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The Seadoo Carb Rebuild Thread

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Location
Texas
Water Crafts
1997 SeaDoo GTI 720
1998 Lavey Craft Seabring 20.2 with 200 Mercury
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.
I have the exact same scenario....looking for replies as well
 


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71
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Location
Texas
Water Crafts
1996 Seadoo XP
1997 Seadoo XP
Can you send me a pdf of this procedure so I can rebuild my own carbs?
I have the OEM Mikuni carb kits. Will these work?

Update: I was told these were JUNK !!
 

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Location
White Lake, Michigan
Water Crafts
2002 GTX DI
2003 RX DI
I followed your instructions and all is well with the popoff test (38 and drops to about 33) except one minor thing.

If I hook the outlet and inlet like you show and go through the fuel pump all is good.

However, if I cap the outlet on the carb and do popoff through the inlet of the carb it leaks through the inlet of the pump. Is this normal or are the check valves on the pump leaking? I've tried to go through the mikuni manual to see if the cross section would help and I couldnt tell.

If a check valve/disc is leaking how do I verify which one?
 
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10
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1
Water Crafts
95 XP, 97 SPX
I am trying to get my pop off pressures right on my carbs. The OSD spec seems high to me for my ski (40-56psi), but I'm trying to get close. I have a pair of springs that get to 40psi, but they don't pop "clean" like the lighter springs i have. They hold after they bleed back down to about 32psi, they just don't "pop". Is the "pop" a MUST HAVE since they do reseal?
 

dontilgon

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Location
NY
Water Crafts
1996 XP
1996 GTX
1997 GTX
Great write up but of course I found it after completing the job yesterday. I couldn’t figure out which side had the ink. I’m guessing I put them in backwards cause she not running . Back to the work bench.
 

mikidymac

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1996 HX
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Great write up but of course I found it after completing the job yesterday. I couldn’t figure out which side had the ink. I’m guessing I put them in backwards cause she not running . Back to the work bench.
The easiest way is just a dab a brake cleaner on a rag. It will remove the ink and not damage the plastic so you can see what side it is on.
 

seadoosnipe

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Location
Deep South
Water Crafts
1997 Challenger, 1997 GTX , 1991 SP and a shop with 2 spare 787cc's and a bunch of parts laying arou
View attachment 34647
I use the Thomas & Betts expensive zip ties with the stainless locking tab for all the connections and have never had a leak or issue. Don't go cheap on these.
View attachment 34648
And we are finished. I will update this with the accelerator pump rebuild supplement and carb installation shortly.
L
I used this thread to start tearing down my carburetors today. thank you miki for pointing it out to me.

the one small item that I thought would improve the process would be to use firm pipe cleaners instead of the Q-tip. you can buy a load of them on amazon for about 6 bucks. the brand is "ZEN". if you can't wait that long for them to arrive in the mail, you can probably also find them at the local smoke and sex shop.

What an excellent thread, wonderful information, breakdown and expanded views are awesome. I’ll put a couple comments in, that really can be taken with a grain of salt. The carbs have a 3 phase operation. Your first few RPM are on the low speed jets. Then into transition, you’ll be getting fuel from both, the high and low. While reaching WOT, your totally operating on the high speed jet.

Remember, the low speed adjustment is the only jet you enrichen or lean out. The high speed isn’t actually adjustable, it should always be closed. If you look st the exploded view of the Mikuni manual, you’ll notice it’s actually a bypass around the jet.

The jet skis do not use the accelerator pump. Those are only found on the boats, Challengers and Speedsters, etc... thats because the fuel is introduced to the engine by vacuum. The pulse fuel pump only ensures the fuel loop is completely filled with fuel.

Last thing is jetting. If your at sea level, the standard Mikuni is jetted properly. If your in Colorado, with the mile high elevation, there is less oxygen for combustion, so you need to re-jet ur carbs. The floatless Mikuni carbs are the best in the market.

Great job in this thread, well written!
 

mikidymac

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L



What an excellent thread, wonderful information, breakdown and expanded views are awesome. I’ll put a couple comments in, that really can be taken with a grain of salt. The carbs have a 3 phase operation. Your first few RPM are on the low speed jets. Then into transition, you’ll be getting fuel from both, the high and low. While reaching WOT, your totally operating on the high speed jet.

Remember, the low speed adjustment is the only jet you enrichen or lean out. The high speed isn’t actually adjustable, it should always be closed. If you look st the exploded view of the Mikuni manual, you’ll notice it’s actually a bypass around the jet.

The jet skis do not use the accelerator pump. Those are only found on the boats, Challengers and Speedsters, etc... thats because the fuel is introduced to the engine by vacuum. The pulse fuel pump only ensures the fuel loop is completely filled with fuel.

Last thing is jetting. If your at sea level, the standard Mikuni is jetted properly. If your in Colorado, with the mile high elevation, there is less oxygen for combustion, so you need to re-jet ur carbs. The floatless Mikuni carbs are the best in the market.

Great job in this thread, well written!

Thank you for the kind words.

Just a FYI, the skis started using the accelerator pumps about 1997.
 
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Location
West Coast
Water Crafts
1996 Sea-Doo SPI
Here you can see the cleaner starting to flow out of the large hole at the 10:00 position and a small stream out of the three small holes at the 11:00 position just below the "8" stamping. IF you don't get any flow put the low speed adjuster screw back in about 1 full turn once the threads catch.

View attachment 34595
Now we have a good strong flow out of all four holes. Now remove the low speed screw and blow everything out with air.
I only get flow out of the large hole and one of the three small holes even after putting in the low speed adjuster screw.

How can the 3 small holes be cleaned and cleared?
 
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Location
Fargo, ND
Water Crafts
1996 SeaDoo Speedster
@mikidymac thanks for all the great pics and info in this carb rebuild thread! It appears that the carbs on my 1996 Speedster are just a little different than what you have pictured. Specifically I'm talking about where you are clearing out the 4 holes inside the carburetor, where you shoot cleaner through the pilot jet. My carbs only have 1 passage there, and there's a number 7 stamped in the casting of the carb. Hoping this is normal on a Speedster.

*EDIT* My carbs do have the 3 small holes as well, I just couldn't see them due to the carbs being very dirty. Made sure to shoot a lot of brake cleaner and compressed air in through the pilot jet to see that the passages were nice and clean.

"Next is one of the most important parts of cleaning the carb. In the pilot circuit there are three small hols and one large hole that meter fuel into the carb at idle and just off idle and it is typically the three small ones that get plugged. This will cause a poor idle and a stumble or hesitation off idle when you start getting into the throttle.



This is looking into the carb from the bottom with the butterfly held open.




Here you can see the cleaner starting to flow out of the large hole at the 10:00 position and a small stream out of the three small holes at the 11:00 position just below the "8" stamping. IF you don't get any flow put the low speed adjuster screw back in about 1 full turn once the threads catch.




Now we have a good strong flow out of all four holes. Now remove the low speed screw and blow everything out with air."


The other thing I'm wondering about is how close should the pop off be between a MAG and PTO carb? So far I just have the port side carbs done. I'm using all genuine Mikuni carb repair kits, new Mikuni 1.2 needles and seats, and brand new needle valve arm springs. Pop off pressure on the MAG carb was 43psi, and the PTO carb was 56psi, after installing all of the new genuine parts. I did try bending the arm a tiny bit to see if the PTO carb would come down some, but it did not change at all. Tried the old arm from the carb and that made the pop off go even higher, so I reinstalled the new arm from the carb kit. Should I try to get that pop off a little lower still? Or just leave it since its all brand new genuine Mikuni parts?

*EDIT* my pop off tester hose was leaking, so once I fixed that, all 4 carbs pop off between 52-56psi, which is at the upper end of what the shop manual says it should be. Seems to be all good.
 
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jdober

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Water Crafts
2001 Seadoo RX
Great write up mate. Thanks

Just wondering when you put the carbs back in if theres any adjustments needed to be done with choke/accelerator?

I have also heard things about having to prime/sync/remove air from the oil lines? What do you recommend for this? This is the main thing stopping me from doing this on my ski as ive heard many stories of people blowing their ski up.



PS. Does anyone know the easiest way to get the airbox/carbs out of a 2001 seadoo rx? Ive been told you don't need to remove anything but i cant seem to get the air-box out without removing the e-box or something else. Theres no room.

Thanks In Advance
 
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38
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Location
Nebraska
Water Crafts
2003 GTI
Restoration in Progress 96 XP
Great write up mate. Thanks

Just wondering when you put the carbs back in if theres any adjustments needed to be done with choke/accelerator?

I have also heard things about having to prime/sync/remove air from the oil lines? What do you recommend for this? This is the main thing stopping me from doing this on my ski as ive heard many stories of people blowing their ski up.



PS. Does anyone know the easiest way to get the airbox/carbs out of a 2001 seadoo rx? Ive been told you don't need to remove anything but i cant seem to get the air-box out without removing the e-box or something else. Theres no room.

Thanks In Advance
Best write up on the forum!!
 
Messages
114
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Location
West Coast
Water Crafts
1996 Sea-Doo SPI
I only get flow out of the large hole and one of the three small holes even after putting in the low speed adjuster screw.

How can the 3 small holes be cleaned and cleared?
For anyone else running into this, solution was to use a small pin and a strand from a strong wire brush, held with needle nose pliers along with carb cleaner to get the three small holes cleared on my SB38 carb.
 

etemplet

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Location
Louisiana
Water Crafts
1996 SPI, 1996 GTX, 1997 GTX
I figured the best place to post this was on the carb thread so here goes. :D

I have THE MOST Difficult time putting the little valve discs for the fuel pump into position. I have that stupid little tool and punches a hole straight through the rubber grommet if you apply much pressure at all. I have ruined a few pump valve discs fighting this situation. Any insight on this OR is it already covered in the thread? It sure isn't a walk in the park for me.
 

mikidymac

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First make sure you use the correct size ball tip allan wrench, too big and it will punch a hole in them. Then I use just a small dab of silicone grease. Finally when pushing I move the wrench in a little circle to work the rubber into place.
 

etemplet

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1996 SPI, 1996 GTX, 1997 GTX
As I was typing my response I thought of a modification to the tool that would be much more effective. I'll have to post a picture of my current tool.
 
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Location
Maryland
Water Crafts
1995 Gtx
I rebuilt both carbs on a 2000 951. The engine fires up and idles nice, as soon as I give it throttle the engine will race until shut it off. I did have to replace the linkage arm between the two carbs. Any ideas?
 

etemplet

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Location
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Water Crafts
1996 SPI, 1996 GTX, 1997 GTX
Intake leak or it's really lean. Open the low speed adjuster and see if that helps. Did you rebuild the accelerator pump? I've had the bellows on those miserable little suckers give me problems. :)
 

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