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bike carb jet size?
scotty g - 16/1/12 at 09:04 PM

Hi all,
i'm putting together a shopping list of parts i need for my zetec install, thinking i'll probably go bike carbs ( i believe 600cc is about the right size?) and was wondering if they need to have the jets modded or anything else tweeking?
Cheers.
xxxxxxx

austin man - 16/1/12 at 09:10 PM

I have a 1.8 zetec with ZX9 carbs i believe they are drilled to 1.6mm

macc man - 16/1/12 at 09:18 PM

It depends on the engine size and ultimate use of the car. I have a 2.0 zetec with zx9r carbs. An 1800 zetec would be ok on zx6r or similar. These are usually cheaper and less in demand. Try to find a later set with tps fitted already. With regards to jet size start off small and go up in small increments. Best course is to get it set up on a RR by an expert. Worth the cost IMHO.

[Edited on 16/1/12 by macc man]

scotty g - 16/1/12 at 09:26 PM

Forgot to say its a 1.8 blacktop.

Gear Monkey - 16/1/12 at 10:43 PM

Excuse my ignorance but what are the advantages of bike carbs over the standard fuel injection? Simplicity? Weight? Power?

Paul

atspeed racing - 17/1/12 at 11:24 AM

A main jet size on bike carbs would not give you the correct mixture overall. To correctly calibrate the carb over the entire rev range you would have to reprofile the needle as well.

scotty g - 17/1/12 at 06:18 PM

Are there any companies out there that do this?

Craigorypeck - 17/1/12 at 11:43 PM

quote:
Originally posted by scotty g
Are there any companies out there that do this?


I would also appreciate suggestions as to who is capable of this?

To get my fuelling right on cruise the top end is way too rich. needle needs a slight modification at the thickest end.

Thanks

atspeed racing - 18/1/12 at 08:16 AM

I can reccomend...ME
I calibrate bike carbs correctly.

Craigorypeck - 18/1/12 at 08:45 AM

Aha! Perfect! I'll have the needles out soon enough and I'll be in touch.
Maybe you could supply a different profile needle thats more suited rather than modifying mine.?
You have email I can contact via?

Thanks

whitestu - 18/1/12 at 09:11 AM

I have ZX6 carbs on my 2.0 Zetec and they work great. They are 38mm which is plenty big enough for a standard tune 2.0 Zetec.

atspeed racing - 18/1/12 at 09:40 AM

quote:
Originally posted by Craigorypeck
Aha! Perfect! I'll have the needles out soon enough and I'll be in touch.
Maybe you could supply a different profile needle thats more suited rather than modifying mine.?
You have email I can contact via?

Thanks


All needles are made to suit your car not available off the shelf. We would need the car to do this.

Craigorypeck - 18/1/12 at 10:29 AM

quote:
Originally posted by atspeed racing
quote:
Originally posted by Craigorypeck
Aha! Perfect! I'll have the needles out soon enough and I'll be in touch.
Maybe you could supply a different profile needle thats more suited rather than modifying mine.?
You have email I can contact via?

Thanks


All needles are made to suit your car not available off the shelf. We would need the car to do this.


That would be a problem as i live in Northern Ireland..

To get it to run proper on cruise the needles have to be raised via clip out of the main jet, this in turn leaves it running dragster type afrs in the upper rev range.. so basically what i need is the tapered profile to extend a bit further up the shoulder- therefore giving the same fuelling on cruise as if the needles were raised.. Know what I mean??
I understand the best situation would be to have the car at your workshop but maybe it can be done via post?
Kindest Regards
Craig

scotty g - 18/1/12 at 01:04 PM

quote:
Originally posted by whitestu
I have ZX6 carbs on my 2.0 Zetec and they work great. They are 38mm which is plenty big enough for a standard tune 2.0 Zetec.


Are you running them as standard or have you done any mods to jets/needles?

daviep - 18/1/12 at 01:17 PM

quote:
Originally posted by Craigorypeck
quote:
Originally posted by atspeed racing
quote:
Originally posted by Craigorypeck
Aha! Perfect! I'll have the needles out soon enough and I'll be in touch.
Maybe you could supply a different profile needle thats more suited rather than modifying mine.?
You have email I can contact via?

Thanks


All needles are made to suit your car not available off the shelf. We would need the car to do this.


That would be a problem as i live in Northern Ireland..

To get it to run proper on cruise the needles have to be raised via clip out of the main jet, this in turn leaves it running dragster type afrs in the upper rev range.. so basically what i need is the tapered profile to extend a bit further up the shoulder- therefore giving the same fuelling on cruise as if the needles were raised.. Know what I mean??
I understand the best situation would be to have the car at your workshop but maybe it can be done via post?
Kindest Regards
Craig


Sorry for the hijack

I could be barking up the wrong tree btu if you are going rich at wide open throttle then to me that would suggest that the main jet size was too large?

Very condensed setup procedure would be:

Set the main jet size first to give the correct afr for WOT, then you set the needle which controls mixture from just above idle until nearly WOT and then set idle.

Davie

whitestu - 18/1/12 at 02:22 PM

quote:

Are you running them as standard or have you done any mods to jets/needles?


The jets were drilled to 1.6 mm and needle height adjusted to get AFR right. I haven't done anything to reprofile the needles. I've always thought that reproducing exactly the same profile over 4 needles by hand would be nigh on impossible.

The car has been running for a couple of years like this and has good MPG and seems to have the power I would expect, though has never been on a rolling road.

Stu

whitestu - 18/1/12 at 02:23 PM

quote:

Set the main jet size first to give the correct afr for WOT, then you set the needle which controls mixture from just above idle until nearly WOT and then set idle.


That's exactly what I did.

Stu

Craigorypeck - 18/1/12 at 07:13 PM

WOT at red line has an afr of 12:1 which isn't too bad its the other areas I'm having trouble fine tuning.
Setting the needle at certain heights works ok for certain areas but another area is then compromised, believe me I have tried every possible combination with clips and shims and jets. I have a wideband and driven the car for a year so I know exactly what needs done.