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R1 air corrector bore size
RobBrown - 17/9/13 at 10:11 PM

I've drilled mine out (previously soldered closed by someone else), which has removed the brass insert so I need to know what size to re-drill a new brass insert to, to bring them roughly back to stock.

Thanks
Rob

BaileyPerformance - 18/9/13 at 09:30 AM

I did a 318 BMW recently with R1 carbs, we used 2.0mm mains and 0.3mm air correctors, fuelling was very close.

RobBrown - 18/9/13 at 03:11 PM

quote:
Originally posted by BaileyPerformance
I did a 318 BMW recently with R1 carbs, we used 2.0mm mains and 0.3mm air correctors, fuelling was very close.

Does that mean you soldered and re-drilled them to 0.3?

As far as I can tell the air corrector (the one that's usually blocked) is a factory insert and isn't available on the standard parts list for these carbs (5JJ Year 2000 R1). It doesn't show up on any diagram schematic.

RobBrown - 18/9/13 at 03:14 PM

BTW its the one that looks like a blob (Marked A) on this picture that I have redrilled out and need to replace
Does anyone have a picture where they haven't blocked it


[Edited on 18/9/13 by RobBrown]

jacko - 18/9/13 at 05:36 PM

I am sure when boggs blocked my air correction holes they used 2.5 alloy rod that had to be knocked in to the brass hole
so at a guess the hole in the brass would be 2mm
This is on zx9r carbs so yours may be different
Jacko

BaileyPerformance - 18/9/13 at 05:51 PM

quote:
Originally posted by RobBrown
quote:
Originally posted by BaileyPerformance
I did a 318 BMW recently with R1 carbs, we used 2.0mm mains and 0.3mm air correctors, fuelling was very close.

Does that mean you soldered and re-drilled them to 0.3?

As far as I can tell the air corrector (the one that's usually blocked) is a factory insert and isn't available on the standard parts list for these carbs (5JJ Year 2000 R1). It doesn't show up on any diagram schematic.


yes, we soldered up the factory inserts and drilled

RobBrown - 18/9/13 at 08:01 PM

quote:
Originally posted by jacko
I am sure when boggs blocked my air correction holes they used 2.5 alloy rod that had to be knocked in to the brass hole
so at a guess the hole in the brass would be 2mm
This is on zx9r carbs so yours may be different
Jacko


Thanks - The insert size is 3.5mm, so 2mm would make sense. Although I'm not convinced from what I have pulled out, the top of the insert is the same diameter as the bottom of it

As BaileyPerformance suggests I may start off small (0.5mm) and get bigger.

From my other post this will either be the thing that was wrong in the first place or just another red herring.

BaileyPerformance - 18/9/13 at 08:39 PM

quote:
Originally posted by RobBrown
quote:
Originally posted by jacko
I am sure when boggs blocked my air correction holes they used 2.5 alloy rod that had to be knocked in to the brass hole
so at a guess the hole in the brass would be 2mm
This is on zx9r carbs so yours may be different
Jacko


Thanks - The insert size is 3.5mm, so 2mm would make sense. Although I'm not convinced from what I have pulled out, the top of the insert is the same diameter as the bottom of it

As BaileyPerformance suggests I may start off small (0.5mm) and get bigger.

From my other post this will either be the thing that was wrong in the first place or just another red herring.


The standard air corrector is a stepped insert, outer edge is about 3.5mm, first part of the internal bore is about 2.0mm, the actual jet size is very small, less than 0.5mm as standard.

When the jets are blocked it only the first part if the jet that is filled.

You need around a 2.0mm main, drop the needles to lowest point, start with 0.3mm air corrector, If rich at top end drill the air corrector bigger.

When bike carbs are fitted to larger car engines the main jet does play a part in the idle fuelling as well as the idle system, so a way too small main will hamper starting.

redturner - 19/9/13 at 10:16 AM

My R1 s, on a DanST manifold are fitted with Weber 180 main jets (1.8mm) After a couple of dyno runs we blocked the a/c jets with plastic padding stuff and before it set the operative pushed a very fine piece of wire through then when set drilled them to 0.5mm then after a couple more runs he re drilled them to 0.75mm and the AFR was almost perfect. This is on a Standard 2 ltr Black Top.

BaileyPerformance - 19/9/13 at 10:27 AM

quote:
Originally posted by redturner
My R1 s, on a DanST manifold are fitted with Weber 180 main jets (1.8mm) After a couple of dyno runs we blocked the a/c jets with plastic padding stuff and before it set the operative pushed a very fine piece of wire through then when set drilled them to 0.5mm then after a couple more runs he re drilled them to 0.75mm and the AFR was almost perfect. This is on a Standard 2 ltr Black Top.


More evidence of NOT to block air correctors, we have seen several cars with correctors blocked, start small and work way up is best. Don't forget that light throttle cruse is very important, check light throttle afr every time you make a change. The BMW we did idled at 14, cruse at 14.5, full throttle 12.8. As close as you will get with any carb.

redturner - 19/9/13 at 10:32 AM

I would point out that my engine is in a single seater hill climb car and is flat out from the lights going green.....

[Edited on 19/9/13 by redturner]

RobBrown - 19/9/13 at 01:42 PM

quote:
Originally posted by BaileyPerformance
You need around a 2.0mm main, drop the needles to lowest point, start with 0.3mm air corrector, If rich at top end drill the air corrector bigger.

When you say lowest point is that the clip in the top position (leanest), so that the needle sits low.

Thanks - shame you are not round the corner.

BaileyPerformance - 19/9/13 at 10:30 PM

Yep, the needle position should only effect the light/medium fuelling, with a 2.0mm main you most likely will need the needle at the leanest position, clip at the top.

Get the WOT fuelling right first, if rich drill out the air corrector until you get it 12.5-13afr.

Try and get 14afr cruse, if leaner move the needle up until the fuelling comes right.

Your not that far away, we have had customers travel from London, Scotland, Channel Islands!