View Full Version : Getting to the carbs

12-31-07, 02:02 PM
I am a new Seadoo owner, bought 1996 GTI & 1997 GTS, both seem to have carb problems. (from the best of my knowledge)
The GTI has a new top end, the guy said he did a tune-up, but the ski is running bad and rough, having to choke it to keep it alive. (not running good at all)
The GTS had a small hole in the cooling pipe (I fixed it) and now it still boggs out when given throttle. To me the carbs are suspect, but I am having a hard time getting the black box off on top to get to the carbs...... I've never taken it apart, is it easier to have it taken in to check out or can I get to the carbs myself? I have a owners manuel and still can't figure the trick to get the box off? And ideas??? I know there are a lot of smart people out there! Thanks for any assistance... :)

12-31-07, 02:15 PM
The GTS has the 717cc engine with twin carbs. Not to hard to get to and I know how much a pain the black breather box can be. Looking down at the box, you should see 6 plastic locking clips. You have to get all these to slide open to be able to pull the top cover off. On one side of the clip, you'll notice a piece of plastic wedged behind another. You have to push that plastic to the side and slide back. Do that to all six. Then you should be able to pull the cover off.
Careful removing the carbs. With it being as old as it is, the bolts may be seized with a white powdery substance. Not exactly what causes this but several members have broken bolts trying to remove them. If the bolts are really tight, try and spray penetrate on them and let them sit over night before trying again.

01-01-08, 12:18 AM
Since I have little experience with removing this black box, it seemed really a tight fit and not friendly working area at all. I have done some work on motorcycles and they have more room to work than the Seadoos. I think I was able to get 3 sides of the black box open, and I guess there are clips in the back (hard to reach area) I didn't see them, but think they must be there also? I really am thinking of investing in a mirror kit so I can see in hard to reach areas. I have big hands and it's hard for me to get around the area with little room.

So the GTS has twin carbs, and the GTI has one? I will follow your advise, thanks a lot. I have read some of your other posts and you really know what you're talking about. (I wish you were my next door neighbor with all your knowledge!) Thanks a lot and maybe tomorrow I will try and get all the clips off the black box and open it up so I can remove that area to get to the carbs.

I think I need to check the filter, and the jet. Do you think I should just try and clean everything out and put it back together? Or try and get carb kits and try to re-build it? Or buy new fresh carbs?

I gotta get there first, so thanks and I will give it another go tomorrow.
:cheers: Happy New Year!!!

01-01-08, 10:27 AM
No they both have twin carbs. Yesterday, I cross read my information. The 96 model GTS ran the 587cc Rotax but in 97, they changed over to the 717cc. So both of your Doo's should be running the same engines. They should both have twin Mikuni BN-38i diaphragm carbs.
Like you, I grew up on motorcycles and your so very right!....I used to complain about the tight areas of a motorcycle. That is until I got my Doo!....I have a 1997 model Challenger. I think I'd try and take them off (and be careful of the white powder type corrosion) and just go through them. Clean them up, check the filters ect....because that's what I did and they ran like a champ. I may rebuild them in the next coming season, just to do it.
You should have 2 latches on the top side, bottom side and one on each side.
I'll double check to make sure a little later in the day!........

01-01-08, 11:22 AM
Yes the Spark arrester (black box) does have 2 clips per side. They all push toward the outside leading edge. Push the top of the clips then slide it to the outside edge. If you see one clip in view then you'll understand how they clip on. I would clean and reassemble the carbs and see if that doesn't do the trick first. While you have the carbs off, if they are missing lots of paint, I would remove any loose paint and wipe them down with thinner, and spray a light coat of paint on them to protect them from corrosion. Primer first than paint.

01-01-08, 12:15 PM
Good point Karl, make sure you look at the corrosion on the carbs. Be really careful when you attempt to remove them, especially the mag carb. It seems to be the one most have a problem with.
The spark arrestor that KustomKarl refers to is bolted at the top of the carbs, it's a metal mesh screen. The black box is basically a way to induce air into the engine while making sure you don't get any water in it. Unless you flood the engine compartment.

01-01-08, 12:40 PM
Both problem Seadoos were owned by the same person(s) and they simply neglected them. The GTS I think they didn't flush out proper after use in salt water due to the holes in the cooling pipe. (I found other welds when I took off) and the GTI a kid got a rope caught in the propeller and flipped it over to remove it in the ocean and got water inside it. So my carb problem on that one might be because of the salt and stuff getting in the carbs.

Any thoughts what to do after the carbs were sunk in salt? :ack:(the ski is really in bad shape as far as its operation after the top end re-build. I would never take it in the water yet)

Thanks for both of your postings!:hat: You've helped me a lot and gave me the will to keep moving forward on this! Thanks....

01-01-08, 01:06 PM
Bryan, if you've got one that was upside down and underwater.....if they didn't flush it after they brought it back home. There could be serious problems to the internal components of the engine. First thing I'd be worried about is the condition of the combustion chambers and around the rotary shaft seals. But if it's run since, the two cycle oil has coated the parts, thats a good thing.
You said the upper end was rebuilt. This was after the flip? Does it smoke real bad?
I've been working with a 787cc that went under water. It is a mess. You can check out the photos in the thread down in the boat section, "a look inside the 787". Being new to the Rotax engine, you may find it interesting. There are actual pictures from my workbench of the parts.

01-01-08, 01:07 PM
The best thing to do is remove them and have a good look see... You might want to join as Premium member so you can download a Manual for your model and see what the specs should be. As a member you can download any or all the manuals you want and read them on line as a pdf file or download them off and print them for personal use. Click on the link at the top of the page under "seadoo manuals" for details. Let us know if you need any more help. This is a friendly place with many members eager to help out.

01-01-08, 03:30 PM
I had someone remove the engine from the GTI and go over it. He said there was some kind of lock which prevented damage to the lower end.:) The top end was dust. I had him re-build it with new piston, rings, and whatever magic he did.

He said he did a major tune-up. But knowing the ski was under water like that and a re-build, wouldn't it seem wise for him to check out the carb?

It starts and runs bad. I suspect the carb needs to be worked on? I finally got into the GTS carb today (not under water) and it seemed to look fairly good except I am having trouble with it dying out. I think I have to adjust so more fuel enters the carb, the carb is starving for fuel..... Any thoughts?:toetap05:
Thanks a lot!

01-01-08, 05:06 PM
There's a couple things here, your fuel lines have to be tight, no air getting in. The fuel system is touchy in that regard. If you can grab one and snatch it off pretty easy, it ain't tight enough.
There is a little check valve and fuel filter inside the carb. The filter isn't much bigger than the eraser head on a pencil. Pretty small. When you carefully pull the carbs apart, clean them out. Also, the setting on your carbs....the low speed screw is about the standard 1 and 1/4 give or take a little and the high speed screw shouldn't be messed with. It's preset. If you have to turn it, just turn it a little either way. No more than a quarter. Also, you'll need to check the fuel line vent. If your vent and check valve is stopped up, well, I'm sure I don't have to explain that one to you. But give it a look see. Let me know what you find out!.......

01-01-08, 05:51 PM
I ended up just taking all the carbs off the skies. The GTI has a double carb and one of the filters was full of muck & oil grime. I need to soak them in something to get the stuff off them. Now since the carbs are off, do you think it's best to go through them, leave alone and just clean more, or just get all new? I need to get them running like factory.

01-01-08, 05:59 PM
If you know Mikuni carbs, like the ones on my old racing motorcycle, they build a durable carb!.......as long as you got all the parts and there isn't anything broken, I'd say you just need to give them a good cleaning. After you let them soak, try to blow all the ports out. You can use one of two things, the little red plastic tube on the side of the can of carb cleaner and blow them clear, or compressed air in a can, that you can buy at Wal Mart. It's used to clean the inside of computers.
I think your getting close if you found oil and much in the carb filters. If they did their job, you may not have to clean much further. BUt I'd soak them a spell in a good parts cleaner. There's a little flapper type check valve that's pretty fragile. Be careful not to tear it..........Hope to hear you've got them running in the near future!:cheers:

01-01-08, 09:57 PM
I was able to pick up a gallon of good parts cleaner, and took all three carbs apart and give them a good soaking. There was a good amount of sand-like stuff and gunk in most of the areas where the black gasket type of areas on both sides of both carbs for the GTI. All cleaned and back together (I cleaned it little-by-little so I wouldn't mix up parts)

The signle carb for the GTS & The double carb for the GTI are now all clean and back together. I read it is good to spray paint areas that paint flaked off during the tear down. I painted the carbs black again (to avoid future rusting) and they are now drying. I will start assemblying the carbs fresh tomorrow morning after work.

Now becomes the fun, putting it all back together!:hurray: I need to make sure the throttle is set right & the oil pump is hooked up. I have a SeaDoo Manuel that I downloaded online and it has helped so far. I'll do some more reading now on the carbs as I am ready to assmeble them soon.

Once again, thanks much for all your help, I am doing this myself as a good challenge:agree:

01-02-08, 12:21 PM
Great job so far...keep us posted if you have any questions or concerns. Also give us a heads up when your project is complete... with the end results.

01-02-08, 10:24 PM
The main jet, is it under a area with two philipps head screws?

Today has been more busy than expected & the skis were at the bottom of the list:confused: Tomorrow is a new day though! hee hee

Okay, I read the seadoo book and it said the main jet you have to take two screws off to get to it, is that correct??? I tried to get the plate off and the screws seemed soft and were stripping out easy.....:reddevil: If the main jet is under the cover with two screws, I really want to get to them. That area was really gummy and just plain bad. So if it's true the jets are in that area, they must be pretty messed up (clogged)

Please let me know if the jets are under a plate in the carb, because if so, I'm in trouble! I tried soaking the screws in thread loosener stuff, but they are locked on pretty good..... Just want to make sure I can check the jets out before trying to get the carbs back together, any thoughts or ideas???

Thanks a lot!!!


01-02-08, 11:13 PM
I answered your PM Bryan.