300/440/550 Loose Ride Plate

[WheeliePro]

I just bought a 1986 JS550 with a bunch of mods. It has an aftermarket ride plate, but the rear two screws seem stripped out. They aren't falling out, but you can wiggle the rear of the ride plate up and down maybe a 1/4" to a 1/2" at most. Could this explain why it porpoises so badly? I am new to stand-ups and can only compare to a friends SXR, but it seems to porpoise in anything but absolutely perfect smooth water.

I've tried moving around on the ski while riding but riding all the way up front still doesn't fully correct the problem. Is the play in the ride plate to blame? I've heard that there is an expoxy I can fill the screw holes with and re-tap the holes. Does anyone know what this stuff is and where to get it?

Thanks.

 

[screaming440]

mariner use to sell oversized inserts but i don't know where you could get them today.

i replace mine years ago and they are still tight.

i've taken some out of a few of the skis i've parted. they are easy to spot cuz they have a slot in them for a flat screw driver.

 

[Mag]

Put a time-cert in each hole, you can get them online at mcmaster.com.
They are kind of like heli-coils but much better.
I'm not sure but it kind of makes sense to me that the ski would porpoise.