Seadoo 717 hard start

[skrillac]

I went ahead and replaced the y fitting today. Pressure tested the carbs again with all the hoses in place (except the return). Pressure held fine.

Ski was hard to start on the trailer today. I probably cranked it for a solid minute or two, in 30 second intervals. Some of that time may have been getting fuel into the mostly dry carbs. Took the old plugs out and put paper towels over the head and spun it over to see if fuel was coming through. Towels had a small amount of gas on them, so it looked like I was getting fuel through. Put in new BR8ES plugs and spark testers so I could visually see spark. Spun it over 3-4 times 30 seconds. Would not start. Was finally able to get it to start by giving no choke and a bit more than 25% throttle. Ran it on the hose for 5 minutes or so while I tried my best to set low idle to 3000rpm.

It started at a pretty low rpm 2500ish then I revved it a couple times and it jumped up and then fell back down to around 3500ish. Thus began my back and forth attempts to adjust the idle. Turned it back out (left) a turn, revved it, then the rpms were too low again 2200ish. Turned it back up a bit (less than a turn), revved it, rpms were too high. Turned it back out a small amount, then I revved it, checked rpm again. Rpm was 3150. Revved it some more, 3200. Turned it back down a tiny amount, revved it under 3000. etc

I don't think I have addressed my issue with difficult starts. It seems that the issue is likely due to fuel delivery when I go to start the ski. Most likely carb-related. Gonna go try and put the ski in the water and then idle around for 30 minutes or so and come back and check plugs @burtshaver2021

 

[burtshaver2021]

I’m grasping at straws, not sure if this makes any since or not as I can’t recall anyone mentioning for sure exactly how they work but it seems you don’t have any fuel available when you go to start it. I’m wondering if the first Mylar disc on the fuel block , if it were leaking or if there was a hole in the grommet that holds it in place, if that would allow fuel to drain back out of the fuel block? Also when you were checking the 3 small holes in the carb throat, did you verify that carb cleaner was coming out of there? I know you said you seen it coming out the big hole for sure and out 2 of the small holes for sure, but was it coming out all 3 small holes?

 

[burtshaver2021]

Also where are you set at now for the low speed screw?

 

[skrillac]

Also where are you set at now for the low speed screw?

I took the ski out a few hours ago. Basically feels the same as it did before. Same throttle responsiveness, same speeds. I was at 1 turn out from closed on the low speed screw. This time I set both carbs to 1.25 turns out from closed. I also adjusted the throttle synchronization so that the throttle positions are a bit more in sync than before. I verified this with a bore camera. Both throttles open to the same positions roughly as observed from the naked eye.

When starting the ski, this time I've discovered that i just need to give it 25% throttle and it will usually start within 30 seconds. I started the ski that way on the water, verified 1400-1500rpm with tach (at launch my idle was 1400ish rpm. after punching it out of the no wake zone and idling back down, I got somewhere around 1500ish rpm). Drove it around for maybe 30 minutes to an hour. Let it sit for 15-20 minutes. Was able to start the ski the same way, 25% ish throttle.

So to recap:
Reset rotary valve timing to within +3-4 degrees of spec (tolerance is +-5, verified 3 separate times with dial indicator)
Checked rotary valve lash at 0.013-0.014 inches (spec is 0.010 - 0.014in, verified 2 times at 45 degrees with oring of cover removed)
Replaced battery as it failed load tests
Compression tested at 133ish lbs per piston. My rebuild a few years ago yielded 135psi per piston
Tested spark
Reattached exhaust pipe (separate issue, had come loose and was spraying water into hull)
Tested carb popoff. Mag side carb 40-42psi. Pto side carb 35-36 psi . Both carbs held 10psi pressure for several minutes (individually, and connected together).
Found y fitting of fuel line leaking air. Replaced. Performed pressure test of carbs again. Held 10 psi pressure for several minutes. No leaks
Brought idle of carbs up to 3000-3100 rpms on trailer. Around 1400-1500rpms on water.
New spark plugs. Verified gaps

@burtshaver2021 if i'm able to start the ski with only 25% ish throttle and no choke, wouldn't that imply I'm running slightly rich at startup/starting? The weird thing is, until July of '25 I was running the carbs a bit more lean than the manual states. I had them running at 1 turn out from closed. Now they are at 1.25 turns out from closed, like the manual says. The manual says to turn the low speed screw in/out 0.25 more/less than spec to help with tuning. I already was at that position before making this thread. Should i turn the low speed screw in 0.50 turns on both carbs to help lean it out?

The fuel block may be the next thing I check. I recall having difficulty installing that rubber grommet for one of the mylar discs. I don't think I replaced the other because of how hard it was to install the first.

Attached are the new plugs after running the ski no more than an hour. Most of that time was idling through no wake zones. I may have run the ski full blast for 10 minutes overall. Also the plugs smelled like the full synthetic oil I'm running. I've verified my oil pump timing is perfect, right on the mark.

 

[burtshaver2021]

I’m really at a loss as to what to think, those plugs look rich, Stock settings is 1 1/4 turns out correct plus minus 1/4 turn? I wouldn’t turn them in any more than the 1/4 turn that’s allowed, putting you at one turn out again. Everything is stock correct? Air box? When reading the plugs, you have to use new plugs and then drive at a certain rpm only , in your case I guess that would be at idle where the problems are correct? I’m on vacation at the moment and don’t have my laptop to read through the mikuni carb manual. There is a test in the manual for those discs.

 

[burtshaver2021]

Just reading the Seadoo source specs for your machine. I see pop off listed at 36-60 with 55 being optimal. That’s how I read it anyways. I’m almost positive these work best when they are in the higher part of the pop off range and yours is low, within range, but very low. Did. You get new needle and seats with the kit from OSD? Where they 1.2 needle and 80 gram spring? Did you order the new levers with them? Odd that they are so far apart and quit low. Did the levers sit flush with the carb body? Did you bend them? I don’t bend them. I was baffled but after reading through your posts again and looking at the Seadoo source page, could be on the right track here as the pop off does affect up to 1/4 throttle . I will check back and see what the specs were for my HX and XP. But I’m sure they were popping in the higher portion of the range

 

[burtshaver2021]

The pop of was listed at 40-56 for my 95HX and mine popped at 50. Ran great. I’m thinking your pop off is to low. Either the wrong spring or the lever is bent.

 

[skrillac]

@burtshaver2021 I ordered OSD1272 from osdmarine back in October of '21. The email I received indicates that i ordered the optional needle arm/pin set as well with the back to oem kit.

1 x OSD "Back To OEM" Sea Doo Dual Carb Rebuild Kit (1995-1997 717) (OSD1272)
Fuel System Opt. Extras Needle Arm/Pin Set

According to OSDmarine those needle valves were 1.2 OEM MIKUNI Coated VITON. I remember replacing the needles and seats in these carbs with those from the OSD kit. I'm not sure about the gram weight of the springs. But they were also replaced with those from the OSD kit. I'm not 100% positive about this, but I might have bent one of the levers up a bit. I can't remember if that was in the seadoo carbs or another toy entirely.

I may see about ordering just the fuel pump check valves/grommets (grommet install tool too), levers and springs for a 717 dual carburetor. Or just an entire kit and keep some parts on my shelf.

Everything is OEM on this ski, except for 1mm over pistons.

 

[burtshaver2021]

I wish someone else would comment here on this but I’m pretty optimistic on the pop off being to low. Pop to early allowing more fuel in. Your plugs look rich. Symptoms indicate that it’s loading up on fuel.

 

[burtshaver2021]

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[ATTACH type="full" alt="Dr Honda"]68291[/ATTACH]

Dr Honda​

Well-Known Member​

• Oct 2, 2010
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• #4

1) Yes... people do it all the time. They don't know about properly setting the carbs... and they just throw in any spring they have.

2) If you have a spring that is getting you to 28-30... then you are close. I would use that, and bend the arm down slightly. That will get you to the 30/32 range, and then you will be in spec. (do not bend the arm down more than 1mm past level with the carb body)

If you run the pop-off pressure low... you may cause the bottom end to be a little rich... but that can normally be corrected by turning in the low needle a little. If the pop-off pressure is excessively low, you could get a hard starting problem. (it will act a little flooded) also, you could get a mid transition that is a little rich. BUT... at 30 PSI, it shouldn't have a problem.

As always with a 2-stroke... you want to error on the rich side to be safe.

Found this post which confirms my thoughts that the low pop off is causing a rich condition on the low end.

 

[skrillac]

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[ATTACH type="full" alt="Dr Honda"]68291[/ATTACH]

Dr Honda​

Well-Known Member​

• Oct 2, 2010
• 
  
• Add bookmark
• #4

1) Yes... people do it all the time. They don't know about properly setting the carbs... and they just throw in any spring they have.

2) If you have a spring that is getting you to 28-30... then you are close. I would use that, and bend the arm down slightly. That will get you to the 30/32 range, and then you will be in spec. (do not bend the arm down more than 1mm past level with the carb body)

If you run the pop-off pressure low... you may cause the bottom end to be a little rich... but that can normally be corrected by turning in the low needle a little. If the pop-off pressure is excessively low, you could get a hard starting problem. (it will act a little flooded) also, you could get a mid transition that is a little rich. BUT... at 30 PSI, it shouldn't have a problem.

As always with a 2-stroke... you want to error on the rich side to be safe.

Found this post which confirms my thoughts that the low pop off is causing a rich condition on the low end.

@burtshaver2021 Is the popoff for both of my carbs too low? Or just the one reading 35-36psi? Because both plugs look identical. I have a dual carb 717. I'm not sure whether there would be a significant difference in plug fouling with a 5-6psi popoff difference between the 2 carbs. I have run a few sets of plugs in these skis and they both look identical when I go to change them out.

 

[burtshaver2021]

I think it would be better if they were both raised. I would message Nick through the OSD website to be sure of the correct spring. Mention your make and the desired pop off. And order new needle pin levers

 

[burtshaver2021]

Thread 'Pop off pressure'

Jan 18, 2018

Getting the carbs built and getting a pop off of about 37 with new springs. Old spring was 60 on mag and couldn't get a pop off while using pto spring on mag carb. No old pop off before rebuild because needle was stuck to seat on both carbs and mag carb needle had a broken metal bracket the pivot arm goes through. My question is, is have a 37 pop off when the guide states it should be 36-62? I think 62 is the high number, it might be 60. The ski is a 96 GOT with 717 and twin bn-38 bikini carbs. What would happen with a pop off at the bottom limit

• andrewterri
• Replies: 49
• Forum: 2-Stroke Sea-Doo PWC Forum

This thread says it is 1.2 needle with 95 gram spring.

 

[burtshaver2021]

M

Thread '96 gti not running good unless i choke it halfway. found exhaust leak'

May 25, 2017

I changed all fuell lines bypassed selector blocked off one supply port . left the vent as factory contions I check the check valves etc I used after market filters I put two in line before carbs
this is a twin carb 717 motor .
motor only runs good with the choke plate half closed and it has to block the center of carb (the center being the about 3/4 inch round don't know the proper name if that part of carb)
the guy before me said he had a bog problem. so I rebuilt carbs with after market kits I used original spring inside carb for needle valves.
did find that the exhaust is leaking...

• motoring
• Replies: 39
• Forum: 2-Stroke Sea-Doo PWC Forum

Post number 6 in this thread says a 1.2 needle with a black 80 gram spring, so I don’t know what to tell you. The previous post said a 1.2 with a 95 gram spring. Pretty sure Seadoo source says 80 gram. But I do believe your pop off is to low and that you need new levers because they have been bent at some time

 

[skrillac]

Thread 'Pop off pressure'

Jan 18, 2018

Getting the carbs built and getting a pop off of about 37 with new springs. Old spring was 60 on mag and couldn't get a pop off while using pto spring on mag carb. No old pop off before rebuild because needle was stuck to seat on both carbs and mag carb needle had a broken metal bracket the pivot arm goes through. My question is, is have a 37 pop off when the guide states it should be 36-62? I think 62 is the high number, it might be 60. The ski is a 96 GOT with 717 and twin bn-38 bikini carbs. What would happen with a pop off at the bottom limit

• andrewterri
• Replies: 49
• Forum: 2-Stroke Sea-Doo PWC Forum

This thread says it is 1.2 needle with 95 gram spring.

Hmmm. I'm pretty sure those springs in those carbs were that dark black looking spring. Got those from osd in '21.



According to seadoosource :

​

1996

GTI

717

270500278

270500279

BN-38I (SB)

MAIN-130 PILOT-67.5

1.2

270500267 (80)

55 psi (36 - 60 is manual spec)

LOW- 1-1/4 HIGH- 0

-

I feel like I've heard I'm supposed to be using an 80 gram spring, and I probably am right now. I can ask osdmarine about the ones the provided in their kits. But maybe that 95 gram spring would help my issue. Looks like that would raise popoff by about 10psi. I'll ask osdmarine about all this.

 

[mikidymac]

1996 GTI twin carb should use 80 gram, black springs. With a 1.2 seat you should be close to 55 psi pop-off. If you are at 36 psi something is not correct, either the seat, arm or spring. Those are the only 3 things that control pop-off.

 

[skrillac]

I went ahead and ordered x2 1.2 needles/seats, 2x 80 gram (SEA DOO 270500267) springs and levers, and x2 screw/retaining plates for the needle/seat. Ordered from osdmarine.

2 ea.	VALVE-NEEDLE 1.2 (SEA DOO 270500263)
2 ea.	O-RING (SEA DOO 270500127)
2 ea.	LEVER-VALVE (SEA DOO 270500128)
2 ea.	SPRING (SEA DOO 270500267)
2 ea.	SCREW (MIKUNI - NEEDLE VALVE PLATE RETAIN) (SEA DOO 270500155)
2 ea.	PLATE (RETAINS PUSH IN NEEDLE SEAT) (SEA DOO 270500125)