I'm too much of a virgin in the mini scene to figure this out so i am wondering firstly what's the diffence with HS2 and HS4 twin su's and secondly what would i need to do to make it run with an 1100(modifications that is) properly or would i be wasting time/money effort and run a 1275 with bore ect ect?

HS2 is 1 1/4" carby
HS4 is 1 1/2" carby

on a modded 1100, a hs4 or even a hs6 would be suitable, but hell, if ya got a 1275 lying around, get on it

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Here am I sitting in my tin can far above the Moon
Planet Earth is blue and there's nothing I can do...



“A turbo: exhaust gasses go into the turbocharger and spin it, witchcraft happens and you go faster.” - Jeremy Clarkson

Twin HS2's or preferably a single HS4 on a good manifold is what I would run on an 1100.

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there`s nothing wrong with twin 1&1/2s on a small bore,,, "IF" you already have them that is

but not sure it`s worth the time. money & effort to go out of your way to get them just because i said they`d be cool... a single 1&1/2 is fine really

if you have a 1275 sitting there looking pretty & if you already have said twin 1&1/2 carbs set up, sitting there looking pretty, then bung them together my friend

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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.

i wish i had a 1275 lying around just thought id add that in cause the 1100 in it has overheated! probably as a result of driving it around after sitting in an old mans shed for 4 years so next month the whole motor will come out and get a going over/rebuild and thinking which way to go, whether to stick with this motor and modd it(ie twin su's, turbo or supercharge setup) or source a 1275 or just leave it mild pending overall costs considering the 1098 k motor was already in it not the original motor setup of the 998 so the original factor is not an option but as Clarkson says 'More Power'is a good argument

How about twin HS4?

Is it a daily driver? If it is get it rebuilt stock, maybe a light head job if its cheap.
Then buy a 1275 and build that for a fast road engine. Then slot it in down the track and your laughing.

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Simplify and add lightness

Good advise considering when it finally gets back on the road she'll be a daily. Just get excited when i have to pull a motor i always think 'maybe i'll just do this and it might go better if i alter it like that'

Nothin'n wrong at all with a coupla BIG JUGS..
Go twin HS4's

single HS4 on a good manifold will be ample.

What I have
Just built a 998 with a 1098 crank nice head, nice Cam & nice exhaust
I have a 1 1/2 on a good inlet manifold that matches with the head & SU. Its goes good

My wifes daily drive is a 1098 with bigger Cam and head has had more work with the Carb matching the head and the exhaust is also a LCB. It has a HIF44 (1 3/4) carb and have never had to touch it.
In say all this you could also go a Dellorto 40 as many do also

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Stop Licking the Dog...I Don't Care Who Started It

okay then....what is and does the dellorto 40 do then? webber is it?

Gone are the days when people left 1275 engines lying around... These days they are kept wrapped up in Cotton wool. That is how I keep my stash of them any way !!

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DID I MENTION THAT I AM THE BEST SUPPLIER FOR MINI ELECTRICAL PARTS AND REPAIRS?
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A 40mm Dellorto is much the same as a 40DCOE Weber.
But they are cheaper to buy s/h, easier to tune (IMO) and are more economical on a road car than a Weber is. Usually.

Advantages over single or twin SUs-
1. Throttle shafts have ball bearings and seals, so they don't wear and suck air like SUs do.
2. They are basically 2 carbs in 1 body on a common throttle shaft so don't need synchronising like twin SUs do.
3. Easier to tune, as they have real air and fuel jets, not 1 out of 700+ needles to pick.
4. Once jetted right, they stay in tune.....
5. Better throttle response, once on cam.

Disadvantages-
1. Poorer low speed throttle response. So you just don't treat the throttle like a light switch.
2. Noise/music- they ain't quiet.
3. They do use more fuel than SUs do. But, it's worth it.

Here's a Dellorto (45mm) on my 1412 stroker, on GR's engine dyno. A 40mm looks the same.

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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.

Doc why is this the case....Japanese manufacturing?