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Dismantling Su carbs
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petermeachem



Joined: 23 Sep 2013
Posts: 358
Location: Chichester Sussex

PostPosted: Fri Jan 10, 2014 10:02 pm    Post subject: Dismantling Su carbs Reply with quote

I've a couple of MC2 Su's which I've had for years and want to sell. I want to make them prettier first. They don't look bad but I just can't take them to bits. The suction chamber is held on by one screw on a lug (screw removed) and what looks like a dowel pin on a lug diametrically opposite. I can't get the chamber off. I've been dosing it in plus gas for days and it won't shift at all. Any ideas?
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47Jag



Joined: 26 Jun 2008
Posts: 1480
Location: Bothwell, Scotland

PostPosted: Fri Jan 10, 2014 11:07 pm    Post subject: Reply with quote

Peter,

Could you pry between the piston and the carb 'floor' with something to lift piston and chamber?

Art
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petermeachem



Joined: 23 Sep 2013
Posts: 358
Location: Chichester Sussex

PostPosted: Sat Jan 11, 2014 8:29 am    Post subject: Reply with quote

I'm wary of putting any force on the body. I was wondering if I took the jet off if I could use a drift through the jet and onto the piston, not sure how much room there would be
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ka



Joined: 03 Dec 2007
Posts: 600
Location: Orkney.

PostPosted: Sat Jan 11, 2014 8:43 am    Post subject: Reply with quote

I stand to be corrected, but believe the top body is held down with two screws, therefore the 'dowl' side could be a sheared off screw, that is why the body is not parting with reasonable force.
Try drilling it out of the top body, then soak with penetrating fluid, and we should have Robert, your fathers brother knocking at the door.
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KA

Better three than four.
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petermeachem



Joined: 23 Sep 2013
Posts: 358
Location: Chichester Sussex

PostPosted: Sat Jan 11, 2014 1:27 pm    Post subject: Reply with quote

ka, you are right. Why didn't I check with the other half of the pair I have in a box in a garage instead of assuming it was a pin?
It's not going to be easy to get out, the chamber is in the way of a drill chuck. I might be able to get to it with my modelling drill (cheap dremel)
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petermeachem



Joined: 23 Sep 2013
Posts: 358
Location: Chichester Sussex

PostPosted: Sun Jan 12, 2014 10:04 am    Post subject: Reply with quote

Thinking about this the hole in the lug on the suction chamber isn't threaded is it? So I shouldn't have to attempt to drill it out. I'll continue with other methods
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Bitumen Boy



Joined: 26 Jan 2012
Posts: 1733
Location: Above the snow line in old Monmouthshire

PostPosted: Sun Jan 12, 2014 11:37 am    Post subject: Reply with quote

How about some hot water on the suction chamber? Might just expand it enough to get some movement. I'm not familiar with these early SUs, but I'm guessing they're a similar alloy to more recent types?
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Roger-hatchy



Joined: 07 Dec 2007
Posts: 2135
Location: Tiptree, Essex

PostPosted: Thu Jan 16, 2014 5:19 pm    Post subject: Reply with quote

The SU MC (motor cycle) 2 carb has two screws holding the vacuum chamber to the main body,
it will rotate once you have the screws removed,
it will fit either way round,
it is not threaded to the body and the vacuum chamber screw holes
are not threaded, it is threaded in the main body.
The piston has a keyway to line it up in the main body.
With the carb of it might be possible to get at the screw from below.

I have an exploded diagram of the MC2 some where
I'll post it as soon as I find it.
And some photos
The DLM has two MC2's fitted and I have lost count of the times
I have stripped and rebuilt them.

Roger
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petermeachem



Joined: 23 Sep 2013
Posts: 358
Location: Chichester Sussex

PostPosted: Thu Jan 16, 2014 5:23 pm    Post subject: Reply with quote

One screw has sheared and they are properly stuck. I give it a squirt of penetrating every time I go past. Next I'll pour boiling water over it.
I've taken loads of old su's apart, never had a problem before
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ka



Joined: 03 Dec 2007
Posts: 600
Location: Orkney.

PostPosted: Thu Jan 16, 2014 7:21 pm    Post subject: SU carb on a Motor Cycle. Reply with quote

I know that the Mk1V Commando, that was never made, was to have an 11/2" SU on it, as I have the same carb, and a manifold from the Norton Casting on my Mk11a.
But I am intrequed, what motor cycle was produced with an SU Carb?
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KA

Better three than four.
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petermeachem



Joined: 23 Sep 2013
Posts: 358
Location: Chichester Sussex

PostPosted: Thu Jan 16, 2014 10:13 pm    Post subject: Reply with quote

If you google 'su mc2' there seem to be quite a lot. What intrigued me is why they seem to end up on Ford Specials, I think Aquaplane sold them but I've no idea why, must be some sort of clearance issue.
http://pre67ford.hyperboards.com/action/view_topic/topic_id/1920
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Rosco663



Joined: 17 Dec 2012
Posts: 257
Location: South Australia

PostPosted: Wed Jan 29, 2014 6:37 am    Post subject: Reply with quote

I have had success boiling small items, such as carbies, in a saucepan full of water with a small quantity of Sugarsoap added. Seemed to break down some of the corrosion quite quickly and also has the benefit of applying heat which is always a good idea for stuck parts. .

After simmering for about 20 minutes remove the parts, give them a quick rinse then air dry then hit it with a squirt of 50/50 Acetone/Automatic Transmission Fluid or any other good penetrating fluid. Then attempt to get some movement between the parts.

Don't be tempted to soak in this solution for extended periods as porous materials can absorb this liquid and adverse chemical reactions can occur.

I did this exercise in the shed on a camp stove - don't tell the missus about the saucepan Wink
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petermeachem



Joined: 23 Sep 2013
Posts: 358
Location: Chichester Sussex

PostPosted: Wed Jan 29, 2014 7:31 am    Post subject: Reply with quote

Plenty of things to try. I've been a bit busy getting rid of things and selling bits as the house is sold so the carbs have just sat there. Must get back to them soon. Sugarsoap is excellent stuff for degreasing. I washed the kitchen down with it once and all the skin fell off my right hand, will wear marigolds next time
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