I pulled the twin HS2's apart for a clean before the Asparagus Job, and while putting them back together just now I had a massive WTF moment.

I've had these carbs apart dozens of times over the years, and I just noticed that one spring is longer than the other by 20mm

Neither have any hint of a paint code on them. The shorter of the two is 120mm long, the longer is 140mm. Coils on both are about .032" in diameter.

Can anyone tell me what I have here? Also, can anyone tell me what spring (red/blue/whatever) would be most suitable for twin HS2s with M needles on a warm 1150?

Out of interest, I pulled the spring out of the single HS4 on my 998 van, but it's 125mm long and about .038" in diameter, and (perhaps in my imagination) feels slightly stronger than the 120mm one.. so I'm hesitant to throw that one in...

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Simon

The adventures of an owner builder in the Tallarook Ranges

oops! does it take the same amount of effort to lift them up?

red springs are likely to be the best - Vizard lists them with M needles for a modified 1098

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did I tell you that I won a trophy?

Cool, thanks for that. Any idea what length/diameter the reds are?

I think the reason I noticed it this time was because I had the air filters off to replace them, and instinctively stuck my finger in to check the pistons were falling freely, and one of them (do you think I can remember which one now? ) felt a little lighter, as if it had low dashpot oil.

[edit] I've got them back together now, and maybe I'm imagining it but the longer one feels lighter...

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Simon

The adventures of an owner builder in the Tallarook Ranges

I've got about 6 springs all different - so in the end I just bought two new red ones for the twin HS2's

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David L


My greatest fear in life is that when I die my wife will sell my Mini and tools for the price I told her I paid for them!

there are two red springs. they vary in the length at the same load.
One is 4 1/2oz at2.635" and the other is 4 1/2oz at 1.530"
one type was fitted to 1 1/4" carby and the other to 1 1/2"carby. The idea is to have the same amount of resistance for uniform piston lift, but the piston travels a different distance.
Now to confuse matters more there are quite a few springs that look totally different,but because of the pitch of the spring and the diameter of the wire they end up with the same load at the same distance.

Do you have two springs that are exactly the same, if so fit those and try. This will give you a starting point.
The SU Manual recomends red springs, but the tune-up data book says for fast road/race engine use a blue spring. A lighter spring will allow the piston to lift quicker, but the needle has to match.

Have fun!!!!!!!

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Research is the difference between speculation and investment. Anyone who copys some one else will always be second
www.minisprintgt.com

Nup, I don't.. I'll see if I can source a couple of reds to start with. Maybe I should get the digital scales out and measure the two I have at the same length, who knows they might be close enough.

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Simon

The adventures of an owner builder in the Tallarook Ranges

Simon, The weight refers to the total applied force to the spring for the total distance the spring is compressed.
The tool that SU use is a holder that the spring sits vertical in, and it has a rod that goes thru the spring. The rod has a pre-determined weight and as you add weights to the rod the spring compresses and the length is measured. [MR. Hooks law]

I will have a look thru my collection as I am sure I have some reds for 1 1/4" carbys. I can send them to you if you want to try them.

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Research is the difference between speculation and investment. Anyone who copys some one else will always be second
www.minisprintgt.com

Yeah, I was thinking of the inverse, applying force to both springs such that they're the same length, then measuring that force. Either way, it'll tell me if the springs I have are equivalent despite their length difference.

Thanks for the offer of the reds, I'll see if I can find a couple close by first

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Simon

The adventures of an owner builder in the Tallarook Ranges