what do you mean by if the needles fit? sorry i dont know how needles work in carbies yet

If it physicaly fits into the carb

The working principle is quite easy.
You stick a needle in a hole and flood the hole with gas.
Then you screw that needle onto a piston which raises when the throttle opens and vacuum in the carb changes.

The needle gets thinner and thinner to its tip.
So the more it's drawn out of that hole (which is the jet), the more gas can mix into/with the airstream.



So you chose (or make) a needle which has the right diameter at the right hight to provide the right mixture for YOUR engine.
You sure can make a needle to suit your engine - but that's not an easy job so it'll be very easy to use that carb if the standart SU needles fit.

Erm - hope you understand what i'm writing, my english isn't that good, especially in technical terms

Cheers,
Jan

PS: thats the basic principle of an SU, there are more influencies to mixture like damper, piston springs.

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No speakers, no bodykits, no six-inch spacers, no spak filler, no bullshit

You're making perfect sense jan , love the image of the SU working by the way , might have to use that myself to explain them to people ass a lot can't grasp the idea .

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Oh ok, My friend said that the jets have been replaced or something. How do i know what needle is for my engine?

why do I find that animation erotic?

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did I tell you that I won a trophy?

i was waiting for someone to say that....you put the needle in the hole?

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oil leak?..what oil leak..that puddle under the car is just sweat from all that horsepower

Jan,,, you have done exceptionally well,,, the best/easiest i`ve ever seen/heard it explained,,, well done

& Simon,,, you`re not the only one i love cartoon sex,,, oops,,, er,,, um,,, did i say that out loud ???

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No offence intended here but--> anyone writing a book about minis 30 years ago may not have experienced such worn or stuffed-with components as we are finding these days.

You should put your heart & soul into everything you do.

will i just need to buy a needle to suit my engine and fit it, or do i need to make any other mods to the carb?

Have you got a normal SU needle lying around, or from your other carb? If that fits into one of those, yes, just buy a needle to suit.

can i use the needle thats in my 1.25" carb in the 1.5" or do bigger carbs have different needles

Good question! IIRC they all have the same needles... someone care to verify. I haven't tried different needle/jet combos

The 1.5" needles are bigger. The main drama might be the design in which the way the needle fits the piston in the Jap instrument. Midel may have a conversion kit, same as when you change the spring loaded 1.5 needle to fixed needle in Mini HS4's - You may be lucky.

so i will have to go out and buy a needle

Hey Pete - have you breathing too many of those tile glue fumes???

HS4s are 1.5s .??.. and 1 1/4s and 1 1/2s both use 90 thou jets and hence the same family of needles (albeit different needles due to the different air flow each type provides). The conversion kit to change fixed to floating needles is a simple holder that costs a few $$ (I think my last ones cost less than $5 each.

One of the SU catalogues should identify an appropriate needle for a stocko 1.5 equipped 1100.

Cheers, Ian

Vizard is suggesting M1 or BQ, but for a datsun carb, who knows...

but cookie, I reckon you're nuts using one when you can get proper 1.5" SU's for nothing...

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did I tell you that I won a trophy?