Rebuilt but carb issue? 94 xp 657x

[KennethPaltrow]

So I just rebuilt my 94 seadoo xp 657x, sbt parts. Rebuilt carbs with mikuni. Cleaned the needle seat so it will slide right out. The low/high we’re adjusted as per manual specifications. It will start and run for a second I’ll kill it and start it and it will flood and not run. I can take the carbs off take the cover off empty the gas and it will start up and do the same thing. What am I missing?

 

[The_Doctor]

Did you replace the needle and seats or just clean them? Could be leaking....causing it to flood?

 

[etemplet]

Ditto and did you go to the low side on the pop-off pressure?

 

[mikidymac]

So did you get SBT carb kits or genuine Mikuni.

Also you need new needles and seats, Mikuni not aftermarket.

 

[AKnarrowback]

My personal experience with a 94 xp 657x.

I rebuilt the entire machine, motor, pump, carbs. I had a terrible time getting rid of a low end bog.

The two things it ended up being was the rotary valve clearance was too large, solved at the machine shop.

The other was pop off pressure. I do not know if the carbs were messed with by one of the previous owners but the pop off was down around 16 to 18psi. The Sea-Doo source page shows 16 to 21psi. The mikuni chart for seat size and spring strength does not have a combination for the 1.5 needle and seat in the 94 xp that produces a pop off that low. I had an aftermarket carb kit with 4 sets of springs, who knows what tensions, where I found a set that brought my pop off up to a consistant 28psi on both carbs. This is the only time I strayed from the "use mikuni parts only" in my carbs. The end result was a machine that has as little low end bog as you can get for a stock, carbed machine.

Even looking at the SD source page for carb specs the 94 xp 657x stands out as having abnormal low pop off pressure, even when compared to the other two 657x models.

The pop off and impeller pitch for the 94 xp were two things that never made sense when looking at the "trend" of other models. The impeller was pitched way too high.

The 271000400 (rh speedster 95) impeller is what I tried because my Friend had a brand new on collecting dust. It solved a lot of low end issues as well and gives me 51ish on the top end.

 

[mikidymac]

That chart is known to have a few errors. If there’s a question check the seadoo parts diagram to verify jetting, needle seat size and springs for your particular model.

 

[KennethPaltrow]

I cleaned the seats with fine grit sand paper smoothed it out. It blew up because the back cylinder hi speed jet was lean and the mag side hi speed jet was rich. Whoever messed with the carbs had the high speed jets opposite each other. Would just cleaning the seat cause it to all of a sudden flood, I put it back exactly as I took it apart aside from cleaning the seats, I’m pretty sure I didn’t mix the needle/seat combo up but if I did would that affect if they were both set correctly anyway? Could I put an in line fuel filter in and run it straight from the tank if the carbs aren’t the issue? Cause I’ll pull the gas line off the carb and it will drip out but not a good solid flow, maybe it isn’t flooding maybe it’s not getting enough gas? It looks wet in the cylinder and if I pull the cover off the carb it’s full. I’m new to it so I’m not really sure what exactly I’m looking at thought if I went in detail maybe a veteran would know and point me in the right direction

 

[KennethPaltrow]

Also I replaced the rest of the fuel lines with the black rubber lines not clear lines would that affect the vacuums pull?

 

[KennethPaltrow]

Sorry for making a third post about the same ski I didn’t see an option to delete old ones. So I bought a ski he reran some gas lines but not the ones for the fuel selector switch to the fuel filter, I want to say he ran one straight from the tank to carbs, but I reran all the gas lines including vent using black rubber not clear. But it blew up cause one of the high speed jets was set on lean the other on rich, they weren’t set the same it blew up etc etc. So I rebuilt it with sbt pistons etc, cleaned rebuilt carbs mikuni etc I used the original needle and seat, cleaned the tank put 93 in it. It will start fine run I’ll kill it go to start it back up and doesn’t wanna run. Pull the gas line off carbs I’ll get drips but not a good flow. I originally thought I screwed the carbs up but I feel like it’s not flooding like I initially thought I feel like the fuel pull isn’t strong as it should be. The fuel filter cup is filled up the carbs are full of gas but like I said when I pull fuel line off of carbs I get drips not a line drain, and I’m pretty sure he ran the fuel line straight from tank to carbs and I think what I’m going to do is swap the stock fuel filter cup to an in-line filter instead of the cup so I will still be able to use fuel selector switch or should I just run a line from the tank to the carbs with an inline filter and bypass the fuel selector?

 

[mikidymac]

Don’t use an inline filter, just the stock strainer.

You should install new needles and seats. Did you install new springs or reuse the old ones?