Reliant SU Carb safety advice

[morrag]

Well, my point has obviously been missed regarding the maintenance of an SU to prevent habitual "flooding", however, the standard 850cc motor that most seem to run, is so under stressed, and in such a low state of tune, that the SU is more than adequate for its performance capabilities as standard. Before such a motor can take advantage of superior carburation it's breathing capabilities require suitable enhancement, otherwise,sadly, like a noisy exhaust system, your just kidding yourself, Morrag

[fifer]

Originally posted by Morrag ;
Well, my point has obviously been missed regarding the maintenance of an SU to prevent habitual "flooding",

Not missed by me and agree that pre-emptive maintenance is the best thing for everything . However ,when upgraded parts are built by the manufacturer to improve the safety aspect of their products , then I will fit those at maintenance time  .

Originally posted by Morrag ; however, the standard 850cc motor that most seem to run, is so under stressed, and in such a low state of tune, that the SU is more than adequate for its performance capabilities as standard. Before such a motor can take advantage of superior carburation it's breathing capabilities require suitable enhancement, otherwise,sadly, like a noisy exhaust system, your just kidding yourself, Morrag

That is spot on info and the Reliant lump can have a good few ponies released with minimal or no outlay .
The standard Reliant 850cc engine is supposed to produce around 40bhp but some folk have had them tested and some were as low as 30bhp .
So if , for example , the following modifications released a power gain of 20 percent then a 33 bhp motor will end up with around the original 40 bhp and the 40 bhp motor would be 48 bhp .
But would the 33 bhp motor have the capability to leap right up to 48 bhp ??
The inlet manifold is easily adapted with just an electric drill or a wee Dremel type tool or just a few files and emery.
The same principle can be applied to the head to take full advantage of the modified inlet manifold .
The Exhaust manifold was produced with 2 different port sizes and can be opened out , of course again matching with the ports in the head .
Goes without saying that all these items have to be matched to the gaskets .
The manifold gasket can be modified to take advantage of the inlet manifold improvement .
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Have details of any of these modifications been put up on site ?

[morrag]

In fact what you need is one of these!.............................

[fifer]

Wish I could still get one at THAT price ; It would save me a lot of time and effort as my arthritic fingers do not work as well nowadays  .
I would love to have seen if they took the metal between the inlet ports away by tapering the sharp face where the manifold gasket fits but unfortunately I cannot blow it up far enough and it is at slightly the wrong angle .
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[hunter]

I have two similar heads,Maybe a little bit more been done to mine,
Having said that at that price i think I'll have a couple more

[fifer]

Head and manifold just starting to be modified ;

Head showing original metal between the inlet ports on the left and the starting to be modified inlet ports on the right .

Reliant SU Carb safety advice

Manifold starting to be modified to suit the head and the ports

Reliant SU Carb safety advice

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[hunter]

For what i can see of the pic,The inlet ports have a fair spacing,No knife edge.

[tbone]

Have details of any of these modifications been put up on site ?

We have covered the inlet manifold mod, may be of interest to some if you can post details  of them all though?

[morrag]

As advertised in "Motorcycle Mechanics",April,1970,priced two shillings and sixpence, or for 'younger' readers. 121/2pence!! them's were the days! Morrag

[digger06]

Me ; Same as Merv above  
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34 ich,
25mm venturi , needed the manifold bolts turning 90 deg like a 750 engine, but then went straight on, (i ported the manifold to mate it better though,)
got it off a guy who suffered poor hot starting with it, but i dont get that problem (he had it in a 3 wheeler car)
fifer, it was off wrighty on your favourite site ,
runs great, better power everywhere

[fifer]

Originally posted by digger06 ;
got it off a guy who suffered poor hot starting with it, but i dont get that problem (he had it in a 3 wheeler car)

Yep , the Reliant lump prefers the fresh air and once released from its fibreglass overcoat can pull the skins of rice puddings .
Yeah , had a few conversations over the Dog & Bone with Wrighty when he first joined .
The SU carb is a simple carb and will run under all conditions and does not ask for much BUT , as you have proved , other types of carbs can be better if you can get the size and jetting correct for your particular engine / exhaust system .
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[fifer]

Originally posted by tbone  ;
We have covered the inlet manifold mod, may be of interest to some if you can post details  of them all though?

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New topic started re ; Exhaust Manifolds at

http://www.mankymonkeymotors.co.uk/forum/index.php?topic=10694.msg134949#msg134949
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