7 replies to this topic

[andy26nash]

I have an 850 mini with a HS4 carb. this is not the original carb and I do not know the history but has had a stage 1 kit fitted so it has a K&N filter and AAF swinging needle. The needle has a flat side not sure if this is intentional or due to wear.

 

The engine is running too rich, rarely needs the choke, the exhaust pipe is sooty, you can smell petrol and at MOT it was a real struggle to get it within acceptable limits. without the expense of a rolling road session I was hoping somebody could tell me what would be a good needle to try for this combination. looking to improve the economy.

 

Any suggestions welcome

[Mini Manannán]

Have a play around on the compare-o-rama: http://www.mintylamb.co.uk/suneedle/

[jaydee]

You have to hook it up to a gas tester and set it at 3.0 CO at tickover

AAF will probably be a bit rich anyway

[andy26nash]

Thanks for the pointers

 

So looking at http://www.mintylamb.co.uk/suneedle/ just to check my understanding.

Compared to the AAF needle:

An AAQ needle would be leaner at wider throttle openings?

An AAN would be leaner across the board?

 

On the gas tester: when connected for the MOT even with adjusting the mixture nut could not get down to anywhere close to 3

[jaydee]

Assuming adjustment has been done correctly, if cant get close to 3.0 CO your needle and jet are both worn and need replacement

[carbon]

Flat side on needle is wear, you won't be able to set idle CO and pull properly just off idle.

 

As Jaydee says, fit a new needle.

 

I would not worry about the jet, as any wear on the jet can usually be adjusted out unless really bad. And needle is a lot easier to change.

[Fast Ivan]

Or maybe get it on the rollers with a decent tuner who can do custom needle work

[KernowCooper]

Or maybe get it on the rollers with a decent tuner who can do custom needle work

And thats like finding Hens Teeth, lots will do the RR bit but those skilled enough to profile a needle are few and far between, which is why there is so many Modified Classics running around with flat spots or very weak/rich