96 spx compatible alternative dual carbs?

[k_dog345]

I have a 96 seadoo spx, and I was wondering if there are any new alternative dual carbs that I could install in place of the stock ones? I cannot find a source that sells these carbs new, only used on eBay. OSD marine unfortunately does not stock them. And I have no idea how to tell if a set of alternative carbs would work for this machine.

I’ve had way too much trouble with my carbs after rebuilding them and I’m now convinced that the aluminum is just damaged

 

[k_dog345]

I guess I should mention my symptoms. The ski hardly wants to idle. If I go down to idle, or turn the ski off for more than a few seconds it acts loaded up when I go to accelerate and I have to play with the throttle to get past the bogging then it will run great, especially at higher rpms!

Prior to cleaning the carbs, I noticed MAG carb was set stock (L = 1 1/4, H = 0) but PTO carb was set L = 1/4, H = 0. I reset to stock, had the symptoms, switched back, still have the symptoms. Before I sunk my ski in saltwater, it ran like a dream. Since then I’ve had to replace my rotary valve cover, there is a slight nick on my bottom case, compression in both cylinders are 120 PSI (and have been since I’ve owned the ski last 3 years). I know it’s low, but it was running great. There was some rust on the components in the carbs, especially MAG side that I carefully cleaned out. I was able to get both to pop off at 60 psi, drop 10 psi with no bleed off. Led me to think I would be ok, but still having these symptoms!

I’m a bit stumped! Swapping the carbs sounds like a good step, but maybe there’s another opinion? Hell as much work as I put in this I almost want to cut my loss, sell the thing, and let it be another persons problem but I just can’t get over this V4 hull. So fun!!!!

Really though, if this sounds like a carb issue I would spend good $$ to get replacement alternative dual carbs for better performance. I’ve heard of people doing this to some skis, but haven’t come across anyone doing this to a 96 SPX

 

[mikidymac]

60 psi is really high, what needle seat size and springs are you using?
Genuine Mikuni carb parts?
Replace the fuel selector, gray fuel lines and strainer o-ring?

 

[k_dog345]

60 psi is really high, what needle seat size and springs are you using?
Genuine Mikuni carb parts?
Replace the fuel selector, gray fuel lines and strainer o-ring?

@mikidymac coming to save the day again 60 PSI is the high end of stock settings. Which from what I understand, it's better to be on the high side than the low?


Yes to all of your questions, used genuine mikuni parts (including needle and seat - ensured correct size), using same stock spring, replaced all gray fuel lines, completely replaced fuel strainer and fuel selector. Did a full fuel system rebuild.

 

[k_dog345]

Bump - can anyone help me out?

 

[k_dog345]

Another bump with additional problems

Now I'm noticing an overheating condition. I overheated and cracked my exhaust!!! F***!!! I installed new plugs, warmed engine up, full throttle for 10 seconds (riding), shut off without disengaging throttle, checked the plugs and they were SNOW white.... I did this process over and over, richening my carbs as I went (low speed screw), but I was still running lean. I richened them up so much, my low speed screw on the MAG carb rattled out on the way back.... my question is, WTF? Why would I be overheating/running lean like this? What do I need to check?

Also, maybe 60 PSI is too high? IDK... don't mean to muddy the water. I still am looking for alternative carbs that I can buy new....help is very much appreciated

 

[k_dog345]

Just came across this

When does it become necessary to adjust pop-off?
When personal watercraft come from the factory they have fairly high pop-off due to the fact that they also have somewhat restrictive air intake systems that cause the engine to generate very high manifold pressures; the higher the manifold pressures, the higher the pop-off pressure required to properly regulate the fuel delivery to the engine. As you modify or change your watercraft's flame arrestor to a less restrictive type you will most likely start to experience a lean hesitation caused by a decrease in manifold pressure. This change will require an adjustment in pop-off pressure to regain crisp throttle response. Because most
aftermarket flame arrestors are less restrictive than stock, you will need to decrease pop-off to compensate.

Could the fact my pop off is 60 PSI be the issue of all my woes?? I guess I can decrease to 50 (or lower) and see what happens? suggestions? I really don't want to have to pop my carbs off again more than once... compression is 120 PSI both cylinders (yes, I know it's low - but runs good enough for me for a season)

 

[mikidymac]

You still have something really wrong with your carbs. A stock seadoo will run perfectly with the stock settings.
Also backing out the LS screw isn't going to do anything if you are running lean at wide open throttle. The LS screw only adjusts the mixture at idle.

 

[k_dog345]

You still have something really wrong with your carbs. A stock seadoo will run perfectly with the stock settings.
Also backing out the LS screw isn't going to do anything if you are running lean at wide open throttle. The LS screw only adjusts the mixture at idle.

understood, what would cause my lean condition at full throttle you think? Should I richen the high speed screws a bit you think?

 

[k_dog345]

Also, given the information I just found ^ would you suggest that I try to lower my pop off psi ?

 

[k_dog345]

Here’s what my spark plugs looked like at full throttle

 

[k_dog345]

Tonight, I had a buddy of mine suggest that maybe it's my oil pump adjustment.... throttle cable not synced with my oil pump? Thoughts? I'll definitely be digging into this one now.

 

[mikidymac]

Those plugs are really lean to the point you risk damaging your engine.

 

[k_dog345]

Those plugs are really lean to the point you risk damaging your engine.

Yes, I know.... Checked the oil pump, when pulling full throttle there was still play in the oil lever arm.... check this video out to see what it's doing:

As you can see, at neutral setting the markings line up.... but there is still play in the arm at full throttle? Is this normal? I don't see information on that in the manual. If I need to tighten this cable, is the manual referring to the 'jam nut' by the oil pump lever? (seen in illustration)

 

[mikidymac]

Yes, that is normal. I would say you have a lean fuel issue not a lack of oil issue as long as your oil pump is aligned and no air in the lines.

I also see you have the original 3/32" oil lines which need to be replaced before they break and ruin your engine and the oil looks really dark.

 

[k_dog345]

Yes, that is normal. I would say you have a lean fuel issue not a lack of oil issue as long as your oil pump is aligned and no air in the lines.

I also see you have the original 3/32" oil lines which need to be replaced before they break and ruin your engine and the oil looks really dark.

Thanks.... so this all comes down to the carbs. I need to replace them. Was recommended to lookup 'Novi Carbs', but looks like their site is down.... I am clueless when it comes to determining what aftermarket carb would work for my ski... any suggestions?

 

[mikidymac]

Why do you want aftermarket carbs? The stock ones are perfectly fine and on a stock engine you are wasting your time and money.
If you think your carbs are beyond repair you can get good used ones from Westside Powersports Seadoo. Not sure if OSD can get you new ones or not.

 

[k_dog345]

My fear is getting parts that aren’t also damaged... I like to go new when I can, and the only reason I would go aftermarket. I have no intentions on selling my ski, so I don’t mind dropping the $$ on it! But hey, if you think it’s a waste of time, maybe it is... thanks for referring me to this site. I called, it’s $140 + $130 for carb kit. Not bad I guess. If I can’t get any information on aftermarket soon I’ll be going that route.

 

[GGuillot]

My fear is getting parts that aren’t also damaged... I like to go new when I can, and the only reason I would go aftermarket. I have no intentions on selling my ski, so I don’t mind dropping the $$ on it! But hey, if you think it’s a waste of time, maybe it is... thanks for referring me to this site. I called, it’s $140 + $130 for carb kit. Not bad I guess. If I can’t get any information on aftermarket soon I’ll be going that route.

Compression is low at 120, you'll need to do a rebuild sooner than later.

The carbs on both of my skis were bad and needed a rebuild. Get the full OEM genuine kits w/needle seats, in doubt get new springs also. Spend some time stripping them down to a bare barrel, use a ton of brake or carb cleaner and blow out with highly compressed air. Go through every little hole, remove the jets and insect/clean, remove the HS and LS needles and install new orings, assemble back with touch of lithium grease so they seal well. Then when you've done blowing everything out, go back and do it several more times. Use everything in the kits... Take you time and be through, ck the pop off, set the needles at stock settings and put the carbs back on the ski with new base gaskets. Adjust, sync, and verify every cable, oil, choke, and throttle. Crank up and set the idle close to 3k on the trailer, then go see what happens. If you're still having problems, you may have fuel line issues, now would be a good time to replace all the lines, fuel selector, and fuel strainer oring. If you still have problems, do a fuel line bypass to narrow it down.

If you spend good time on the carbs, with good oem parts, it'll reward you...

 

[k_dog345]

Compression is low at 120, you'll need to do a rebuild sooner than later.

The carbs on both of my skis were bad and needed a rebuild. Get the full OEM genuine kits w/needle seats, in doubt get new springs also. Spend some time stripping them down to a bare barrel, use a ton of brake or carb cleaner and blow out with highly compressed air. Go through every little hole, remove the jets and insect/clean, remove the HS and LS needles and install new orings, assemble back with touch of lithium grease so they seal well. Then when you've done blowing everything out, go back and do it several more times. Use everything in the kits... Take you time and be through, ck the pop off, set the needles at stock settings and put the carbs back on the ski with new base gaskets. Adjust, sync, and verify every cable, oil, choke, and throttle. Crank up and set the idle close to 3k on the trailer, then go see what happens. If you're still having problems, you may have fuel line issues, now would be a good time to replace all the lines, fuel selector, and fuel strainer oring. If you still have problems, do a fuel line bypass to narrow it down.

If you spend good time on the carbs, with good oem parts, it'll reward you...

Yeah, I've gone through the whole carb rebuild... I guess they are just bad.... but compression low at 120, I wonder if I should just do a top end rebuild only. Or just get a whole new SBT engine and start new.... IDK. Rode all day today, at low speed/RPM lots of hesitation and up/down RPM until it smoothed out. Still, I'm not getting the power I feel like it should be pushing. Not snappy like it used to be. Carbs reset back to stock.

 

[GGuillot]

Yeah, I've gone through the whole carb rebuild... I guess they are just bad.... but compression low at 120, I wonder if I should just do a top end rebuild only. Or just get a whole new SBT engine and start new.... IDK. Rode all day today, at low speed/RPM lots of hesitation and up/down RPM until it smoothed out. Still, I'm not getting the power I feel like it should be pushing. Not snappy like it used to be. Carbs reset back to stock.

I'd spend money on a top end rebuild before I'd spend money on different carbs, you need a rebuild anyway if the 120 compression number is accurate.

 

[k_dog345]

I'd spend money on a top end rebuild before I'd spend money on different carbs, you need a rebuild anyway if the 120 compression number is accurate.

I think I’ll follow this advice, I think the last owner may of not rebuilt correctly before he sold it to me (or I was lied to). It’s been 120 since I’ve bought it, and was told it had just been rebuilt.

So, just curious what bore size you’d go with? From what I understand bigger bore means more power but less fuel efficiency. Any other caveats or things to keep in mind? I think I’d want to go 1.5mm (biggest bore) unless there’s a bad caveat with it

 

[GGuillot]

So, just curious what bore size you’d go with? From what I understand bigger bore means more power but less fuel efficiency. Any other caveats or things to keep in mind? I think I’d want to go 1.5mm (biggest bore) unless there’s a bad caveat with it

On any engine, I always go with the lowest bore you need to clean it up, you're not really gaining more power going a mm or so larger. Plus there's other concerns, cylinder squish to worry about, thinner cylinder walls, I'd keep as close to stock bore as you can.

 

[mikidymac]

Only go the next size up needed to clean up the cylinders. Your machine shop is going to have to tell you what size to get, you can’t just guess.

 

[k_dog345]

Is there anything I've posted in my threads that are indicative that I need a full engine rebuild? I'd hate to add a new top end just to find out that my bottom end is failing too.... I wonder if the rotary valve cover damage was already there from previous owner... I'm not pooling any oil in my cylinders. Also, when I had the head off I did not notice any scoring.

My only symptoms now as stated are hard start, difficult to get past 1/4 throttle (once over it runs good), degraded performance when going into maneuvers, and leaning out at full throttle. My intuition says it's just a carb issue (or other fuel issue) + low compression (needs top end).

I'd hate to go through a full engine rebuild if I do not need it, but I'm considering the idea.