I have read a few threads over the months of people fitting bike carbs to a multitude of engines. I have also observed a lack of comments over how people have found them to use and set up etc.

OK - now to the point. How good are they? Any pitfalls? Performance vs economy vs driveability? etc? etc? Would you do them again? Are they better than Webers.
Please start reply with summary of application and if poss back up claims with accurate data.

[Edited on 31/1/06 by DarrenW]

Fitted Suzuki GSXR 38mm carbs to my 1800CVH

Made my own manifold from mild steel 'Locost!',

From the outset the car started easier and ticked over very smoothly.

The pilot jets remained standard 35 I think ,and I experimented with the needle position, this effects 1/4 to 3/4 running.

Spoke to Bogg Bros , they suggested I start main jets at around 150 ,they wher 115 standard, being a disbelieving so n so I took the jets up in smaller increments, by gradually drilling them larger, I ended up at 1.60mm (160) I get a reasonable guide to mixture strength from the onboard lamda senser with 10 led gauge ,which can be built very cheaply,the car has not been on a rolling road, and would no doubt be improved if it were.

Having said the the car starts and runs fine ,and is quite economical, the mixture gauge and the spark plug colour says the mixture is on the right planet!!

Would I use them again ? yes , because of the variable venturi they give a very seamless and smooth transition from low to high revs, you get the tractability of small carbs low down, then they open up to give you the power at the top end, NO flatspots!!

Bearing in mind the Locost element you will never get a pair of Webers for £40 - £60.

The only downfall I can think of is that parts are expensive , so it could be cheaper to just get another set of Ebay ,if you need too much, (main jets £5 each ,but Weber ones fit! , plastic slides £30 each!!)

[Edited on 30/1/06 by Surrey Dave]
Rescued attachment Carbs On Car 6 vvsml.jpg

Same comments as Dave - Bogg Bros did my setup for me. Honda Blackbird carbs on to my 2.0L zetec. I bought a second set of carbs from the breakers for £100 so I have cheap spares!.

The blackbird carbs:

1. use 1/3 less fuel than the weber 45's I had previously.
2. the low speed / off idle problems I had with the webers no longer exist
3. I have connected and calibrated the honda throttle pot to my GEMS ecu for full 3D ignition.
4. They seem to stay in tune (they haven't gone out of tune in 6 months) longer than the weber 45's.

I would definitely use them again.

[Edited on 30/1/06 by givemethebighammer]

Thanks guys, thats exactly what i was looking for.
It looks like you both went the diy route. How did you find them to set up and get running nicely? Have you been restricted on where you can get them tuned seeing as they are a bit specialist? Im also interested to hear if you have a tangible increase in torque and power.
Do you have pics of manifolds in archives? Im tempted to make my own in steel as well. Im interested how people get the spacing right etc.
As you can tell im in suss them out mode and need to decide if they will be better than twin 40's etc.

Does anyone know much about ZZR carbs and suitability for a now mildly tuned 2.0 pinto - later to be better tuned???

[Edited on 31/1/06 by DarrenW]

Hi Darren i have fitted zx9r carbs to my pinto 2lt in about 3 weeks i will be going on a R Road i will post how i get on with it . If you look in my archives under zx9r carbs there is some photos of my manifold etc Jacko

Manifold
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Manifold Too
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this is great info. many thanks.

Ive just been given a set of ZZR1100 carbs (Thanks Guiness). 40mm chokes. Spacing of carbs will be a challenge to get manifold spacing right.
What would stop me just having basic manifold with simple straight stubs sticking out, maybe at an angle then having flexy pipes (bit of Samco?) to join to carbs? I know carbs have to be held at an angle for the floats but the bodies could be stabilised by a semi-flexy bracket.

Do all bike carb needles have the 5 position tops on them or only dynojet kits?

Does anyone know where i can get 4 K&N to fit ZZR's or a single pipercross from?

Jacko - your manifold has vacuum take offs - is this to suit your carbs or do they all need this?

At the moment things seem to be getting decidedly complicated but this is probs cos my investigations have just started and i have more q's than answers. Im actually surprised how simple the carbs look compared to webers.

Just have done with it and stick a whole bike engine in. You know thats what you really want. And don't try to deny it.................

Hi the vacuum pipes are there so i can balance the carbs and use one for the dizzy vacuum. But you can use a synchrometer if you have one like they use on webers It is not to hard to make a manifold like mine if you can weld and use a hacsaw Jacko

Will it work to only use one for the vacuum advance? It's only drawing a quarter of the time.

I've been puzzling over this for a bit. Don't see that you can connect all 4 together either, as you'd just end up with a flow of air back and forth between carbs. Someone on the forum mentioned using check valves (a long time ago, couldn't find the thread again), but I don't see that working either.

I thought the approach for bike carbs was to not use the vac advance and then modify the centrifugal advance springs.

Has anyone sorted this out for real?

My GSXR carbs have vacuum take offs built in with blanking caps, I did link them all and use them with the standard ignition at first.

quote:

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Originally posted by Surrey Dave
My GSXR carbs have vacuum take offs built in with blanking caps, I did link them all and use them with the standard ignition at first.

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The standard 1.8cvh ignition relies heavily on a vacuum feed , but since fitting the Megajolt I have only mapped it for 2D operation so far .
although it has a MAP sensor fitted,

There is no good way to use a vacuum advance with bike carbs, weber 40/45's etc.

if you connect it to just one part of the manifold then the vac advance just gets pulses of vacuum which makes the dizzy sound as if one of the bob weights is hitting the side of dizzy all the time......

if you connect all the manifold inlets it might just possibly work but I suspect that instead of providing a vacuum to the dizzy it just pull air from one of the other inlets.

if you have non return valves then the advance won't back off again when it needs to.

So the solutions are to get a properly modded dizzy which is designed to run without a vac adv. or use megajolt or the like.

using a Vac Adv. dizzy with the advance just disconnected will not be a good solution as the advance curve will be all wrong - you will be able to have it ok at idle but not at speed or vice versa but not both.

Cheers

Mark

Mark what can you tell me about megajolt? it may be the way to go with my engine Graham

quote:

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Originally posted by DarrenW
Do you have pics of manifolds in archives? Im tempted to make my own in steel as well. Im interested how people get the spacing right etc.

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PIC
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quote:

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Originally posted by jacko
Mark what can you tell me about megajolt? it may be the way to go with my engine Graham

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