Question about re-jetting

So i have a 1981 KZ 550 LTD C2. when i got it the bike had been sitting for 12 years. i cleaned it up and got it to fire up and all, but i noticed that the previous owner had out a 4 into 1 Vance and Hines exhaust on the bike. i was wondering if there were any suggestions on whether i should re-jet my bike, and if so what are your recommendations.

DareDevil44 wrote:

So i have a 1981 KZ 550 LTD C2. when i got it the bike had been sitting for 12 years. i cleaned it up and got it to fire up and all, but i noticed that the previous owner had out a 4 into 1 Vance and Hines exhaust on the bike. i was wondering if there were any suggestions on whether i should re-jet my bike, and if so what are your recommendations.

Hello, DareDevil44, and WELCOME to KZr!

Might have already been re-jetted.
Or may not need re-jetting.

Imo, jetting is best addressed LAST after all other components are known to be relatively perfect, such as ignition timing, compression, valve clearances, spark quality, fuel delivery, float bowl fuel levels, etc.

Carb fiddling absent the foregoing conditions is imo largely a waste of time and effort.

Given the foregoing, spark plug readings following a high speed throttle chop should help determine whether different main jet sizes could be beneficial.

After sync and pilot screw adjustments, primary jetting should afford a smooth steady idle and strong pull away.

Good Fortune!

ok, well when you give the bike throttle then quickly pull off the engine wants to give out. i dont know if that was what you were meaning by throttle chop