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[badger man]

Message for Gwilly.

Thankfully a bit of dry weather so started to set up carb using Jacobs suggestions so I have a 30 pilot,2.5 slide, p4 needle jet and a drilled out to 1.5mm mainjet, but to get a reasonable coloured plug I've still had to put the needle on the bottom grove (richest) and put two ba washers under the clip plus blank half the bellmouth off to restrict the air flow, goes ok but might revert back to conical airfilter for while its real cold and try the bellmouth again in the spring when the airs not so cold, the bellmouth must flow a lot more air than the conical filter.

[JTL]

The bellmouth might not flow more air, but it does it in a much more even way (my experience). Maybe it has to do with less turbulence or just air being rammed directly into the head?... If the air is cold the density is different from a nice summer day. As you might already know it's question of oxygen molecules for the combustion. Using a 28 mm it's my experience that it's too small, even with a bellmouth, but this is for an average danish summer day. I have been using a 30 mm Amal MK2 with a bellmouth too, and it's so much better (pilot jet 25, main jet 190, needle jet 105, needle 2A1 second groove from top, air vent 3.5, throttle slide 3,5 ), but the carb body is broken, so I had to swop back to the Mikcarb. Now I just waiting for spring and to replace the carb with a 32 mm body for my Amal... Jacob

[badger man]

Hi Jacob.

Thanks for your info, yes you are probably right about the ram effect in relation to the bellmouth and the 30mm concentric being a more suitable size so will have to check the piggy bank, but the bike runs ok on tickover ,pickup and mainjet just problematic on the needle, its been mentioned to me that needle jets have to be matched to the needles and that the standard needle fitted to the micarb will be a mismatch to the p4 the correct needle being richer, any thoughts on this? as I said in my last post to Gwilly ill probably go back to the conical for the time being if I cant get any info on needles more suited , by the way what needle position are you using?

[JTL]

In the online parts catalogue there is only listed one jet needle for the Mikcarb. When I ordered a variety of jets some time ago I thought also more different needles would be nescesary, but still only one available. I guess that's the one that goes for all needle jets. It's different with Amal... If you have problems with pick up it's usually the throttle slide cut away that is the reason. Try and error is what I used when dealing with this. Carb jetting is a lot of try and error. It can be very frustrating, but when everything is running nice and smooth it is a blast. I guess you have to step up to a 32 mm carb to fix your jetting in a satisfying way... Sorry, can't remember which groove the needle is fixed in (middle or one lower)... Jacob

[badger man]

Jacob.

thank you for your help, seems what's needed then is a 30mm mk2 amal and Ill try the set up you suggested as I have a standard head .

Badger.