tkx 440 jetting

[finnyfarm]

I have a 1979 tkx 440 w/ a mikuni 36, does anyone know what the stock jet sizes were? It's running really fat after it warms up. Any tuning help would be appriciated

[obj1]

290 main, 35 pilot and 125 power jet. clip in middle of needle. run GOOD oil and 92 or better non-ethanol fuel. Keep air intake system in place.

[scorpionsense]

Can you tell me what needle to run in this carb?
Can you tell me why a non-power jet carb runs about the same jetting? If the power jet is useful, wouldn't a non power jet carb be lean at WOT? OR If a non power jet carb works with this jetting, wouldn't a power jet carb be rich on top? The amount of air at full throttle doesn't change so why the powerjet difference?

[scorp11]

Jan 22, 2012 0:10:36 GMT -5 scorpionsense said:

Can you tell me what needle to run in this carb?
Can you tell me why a non-power jet carb runs about the same jetting? If the power jet is useful, wouldn't a non power jet carb be lean at WOT? OR If a non power jet carb works with this jetting, wouldn't a power jet carb be rich on top? The amount of air at full throttle doesn't change so why the powerjet difference?

Needle - 6DH4 in 1979. In 1980 if you had the update kit installed, they switched to a 6DH21, Stock in 1980 was 6DH4, same as 1979

I suspect if you were running a non powerjet carb, you would be looking at closer to a 360 main jet in it for this motor. The 1980 Stings and TK's actually came with a 360 or 380 main jet in the power jet carbs from the factory. Only to be leaned out later by a TSB. There were no non-powerjet carbs on these from the factory.

I know guys who have switched out of the 36 mm power jets to a non powerjet single carb and all of them ended up with a 38 mm Mic with around that 360 main jet.

A guy I talked to had a formula for what size power jet + the main jet = a regular carb with no powerjet circuit, but I don't remember it. And yes, the non-powerjet carb had a bigger main.