05-30-2011, 08:15 PM #1
New Jet Ski Owner (well, new to me)
I just picked up my first Jet Ski's, a '98 750 STX and a '98 1100 STX. They seem to be in reasonably good shape, but never having owned skis before I have a BUNCH of questions.
For the sake of brevity I'll break them up as I come across them.
For now, I am just cleaning them up. They had been outside for a little while so I wanted to wash and wax them, as well as clean the bilge's out. The previous owner had them serviced soon before I bought them, new batteries and the lot. My question now, is about fuel and oil.
I have no clue how long the fuel and oil have been in these skis. Both oil tanks are full, both gas tanks about half full. Would it behoove me at this point to drain both tanks and "start over"? Part of the service done was the carbs, but if the fuel in the tank is old it could gum them up in short order. I'm not sure about the oil, does that stuff get old?
Also, (sorry for the long first post) do I have to run 91 octane in the skis or is 87 OK?
05-31-2011, 05:38 PM #2
Welcome aboard, barthel!
Oil is OK, but I'd drain the gas. If you run them on the hose, remember NEVER run the water unless the engine is running! Start the engine, turn on the hose. Turn off the hose, THEN turn off the engine. Running the water without having the engine running can allow water to flow backwards through the exhaust system into the engine, resulting in major engine damage. You can run the engines at low to moderate RPM for about 15 seconds without water.
Due to their age, it would be a really good idea to replace the oil lines with polyurethane hose. The original hose will get brittle and crack. Secure the hose with stainless steel safety wire and make sure you bleed all the air from the system prior to running the engine.
Oh, yea, 87 octane is all that's required unless the compression ratio has been modified.
I've found a couple of cooling passages on the stator housings on the 1100/900 series engines that were plugged with debris. I'd suggest that you remove the hose that goes to the stator housing (front of engine where the oil pump is mounted) and try blowing through it. If you can't blow through it, you'll need to remove the cover plate and clean everything out. If that's the case, you'll need to order new O-rings for the cover.
05-31-2011, 07:16 PM #3
Thanks for the heads up, I'll check those lines and the stator housing. I've been wrenching for years but this is my first crack at PWC's and 2 stroke engines at the same time. =)
06-01-2011, 09:47 AM #4
Check the compression to make sure the enigne is tight:
750 - 150 psi.
1100 - 120 psi.
06-01-2011, 05:36 PM #5
I'll be sure to check that when i pick up a compression tester.
I pulled the seats and checked the lines,they seem to be PE lines already and looked to be in good shape. I pulled the plugs on the 1100 and they look they should be changed, so I'm doing both tonight.
I'll report back when I get the compression check done.
06-05-2011, 06:23 PM #6
06-05-2011, 06:31 PM #7
Would it matter if I didn't have the throttle opened up? I just read a thread about checking a 2 stroke and I didn't touch the throttle. I plugged in the tester, hit the start button 'till the needle stopped jumping.
06-05-2011, 08:50 PM #8
The throttle should be open. Elevation is also a factor. If you're in the mountains, it will be low. Your 750 numbers sound fine to me, the 1100 sounds a little low.
06-05-2011, 10:48 PM #9
Yeah, that's what I thought. I'll have to try it again with the throttle open.
Elevation is not an issue, I'm basically at sea level. =(
06-06-2011, 05:08 PM #10
Tried it again with the throttle open, I'm getting between 110/115 on the 1100. It came up just a bit.
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