I picked up 2 1998 Sea Doo GS and now I have noob questions

Status
Not open for further replies.
I'm pretty sure I paid too much for these. They were $3k, but I haven't seen a pair that looked this clean for that sort of price so I pulled the trigger. I don't really know anything about PWC's. I've always been happy with my kayaks and fishing, but my kids talked me into getting these older GS Sea Doos. They looked pretty good for their age and started up and ran just fine while we were looking at them. I've worked on small engines and cars for years, but these things are a little different animal being that they are in the water and I'm not familiar with them at all.
They seemed to run good and with 2 of the exact same model, I figured that may be handy for trouble shooting since I could swap parts back and forth to determine what part may be bad.
I was doing some reading online and figured those old grey colored fuel lines needed to be replaced before we do much else with them. I was looking around at a few things and noticed this broken area on a mount at the rear end of one of the GS's (see 1st 2 pictures). Is that something to be concerned about? The fiberglass is clearly broken, but I don't know if it is that big of a deal or not.
They said they had replaced the wear rings last year. They said they always worked great with the exception that it took a while for them to start when they were cold. From what I've read, that seems to be normal.
I noticed that each one of these had some sort of oil in the bottom of the hull that you can see in pictures 3 and 4. I didn't notice that it was oily until today (I thought it was a little water when I was looking at them before buying). I'm not sure what that is. It isn't 2 stroke oil like I'm used to seeing. Could it be something used when winterizing them? Also, I noticed a gash in the hull on one and they said that it doesn't look good but that it doesn't leak there. I am adding a picture of that as well. Should I patch that area? One of them has a tube under the seat that you can see in a picture. They said when they bought them in 2012, that tube wasn't in one of them and they have been using it without it with no issues. It must serve a purpose, it looks like an air tube or something. Should I try and locate one for the GS that is missing it?

Sorry for the long first post! I appreciate any help or information y'all can give. Thanks!

IMG_20200416_091118593.jpgIMG_20200416_091131748.jpgIMG_20200416_090832623.jpgIMG_20200416_090843502.jpgIMG_20200416_091539475.jpgIMG_20200416_091346205.jpgIMG_20200416_091522644.jpg
 
Last edited:
Okay, so you dove into the deep end of the pool....gotta sink or swim now.
They start and run....that's bonus right out of the chute and a little dock rash here and there can be patched up without too much effort.....so long as the hulls are sound, shouldn't be a big hassle (that'll buff right out..;)).

The conventional wisdom is to replace all old grey fuel lines with conventional 1/4" black automotive lines. Also, rebuild the carbs with ONLY genuine MIKUNI parts, etc....at a minimum, since they run, is to a least open the carbs and check the little internal fuel filters...BUT if you are pulling the carbs to do, might as well go whole hog and do the job right.

There is always a bit of oilyness in the bottom of these skis....but check to make sure your oil tank(s)/tank bottom grommets are not leaking and/or the tanks are not cracked (if cracked...there are repair videos on YouTube), check oil hoses and especially the ends of hoses....hose clamps tend to dig in and cut through over time and vibrations.

3K for 2 skis isn't that bad, did the trailer come with that too?....overall, not a terrible price for 2 running skis.

Welcome to the ski club (of happiness and misery.....at any given time....:oops:). Use the forum often....lots of people really know these beasts inside and out...get your hands on the Shop Manual too....free download, just search around for it.

Another simple thing::::eek:ften overlooked or ignored.....Those little black boxes in the bottom the skis are bailers, as these skis always take on some water during "active" use.....just pull those bailers out from under their SS clips and clean them out (when I got my '96 and eventually checked them), they were plugged up with all sorts of smutz/debris.....keep them clean and flowing so they can suck the water out of the hull when the skis are being used....just a little thing....you can clean the tubes too while you're at it.
 
Last edited:
First those skis look really clean and the 720 engines they have are some of the most reliable ones seadoo has made so you did good.

1. Yes, you need to replace the gray fuel lines, fuel filter o-ring and fuel selector as well as rebuild the carbs sith only Genuine Mikuni parts before you ever try to ride them.
2. It looks like it is using the correct seadoo oil API-TC rated so I would replace the inline oil filters and the small 3/32" oil lines from the oil pump to the intake manifold.
3. Change the pump oil and inspect the wear rings and impellers.
4. Fix the fiberglass damage with some MarineTex and call it good.
5. Yes, you need to replace the air inlet tube as it seals the seat and directs air and water into the bottom of the hull.
6. Yes, that is leaking 2-stroke oil. The most common places to leak are the rubber grommets on the oil tank that need to be replaced and the hoses that go into the side of the engine block.
Make sure you don't mix oil brands.
Contact Nick or Jess at Westside Powersports Seadoo as theye can supply you with everything you need. @Minnetonka4me
 
Definitely go for the full carb rebuild! Those grey fuel lines aren’t compatible with the ethanol in today’s fuels, and break down to release a green gooey sludge that finds its way into all the little orifices in the carbs. Make sure you get the lines changed, and the fuel selector replaced, and then clean and rebuild the carbs using the carb rebuild sticky on the forum. The worst thing you can do to these motors is run them lean, and trying to ride them with that goo in the fuel system is a sure fire way to do that!
 
Well, maybe I didn't do too bad on the price! That is a relief. Yes, the price was for the 2 skis and the trailer. The trailer is a Yacht Club and in really good condition. These were all kept covered in a barn when not in use. Will definitely do the fuel and oil lines, filter and carb rebuild as suggested. Is normal procedure to pull the tanks and clean them out when doing a complete fuel/oil system overhaul? Are their any fuel hoses inside the tanks or just external fittings?
Here are a couple more pics. That last pic shows a spot where I guess the gel coat has been damaged. I noticed a spot here and there that look similar on the bottom of the hull as well. Will the Marine Tex work on those areas? Looks like it is an epoxy putty, so I would assume you clean/prep the area, kneed and apply the Marine Tex and sand it smooth?

IMG_20200416_091725530_HDR.jpgIMG_20200416_091510387.jpgIMG_20200416_091804230_HDR.jpg
 
Well, maybe I didn't do too bad on the price! That is a relief. Yes, the price was for the 2 skis and the trailer. The trailer is a Yacht Club and in really good condition. These were all kept covered in a barn when not in use. Will definitely do the fuel and oil lines, filter and carb rebuild as suggested. Is normal procedure to pull the tanks and clean them out when doing a complete fuel/oil system overhaul? Are their any fuel hoses inside the tanks or just external fittings?
Here are a couple more pics. That last pic shows a spot where I guess the gel coat has been damaged. I noticed a spot here and there that look similar on the bottom of the hull as well. Will the Marine Tex work on those areas? Looks like it is an epoxy putty, so I would assume you clean/prep the area, kneed and apply the Marine Tex and sand it smooth?

View attachment 47333View attachment 47334View attachment 47335
For their age...those skis are looking good. Why can't I ever find a sweet deal like that :mad: with a double trailer to boot....lucky dog! Give the skis a little love and they will return the favor......BTW....it all looks intimidating and complex....but do your research here and with the shop manual, poke around in here, trace things....it all starts to make sense after a while......the only DUMB question is the one you don't ask....if you don't know something...ASK, we've all been in your shoes. Questions are FREE, mistakes can be costly.
 
You can siphon the fuel tanks pretty much dry. You have to pull the engine to get the tank out of that model so it isn't worth it.
Yes Marinetex is white so no painting and it will look fine.

I would also look at getting some Hydroturf mats for them.
 
Another simple thing::::eek:ften overlooked or ignored.....Those little black boxes in the bottom the skis are bailers, as these skis always take on some water during "active" use.....just pull those bailers out from under their SS clips and clean them out (when I got my '96 and eventually checked them), they were plugged up with all sorts of smutz/debris.....keep them clean and flowing so they can suck the water out of the hull when the skis are being used....just a little thing....you can clean the tubes too while you're at it.

I think I'm following you here. The boxes with the red arrows pointing at them in this picture?

black boxes.jpg
 
The best thing you can do before you start working on them is the spray the insides down with Castrol SuperClean or Purple power and let it soak for a few minutes. Then make sure the drain plugs are out of the back of the hulls and hose it down really good with the front of the trailer elevated.

It will get ot mess and oil out so you aren't working it the oil slime.
 
The best thing you can do before you start working on them is the spray the insides down with Castrol SuperClean or Purple power and let it soak for a few minutes. Then make sure the drain plugs are out of the back of the hulls and hose it down really good with the front of the trailer elevated.

It will get ot mess and oil out so you aren't working it the oil slime.
I will definitely do that! Any areas I need to make sure water doesn't get into when cleaning out the inside?
 
I will definitely do that! Any areas I need to make sure water doesn't get into when cleaning out the inside?

Not really, with the stock airbox there is really noting to worry about. The airbox should have a rubber plug on the top but if it is missing put a piece of tape over it to keep water out. Also don't use high pressure on electrical parts either.
 
Yes, not far at all. I've learned a lot from the members on this forum. Great resource.
Yes, this forum will be very helpful! I've downloaded and glanced through all the parts, service books and the owners manual. They seem fairly simple, but definitely more complicated than air cooled 2 strokes. That rotary valve setup is pretty neat. I hadn't seen a rotating plate/valve like that before. The carbs look pretty simple and straightforward to clean and rebuild. I just have to start gathering up parts now!
 
Just remember, ONLY GENUINE MIKUNI parts.
I ordered the genuine parts that have Mikuni on the packages!
Any thoughts on fuel hose? I picked up regular 1/4" cheap stuff for carburetor engines but now I'm thinking maybe I should get Marine rated stuff. I saw one hose in there that was Shields 368 USCG rated that I guess someone used in one of the sea doos at some point. I can take the other stuff back if need be because it was prepackaged, not by the foot bulk roll stuff.
 
I ordered the genuine parts that have Mikuni on the packages!
Any thoughts on fuel hose? I picked up regular 1/4" cheap stuff for carburetor engines but now I'm thinking maybe I should get Marine rated stuff. I saw one hose in there that was Shields 368 USCG rated that I guess someone used in one of the sea doos at some point. I can take the other stuff back if need be because it was prepackaged, not by the foot bulk roll stuff.
I don't believe we've ever called out any specific hose type....bulk 1/4" black auto hose seems to be the norm.....readily available and cheap enough. Personally I like the circular pressure rings (put on with pliers) as opposed to worm drive clamps...but to each their own.
 
I found the 13.3 oetiker clamps that fit these size hoses perfectly at Lowe's. They are made for 3/8" PEX plumbing applications, but they are the Oetiker 13.3 clamps, it is listed on the clamps!
 
I found the 13.3 oetiker clamps that fit these size hoses perfectly at Lowe's. They are made for 3/8" PEX plumbing applications, but they are the Oetiker 13.3 clamps, it is listed on the clamps!
The oetiker clamps are great but not re-useable...once they are squashed close they have to cut off and replaced....and the squeeze tool is $65.00 @ Home Depot (unless you already have one), and sometimes you don't necessarily have the room to squeeze the oetiker clamps right where you want them. The 1/4" hose on the fittings is fairly tight and the pressure clamps have never let go, so I prefer them and it's a breeze to take them off/on for any servicing needs....but whatever works for you, go for it.
 
Status
Not open for further replies.
Back
Top