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Mercury carburettor handing.

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Mercury carburettor handing.

Posted by jonathan_clinkard at February 22. 2017

The carburettor we fitted to my Mercury when it was changed from twin carbs to a single unit, is I presume right handed, the tickler on the right hand side. I plan to buy a new concentric at some stage and  just need to confirm that a RH unit would have been fitted when the machine was new? Thanks in advance to anyone who replies, it will be most appreciated. Joff Clinkard.

Re: Mercury carburettor handing.

Posted by Andrew Heathwood at February 22. 2017

Hello there

Yes looks like RH unit as you reckoned. See article

http://www.britcycle.com/Manuals/MercuryDist.pdf

I'll check for other sources of info.

Andy

Re: Mercury carburettor handing.

Posted by Andrew Heathwood at February 22. 2017

Just checked in Roy Bacon's Norton Twin Restoration book and there is a clear picture captioned '1969 Mercury...' on page 75 showing the single RH Amal Concentric.

Andy

Re: Mercury carburettor handing.

Posted by howard_robinson at February 22. 2017

hello Joff -  Yes I agree a R/H 900 type unit should be fitted. However the actual size may require some measuring.  The Mercury head is a modified Commando unit and not an upgrade to the 650SS head that preceded it.  As such the inlet port diameter should be anticipated to be 30mm.  The single carb manifold used on the Mercury may well have been the same as that used on the 650 Standard and the early Atlas single carb versions.  Both these bikes had a single 1 1/8 inch Monobloc and this is about the same as 28mm.  I have owned and measured several of these manifolds but only on two occasions have seen a 30mm variety.  I should check your manifold and inlet port sizes and consider your options.  The last thing you need is a step between the carb and manifold and manifold and head.  My Mercury (208) runs quite quickly with a 28mm tho' I did have to blend in the manifold. Cheers, Howard

Re: Mercury carburettor handing.

Posted by David Cooper at February 22. 2017

..all of which dimensions are further complicated if the inlets to the head have the sleeves as fitted to 88SS and (I think) 650SS.  In other words - the entry port on my 88SS is bigger than the carb (undesirable, as Howard says) so it has sleeves inside.  They were missing when I acquired the bike and I made my own from sheet aluminium annealed and rolled to suit.

Did Mercury have sleeves? 

Re: Mercury carburettor handing.

Posted by howard_robinson at February 22. 2017

 

No David,  the Mercury head was derived from the Commando and never had the sleeves fitted as per the "downdraught head 88 SS" and the 650 SS.  I don't think that the Atlas ever had the sleeves fitted either and neither do I believe that the late 650SS with the Concentric carbs had the sleeves.  It's a minefield for the unwary........Cheers,   Howard

Re: Mercury carburettor handing.

Posted by anna jeannette Dixon at February 22. 2017
Previously jonathan_clinkard wrote:

The carburettor we fitted to my Mercury when it was changed from twin carbs to a single unit, is I presume right handed, the tickler on the right hand side. I plan to buy a new concentric at some stage and  just need to confirm that a RH unit would have been fitted when the machine was new? Thanks in advance to anyone who replies, it will be most appreciated. Joff Clinkard.

 

Hello  YOUR Carburettor will be a Left hand  with tickler to the left-hand side   and with twin carburettors you have a Rh hand and Left hand  So to go to single Carburettor  you only need the left-hand carburettor and change the jetting     yours  anna j

Re: Mercury carburettor handing.

Posted by anna jeannette Dixon at February 22. 2017
Previously David Cooper wrote:

..all of which dimensions are further complicated if the inlets to the head have the sleeves as fitted to 88SS and (I think) 650SS.  In other words - the entry port on my 88SS is bigger than the carb (undesirable, as Howard says) so it has sleeves inside.  They were missing when I acquired the bike and I made my own from sheet aluminium annealed and rolled to suit.

Did Mercury have sleeves? 

Hello your referring to pre-heater sleeves   the first machine to have these was the Manxman 650  and somewhat later on the model 88ss and 650ss  models  after April 1961  but the Manxman 650 was built from November 7th 1960  well before the 650ss and model 88ss   

Re: Mercury carburettor handing.

Posted by howard_robinson at February 23. 2017

hello - i didn't think it would be long.  This topic was not related to the Manxman 650 - until now ?   Roll-on March !!  I'm out of here until that time.  Cheers, Howard

Re: Mercury carburettor handing.

Posted by dominic_gomes at February 23. 2017

My mercury runs a 32mm 900 series carb. Manifold I have was worked a little to match the carb diameter. Works very well. About 14% more volume over the 30mm std unit at WOT.

Re: Mercury carburettor handing.

Posted by philip_ham at February 23. 2017

Jonathan,

If you look at the brochure in Andrew Heathwood's reply you will see that the carb is an Amal Concentric 930, fitted with a 280 main jet.  The tickler is on the RIGHT hand side, which is the same as my Mercury, which I've owned for over 20 yrs now.

I do have a copy of full workshop manual, and the only difference from the standard manual was a stamped insert with the carb specifications, plus a section on the electrics to cover the capacitor ignition system.

Regards, Philip

Re: Mercury carburettor handing.

Posted by jonathan_clinkard at March 08. 2017

Thanks to everyone for your helpful comments. The manifold I have used needed very slight alteration to eliminate the step up to the 930

concentric bore, and runs beautifully. When the bike had twin carbs,

they needed regular adjustment, which of course has now been eliminated and one knows both cylinders receive the same mixture.

I rather fancy using an aluminium concentric when they get round to

making one.

Best regards, Joff Clinkard.

 

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