The Seadoo Carb Rebuild Thread

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Location
Canada
#76
Can you tell me if you purchased a specific size JIS screwdrive ? I've looked on ebay and looks like the 2 larger suppliers are Vessel and Horizon and they offer different size tips or sets with different sizes.
I believe its a #2 jis screwdriver. Somebody correct me if im wrong.
 


Messages
49
Likes
3
Location
Lake of the Ozarks
Water Crafts
2001 Seadoo GTX
#77
I have a question about the low and high adjusting screws. So my seadoo ran well before getting into the rebuild process, so I am curious to whether or not I can leave the screws alone and still effectively clean the carbs and rebuild? I read this tutorial over and over and I didn't see why the screws were removed am I missing something? Also how did you count the turns of up to 5/8th (I'm referring to your blue sticky note numbers)?

Oh and my carbs look quite different I have the BN46I twin carbs in the 2001 Seadoo GTX. They have so many more lines hooked up to it. I have identified the return and supply fuel lines but there are these super tiny black hoses connecting to both of them and I'm not sure what these are (I think they are vacuum lines but not sure).

Thank you great tutorial!
 
Last edited:
Messages
35
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0
Location
Canada
#79
I just did my carb rebuild (as per this thread)...and it went great. This was incredibly helpful...thank you.
I re used the oem springs and rebuilt with oem kits and new needle/seats (1.2). I got a pop off pressure of 50 psi? Is that too high? The spec was 36-60. Its a 96 spx with a 720 engine. Seems to run pretty smooth. Havent done a good wot plug chop yet.
 
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8
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0
Location
usa
Water Crafts
1995 Sea-Doo XP
#80
I just did my 95 717 and my pop off was about 50psi too. I thought this was too high so I subbed springs and whatnot till I got about 38. Everything is good, runs strong EXCEPT it tends to flood and is hard to start when warm, the needle does hold pressure but since I set my pop off so low, it could still be leaking if it's supposed to be 15 psi more than I have it set. Running at WOT for any more than 10 seconds, it just cuts out until I let off the throttle. Adding choke kills it completely at WOT. So when I get time I'm gonna set my pop off back to the upper 40s. Here's something from SBT I found that says pop off on those models should be higher. The Sea-Doo manual I have says it should be low 20s which I can't believe and we have determined is a misprint. Since yours is running good, I'm gonna increase pop off and double check the fuel selector for air leaks.
 

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sretooh

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Water Crafts
95 XP
96 SPX
#81
crackenzag, It sounds like we’ve had identical summers. I bought two mid 90s Sea-Doos on a double trailer and have been wrenching on them ever since. There are a few miss prints in the manual and you found one of them. I’ve rebuilt one carburetor and about to rebuild the upper and lower end of an engine. On the other one I’m replacing the wiring and all the bearings in the jet pump. One of mine had a hard time starting, the one with the carb rebuild. My hard starting issue was the rotary valve clearance. Your engine that you’re getting upper and rebuilt on, I would check your rotary valve clearance.
 
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208
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4
Water Crafts
1996 SEADOO SPEEDSTER
#82
When installing the round check valves, I broke through the rubber grommets with my 2.5 mm round ended T handle Allen wrench..I also “bent” the check valve itself to where there is a little bit of lift on either end of it due to where it bent in the middle from me pushing the grommet through the check valve.
I ordered 2 more check valves and grommets. (All genuine mikuni).
Is there a trick to getting those grommets to pop through the check valves without bending the check valves? They are pretty flimsy. I’ll try more grease next time of course but any advice is appreciated.

Thanks so much,

Donnie
 

etemplet

Premium Member
Premium Member
Messages
1,972
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143
Location
Louisiana
Water Crafts
1996 SPI, 1996 GTX, 1997 GTX
#83
When installing the round check valves, I broke through the rubber grommets with my 2.5 mm round ended T handle Allen wrench..I also “bent” the check valve itself to where there is a little bit of lift on either end of it due to where it bent in the middle from me pushing the grommet through the check valve.
I ordered 2 more check valves and grommets. (All genuine mikuni).
Is there a trick to getting those grommets to pop through the check valves without bending the check valves? They are pretty flimsy. I’ll try more grease next time of course but any advice is appreciated.

Thanks so much,

Donnie
Where did you get jet the check valves? I'd like to have some spares because like you... I have bent more than one. I don't like installing those things at all. I even purchased the so called tool with no luck. I use a really small screwdriver flat blade to tuck the rubber through the hole. As you know... if it slips... the valve is done. I've been thinking about machining my own design grommet installer but even with that... you can't push very hard or it will pop through.
 

riffe723

Active Member
Messages
356
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33
Water Crafts
(2) SeaDoo SPX - 1997 (sold)
SeaDoo Speedster SK - 1999
(2) SeaDoo Spark 90hp - 2016
#86
Man I really appreciate the people on this page. I know how to rebuild carbs but damn, you guys have some seriously detailed instructions that make the project a piece of cake.
 
Messages
7
Likes
1
Location
connecticut
Water Crafts
1996 Sea Doo GTX
#88
When installing the round check valves, I broke through the rubber grommets with my 2.5 mm round ended T handle Allen wrench..I also “bent” the check valve itself to where there is a little bit of lift on either end of it due to where it bent in the middle from me pushing the grommet through the check valve.
I ordered 2 more check valves and grommets. (All genuine mikuni).
Is there a trick to getting those grommets to pop through the check valves without bending the check valves? They are pretty flimsy. I’ll try more grease next time of course but any advice is appreciated.

Thanks so much,

Donnie
I remember having the same problem of poking through the rubber grommet with a small allen wrench. I remember reading somewhere afterwards that someone recommended using dental floss around the end of the grommet that goes through and use it to pull the grommet through the hole. I don't remember if they said to use a slip knot (which may be difficult to remove afterwards) or just cross the two side of the floss over each other, thread both ends though the hole and pull them to get the grommet through and then just pull one end of the floss through when your done. I will definitely try this next time
 
Messages
154
Likes
20
Location
Toronto, ON
Water Crafts
1997 Seadoo GSX
#89
I remember having the same problem of poking through the rubber grommet with a small allen wrench. I remember reading somewhere afterwards that someone recommended using dental floss around the end of the grommet that goes through and use it to pull the grommet through the hole. I don't remember if they said to use a slip knot (which may be difficult to remove afterwards) or just cross the two side of the floss over each other, thread both ends though the hole and pull them to get the grommet through and then just pull one end of the floss through when your done. I will definitely try this next time
There's a video on YouTube showing a guy that does this... I tried it and it didnt work too well for me. What I've done with two sets successfully now is dip the tapered end of the grommet in vaseline and then just by hand work it through. Set the check valve in the recessed hole and push the grommet through the valve, it will be supported enough that it doesnt bend. Then just massage the grommet through.

Patience is key.
 

mikidymac

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Location
California
Water Crafts
2003 GTI
2001 XP
1996 XP
1996 HX
1991 Superjet
2001 Superjet
#90
I actually apply lighter pressure and just keep wobbling the Allen wrench in a circle to slowly work it in. If you just push hard or will punch through the rubber and ruin it.
 

lithium2g

Active Member
Messages
20
Likes
1
Location
Australia
Water Crafts
Seadoo Speedster 1998
#91
Dude you are all over this stuff. I'm pretty sure I can see green stuff in the fuel line on one of my engines so probably need to do this sooner than later. Shit it looks like a big job. How long do you reckon this takes to do?
 

mikidymac

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Water Crafts
2003 GTI
2001 XP
1996 XP
1996 HX
1991 Superjet
2001 Superjet
#92
Should only take a couple hours your first time.
 
Messages
26
Likes
2
Location
Dallas, TX
Water Crafts
1995 Seadoo SP
1996 Seadoo GSX
#93
Thanks for the awesome writeup. Just ordered the Mikuni kit and pulled my carb off. Now just have to build a pop off pressure tester and I will be set. Thanks!!
 

goodtoogo

New Member
Messages
6
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0
Water Crafts
96 xp800
#94
The pop off valve needs pressure to pop. Where is that pressure generated under normal operating conditions? Secondly what exactly is the purpose of the pop off.
 
Messages
154
Likes
20
Location
Toronto, ON
Water Crafts
1997 Seadoo GSX
#95
The pop off valve needs pressure to pop. Where is that pressure generated under normal operating conditions? Secondly what exactly is the purpose of the pop off.
The Pulse line (crankcase pressure) actuates the fuel pump membrane. The pump is what creates the pressure.

Seadoo carbs don't have floats (wouldnt work well). So in lieu of that a fuel pump is used. The purpose of the pop off is the point at which the needle valve will open and let fuel into the carb metering chamber. It can affect the air fuel ratio delivered to the engine.
 

mikidymac

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2001 XP
1996 XP
1996 HX
1991 Superjet
2001 Superjet
#96
The Pulse line (crankcase pressure) actuates the fuel pump membrane. The pump is what creates the pressure.

Seadoo carbs don't have floats (wouldnt work well). So in lieu of that a fuel pump is used. The purpose of the pop off is the point at which the needle valve will open and let fuel into the carb metering chamber. It can affect the air fuel ratio delivered to the engine.
Actually that is not correct.

The vacuum generated by the engine creates a negative pressure in the carb body which causes atmospheric pressure to push the diaphragm in, compressing the arm spring and opening the needle. The size of the seat and pressure of the spring determine the vacuum needed to overcome the needle.

When testing the popoff you are just testing the calibration of the spring and needle and seat, this actually has no relation to how the carb actually functions when it is running. This is also why changing just the ari cleaners can require changing springs, needle and seat as well as jetting.
 

goodtoogo

New Member
Messages
6
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0
Water Crafts
96 xp800
#97
Ok I think I've got it. The carb does not have floats to control the fuel flow . The needle has to move to allow fuel into the carb. The spring seats the needle. The needle is moved by pressure on the diaphragm which is induced by vacuum from the motor turning. Now I have confused myself and created a new question. Why do we then pump pressure when needing to create vacuum when setting up the carb? What I am learning is that this set up is critical to the running of these motors.

I am in south africa and expertise on these older 2 strokes is limited. Thanks for the feedback , enjoying this site and the wealth of info and willingness to share.
 

mikidymac

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2001 XP
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1996 HX
1991 Superjet
2001 Superjet
#98
Basically testing the pop off is checking the needle and seat as well as the spring pressure. It is just a test and not the way the carb actually works when running.
 
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1
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Water Crafts
1997 GTI & 2002 XL700
I'm a newby on here. I have been repairing my own seadoo's and never had any issues until now. I'm working on a 97 GTI 717. I test it out this past weekend and it would bog out at WOT. I removed the carb, cleaned it and replaced all the seals and gaskets. Carb was clean and so was the filter! Ran the same way. I replaced all the fuel lines and cleaned the fuel selector and still bogs. What am I missing? I've done this carb a few times before and never had an issue.
 

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