Keihin 41mm FCR fitting tips + Can I junk the fuel pump? - Ducati.ms

Iconic944ss · Jan 26th, 2007, 5:06 am

Hi Guys,

Couldnt turn down a set of 41FCR's on Ebay UK so, I'm currently overhaulling them before looking to fit.

Any installation tips please - I've had a good look through the site and realise I might need another throttle and cables.

I almost wish I'd got split singles so I could use the malossi inlets but I can't face rebuilding the battery tray as I've installed a bigger battery, turned the starter solenoid around and am also about to fit Dyna coils, anyway I think I'll be happy with the twin FCR's if they are as good as I've been told.

Also - with them being pumper carbs, do I need to keep the fuel pump or can I get a tiny bit more fuel in the tank by removing it?

All tips appreciated

Cheers - Frank

bruce19 · Jan 26th, 2007, 6:06 am

I did the 41 mm FCR's on a '96 SS/SP. At the same time I did the 944 kit, light flywheel, and a bunch of other mods. My FCR's were mounted on Malossi short intakes so the fuel became a gravity feed system. So, I was able to jettison the fuel pump. Worked well, too. I would bet that unless you put those carbs below the tank you won't be able to lose the fuel pump. Just seems logical to me. BTW, can you explain what "pumper" carbs are?

gorma900 · Jan 26th, 2007, 7:12 am

Frank,

Congrats on the new carbs - you WILL definately enjoy them a lot, believe me!

If they are dual mounted you cannot loose the fuel pump as the lowest part of the tank is lower than the float bowls. If they we singles mounted on the short inlets, then you could have gained a few millilitres of fuel space in the tank by taking the pump out.

You're right, you will need new throttle and cables, don't know if you have it, but the FCR kit usually comes with an K&N filter too, but I wouldn't say it's a requirement. The carbs should have the adapters to the stock manifolds and airbox - other than that, it's just a bolt-on excersize.

Here's a link to where you can get cables and other spares for the FCRs if you can't find it in the UK:http://www.ca-cycleworks.com/shop/ca...cati/fuel.html

RichD · Jan 26th, 2007, 7:21 am

I believe the seperate carbs come with larger seats for operation without a fuel pump.

To run YOUR FCR's without one you will need to replace the float valve needle/seat in each carb (not hard to do) with ones larger in diameter.
It WILL run without changing them, but the fuel level in the carbs will not be right, and at full throttle (after several seconds) the bowl will start to dry up and you will lose power. If you have high compression pistons it WILL start to ping as the fuel mix leans out excesively. Ask me how I know!

The instruction sheet that comes with the FCR's when you buy a kit new covers this... It has the part #'s required to do the pumpless conversion. I still have a copy, if you want I can scan and Email it to you.

ALSO:
"If you're running a ram-air setup, and using gravity feed rather than a pump to move the fuel from the tank to the carbs, you'd better route the fuel tank vent to the inside of the airbox or you'll wonder why it keeps sputtering at the end of long straights. 160 mph worth of air pressure in the float bowls and only ambient pressure in the tank will seriously slow down or even stop the fuel coming in from the tank, and the float bowls will run dry. You need to put airbox pressure into the tank to keep the fuel flow constant at various speeds."

Read more about this here: http://www.factorypro.com/tech/carbkei.html

If you do run a fuel pump and it craps out, enough fuel will gravity feed to get you home -at least it will on my bike!

If you need anymore info or want the install sheet PM me.

Good luck!,
Rich D.

RichD · Jan 26th, 2007, 7:27 am

Quote:

Originally Posted by bruce19

...BTW, can you explain what "pumper" carbs are?

They have an accelerator pump that squirt fuel into the venturi when you open the throttles.

Like your old Chevy Nova! (did you have one?) you know... pump the gas pedal twice and turn the key...

Oh BTW, ICONIC944S: You will have to do the same "trick" to start your bike in cold weather due to the fact the FCR's do not have a choke!

gorma900 · Jan 26th, 2007, 8:33 am

Here's some installation tips: http://www.ca-cycleworks.com/shop/pa...upplement.html

bruce19 · Jan 26th, 2007, 8:37 am

Quote:

Originally Posted by RichD

They have an accelerator pump that squirt fuel into the venturi when you open the throttles.

Like your old Chevy Nova! (did you have one?) you know... pump the gas pedal twice and turn the key...

Oh BTW, ICONIC944S: You will have to do the same "trick" to start your bike in cold weather due to the fact the FCR's do not have a choke!

Actually that's what I thought. I asked because if that's true (as it is) it would have no effect on use/non-use of a fuel pump. I thought maybe there was something I didn't know about it. Didn't have a Nova but that is the way they worked on my '96 SS, of course. Thanks.

Iconic944ss · Jan 28th, 2007, 4:54 pm

I think the Ca-Cycleworks addition is pretty good but, does any-one know or can post a copy of the actual installation instructions please?

I can't even find any on the SUdco or Keihin websites

Cheers - Frank

Duc_Fighter · Jan 28th, 2007, 5:02 pm

Quote:

Originally Posted by bruce19

Actually that's what I thought. I asked because if that's true (as it is) it would have no effect on use/non-use of a fuel pump. I thought maybe there was something I didn't know about it. Didn't have a Nova but that is the way they worked on my '96 SS, of course. Thanks.

Yes, it's true. I have 39mm fcr's on my 86 gixxer 750. I have to do the same thing.

96SP · Feb 11th, 2008, 12:18 am

Thinking of getting some FCR41s when I get the $$$. I want them not only for the acclaimed response but also to do away with the carb icing I always get in cold weather (<40 F) with the stock Mikunis. Anyway, is there more to the cold starting trick for the FCRs than twisting the throttle twice before turning the key and hitting the starter? Do you have to stand there and continually rev the engine? How long (typically) before she will idle? Thanks-

96SP

Quote:

Originally Posted by RichD

They have an accelerator pump that squirt fuel into the venturi when you open the throttles.

Like your old Chevy Nova! (did you have one?) you know... pump the gas pedal twice and turn the key...

Oh BTW, ICONIC944S: You will have to do the same "trick" to start your bike in cold weather due to the fact the FCR's do not have a choke!