300/440/550 what do i have here

[Qsportperformance]

i bought a 1989 js550 about 4 years ago and everything was fine until last year i blew the head gasket. no big deal ordered a new gasket and different stock head because mine had a small dent in it. however when they arrived neither the head nor the gasket fit they are both missing one hole on either side. i didnt think too much of it as i wasnt very specific about it being a js versus a sx and assumed it was just a mistake and that they had different bolts. then i go ahead and buy another one looking to get the ski running for the summer. this time i specified exactly what ski i have and what i need and i got a gasket with the same pattern.

is my engine different than an average 550 or whats the deal

thanks for any help, im just trying to get this going before we leave for the river.

 

[Ĥölënböt]

urs is not a reed motor

u prolly got 440 parts or your motor is a 440 or u just need to wiggle the studs to slip into the holes

 

[Big Kahuna]

just drill the holes for the center studs. make sure toe bore matches the gasket where the reinforced metal is (This part squishes).

 

[screaming440]

that is probably an aluminum 440 cylinder. they used these till 78 or so and they have two more bolts in them. the newer heads still have the bosses for those bolts but they are not drilled.