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Firery Fred
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« on: January 09, 2014, 09:24:21 AM » |
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Fancied trying an su carb on my xs, someone piped up that they were available, albeit years ago, for bikes , ie smaller. Anyone any ideas ?
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It's better to have a gun,(welding),and not need one than need a gun and not have one
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Olds
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« Reply #1 on: January 09, 2014, 09:53:33 AM » |
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Smallest SU that I know of is the 1 1/8" used on very early Sprite. Should imagine they would be hard to get in good condition.
Would have thought that 1 1/4" (32mm) as used on Reliant 850 and a lot of other small cars could be used and easier to come by.
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Getting older but no wiser! Just using bigger hammers.
The answer to most problems, fire and lots of it.
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Dslam
Sr. Member
Karma: 13
Posts: 457
Wot ho chaps, its bloody Whitworth!!
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« Reply #2 on: January 09, 2014, 10:52:09 AM » |
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Have a look at this link from Burlen fuel systems who reproduce new SU carbs. Triumph 6T Thunderbird from 1951-56 used an SU (MC2 type) http://sucarb.co.uk/carbspec/carburettor/spares/id/2504/If the linky not working just copy and paste. Hope that helps. |
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Olds
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« Reply #3 on: January 09, 2014, 11:12:34 AM » |
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That's interesting. It's an 1 1/4" SU for motorcycles, with lever choke.
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Getting older but no wiser! Just using bigger hammers.
The answer to most problems, fire and lots of it.
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morrag
Hero Member
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Posts: 2875
Carpe diem!
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« Reply #4 on: January 09, 2014, 01:03:35 PM » |
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Get your self an as fitted to 'Mini', or similar 11/4" SU, make up an adaptor flange, and bingo! I have done it several times before,over the years, after all, a carb. is a carb. is a.........if you get my drft!The mid 50's did see Triumph use a purpose built SU on their Thunderbird's, but not for too long.I'm using a larger, probably too large! SU on the 500cc Honda GL motor for my 3 Wheeler, but we shall see how it performs,  ...Morrag |
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Beware the Ides of March, But!
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morrag
Hero Member
Karma: 49
Posts: 2875
Carpe diem!
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« Reply #5 on: January 09, 2014, 01:11:00 PM » |
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I have attached a pic to illustrate!  ...Morrag |
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Beware the Ides of March, But!
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Manky Monkey
Administrator
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« Reply #6 on: January 09, 2014, 07:34:35 PM » |
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There's a guy on Ebay who makes cast aluminium casings & manifolds for XSs. I bought a pair of inlet manifolds from him to fit Amal carbs to mine, (2nd one down on the left). He makes them to fit an SU to an XS, (3rd & 4th down on the left). Cast stuff |
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« Last Edit: January 09, 2014, 07:36:46 PM by Manky Monkey »
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On the last freedom moped out of Nowhere City.
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Firery Fred
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« Reply #7 on: February 02, 2014, 07:08:36 PM » |
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Thanks everyone ,my mate has one that might be coming my way,when we can agree a price that I can afford. It's the smallest I've seen but of unknown origin , so we'll see
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It's better to have a gun,(welding),and not need one than need a gun and not have one
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kapri
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« Reply #8 on: February 02, 2014, 09:05:30 PM » |
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On a normal carb venturi affects air velocity = fuelling and pick up . SU is variable venturi so will only rise as far as air requirements though too large a starting point will affect low end torque . Using an SU on a 500c revving to 10,000 then best size woudl be something used on a 1000cc car engine as same CFM requirements to be met at 5000 rpm.
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Firery Fred
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« Reply #9 on: February 06, 2014, 10:56:23 AM » |
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He's had this carb on an XS and it ran great once set up correctly
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It's better to have a gun,(welding),and not need one than need a gun and not have one
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