RESTO 1996 Seadoo XP not running correctly

[AdamG]

Hello. New to the forum and trying to get my 96 XP on the water.
Symptoms-Starts and idles fine out of the water. Revs out of the water. Hard to start in the water. Does not rev in the water. Sometimes hear burst of air coming from the carbs when running. Here are the things that I have checked/replaced-Compression=150 on both cylinders, Rebuilt both carbs with Mikuni kits (pop off at 28 and replaced needle and seat), Rotary valve cover replaced from SBT (still getting .020 doing the squish solder test with new cover which is out of spec), confirmed rectifier is good. Any thoughts or suggestions would be greatly appreciated. Here is a youtube link to it running in the water. Thanks for any help/suggestions.

 

[Tboy]

Just a guess but really looks like it’s loaded up.
Empty tank, check all fuel lines replace filter and check valve,new plugs and gap them

 

[JC-SUPERJET]

Well if there is too much space between the Rotary Valve and the Cover then it's going to be hard to start and will not run in the water.

If the clearance is too small, the Rotary Valve will overheat and cause interference issues. Metal expands with Heat obviously.

If you knew the Rotary Clearance was off, why ignore this? Get the Clearance fixed within 0.10" to 0.14".

 

[AdamG]

Well if there is too much space between the Rotary Valve and the Cover then it's going to be hard to start and will not run in the water.

If the clearance is too small, the Rotary Valve will overheat and cause interference issues. Metal expands with Heat obviously.

If you knew the Rotary Clearance was off, why ignore this? Get the Clearance fixed within 0.10" to 0.14".

I completely agree with your point but I assumed since I got a rebuilt one from SBT it would have the correct clearance. I not sure if I am doing the solder test correctly (wrong solder, too big, expanding a bit after I unscrew it). I just got some feeler gauges and will pop the carbs off and see if it is still out of spec. I have not checked the check valves in the fuel system yet. I will try that as well and report back. Thanks for the replies.

 

[JC-SUPERJET]

On both Tests, the O-Ring must be removed first, then the Clearance can be measured.

 

[AdamG]

@JC-SUPERJET
The O-Ring was removed during the solder test. Question-I did look at the check valves and here is what I found on both-The one that exits below the rub rail is completely clogged. No air in or out. The one that exits through the handle bars lets air in and out with a little pressure. Would the clogged one cause the engine to run poorly? If I remove both check valves, would I be able see if the engine runs correctly? I will obviously replace the clogged one but just looking to diagnose.

 

[TheGTIjetguy]

Well if there is too much space between the Rotary Valve and the Cover then it's going to be hard to start and will not run in the water.

If the clearance is too small, the Rotary Valve will overheat and cause interference issues. Metal expands with Heat obviously.

If you knew the Rotary Clearance was off, why ignore this? Get the Clearance fixed within 0.10" to 0.14".

+ 1 on the rotary valve.
Also, check your exhaust hoses for soft spots and water box for loose baffles. An exhaust restriction due to a failing hose or bad water box can cause what your having. From the video it looks like the ski doesn’t want to idle after being reved and then picks back up after a second. Also, lots of smoke and you mentioned backfiring through the carb. Classic clogged exhaust stuff.

 

[AdamG]

@JC-SUPERJET @TheGTIjetguy @Tboy

Thanks to all the comments and suggestions. Update to my progress: FIXED!!! Story below incase someone runs into the same problem:

I rechecked the Rotary Valve Clearance with feeler gauges and it is within spec @ .014. I also retested with the solder method and was getting between .018 and .020 so the solder I used seems to expand a bit after I loosened the RV cover to measure it which is why I initially thought it was out of spec. I re-gapped the plugs and started it on a hose and it revved and ran fine fine. I put the ski into the water and started it up with little trouble but when giving it gas, it was doing virtually the same thing as it was in the previous video I posted, not running up RPM's, producing a ton of smoke and running really rough. After running it for a few minutes in the water I killed it and, on a whim, touched each spark plug to see if they were hot. One was hot and one was a little warm. These plugs are brand new so I assumed both plugs were good. I swapped cylinders 1&2 plugs and the problem followed the plug and did not stay on the cylinder. Luckily I had one of the old plugs in the front compartment and threw it in. Started it up and it ran like a scalded dog!!! It still has a little hesitation/bog at half throttle but rips once you get past half throttle. I think a little carb tuning should smooth it out. Any suggestion on that would be appreciated. Thanks again for the help and suggestions. Moral of the story-start with the basics (Air, Fuel, Spark) and work from there. Never assume because we all know what happens when we do...

 

[JC-SUPERJET]

Glad to hear it's fixed.

What Brand Spark Plugs?

 

[AdamG]

NGK BR8ES

 

[fatblockabody]

+ 1 on the rotary valve.
Also, check your exhaust hoses for soft spots and water box for loose baffles. An exhaust restriction due to a failing hose or bad water box can cause what your having. From the video it looks like the ski doesn’t want to idle after being reved and then picks back up after a second. Also, lots of smoke and you mentioned backfiring through the carb. Classic clogged exhaust stuff.

Yup, I had one exhaust hose that split all the way down near the exit on a GTX. What a pain that was to find/figure out.

 

[AdamG]

@JC-SUPERJET @TheGTIjetguy @Tboy
Ok. Thought I had my problem fixed but still not running right. It starts up easy in the water and will rev great in the water on the trailer. Once off the trailer it is very sluggish. Once up to WOT for a few seconds, it just dies. It starts right back up and does the same thing over and over again. Any suggestions on where to start would be greatly appreciated.

 

[POPPS]

Fuel starvation at the fuel selector or in the carb circuit.