Tillotson Carb Adjustment

[WVbiker]

While similar, the procedure for adjusting a Tillotson carburetor varies slightly from the Simplex Automatic Owner's Manual of Operation and Maintenance to the Tillotson Manufacturing Company, Original Carburetor Equipment List Manual. The main difference is the sequence for adjusting the Idle Speed Screw and High Speed Mixture Screw, and the throttle position during adjustment of the high speed screw.  Which procedure do the majority of you owners follow?

[Ricks]

I follow the Simplex manual procedure.  The bikes seem to run well at speed and idle.

As a side note,  I have found that the Simplex reproduction carburetors need the needle valve adjusting screw opened closer to two turns.

[WVbiker]

Thanks for your input Rick. I think I remember reading in an earlier post that the main nozzles and idle tubes vary slightly from the original Tillotson carb and the Repo carb. That being the size and number of holes from one to the other.  You say that the needle valve adjusting screw should be opened closer to two turns rather than one turn on a repo carb.  Is that taking into account modifying the nozzle and idle tube on the repo carb to match the original carb, or rather without modifying them and leaving them as supplied? 

[Ricks]

That was with drilling two additional holes to match the original.  Wayne has tried both drilling and leaving with just two holes, and he has not noticed much difference.

[WVbiker]

The carburetor on my 56 model Simpkex is a repo, but I doubt that it has been modified. I plan to still take your recommendation for adjusting the carb.