rough start on carb needles

[814CWE]

mg1100 engine.12g295 head std mg1100 cam with 2 ring i.d markings
maniflow freeflow and rc40 (recieved well packed thanks minispares north)
running twin hs2 with pancake filters ..

i know it will need setting up but what needles shud i use to get up and running??

[InimiaD]

Try this very useful info.

http://mk1-performance-conversions.co.u ... l_carb.htm

[carbon]

The MG1100 with twin HS2s ran GY needles, with your filters and the RC40 these are likely to be a bit on the weak side so as a starting point M needles are probably a safer bet, using blue springs.

[Lord Croker]

While on the subject of SU needles, I have just prepared a friend's Mini for MOT, which it flew through, but I noticed on the way to the test, it is running dangerously lean at high RPM. It's a 998 A+ bored to 1040 with a 948 cam, polished & ported head, flat top pistons, (9.5:1 compression) LCB, 1.75 exhaust system & pancake filter. It has the HS4 carburettor with the swinging needle. Am I right in thinking an AAU needle would be a good starting point? I have a selection of needles for twin set ups, but have done little experimenting where singles are concerned, so any advice would be much appreciated.

[carbon]

For your 998 running weak at high rpm also worth checking that the dashpot spring is the red one. Even within red springs I have seen quite a variation and have managed to sort a 998 that was running lean at higher speeds by a stronger red spring. A recently acquired Minispares red springs from 12 months back was particularly good for this.

[Lord Croker]

Thanks for that, carbon. I will certainly look into that when I take another look at the car next week, with any luck, I might even have a red spring.

[814CWE]

got a pair of new m needles

all the springs i have have no olour markings,,,is there a visual difference?

[carbon]

First check is that the springs are about the same length. Then the best way of roughly checking what colour spring you have with HS2 carb is :
- take one damper pot, remove damper rod and drain all oil
- remove needle from piston, clean pot & piston
- turn damper pot upside down, put spring in
- put piston onto spring, see how far down it goes

If the piston goes right down then its blue
If it hovers with some of the ridged edge showing its red
If it pops out onto the floor its yellow or green

This just gives you a starting point. Matching the springs is a completely different ball game...

[Lord Croker]

For your 998 running weak at high rpm also worth checking that the dashpot spring is the red one. Even within red springs I have seen quite a variation and have managed to sort a 998 that was running lean at higher speeds by a stronger red spring. A recently acquired Minispares red springs from 12 months back was particularly good for this.

To finish the story on this Mini, I fitted the red spring, which improved the high rpm running considerably, I then decided to try an ABA needle, which is what my engine runs on, being in a similar state of tune, but not bored, & that 'put the icing on the cake', it went like a scalded cat, but ran very clean, in fact I had a phone call from the owner tonight, "What have you done? I never got home from work as quick in my life!" Job done, I think. Thanks for the info.