Forum

[ric]

'modern fuel incompatible with the float needle valve tip?'
always a good one to throw in to any non EFI fuel related conversation

[dazza]

Yes ric funny that the last tank I filled her up with super unleaded ? No sure if this could have been a problem should I got back to just normal unleaded fuel

[Mark B]

Super unleaded shouldn't cause any issues that standard 95ron petrol doesn't also do. I always use a premium brand of super unleaded as it contains less ethanol than standard (if any) and is less likely to melt/corrode/dissolve bits of carburettors, fuel lines etc. Until recently I could get 4* leaded petrol in Hertfordshire - old bikes just love that!

[Alan R]

Hi Guys------I thought that VITON ( the rubber tip on a carb. needle valve ) was safe against modern "Petrol" ??.... http://www.martins-rubber.co.uk/blog/wh ... ial-guide/ ( Be patient---it can be slow to load )..

[Revband]

You re correct Alan, viton is not affected.

[dazza]

As the bike is ok again do I just leave it or is it worth inspecting the carb bowl to see if it needs a clean thanks

[Revband]

Just leave it alone they all do it occasionally, you won't find anything if you look it's gone by now.

[Alan R]

Hi DAZZA-----one of the better parts of an AMAL MONOBLOC design is that you can remove the float unit much more easily than it's successor--- the Concentric carb...One part of me says}---- "Leave well alone" whilst the other says}--- "Why not fit the float bowl extension unit" item 29a in that diagramme of yours......The Monoblocs suffer from cornering /banking effects due to the off-set position of the float chamber..One way over-feeds the main needle valve so it'll run rich for a while...whilst the other way momentarily starves the needle valve ie}-- it runs weak for a little while....The float chamber extention is a way of increasing the total volume in the chamber and hopefully balancing some of those errors out...

[Revband]

Alan, you theory is correct if the bike is stationary and you lean it over, however when being ridden centifrugal force keeps the petrol at the same lean angle as the bike.

[dazza]

Thanks Alan I shall do that do I just order the part number 29A and a new gasket then to fit it just turn the tank fuel tap to the off position and the undo the three screws holding the outer chamber cover on and then replace with the new part 29A and gasket then turn fuel tap back on hope this makes sense lol