Ducati.ms - The Ultimate Ducati Forum banner

1 - 11 of 11 Posts

·
Registered
Joined
·
421 Posts
Discussion Starter #1
I am having difficulty understanding what are the compents required to fit FCRs to a carby 900 SS.

I have been trying to find a photo of the components but so far nothing that helps.

Here's what I have worked out so far. If you can correct me and fill in the gaps that would be appreciated.

Typical dual kit includes
  1. Two carbs, operated by a single common throttle mechanism
  2. Two bell mouths
  3. Throttle cables,
  4. Throttle,
  5. Two Spigots, (Not sure where these go and what they do?)
  6. Two airbox adaptors (what do these look like?)
  7. K&N or BMC air filter (which is fitted to the adapted air filter box).

The other option is to mount two singles in which case you need:

  1. Two single carbs each operated by a separate throttle mechanism
  2. Two bell mouths
  3. some sort of linkage to connect the throttle mechanisms of each carburettor?
  4. Throttle cables,
  5. Throttle,
  6. Two manifolds
  7. Two velocity stacks?
  8. Two cone filters.
 

·
Banned
Joined
·
2,916 Posts
1. with a dual carb set up, you have a throttle mechanism, that has
one wire to open the carbs, and another to close it.
push-pull mechanism should be the correct term for that.

with single carbs, you need a different throttle assembly, one that is
able to pull two cables at a time, without the closing feature of course.

2. with the dual set up, you use your standard manifolds, and can
either connect the carbs to the airbox with the air-box adaptors, nice
shiny cnc milled aluminum parts by the way, hence the price, or have
the enclosed blue plastic bellmouths/velocity stacks/spigots attached
only, without airbox, or you can mount single K&Ns to the airbox
adaptors, which would be the case if you would use single carbs too.

3. you need new manifolds for the single carb operation, from
Malossi in example, but they don't fit too well, they have a lot of
play on the studs, and need some extra fixing pins in my opinion,
or you can re-weld the stock ones.
in any case, both carbs won't be connected in a single set-up,
that means you got to adjust them* from time to time, unlike with
the dual set-up, where you have to synchron the both slides just
once.

*adjust the trottle cables would be correct here.
 

·
Banned
Joined
·
2,916 Posts
it ain't that easy, isn't it ? :)

ca-cycle works i.e. does not sell the single kits no more as it seems,
single kits were always supplied without manifolds as far as i know anyway.
if you go single, i'd recommend to buy one downdraft and one regular
horizontal FCR carb, unlike the kit, that supplied two downdraft ones.

There has been a thread lately, with some info from various members
and their set-up for the 41mm Keihin.

:think:
 

·
Registered
Joined
·
421 Posts
Discussion Starter #5
2. with the dual set up, you use your standard manifolds, and can
either connect the carbs to the airbox with the air-box adaptors, nice
shiny cnc milled aluminum parts by the way, hence the price, or have
the enclosed blue plastic bellmouths/velocity stacks/spigots attached
only, without airbox, or you can mount single K&Ns to the airbox
adaptors, which would be the case if you would use single carbs too.
Muschi thanks for the comprehensive answer. I take it that the air box adaptors and the spigots are the same thing?

I am also guessing that their must be an advantage to using singles? (otherwise why would people worry about the exra hassle?)
 

·
Banned
Joined
·
2,916 Posts
yeah could be that spigots and airbox adaptors are the same thing,
there aren't too many parts involved here, so if spigots are not
the blue velocity stack / bellmouth thing, it must be another word
for airbox adaptor.

for the ease of installation and maintenance, and for a typical street
application, where high rpm isn't the biggest concern, i'd probably go
with the 41mm dual set-up and be fine with it.
this way you can keep your airbox, and intake noise within reasonable limits.

:think:

living in europe sucks, see were they got me already, some years ago,
i would have suggested single carbs and open stacks for sure.

:think: ;)
 

·
Registered
Joined
·
89 Posts
Wobbly - if you're interested we can always get together (I'm also in Auckland) and you can check out my bike, I've just fitted the dual FCR kit (from Chris at Ca-cycleworks) to mine. Personally I don't think the additional hassle of singles is worth it for a street bike, ymmv.

The parts I got from Ca-cyclworks were:
- 2xFCR carbs
- Throttle twist grip assembly and dual cables (push-pull)
- 2xAluminium air box adaptors
- 2xAluminium manifold adaptors
- 2xVelocity stacks (not used but stock with the carbs)
- Plug for airbox breather pipe return (you remove the breather)
- No filter with mine (deleted) as I ran a BMC filter already.

You have to cut away some external webbing/bracing from the airbox to clear the throttle cable assembly. If your handlebars don't have a hole drilled for the throttle locating pin you will have to drill one, or grind the pin off the twist grip. For some reason my bars were pre-drilled but the stock grip didn't use a locating pin.

Without rushing the job took my about 3 hours.

Rob.
 

·
Registered
Joined
·
733 Posts
On page 75 of the Sudco catalogue it does show what you get with each kit. It mentions "necessary adaptors" and I take that to mean alloy inlet adaptors that connect the carbs to the original air box rubbers. I bought my set a few years ago and went the easy way with the dual kit. Well worth the money and they get close to new price when sold on eBay.

http://www.sudco.com/Carburetor/SudcoKeihinCatalog.pdf

One other thing if going with split singles is that I think the air box has to be removed so that replacement pod type air filters have somewhere to go. And the back end of that holds the battery, black boxes and coils so you would have to fabricate something. You won't have much luck finding such a thing readily for sale.
 

·
Registered
Joined
·
4 Posts

·
Banned
Joined
·
2,916 Posts
- 2xAluminium air box adaptors
- 2xAluminium manifold adaptors
the manifold adaptors are a part of the carb in my eyes,
not a seperate item like the adaptors for the air-box.
they can be screwed off, of course, but unlike the airbox
adaptors, are always sold with each carb.

cheers. :)
 

·
Registered
Joined
·
46 Posts
http://www.sudco.com/fcrdown_diagram.html

http://www.motorcyclecarbs.com/Keihin_FCR_Spigot_Adapter_Appl_W53.cfm

http://www.motorcyclecarbs.com/Intake_Manifold_Boots_Tube_Ty_P15917C2439.cfm

http://www.carbparts.com/keihin/fcr_exploded.gif

I'm adapting split singles to stock manifolds. It's what I got. While short manifolds may provide some hp gains I don't want to spent the 190 bucks for them and don't like the angle difference of the carbs relative to each other, it's gotta mess with float levels and fuel delivery. what I would call the spigot is the milled aluminum tube that screws into the carb body engine side (can be hard to remove). Interestingly the singles are 39mm ID and the duals are 38mm. The second link notes the dimensional differences between the dual and single spigots, thus the need for the manifold boots in the third link which I've ordered but have yet to confirm will work. Motion pro makes push/pull cables for the singles, available from sudco and others. Cacycles, sudco and k&n have airbox/filter adapters which are dimensionally variable and affix to the other side of the carb body from the spigot via two screws where the velocity stacks could mount if one were so inclined. I'm gonna run pod filters and cut the front off the airbox and keep the back where the battery and coils etc are.
 
1 - 11 of 11 Posts
Top