Hi - this has probably been asked before somewhere, but a quick search didn't give me the answer:
Re: 1 1/4" SU's on the cooper s - I have "M" needles in at present (as were on the car when purchased), and am told that these are the richer needles, and that GY is the standard. (?)
Since the engine rebuild, the car seems to be running a bit rich at idle, but the plugs look fine after a run, so that would suggest it's running ok at revs (certainly goes good ).
I was going to instal richer needles to allow more leaning off at idle without leaning it too far at revs, but as mentioned I now discover I have the richer needles in anyway.
I'm using BP98 with flashlube. Would reverting to the GYs help the idle without leaning off too much at revs?
One of my needles has a bit of a scratch down it - I'm sure that's not helping.
What needles/settings are others using?
Cheers
Peter.

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1969 Mini Cooper S MKII (1330)
1972 Honda 750/4 (his),1976 Honda 400/4 (hers)
1982 Honda CB1100RC (ours)

I was always told that M's were standard Cooper S / Clubman GT.

I once had M's on a warm 1100, and it was too rich.

AH2 is the rich needles for a cooper S. M is the standard.

Try some new AH2s, with a slight decrease in idle fueling, and I think you would be happy. How standard is the rest of the motor? Induction / exhaust, head, cam?

If any of these are different to standard the AH2s will be a starting point, and a rolling road tune with an experienced operator will be the go.

Good luck,

Matt

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68 Deluxe.... it's shiny..... I like shiny!!

Cheers guys for your responses.
The info I got about the "M" was from a SU "specialist" company, so not sure what's happening there
Am running fairly standard engine, though bored to 1330, no porting as such, but cooper s spec cam grind and +10 mains on the crank, standard valves etc. Pancake style paper air filters. Head was just very lightly skimmed, so I guess compression is up very slightly (maybe) - don't know if that effects fueling though.
My mail was that todays fuels are denser and can lead to these issues (I'm certainly no expert) and that richer needles sorts the problem mostly.
Thanks for your suggestions.
Cheers
Peter.

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1969 Mini Cooper S MKII (1330)
1972 Honda 750/4 (his),1976 Honda 400/4 (hers)
1982 Honda CB1100RC (ours)

this is a bit of noob question. but is the "needle" the brass pointer in the middle of the carb coming out the bottom of the piston? about 1 1/2 , 1 3/4 inches long? i've got few spare of those. they all look the same. can you tell the difference by looking at them or is it written on them somewhere?

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Sunday Morning Mini Sprint http://www.youtube.com/watch?v=UtGuzqBQ32Q my "rendezvous"

Yeh, from your description that's the bit - mine has the "M" on the top part (not visible when inserted in the piston).
I'm fairly new at this too so it's all a bit of a learning curve at the moment.
Peter

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1969 Mini Cooper S MKII (1330)
1972 Honda 750/4 (his),1976 Honda 400/4 (hers)
1982 Honda CB1100RC (ours)

Yes - the needles are the gold things hanging down from the bottom of the piston.

They all have a code stamped into the shank but you have to take the needles out of the piston to see the code. Each different code represents the different profiles machined into the needles. The taper (profile) of the needle dictates how much fuel is made available for the engine at various points in the rise of the piston.

I find this site invaluable for comparing needles, select M and AH2 and you can see the difference.
http://www.mintylamb.co.uk/suneedle/

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Hey Doc, I can remember drawing up profiles of needles by hand using the tables in a well-worn SU tuning book and some graph paper. Computers have certainly simplified the process nowadays.

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Curly
'64 Cooper 'S' (Group Nb spec)
'67 Mini Marcos GT www.mm7056.wordpress.com

Winsu is a very good program put out by a pom called Scott Beavis for detailing SU profiles and best matching needles to suit applicatiions and motors.

Its very reasonably priced too.

Thanks for that - are you able to offer an easy interpretation of what it shows?
Peter

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1969 Mini Cooper S MKII (1330)
1972 Honda 750/4 (his),1976 Honda 400/4 (hers)
1982 Honda CB1100RC (ours)

Basically the AH2 is richer than the M, all the way up.
Put a few others in- AN, BG, CP4, 6, etc.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Cheers - have ordered some AH2's, so we'll see how we go.
Peter

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1969 Mini Cooper S MKII (1330)
1972 Honda 750/4 (his),1976 Honda 400/4 (hers)
1982 Honda CB1100RC (ours)