1997 Seadoo XP, carbs or something else

[Talbachi]

So, to make a short story endless, bought this ski July 2019, ran ok, but had bad cavitation if 2 people on it and took forever to plane out. Still was able to have many fun days on it. I ride at about 5500 to 6000 ft above sea level in Utah.

I have since then now put a new impeller(Solas 14/22 and the recommendation of Impros) and wear ring, the one it came with was beat to crap... not from me. I have rebuilt the carbs with OEM, old filters were almost all plugged, and have a pop off pressure of 33. Low speed jet is 62.5(should be 70) and the high speed jet is 137.5(should be 142.5)...I assume it had a jet change from previous owner to compensate for altitude.

I have also replaced all the fuel lines.

I have had 3 test trips to the lake, 1 hour drive one way... all three times runs like junk. If i full throttle it dies(lean?). I can get it up to speed if I pull the choke 1/8-1/4. So its obviously running lean...which is not good. Idles great at 1500RPM, but just is so so slow. I grew up riding a 98XP of my bro-in-law so i know what this somewhat should be capable of. I cant even spin a donut. High speed adjuster is out 1/4, Low speed is out 2.25 and still not getting enough fuel. I'm 95 percent sure that all the carb passageways are clean, and accelerator pump is also working great. Ski still has the stock air intake and everything else is stock other than the carb jets.

I'd like to avoid buying new jets but realize that may be my only option. I pulled the RAVE valves today and they were pretty gummy and lots of deposits on them, probably haven't been cleaned in 10 years...got one cleaned out so far, the other will be after work today.

I have not yet tested the compression of the engine, need to borrow tool from brother in law.

What other suggestions do you all have that I should do to get this running decent. I just hate that its a 3-4 hour trip just to test in the water...

Thanks everyone.

 

[JeremyD615]

Well I think I would start by going back to the factory jetting in the carbs. You’re obviously running lean currently, so let’s get it back to factory and start tuning from there. Normally I’d suggest keeping everything right at factory settings, but you’re at a pretty high altitude, and will probably have to make some adjustment away from those specs. I’d just rather see you running too rich rather than too lean. Something else to take into consideration is the fuel you’re using. At that elevation, you should be using 87, if not even 85 octane gas. If you’ve been using premium in it, switch to regular and it may help some as well.

 

[Talbachi]

Thanks JeremyD615, I'll go ahead and order some new jets. I hate spending money on it right now with a 20% pay cut for last 2 months... Here is a picture of PTO rave. Mag wasn't quite as bad

 

[mikidymac]

I run a few of my skis up in the Sierras once a year at 5,600' and don't touch the carbs from the stock settings.
They are a little down on power but never foul a plug or run bad.

 

[JeremyD615]

Thanks JeremyD615, I'll go ahead and order some new jets. I hate spending money on it right now with a 20% pay cut for last 2 months... Here is a picture of PTO rave. Mag wasn't quite as bad

Luckily jets are cheap! It’s not like a motorcycle where you need a whole jetting kit. Just pick up the 142.5 main and 70 pilot jets and swap them out. They should just be a few dollars each...

 

[Talbachi]

Luckily jets are cheap! It’s not like a motorcycle where you need a whole jetting kit. Just pick up the 142.5 main and 70 pilot jets and swap them out. They should just be a few dollars each...

I got them ordered. Should be here in a few days. But won't get to test cause it's gonna get cold here.

 

[Talbachi]

So ran a compression test using a napa compression tester which probably isn't super accurate, but was getting consistent pressure readings of 128 psi on both cylinders. I know 150 is considered ideal. This engine has an SBT rebuilt engine from probably 10 years ago and I am at 4400ft above sea level. Is that enough compression or do I need to work on top end.

 

[mikidymac]

That’s low but should still run considering your elevation.

 

[Talbachi]

I am planning on rebuilding the top end this next off season. Just want to get this ski running decent for the summer. Bro in law just got a 2017 supra 550, need a good ski to go play. New carb jets arrive Tuesday. Rainy cold and stormy until then. Talk to you all then! Thanks for the support

 

[Talbachi]

Ok, so I've been thinking... My pop off pressure is probably too high for the size of LS jet, so reducing pop off would them allow more fuel to be metered? But would want to keep current pop off since I'm getting the bigger normal jets. Also what is meant by a smooth idle? Less vibration, consistent rpm, etc??

 

[JeremyD615]

I would start by getting the carbs back to their factory settings, including pop off. From there, you can make small adjustments until you’re happy with it and it’s not fouling plugs.

At idle, you’re going to have some vibration, but it should hold a constant rpm at 3000 out of the water and 1500 in the water, and not feel like it’s stumbling.

 

[Talbachi]

Got my new jets into the carburetor on my lunch break. What I also found was interesting. One main jet was 132.5 and the other main was 137.5, hard to see the engraving but could easily tell a difference comparing the jets to the sky. Now i just need to get the carbs reinstalled, throttle adjusted, oil pump adjusted and get it up to a lake. 60 degree water with 60 degree temps is a bit to chilly for me. haha

 

[Talbachi]

If I decide to replace the gaskets on the top end, RAVE, Manifold, joint after manifold, is there a specific brand i should lean towards or is it not as critical. It is an SBT Reman engine so i assume it is the 5 hole base gasket as well

 

[Talbachi]

Well I got it to a lake last night for a test. Much much better, now its not starved for fuel. top end was running well, maybe a bit rich, but will need to check that once I get the low to mid range right.

i still need to get the idle right. just a bit low at 1350-1400 rpms. Doesn't want to accelerate quite right out of the hole. wasnt paying enough attention as to whether it be rich or lean, i'm thinking its a tad rich. once its been up at full throttle and cruised for a bit, 1/2 to full is running good. just 0 to full not hitting the powerband every time... but when it does she rips.

What should I adjust? keep messing with the low speed adjusters and idle screw? should I make any adjustments to rave valves? Red Screws are currently level.

I think low speed adjuster is about 1 screw out. high speed is at 0, oil pump is adjusted right, oil was too much when i was adjusting idle and had to adjust that back to be in alignment.

I just want to be able to pull a 360 at 20-25MPH and then have some good power to keep going. I didnt do many tight turns this go around cause I need to get the Stock black airbox on good.

 

[mikidymac]

Idle at 1,500 rpm
Lows at 1-3/4
High at 0.

Are your accelerator pumps squirting?

Also at elevation it is never going to run as good as at sea level and you will always be a little sluggish out of the hole. You just can't make up for the lack of oxygen.

 

[Talbachi]

Mikidymac, why 1-3/4 on the low screw? Manual states 1, +- 1/4? Wouldn't lack of oxygen also mean to use less fuel? Seems that 1-3/4 on low would be too much fuel, ill try it though because i trust you based on other posts.

One other concern is that it seems to back fire lightly on the Mag Side on startup but didnt seem to have issues once running. Should i be concerned?

 

[mikidymac]

Sorry, just checked the seadoo carb spec sheet. IF it is better at 1-1/4 for your altitude go with that.

Backfire and hard starting would point to a leaking needle and seat. Did you check the carbs for leak down before reinstalling them?

 

[Talbachi]

Yes, needle and seat were good and held pressure with no sign of leaks for anything under 25 psi with pop off of 33 PSI. using 80g spring as specified by the manual.

Edit: also did not have any hard starting issue prior to replacing the jets in the carb for the first 3 trips

 

[Talbachi]

I also will be using a new set of plugs on the next trip. these ones were 2 trips old. Accelerators are squirting. Should I delete them?

 

[mikidymac]

1997 XP doesn't use 80 gram springs.

 

[Talbachi]

 

[mikidymac]

It's wrong, the 80 gram are for the non-accelerator pump 787's.
The 1997 XP is different because it does have accelerator pumps. Look at the parts diagram for your ski and you will see it uses a 270500313 spring which is a special 95 gram spring used in the 947 engines and is a Mikuni part number 730-03034.

 

[Talbachi]

ok. Isn't the purpose of the spring to make it so that the pop off pressure is correct? With that being said, technically the spring size is irrelevant as long as the needle arm is positioned correctly and correct pop off pressure is achieved? What is a good pop off pressure? is 33 PSI sufficient?

 

[mikidymac]

No, totally incorrect, pop-off pressure is just a test and not how the carbs function when the engine is running. You have to use the correct spring and needle and seat regardless of what pop-off numbers you are trying to see.

 

[Talbachi]

you are right. but dont tell my wife i said someone else can be right. make sense after i thought about it. the spring could pop with air pressure just fine, but under the vacuum of the engine the diaphragm would open too soon and not properly meter fuel.

Now to figure out what spring is what... ugh.