Carb adjustment

[Hunterb]

Hi all,
I'm new to the PWC world but not new to motors on general. I purchased a 1997 Seadoo GTX with a motor that needs a ton of help. I am currently doing a top end rebuild and replacing the rotary shaft and gear because the gear was stripped. Yes, I split the case and cleaned everything out. I'm sure I'll have more questions about that as I proceed. My question right now is about the high speed needle adjustment. The caps are no longer on the screws. When I looked at them they were adjusted at about 2 1/2 turns out. I know the specs say 0 turns out but does that actually mean that the screw should be turned all the way in and be seated? I'm just not sure what it looks like when the cap is on there and if the screw is actually turned out some number of turns at the factory and the cap simply prevents over adjustment. If anyone has any insight I'd appreciate hearing it.

 

[JeremyD615]

The zero turn spec is correct. The high speed needle should be turned all the way in until it is lightly seated. Make sure you clean the port out out good before you make your adjustment, as sometimes corrosion or gunk can make the screw feel like it’s bottoming our early.

 

[Hunterb]

Ok. Thanks for the reply. This engine was not running when I bought it because it had a stripped RV gear so I don't know what it ran like but the high speed screws were out at least two full turns. Would that make it overly rich at high speed?

 

[JeremyD615]

That should be rich, but many times people will use that screw as a bandaid for something else going on. Is the ski stock? No aftermarket filters or exhaust mods?

If the ski is stock and the carbs are truly clean, the factory settings should be spot on.

 

[Hunterb]

The engine was stock I believe but can not say for sure. The cylinders are at the machine shop right now getting bored so it will be oversize when I put it back together. It seems strange that the high speed screw is set completely closed but it appears that's the way it should be so I'll set them there.
I also noticed the RAVE valve red caps were turned down well past the black housing and, from what I've read, they should be level so I've put those back to the stock setting as well.
Thanks for the replies!
Bruce

 

[JeremyD615]

The oversize will not make any real difference in the carb settings, so start with factory and adjust from there if you feel you need to. The high speed screw is really just a bypass to add additional fuel to the circuit, so if the carbs are jetted correctly, you shouldn’t need the additional fuel.

 

[JeremyD615]

And the rave caps are okay turned all the way in. They should be either turned all the way in, or set flush with the cap, but it’s really just a preference thing. With the caps screwed down, the valves open a little later and feels a bit more “peaky.”

 

[AKnarrowback]

On those caps. I have the same gtx and want to run it around 5000 to get better fuel economy for a ride I want to do, but it runs rough at that rpm. For fun I turned the adjuster from flush to about 6 clicks in and the 5000 rpm range went smooth like I needed it to.

 

[Hunterb]

Thanks! I have a better understanding of what that high speed screw is doing now. I just didn't want to lean it out and have to do the top end again. I'll have to check the jetting to make sure what's in there. I don't want a high performance rocket ski, I am much more interested in reliability and economy than performance.

 

[97explorer717]

I'm redoing my 97 GTX right now as well. Actually rebuilding the carbs at this very minute. I'll do my lows one turn and just a smidge more. Also the highs say mag 0 PTO 1/2. Maybe somebody can verify that. That's what I'm going with from reading. To be honest all I've ever had to do was thoroughly clean my cards, new kits and stock settings. Only thing I've had to adjust after that was idle.

 

[JeremyD615]

I'm redoing my 97 GTX right now as well. Actually rebuilding the carbs at this very minute. I'll do my lows one turn and just a smidge more. Also the highs say mag 0 PTO 1/2. Maybe somebody can verify that. That's what I'm going with from reading. To be honest all I've ever had to do was thoroughly clean my cards, new kits and stock settings. Only thing I've had to adjust after that was idle.

You’re right. The factory settings are below, and the PTO screw is set out more than the mag side.

Main Jet - 142.5
Pilot Jet - 70
LS Screw - 1 Turn Out
HS Screw (Mag) - 0 Turns Out
HS Screw (PTO) - 1/2 Turn Out