300/440/550 440 to 550 question

[Js_440_78]

hey everyone...
I have a 1978 js 440... and are wanting a bit more power out of it...
So ive got a 87 js 550 sx barrel and head and im wondring weather it would fit on the 440 bottom end??
Any help would be appreciated...
Thanks, Ash.

 

[ger87410]

I bet not.

I think all 550sx parts will work on a 550... :shrug:

 

[Mark Gomez]

I used my dads 86 550 crank to get rebuilt and be the crank im using now. However i don't think you can do the cylinder swap because the sx case and the 550 and 440 have a slightly smaller bolt pattern. along with cooling hole placement on the head.
Thats just my 2 cents im not 100% on it.
-Mark

 

[Flat Brapp]

The Sx will not work, the but the piston port will, you will have to clearance the crank cases for larger pistons though

 

[wakeeater]

are you sure it being a 87 set of jugs? if so its a js550 jug not an sx and your good to go just need to clearance the cases as mentioned above

 

[Js_440_78]

no the 550 sx barrel isnt a 87... i will go out and look at it tomrrow...

 

[Flat Brapp]

i didnt read into his post far enough, 90-91 was the first years of the reed engine, so yes your cylinders will bolt on as long as you clearance the crank cases for the larger pistons