Just fitted my zzr1100 carbs on danst inlet to my Zetec 2.0. It idles really well, but out in the road not so good. If I rev it from stationary, it struggles to go above 4K then when I’m the road it is very lumpy and bogs down a lot. Any ideas what could cause this? Carbs were ultrasonically cleaned and then balanced so that shouldn’t be the issue plus I believe they have 1.6mm jets fitted.

I used to have similar problems when I fitted CBR600 carbs to my 1600 x-flow. I followed all the guidelines, drilled out the jets to 1.6mm, and got all the symptoms you describe. Eventually I got hold of an AFR meter and found that the mixture was seriously rich at wide-open throttle, and quite rich at normal running speed.

I ended up with 1.3mm jets that gave me a close-to-ideal mixture at WOT and over-run, but slightly rich at mid-range. I couldn't improve things as it's not easy to fix needle issues on CBR600 carbs, so the only way I could go further was to take the car to a rolling road.


[Edited on 2/11/17 by David Jenkins]

bike carbs require really low fuel pressure.
what fuel pump and or regulator are you using?

I’m running a factory fiesta rs1700 fuel pump with malpassi injection to carb regulator, unfortunately my fuel pressure gauge is playing up though which isn’t helping when trying to set the pressure bang on. Can you damage the carbs running too high pressure?

Way too much pressure, you need a bike pump or an SU type pump, any carbed bike pump will do, fitted close to the tank as on a bilke they are gravity fed to you need to replicate that.

Also check the carb diaphragms are sealed properly in the plastic lids, its a good move to fill diaphragm locating recesses with rubber lube, that stops any leakage.

Been playing with the fuel pressure a bit, got it revving up. Pulled really hard in 1st, not too bad in 2nd then begins to big around 4K in 3rd and so on. Go half throttle for a bit then gets better, if anything feels like it’s being starved of fuel?

Could be fuel vaporisation or tank not breathing

quote:

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Originally posted by r1_pete
Way too much pressure, you need a bike pump or an SU type pump, any carbed bike pump will do, fitted close to the tank as on a bilke they are gravity fed to you need to replicate that.

Also check the carb diaphragms are sealed properly in the plastic lids, its a good move to fill diaphragm locating recesses with rubber lube, that stops any leakage.

---

If your fuel pressure was to high wouldn't there be fuel pissing out of carbs

Float valves can stick open or closed so worth cleaning them if you haven't already done so.

quote:

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Originally posted by chris
If your fuel pressure was to high wouldn't there be fuel pissing out of carbs

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quote:

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Originally posted by r1_pete
Way too much pressure, you need a bike pump or an SU type pump, any carbed bike pump will do, fitted close to the tank as on a bilke they are gravity fed to you need to replicate that.

Also check the carb diaphragms are sealed properly in the plastic lids, its a good move to fill diaphragm locating recesses with rubber lube, that stops any leakage.

---

quote:

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Originally posted by 40inches

quote:

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Originally posted by r1_pete
Way too much pressure, you need a bike pump or an SU type pump, any carbed bike pump will do, fitted close to the tank as on a bilke they are gravity fed to you need to replicate that.

Also check the carb diaphragms are sealed properly in the plastic lids, its a good move to fill diaphragm locating recesses with rubber lube, that stops any leakage.

---

This ^. If you use a pump that was designed for bike carbs, it removes that as a possibility
You need around 2psi. 4psi as a max.

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I have 1.8 jets in a set of R1 carbs and and air correction jets plugged and redrilled to .075mm. I run about 2psi fuel pressure with a small solid state pump.

Cheers guys, one thing I have found is the carbs won’t seal perfectly with the hoses, there are small air leaks not enough to be able to hear audibly but if I spray brake cleaner the engine begins to labour. Anybody recommed best way to get them to seal? It’s on the carb end

Hi, I had a problem with the 'basic' carburettor mountings. They kept falling off, so I doubt they were air tight.

I eventually replaced them with some 'proper' carburettor mounting tubes from ebay.

This is an example. Mine were in a pack of 4 for about the same price.

Ebay 222594342467

Hope this helps.

These look more like what I ended up with.
Ebay 391895376916

[Edited on 3/11/17 by avagolen]

quote:

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Originally posted by avagolen
Hi, I had a problem with the 'basic' carburettor mountings. They kept falling off, so I doubt they were air tight.

I eventually replaced them with some 'proper' carburettor mounting tubes from ebay.

This is an example. Mine were in a pack of 4 for about the same price.

Ebay 222594342467

Hope this helps.

These look more like what I ended up with.
Ebay 391895376916

[Edited on 3/11/17 by avagolen]

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Hi,

I can confirm that my carbs are 40mm diameter, but what I cannot confirm is that the tubes are exactly the ones I purchased.
It was a long time ago.

I have carbs from a ZX6R and the Kawasaki mounting tubes from a ZX9 definitely fitted.

391895376916 look very familiar.

They fitted the carbs and the jubilee clip holds them firmly where as the silicone tubes just 'squeezed' off when the clips where tightened.

I am sorry I cannot be more helpful.

Len.

The ZX9 carb rubbers I have have a flange on the head side to bolt them up so wouldn't work with an aftermarket manifold. I'm not saying all are like this but worth checking you are ordering the right thing if you buy some.




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Yes, be careful.

The ebay number I put in my last post is of the non flanged variety.

Nice one guys, took carbs off today as they had vacuum leaks so took them off and reseated them properly with new clips. Also rerouted my fuel pipes to prevent any vapour lock but sill bogs down, very weird one minute it revs up and goes brilliantly, then all of a sudden still bogs down and then begins to backfire and miss until I lift off for a min, seriously considering dropping the tank and fitting the bike pump just to see....:/