Idles, limps back to dock, but won't run full out.

[WI-RiverRat]

So I bought a ’98 GTX RFI, 787cc about a week ago. My reason my purchase was to get something for my kids to run around with, ski and tube with. I went kinda cheap and old because one is already in college. In 5 years they’ll be gone and on their own.

First weekend out they were skiing and on a pull-out, my daughter hears a “noise” and we go from running great ( pulling skiers etc ) to limp back to the dock. I’m pretty mechanical, but 100% new to jet skis. Here’s what I’ve tested and done, sitting dock side in the water:

Starts and runs at idle, up to about 4000rpm

Checked compression: Multiple tests, The longer I cranked the higher the gage reading:
Not real precise testing methods.
Front: 120 – 150psi, call it 135 – 140psi seems to be average
Rear: 120 – 150psi, call it 135 – 140psi seems to be average
They seem very similar and consistent, cylinder to cylinder.

Starts and runs (rough) on Front cylinder
Starts and runs (rough) on Rear cylinder

Will try and rev up.
When you try and get up and go you get a lot of noise and a fair amount of WHITE 2 cycle smoke out the exhaust.

I’m very familiar with boats and O/B and I/O setups. On a limited test ride, it sounds to me like something is slipping or spinning / not engaging correctly. Newer props have a rubber bushing between the prop shaft and the prop that shears when the prop strikes something in the water. To me this sounds and feels similar.

So any ideas? Where do I look next?
Thanks in advance for any help and ideas.
I’m hoping I didn’t buy a $1500 hole in the water and I’d like to get it back up and running. Summer in Wisconsin is just too short..

 

[jons68]

Not real sure about the smoke and rough cylinders but I would look at the wear ring around impeller. Possibly sucked a stick or like mine on both GTIs the wear ring blew apart in chunks. Made a mess of noise. I could get all the rpms I wanted but things wouldn't go anywhere. Its just regular maintenance to these things.

 

[jcleary93]

Try and isolate where the noise is coming from. Maybe start by pulling the pump off and see if the problem stops

 

[mikidymac]

It depends on what is actually happening. It is a 2 stroke so they do smoke especially if the oil injection pump isn't adjusted correctly.
I am also 90% sure that the RFI skis idle on only 1 cylinder so they are pretty rough.

 

[WI-RiverRat]

Well - I got this problem solved. Turned out I also had 12V low e.g. bad rectifier. Replaced that and off she goes.
Thanks for all the help and advice/