The Seadoo Carb Rebuild Thread

Ryan727

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1999 Seadoo GTX Limited 951 (x2)
#51
IMG_20180705_200009.jpg

This could be a dumb question, but I'm just not sure. That elbow in the above picture. It is supposed to flow right thru, right? I've pulled 3 (both carbs here and a 1 from a spare set I have), and none of the elbows can be blown thru, nor sprayed with carb cleaner. The needle going thru the carb is clear, and I can spray thru it when the elbows are off, but none of the elbows are clear.

Just a bad coincidence that they are all clogged?
 


mikidymac

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01' Superjet
#52
First off do not substitute the springs in the kit. If you have new genuine mikuni needles and seats of the correct size and pop off isn’t in spec buy new genuine springs in the correct weight. Don’t bend the tab more than 1mm from flush with the body.
 

mikidymac

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#53
Don’t remove the elbow if at all possible as the might not reseat. You have to be able to cleanly blow cleaner through them.
 

Ryan727

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1999 Seadoo GTX Limited 951 (x2)
#54
Yeah none of mine are flowing. I'm rebuilding this carb set, my spare is next. But none are clear. Any recommendation for cleaning these elbows? Can't fit the carb spray tube in there. Maybe some wire?
 

mikidymac

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#55
I have plucked a single strand from a wire brush before to clean them.
 

Ryan727

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1999 Seadoo GTX Limited 951 (x2)
#56
Very odd here. So I tried a strand of wire, it went in, but got stopped on the outlet pinhole inside the elbow. My gauge of wire was a little large. Then I boiled some water in a cup, dropped the elbow in for a minute, then pulled it out. When I blew in one end, I get little spurts of water. Almost like it opens up for a sec, then closes again.
 

mikidymac

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01' Superjet
#57
There is probably a check ball in there so air can't enter the pump. IF you are getting a little flow try blasting is with more cleaner and air until it frees up. You should have a nice small stream coming out as it is a very small hole just to squirt a small burst of fuel.
 

Ryan727

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1999 Seadoo GTX Limited 951 (x2)
#58
I think it's free. I had to boil it to free it up first. Now when I spray some drops of carb cleaner and blow on the inlet, it will eventually pop open and let it out. Just kind of spits it out then closes back up. When I stick a dental pick in there, it does feel like a rounded ball inside. I assume it's a check ball as well. I'm assuming the accelerator gives enough pressure to pop it open. Will check once rebuilt and put back together, before re-installation of carbs. Thanks for the input.
 
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Water Crafts
1999 gsx limited
1999 GTX
#59
Great post, just finished my carb (99 GSX) rebuilt 3 days ago, read this today and fortunately I did it 95% right. I may have to go back and do a pressure test (the 5% I forgot). I am now getting a Code 1204 error.
I will use it for the other ski (99 GTX) when I rebuild it.
Thanks
 
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Location
Ohio
Water Crafts
1998 SeaDoo GS
#60
Is there a part number/recommendation for the base gasket?? I don't see it in the rebuild kit pics or the parts manual.
 

mikidymac

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#61
It depends on the model of ski but all of the parts diagram show it, it's typically with the rotary valve cover not the carbs.
 
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Water Crafts
1995 Sea-Doo XP
#63
question: 95 seadoo xp 717. Took apart the carbs as your thread instructed. The high needle, on both carbs, was all the way screwed in. couldn't turn it clockwise at all on either carb. Ski always ran good until the filters plugged and I've never messed with the carbs before now. Appears to have mikuni OE parts in the carbs. Is this normal? the seadoo manual states that the low speed screw should be set 1 3/4 turns out for my model but no info on the high speed screw. From what I can read they don't want you removing the plastic cap and warn against adjustment of any kind. Should I just put them back to all the way in or what's your recommendation for a starting point on the high speed screw?
 

mikidymac

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#64
Crackenzag, your model has the High Speed screws closed, this is the correct setting. I would take them out to clean then put them back in until lightly seated.
 
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#66
Ive got a question regarding pop off pressure. The spec for my spx is 36-60. Should I be aiming for pop off right in the middle of that spec? Im gonna be rebuilding my carbs in a few weeks and i was wondering what the ideal number would be.
 

mikidymac

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#67
Anywhere in that range is fine but I would be expecting 36-40.
 
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1995 Sea-Doo XP
#69
another question: my 95 xp manual says pop off should occur between 16-21 psi for dual carbs. This seems substantially lower than anything else I've read about in this thread. Is that what I should be shooting for or would a little more pressure be better? Sorry, I'm a 2 stroke carb noob.. lol
 

mikidymac

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#70
another question: my 95 xp manual says pop off should occur between 16-21 psi for dual carbs. This seems substantially lower than anything else I've read about in this thread. Is that what I should be shooting for or would a little more pressure be better? Sorry, I'm a 2 stroke carb noob.. lol
I am 99.9% sure that is a misprint as you can't get that low with the spring and needle and seat according to Mikuni. You should be using the 1.2 needle and seat with the Black 80 gram spring which would get you to 36-50 psi.
 
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1995 Sea-Doo XP
#71
Screenshot_20180822-115551.png

So what this says is incorrect? I'm not second guessing you, I just wanna do this once. The carbs were pretty clean inside except for the plugged screens and green goo on the line nipples. The springs we're just fine and I plan to reuse them, just wanted to make sure everything is good before I put this thing back together.
 

mikidymac

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#72
Correct crackenzag, there is no way the 1.2 needle and seat could ever pop at that low of a pressure even with the smallest 65 gram spring. The manual is wrong. Even a 1.5 needle and seat pops at 32 pisi at the lowest.
 
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1995 Sea-Doo XP
#73
Correct crackenzag, there is no way the 1.2 needle and seat could ever pop at that low of a pressure even with the smallest 65 gram spring. The manual is wrong. Even a 1.5 needle and seat pops at 32 pisi at the lowest.
Ok Miki if I may call you that. I'll shoot for mid to upper 30s. Thanks for all your help!

I actually have 2 of these skis. I paid $1500 for both and a double trailer. One of them has a bad top end, cylinders are at machine shop right now and I still have to go through the carbs and replace fuel lines on that one. The other one is the one I'm working on now. Hopefully I'll have 2 good skis and a trailer for less than $3000 when it's done.
 
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Water Crafts
1995 Sea-Doo XP
#74
Carb rebuild done. Runs like champ!

Buuuuttt... It's hard to start after being run. I assume the needle(s) are leaking. Is there any quick way to verify this without completely removing the carbs? I know I'm probably gonna have to remove them anyway but didn't want to unless i knew it was for good reason. I ordered genuine mikuni kits from eBay but I noticed that the needles and seats sent with them weren't genuine... I was a bit upset when I noticed that. I may end up putting the original needles and seats back in it as long as they pass the pressure test. My gauge set up was leaking a little when I was pressure testing and I rushed rather than fix the guage and make sure it wasn't leaking.

I do have one other question. When initially measuring pop off pressure it was like 48 psi. So I bent the needle arm a little till I got about 38psi. Is it possible that I bent the arm too far and the diaphram is holding it open? If that was the case then it should fail the pressure test with the diaphram installed then pass with the cover and diaphram off correct? What's the right and proper way to actually adjust pop off if it's not in spec? Thanks
 

Thor0515

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Water Crafts
1995 GTS and 1999 GTS, and a new 2018 Spark 3up Trixx
#75
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.
 

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