At idle to 1/2 throttle (actually 1/3rd if you want to be picky) you are in the: pilot jet, slide cutaway and needle jet diameter (straight portion above the taper) stages of this carburetor.
-The pilot jet tends to block up with stuff. This equates to leaner running. So we can rule this out!
-The slide tends to wear in the body. Again this equates to leaner running. So we can rule this out! Of course you can effect this in a positive manner by changing cutaways.
-The needle going up and down in the needle jet will wear it oversize. This equates to richer running.
So before you tear your hair out and spend money answer these questions:
So with the above in mind have you replaced your needle jets? If you have replaced your needle jets did you have them measured or measure them yourself? As little a .0005" can make a difference. This can be from wear or improper manufacture.
Comment: Because the straight diameter of the needle (.0985" did you measure this??) does not come clear of the needle jet orifice until approx. 1/3 throttle making another groove to lower it will do nothing below 1/3rd throttle. It will above that, but that is not where you are telling us your problem is.
Comment: Have you had the body sleeved? If you did, what's the slides clearance in the body. To have the standard jetting work you need at least .0035" and a bit more is better. Less clearance increases the signal (manifold vacuum) on the fuel circuits at low throttle openings.
Comment: Do you have all the right kit installed:
Straight spray tube?
4 stroke - cross drilled needle jet for the model carb. you are using? Needle jets for MKII and MKI are different.
Do you have the correct 2 ring needle 622/124 if this is a MKI Concentric
As far as the float, set it up using the Triumph Service Bulletin measuring the top edge of the float at .060" to .080".
Don't assume that new parts are correct EVEN IF THEY ARE STAMPED AMAL
. There are a lot of after market AMAL
parts that are not on specification. Not that AMAL
has never made a mistake they try real hard to get things right. They are also now putting their parts in AMAL
bags which should give the punter more confidence in what they are getting.
This should get you started.