nielsenracing

hey everyone, i'm new to pwc and need some help,
I just bought an 87 js 550 with "rebuilt" motor, I had a hard time starting it, could only get it to run on the front cylinder with the rear cylinder spark plug out and I was spraying in fuel with the primer.
I thought it was timing but the mark lines up with the case half and the timing light is on T when cranking so it should be close.
I did a compression test and 140psi on front and only 60 on rear.
I took motor out and apart and the rear piston skirt is all scrated up bad as it wa hitting the bottom end on the exhaust side.
it is marked up about 3/4 of and inch and the cylinder looks like I can just put the hone in it for a few seconds and clean it up.
do I sand piston and hope for the best ?
how do I align cylinders with bottom end ?
I don't under stand the low compression still unless its the cylinder head as I have flipped the head gasket and swapped piston rings to just check.
the top of the pistons have arrow and a 1.00 on them is this the over sized 1mm pistons ?
any help would be greatly appreciated.
thanks,
brian

p10sdad

Yeah those are 1mm over. I'm not to sure what your asking about lining up the piston with the bottom end? Once you put in the piston and slide the cylinders over it has no choice but to be lined up

nielsenracing

thanks for the oversize info.
I took the bottom end apart to night to find out my problem.
there is suppose to be 2 studs in the corners that have a dowel built on them, well there was only 1 and the other one where the skirt of the piston was hitting the bottom end was just a regular stud. that's why it was not sitting where it was suppose to.
where can I get these studs with the dowel on them ?
thanks,

p10sdad

Try your local Kawi shop, or look on CL for someone who is parting out a 550