Gx160 carb jetting help

[Twisted]

Hello there

Im new to the fourm and need help on main jet size for my gx160. Im planning on removing the govener and doing the following upgrades
-18 lbs valve springs
-custom exhaust (with bends)
-gx140 emulsion tube
-4 degree advanced timing key
-racing air filter with adapter

I was looking into getting #90 main jet but I dont know if this will be to lean or to rich because I have heard that I need a 73-80 and then 90. Tell me your thoughts on what you think.
Cheers

 

[Twisted]

Pics off the kart should be up within the next week and the engine sometime in January

 

[firemanjim]

Whoooaaaa.... Hey, if you put them springs, youre gonna ba able to stop valve flutter sure..... BUT unless you have a billet flywheel, I would not do that..... that valve flutter keeps you from going so high you blow a stock flywheel or con rod. I just removed the gov from my gx160. And Im using a 3 stage candy cane header. And a stock air cleaner. It is a HUGE difference from what it was before.... My future mod plans are an over bore, gx140 head, a billet flywheel and con rod, new STOCK springs, and a better intake.

 

[mckutzy]

It will mainly be motor specific, meaning you will need to run your motor, then determine what it will need after the plug check.

 

[landuse]

Yup, do not use the springs before you upgrade the insides

 

[Twisted]

Thanks guys. I guess I will be looking into a flywheel and rod, I guess I might as well throw in a flat top piston while im at it.
Cheers

 

[Doc Sprocket]

As usual, I'd be much more concerned about the rod than the 'wheel, but if you're going to be upgrading one, best to do both.

Let the engine tell YOU what it needs for fuel after the upgrades. Buy a handful of jets on either side of what you expect the outcome to be (#90). Swap, test, repeat.