coming from USA for example.
 
#71 ·
Due to the supply processing failures of USPS overseas, there is a Keihin FCR MX 41.5 mm available in the US, it is assembled for KTM 525 but it fits for 450 and LC4 as well.
The carb is located in Maryland. It was sent to US as a replacement for the first one which got jammed somewhere in the USPS processing services. After some time Brad received both carbs so the second one I sent is available now.

Price 285 GBP shipped in North America






Assemblies:
- TPS (throttle position sensor)
- Cold start choke
- Hot start choke
- Oversize bowl drain plug
- Fuel mixture screw remote control
- Silicone vent lines + filter case with oiled filter insert
- SS bolts

Mods:
- Fuel atomization improving type needle
- High flow main jet + one spare
- Air flow velocity increasing plates intake side ¼; ½; ¾
- Air/Fuel mixture velocity increasing plate exhaust side ½
- Throttle channel surface treatment

Jetting specification:
- Needle = OBELP 3rd middle clip
- Main jet = #175
- Idle jet = #45
- Starter jet = #68
- Leak jet = #55
- Main air jet = #200
- Idle speed air jet = #100
- Fuel mixture screw up to your needs
 
#73 ·
Hey guys, I can only tell you I'm really thrilled. My Flowpro FCR is the one with the blue vent lines from page one. It went in a '99 Husqvarna 610 e-start model.

My bike now works completely different. Throttle response is so smooth now, even the smallest move on the throttle grip means rev changing, no comparison to before with a Mikuni TM40, there only was a cough with the old carb.

There is an enormous power increase, the bike revs so much freer. It is hard to explain the effect. A buddy of mine didn't want to believe I only changed the carb. He still thinks I did something on the engine itself.

I try to describe the effects.
In low revs the bike now reacts much more comfortable, no chain hacking on the swingarm at all, I now can rev upwards from 2000/min which was impossible before. Mid range has the most improvement I think. Feels like up to 10hp more. So much better than before.
Revving from mid to wot is also improved. Defenately feelable more power. I now have to be more careful in lower gears to keep the front wheel to the ground.

Finally I can say this was the best improvement to the bike I ever did. It really is a huge increase of rideability. And not to forget the goods of these carbs which are very handy. The filter for the vent lines is a great idea. But the air fuel remote is just hammer. In my bike there is no way to easy adjust air fuel rate with the stock screw because everything is in the way. Now, no problem at all. Done in seconds.

I tried a 2006 model. These have the FCR41 from stock, compression 11:1 instead of 9:1 and other small other mods from stock. This bike defenately was pretty less powerful, all the rideability was way off my bike. So I can say a Flowpro modded FCR works far better than a stock one.

And one very important thing: service and support are really the best I ever experienced. Andis' prime principle is having satisfied customers.


This is not a commercial, just a review of a enthusiastic user.

Best regards, Sascha
 
#74 ·
For sale /Plug & Play/ Keihin FCR MX 41.5 mm bore supermoto racing carburettor. Fits all KTM’s 525 EXC; 530; 560 SMR from 2003 up to 2007.

Assemblies:

- TPS (throttle position sensor)

- Cold start choke

- Hot start choke

- Oversize bowl drain plug

- Fuel mixture screw remote control

- Custom welded catch canister including fastening hardware and silicone vent lines

- Velocity stack neck size ø 63.5 mm

- SS bolts

Mods:

- Fuel atomization improving type needle

- High flow main jet

- Air flow velocity increasing plate’s intake side ¼; ½; ¾

- Air/Fuel mixture velocity increasing plate exhaust side ½

- Throttle channel surface treatment

Jetting up to your needs.

425 Eur worldwide shipped















 
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