39mm Keihin FCRs

discussion about the 750 Sport and '89/'90 900SS, which share many mechanicals with the Paso series
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Mustang505
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Joined: Wed Jan 28, 2009 9:27 pm
model: 750 Sport
year: 1988
Location: Auckland, New Zealand

39mm Keihin FCRs

Post by Mustang505 »

Hi
anyone running these? I just bought a set and will fit and try to get them running this weekend so if anyone has some advice or tips please let me know. thanks

Image
Cheers
Clive
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paso750
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model: 750 Paso
year: 1987
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Re: 39mm Keihen FCRs

Post by paso750 »

It looks like the covers of the float chambers have been removed in the past. If that`s done the small rubber boot on the side/accellerator pump is pulled off.
The only thing I`d generally do with used carbs is get some carb cleaner spray and clean them inside and out.
Here`s all I have about Keihin FCRs. (I don`t have any, I have the Mikuni TDMR)
http://www.box.com/s/329ay6zzob9yspyisl01
As the Keihins don`t have a choke you give it two or three hits with the throttle before starting.
Also keep the throttle opening cable in it`s lowest position as it`s hung now or else the throttle slider won`t fully open. (as least that was so on my friends` Elefant I had in the garage the past 4 months)
The rear/higher T connection is the carb breather which you should connect to a small bottle like used on the Ducs with Mikunis.
If you end up having carb flooding issues you may consider swapping the electrical with an underpressure fuel pump.
That`s all that comes to my mind. :)

G.
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higgy
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Re: 39mm Keihen FCRs

Post by higgy »

put the weber back on it :beer: :beer: :beer:
Ducati,making mechanics out of riders since 1946
There's no problem so bad that a little fixing can't make it worse! : )
If it ain't broke keep fixin it till it is
88 750
90 906
92 907ie
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Mustang505
Posts: 134
Joined: Wed Jan 28, 2009 9:27 pm
model: 750 Sport
year: 1988
Location: Auckland, New Zealand

Re: 39mm Keihen FCRs

Post by Mustang505 »

thanks for the info guys.
thanks G, I already have removed the tank pump and run a low pressure vacuum pump so should be fine. I also rebuild all carbs i get so hopefully all good.
Higgy I sold the webber to a guy who was rebuilding a Ford capri V6 long before i read all your info on it. Have since been running 38mm Mikunis. Pity really as I would have liked to try it on the track now, but mine ran so poorly on the road, and not knowing anything about them, just got rid of it.
Cheers
Clive
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ducinthebay
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Re: 39mm Keihen FCRs

Post by ducinthebay »

While you can run the manifolds from a Monster or SS,(which I believe you are already running) shorter manifolds are always better. If you get Malossi short manifolds, you can split the carbs. you will need to put elbows on the ends of the carbs to your aircleaners.

Cheers,
Duc in the Bay
1990 750 Sport x2-Rosso Blanko (900ss copy) & Nuovo Nudo (Scrambler project)
1991 907 -mostly stock
2002 ST4s - Lots of mods.
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paso750
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Joined: Sun Jul 18, 2004 12:00 am
model: 750 Paso
year: 1987
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Re: 39mm Keihen FCRs

Post by paso750 »

Splitting those carbs is not so easy as you`ll need a second throttle linkage etc. Also short carb manifolds will shift the torque curve from low to high end which may be good for track use but imho less preferable for street use. I don`t agree they are always better.
Not being a fan of elbows in general and in special if they are too long, U-shaped etc these filters will fit:
K&N 2530 (was posted here in the forum before. I guess it`s SN-2530)
Image
Unifilter UP4060A (the Keihins shown have the SS/Monster airbox adapters mounted)
Image
Image
Raimair has filter socks that fit over trumpets (use cable ties to hold them)
http://ramair-filters.com/motorbike/fra ... rbike.html

G.

Btw if anyone knows of a spare/cheap set of Keihin FCR (41) inlet trumpets let me know
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ducinthebay
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Re: 39mm Keihen FCRs

Post by ducinthebay »

I must admit, that I only speak from what I have heard about splitting the carbs, as I have not done it myself. But seeing them installed, it seems the faster, easier install is with them together, and use the longer manifolds. It also gives you a chance to actually make an airbox, and the airfilter situation is much easier to resolve. And you can put nice big/long intake velocity stacks (trumpets).

I keep searching to find a good deal on a set of FCRs, as I understand they are the best choice to get the most performance from the Ducati engine. I can't quite swallow $800 for a set. But Christmas is coming......

Cheers,
Duc in the Bay
1990 750 Sport x2-Rosso Blanko (900ss copy) & Nuovo Nudo (Scrambler project)
1991 907 -mostly stock
2002 ST4s - Lots of mods.
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higgy
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Re: 39mm Keihen FCRs

Post by higgy »

Oh Boy FCR envy :mrgreen:

Shoulda kept the weber :lol: :lol: :lol: :thumbup: :thumbup: :beer: :beer: :wacko:
Ducati,making mechanics out of riders since 1946
There's no problem so bad that a little fixing can't make it worse! : )
If it ain't broke keep fixin it till it is
88 750
90 906
92 907ie
User avatar
higgy
paso grand pooh-bah
Posts: 3327
Joined: Tue Jul 29, 2008 9:50 pm
model: 907 I.E.
year: 1992
Location: Hilltown,Pennsylvania
Contact:

Re: 39mm Keihin FCRs

Post by higgy »

I keep searching to find a good deal on a set of FCRs
not to long ago there was a guy had several sets went for around 200, at least the first few till people found him on fleabay, so keep tryin :thumbup:


stacks http://www.ebay.com/itm/Velocity-Stack- ... 2c60eb5661


Manifolds http://www.ebay.com/itm/Ducati-SS-Monst ... 3a6a97a22c


for 175 they should be tricolor at least :wacko:
Ducati,making mechanics out of riders since 1946
There's no problem so bad that a little fixing can't make it worse! : )
If it ain't broke keep fixin it till it is
88 750
90 906
92 907ie
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