demon jr tuning


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By 62galxe - 12 Years Ago
Question on accelerator pump nozzle size. Im getting a hesitation taking off from a standstill. Kinda falls on its face then goes. How much difference will going from a .031 to a .035 nozzle make. Im already running 61 primary jets instead of the factory 59.

Thanks
By GREENBIRD56 - 12 Years Ago
On my engine - that is mostly stock except for the Demon jr and ignition set-up - the carb proved to be very sensitive to the primary float level. Raising it a 1/16 of an inch made an instant change. The Demon has such a large primary bore you are mostly going to tune the whole RPM range off the primary.

Do you have the idle transfer slot set-up as shown in the Demon literature? The primary throttle stop should hold the butterfly so that the exposed opening of the slots -seen from below - appears as a "square". When the carb is re-installed on the engine that screw shouldn't be moved - set the curb idle speed with the secondary. Takes a long allen driver down across behind the choke working from the front - rear throttle shaft stop screw is directly under the vacuum secondary pot. This whole operation took immense concentration on my part - to resist screwing in the primary stop to keep the engine running. Once I learned the secondary adjustment trick - things became more sensible.Smile

I forgot to ask - my bird starts off in second gear as the Fordo autos all do - do you have a stick trans or an auto? Lots of tuning required to overcome the goofy second gear start believe me.....
By GREENBIRD56 - 12 Years Ago
This is an illustration of the idle transfer slot coverage by the primary butterfly....



The Demon has a huge PCV / power brake passageway in the base, make sure that isn't causing your need for bigger jetting.
By Ted - 12 Years Ago

Ditto on what Steve says in regards to the float level. A good starting point is to center the float level in the middle of the sight glass and work from there. Beyond that, double check that the pump arm is adjusted with some preload in it or is within 0.015”of bottoming out at full throttle.
By 62galxe - 12 Years Ago
thanks for the info. working on the carb today. had to adjust the throttle plate position to get the square transfer slot position. they were sticking when i tried to close them that far. them red gasgets on the demon are tough to remove.
By 62galxe - 12 Years Ago
Carb is together again. running better now. It liked the bigger squirter nozzles.