EvolvD

Hi everyone! new to the site..need advise on the very common ss xi bogging issues.. here's a bit of info:

I have 2 93' ss xi 750 dual carb jet skiis, which have ran great for many years. One of them has been acting up frequently the past couple years which has vortec carbs and req's high octane fuel.
Last weekend I took it out and it ran good for about a half tank, it randomly stalled on me twice within 30 mins., then started bogging down and dying shortly after if i gave it more than 1/4 throttle. it would start and idle fine, but 1/4 throttle or more and it would fall on it's face..so i putted back to shore and then wouldn't start at all. i let it sit for a few mins., it would run and idle fine then bog and die with throttle.
So i loaded it back up and we just ran our boat the rest of the day...

When I got it home..i checked everything out:
-pulled the filters...throttle plates and barrels are super clean
-choke and throttle cables and levers operate fine
-plenty of oil and fuel (fuel mixed with octane boost-108 oct)
-pulled plugs..fouled and oil soaked(drops of oil), gap perfect
-peeked into cylinders..rear cylinder very wet with oil/fuel

I replaced the plugs, hooked up the hose and ran it...it revs up just fine on the trailor with new plugs (no load/out of water/cold)
Water spits out the side vent and everything

Worried to take it out again and get stranded!
Note: Carbs just rebuilt by Kawasaki last summer, and we usually have to swap plugs on the problem child each trip..

I guess I'm really looking for someone with the same experiences to point me in the right direction, just wanting to see if i can nail it on the head before having the dealer fix it. I've read a lot of older posts with same issues but nobody ever responded...hopefully someone out there can help me out

(Hoping that it was just fouled plugs, but just worried because a lot of other people have experienced this and replaced just about everything with no results...have had no warning lights or overheating...it smokes pretty good, but i just assume rich mixture and normal oil smokage---I'm a newb to jet skiis and 2 strokes)

-ED
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EvolvD

ouch...nobody

jdonalds

Check your compression. We had a similar problem on our 1993 ss xi. We didn't know what was going on (novice 2-strokers). It ran fine for 50 minutes then stalled. We let it sit, then it would run again, each time for a shorter and shorter length of time. Finally we towed it back to the launch ramp.

We did a compression check and found the rear cylinder had zero compression. We pulled the head and cylinder block. The engine is toast. We've been parting it out. We've been told that running lean will do this.

I hope your situation is better. Don't run it until you have it figured out.

John

EvolvD

thanks a lot for the reply John..I will try that next..i will just check it ..run it for a while...then check it after it starts to act up...
-ED

EvolvD

Well..finally took them back out this last weekend. I did a compression test on the problem skii both cold and after it started stalling: (only took 20 mins.)

cold
front cylinder - 140 psi
rear cylinder - 165 psi

hot (stalling)
front cylinder - 90 psi
rear cylinder - 140 psi

**note: doesn't have the power it used to

Just trying to get an idea of what i'm looking at as far as rebuilding the engine. Is it worth it? what should i expect to find?..etc.

Please if anyone has any experience with this...i'm a master certified auto tech, with sadly not much experience in 2 strokes...
-ED

jdonalds

Sounds like you caught it before the engine may have had extensive damage. If the compression is off by more than 10% you need to do some level of rebuild. It may be as simple as honing the cylinder and perhaps replacing the rings.

The next and more important question is why did the engine exhibit the problem and how do you prevent it next time?

EvolvD

hey john..thanks again

good point..would running high octane fuel on these be bad for them?
this one has vortec carbs and was told to run high octane fuel, it has an oil injection pump, could it be running too lean or rich?

oh..and this one smokes pretty bad, and wastes spark plugs

what should good compression be at on these little things?

EvolvD

or if it has ever been overheated a couple times...

jdonalds

150-160 is good. I'm surprised you had 165 on one cylinder. High octane is fine.

Smoke is a good sign, it means your automatic system is feeding oil into the system.. However a lot of people don't trust the automatic system and convert to premix so they know exactly what their oil and gas mix is.

The real trick is to make sure the mix isn't too lean. Also if you have leaks in the bottom end of the engine you'll blow the engine too. Have your local dealer to a pop-off test to make sure it is in spec.

This site is great for information Personal Watercraft Carburetor Tuning but after working on 2-stroke skis all summer long we've decided we only want 4-stroke from now on. The 2-strokes are too fussy.

EvolvD

wow ok. thanks a bunch for all your replies John. I will update my progress as i go