RESTO 1996 Seadoo GTI rings

[SIMPLEARKANSAN]

May be replacing rings after I do a compression test. After looking it looks like two different styles available? Which type do I need or are the upper and lower rings different part numbers?

 

[mikidymac]

You really need to have the bore measured with the correct tools to determine if the clearances are too big. On most of these engines when the compression gets low it is because the cylinders are worn beyond the spec and need to be bored oversize and new pistons fitted. It is not typical that only new rings are needed.

And on OEM Seadoo pistons the top and bottom rings are different and do not interchange.

 

[SIMPLEARKANSAN]

Thanks. I haven’t measured compression but plan on that tonight. I may still need to just make carb adjustments. I’m also going to disconnect the red wire of the voltage regulator/rectifier and see if that makes any difference

 

[SIMPLEARKANSAN]

Checked PSI and it’s 150 on both cylinders. Took flame arrestor off and notice gas pooling in the arrester like it’s flooding. Pop off on both carbs is 41 and it held at about 35. Should I adjust my pop off higher. It idles pretty well but when I give it throttle it dies. Should I increase my pop off. If I pull choke it dies also. Haven’t checked my spark plug wires or cut them back yet.

 

[GGuillot]

If you can't recall last time it's been done, I'd rebuild the carbs, use genuine OEM, new needle/seats and check the fuel system over. With good compression, most issues like bogging are related to carb and fuel delivery issues. See the link in mikidymac signature block if you go that route, it's a good how to.

 

[SIMPLEARKANSAN]

Just rebuilt carbs. Ordered carb kit from OSD $124. Has OEM Needles and seats. Hard to find definitive pop off for these carbs and ski model. Some places I’ve read 21 psi and others I’ve read 40-56? Mine is 41 because I read the closer to low end of pop off range the better it will run?

 

[mikidymac]

You should be running the 1.2 needle and seat with the black 80 gram spring. Your popoff should be 36-60 psi so 41 is fine. Did you make sure the carb holds pressure when you got it all back together. IF there is fuel pooling in it as you said then it is flooding from the needle and seat not sealing.

 

[SIMPLEARKANSAN]

I’ll double check the seat part#. Yes pressure held after pop off. I’ll recheck tab to make sure they are flush with carb body or a little lower so diaphragm not pushing tab down when cover place on and possibly holding needle slightly open. I’ll check spring color also.

 

[mikidymac]

After it is all back together you should be putting about 10 psi to make sure they are holding pressure if not it will flood the engine.

 

[SIMPLEARKANSAN]

MM after I put the diaphragm and cover back on put 10 Psi into carb like I was doing a pop off pressure test and see if it holds. Block off the other areas as usual. I had a chance to look at the old diaphragms tonight and the little button that pushes on the n/s lever arm is much smaller and not colored red. I bought my carb kit from OSD so I thought the new diaphragms would be OEM?

 

[mikidymac]

Yes, put the carb all back together and just plug the return line. Then pump 10 psi into the inlet fuel fitting and it should hold that 10 psi forever.

 

[SIMPLEARKANSAN]

Thanks. Will that let me know if diaphragm is keeping needle/seat slightly open?

 

[SIMPLEARKANSAN]

I found my answer. That’s the only step I forgot to do after the rebuild. Ski starts up immediately everytime, but was flooding out. All makes sense to me now.

 

[SIMPLEARKANSAN]

Removed carbs and think I found a couple reasons for carbs flooding. Return gas line on PTO carb was plugged backing fuel into the carbs? Also the PO had installed 65 grain springs. He had rebuilt the carbs and I assumed they were original springs until I looked at them today. Same length as the black springs just lighter colored. The funky looking Oring in both carbs is swollen and won’t fit back into its grooves? Is this because carbs stayed so full of gas? If I let them sit and dry will they shrink and return to their normal size?

 

[etemplet]

MM after I put the diaphragm and cover back on put 10 Psi into carb like I was doing a pop off pressure test and see if it holds. Block off the other areas as usual. I had a chance to look at the old diaphragms tonight and the little button that pushes on the n/s lever arm is much smaller and not colored red. I bought my carb kit from OSD so I thought the new diaphragms would be OEM?

If that button is smaller it is not the correct diaphram. That may be your problem right there and a great place to start. Also are you getting fuel from your three little holes in the carb barrel? You need good flow there or it will stumble. They are difficult to clean when dirty. Also verify the seats are the correct size. Higher pop off makes the engine run a little leaner. Fix the diaphrams first.

By the way... I use a soap bubble mix to see if the carbs are leaking and where. Just another check I like to do. No surprises... I don't like em. Good Luck !!

 

[Sportster-2001-951C-Stock]

" It idles pretty well but when I give it throttle it dies. "

This is often caused by corrosion in the low speed fuel circuit, those 3 pilot holes in the bore just before the throttle butterfly plate as etemplet pointed out. Remove low speed jet and idle mixture adjustment screw while cleaning that passage, it can be tough getting all the junk out of there so be thorough. The 3 holes may be imperceptably clogged as well, so I poke a thin wire through them being careful not to enlarge the precision drilled holes but the natural corrosion of aluminum does close them up to smaller diameter causing a lean hesitation.

Consult the Mikuni SBN carburetor manual popoff chart for Seadoo's particular spring and seat diameter combination and then shoot for that, I've found this chart to be bang on as far as I know. Mikuni builds these carbs to Seadoo spec, Seadoo engineering determines their spec based on field testing.

If popoff is too much you can experience lean operation at low speed throttle angle and if pop is too low you will experience crankcase flooding at low throttle angles (such as idling around docks and through no-wake zones).

A benchmark 5 minute hot restart should practically bump start without much cranking if pop and idle mixture are set reasonably. If you find 5 min hot restarts are tough then recheck idle mixture adjustment (Low Speed Mixture Screw adjustment) and confirm popoff.

Lots of places for trash to clog these carbs, all those small and tiny passages are there for good reason and they can be a bear to get whistle clean. You wouldn't be the 1st to experience trouble getting them correct.

 

[SIMPLEARKANSAN]

Thanks for all the help. I was able to spray carb cleaner through low speed jet. I covered the larger 4th hole to increase pressure through the smaller holes. I got good spray through all three. I also blew them out with the air compressor. I'll feed some small wire through each one to verify. I ordered new O rings as the ones that were in there were not OEM and had swollen to the point of no longer working. I also replaced diaphragms with the red button OEM ones. Put in the 80 gram black springs. Once I receive the new O rings, I will re-check pop off and the static 10 psi test. I think I've narrowed down the flooding problem, and will keep you all updated.

 

[etemplet]

If you have good flow though the 3 holes in the barrel.... don't stick anything in those holes as you may create larger problems. If they flow... that is good.... stop there. Sound like you are on the correct path !! By the way, I am no guru just been there a few times. Good Luck !!

 

[SIMPLEARKANSAN]

Ok. Looks like i'm just waiting on the new funky shaped O rings and I'll be good to go.

 

[etemplet]

Mikuni sure is proud of their parts aren't they?

Just a note - I bought a couple of "wonderosa kits" just for the springs (I got a great deal LOL) I used one of the gaskets on a carb I was trying to save using old parts and it leaked like a sieve. I am a person that has to learn why, not just listen to group think. So... I surely won't argue with anyone recommending "Genuine Mikuni Only Parts." sure makes life easier. Problem is... sometimes vendors mislead us. I got to the point where I weighed the carb needles to compare. The new needles are much lighter unless I'm getting ripped off. Good Luck !!

 

[SIMPLEARKANSAN]

I agree. I’ve learned that about the aftermarket kits too. Have new 80 gram springs coming today. As of last night I had no more leaks. Once I replace springs and check pop off again I’ll re-install carbs. I put springs in that I thought were 80 grain and I’m getting 58 psi. I’d like it to be lower. The original springs put me at 41.

 

[etemplet]

I'm messing with a GTI the owner bought new needles and seats. I know they are not mikuni. The Springs only got me to 36psi pop off. I managed to get them both up to around 43. I'd like it around 50. I know with Mikuni needles and seats.... you install it and the right springs and the carbs are generally spot on. Can't argue with that. From my experience the lower end causes the engines to run rich. I had 2 787 GTXs and when I made changes, I did it to both skis and both generally responded the same. Good Luck !!

 

[SIMPLEARKANSAN]

What year GTI are you working on? Mine is a 1996. I read somewhere it's better to have your pop off at the lower end of the range, that there is a risk for running lean if too high. My GTI pop off limit is 60, I guess I could keep at 58?

 

[etemplet]

It is a 1996 GTI. Popping off at 43-45ish. I'd rather 50 but I think it's OK. I'm definitely not lean. I did some pressure testing and changed a clamp and the fuel filter cup. I need another test ride.

 

[SIMPLEARKANSAN]

My new springs that are scheduled to be here by 8 pm today have still not made it. Guess I’ll have to wait till tomorrow. What kind of speed are you getting? This ski has no tach either?