Kz750ltd 4 breaking up

I have a quad I motor swapped with a kz750 Ltd it runs decent up too like 7-8 000 rpm then it breaks up I checked ignition advance it’s and drilled out the petcock for more fuel flow but still it does it what could this be weak spark maybe the motor has good compression the carbs are cleaned and jetted it has 4 snow mobile foam pods with open headers that have 2 baffles in each

Most likely a jetting issue. Another thing to check is the spark advance. Grab the rotor and make sure it turns and snaps back.

You will never get it to run right with that exhaust setup especially if your carbs are constant velocity.

I already cleaned and checked this about 10 times

baldy110 wrote: You will never get it to run right with that exhaust setup especially if your carbs are constant velocity.

it runs perfect on the stand revs all the way up but on the road to 7000 sounds so beautiful like it’s ready to eat then just dies I feel like it’s weak spark and any time you put an heavy load on it the compression puts out the spark I’ve had this happen in my kx80 that had a cheap coil it would always spark just not enough . So do you really think that building a 4-1 for it would really help I’ve been debating it theirs just not a lot of room it’s gonna be a task