Help with 98 SJ rebuild - Seeking Advice

[MadFish]

Hello everyone! I'm new to the forum and would like the advice of those of you who are smarter and more experienced than I.

Back in my twenties I used to race my 650sx in the limited class, so I have some working knowledge of standups, but I have no experience with a SJ, other than riding my buddies SN a few times back in the day.

I just took possession of a 98 SJ from my cousin who left it outside behind the barn for a couple of years (he had the cover on it). When I took the cover off of it and opened up the hood, the entire compartment was filled with water. I'm guessing that it had been there for a while... maybe a year + and over the winter.

My son and I just removed the engine this week and tore it down. The flywheel cover was cracked (from ice I'm assuming. We took the head off and were surprised that there was no rust in the cylinders. The motor would turn freely by hand with the spark plugs removed.

When we took the carb and intake off we could see that the crank was covered by standing water.

We want to rebuild this ski this winter with the intentions of making it into a reliable wave riding machine for lake Michigan, and we'd like to do it without breaking the bank.

My planned mods for this winter will be:

1. reinforce engine compartment
2. intake grate
3. impellar
4. cut pole down
5. footholds
6. Hydro Turf
7. Pipe
8. reeds (the factory ones are full of rust)

Any suggestions on choices that would optimize for wave riding would be appreciated.

Can someone explain the benefits of d-cutting the ride plate (I searched the forums and couldn't find an answer)

As far as the engine goes:

The crank came out easily and besides some mild rust on the bearings, I see no other issues. I don't believe that the cases cracked from ice... Is there anyway to have these pressure checked or tested?

Can I have the crank rebuilt by someone or is there a good source for quality rebuilt cranks?

Stator has a lot of rust on it, do these go bad from sitting in water or is there a chance that they are still good?

For the carbs... Obviously water entered the engine through the carbs and the standing water was pretty much at the level of the carbs when I rescued it. So I'm wondering if there is a resource out there that can test/rebuild them for me if they are still good?

The Ebox... this is my biggest concern! It was under water, probably for a long time. I don't even know where to start with this... any advice would be appreciated.

I'll post some pics tomorrow of the engine and ski so you can get a better feel for what we are dealing with.

On the up side, the ski was free as long as I let him ride it a few times in the summer!

Thanks,

Pete

 

[ksarge91]

Sweet score!

I'd give John at JSS a shout for the ebox and stator. He can completely refurbish them for you like new/better than new for a pretty reasonable price and you can save yourself alot of headaches. If they've been sitting in water I wouldn't bother wasting you're time trying to chase down little issues and just bite the bullet and get it done. You'll save money in the long (possibly short) run. Ask me how I know . Will run you $320 for the ebox and $268 for the stator.

D-cutting the plate will make bring the nose up a bit and make the ski a little more nimble. I'd leave it as is for now and make that decision once you ride it, especially if it's a stock length plate.

@JetManiac on this site can set you up with just about any and all parts you may need at a good price.

 

[Vumad]

Hello everyone! I'm new to the forum and would like the advice of those of you who are smarter and more experienced than I.

Back in my twenties I used to race my 650sx in the limited class, so I have some working knowledge of standups, but I have no experience with a SJ, other than riding my buddies SN a few times back in the day.

I just took possession of a 98 SJ from my cousin who left it outside behind the barn for a couple of years (he had the cover on it). When I took the cover off of it and opened up the hood, the entire compartment was filled with water. I'm guessing that it had been there for a while... maybe a year + and over the winter.

My son and I just removed the engine this week and tore it down. The flywheel cover was cracked (from ice I'm assuming. We took the head off and were surprised that there was no rust in the cylinders. The motor would turn freely by hand with the spark plugs removed.

When we took the carb and intake off we could see that the crank was covered by standing water.

We want to rebuild this ski this winter with the intentions of making it into a reliable wave riding machine for lake Michigan, and we'd like to do it without breaking the bank.

My planned mods for this winter will be:

1. reinforce engine compartment
2. intake grate
3. impellar
4. cut pole down
5. footholds
6. Hydro Turf
7. Pipe
8. reeds (the factory ones are full of rust)

Any suggestions on choices that would optimize for wave riding would be appreciated.

Can someone explain the benefits of d-cutting the ride plate (I searched the forums and couldn't find an answer)

As far as the engine goes:

The crank came out easily and besides some mild rust on the bearings, I see no other issues. I don't believe that the cases cracked from ice... Is there anyway to have these pressure checked or tested?

Can I have the crank rebuilt by someone or is there a good source for quality rebuilt cranks?

Stator has a lot of rust on it, do these go bad from sitting in water or is there a chance that they are still good?

For the carbs... Obviously water entered the engine through the carbs and the standing water was pretty much at the level of the carbs when I rescued it. So I'm wondering if there is a resource out there that can test/rebuild them for me if they are still good?

The Ebox... this is my biggest concern! It was under water, probably for a long time. I don't even know where to start with this... any advice would be appreciated.

I'll post some pics tomorrow of the engine and ski so you can get a better feel for what we are dealing with.

On the up side, the ski was free as long as I let him ride it a few times in the summer!

Thanks,

Pete

I've had good service on new and used parts from @JetManiac and @Rdrttoy

I don't think it is necessary to reinforce the engine compartment unless you plan to try to invert. Regular surf riding of slashes, short re-entries and the like probably wont give you any problems. Reinforcing is more likely to add weight, time and money. I would wait until you are confident enough in your riding skills to want to do something where you might land sideways. I feel similar about reinforcing the pole. A limiting strap is not a bad idea, especially since you can easily hyper extend the pole on subs or stabs. Lots of people will never do anything requiring reinforcing.

Surf riding you need a bilge pump. The best switch I have found is the 3-position rotery switch from JetManiac. DJ_korn , or was it Scorn, anyway, one of them swears by the float switch. I like a rule 500, but people run dual 500s or single 1100, but a single 500 has been sufficient for me. A setup of a bilge, bracket, switch and outlet is about $100. Scuppers and one-ways are no-good for surf, as they let the air vent out and your ski can sink faster if it gets pushed away from you.

A engine compartment drain tube would be okay, and would prevent the ski from ever filling up under the cover again. Also trim is nice, but both of these would depend on how much you are opening the tray. Check for waterlogged foam when you do your foot holds, if it's not waterlogged, I wouldn't mess with it. I would consider if you ever want a lowered hood, and if so, consider moving the extinguisher to a front foot hold before you turf to stay legal.

There is no great source for a rebuilt crank, but SBT is an option. I use a SBT crank now (4 years and 66 hours as of today, no issues) and that is what Jetmaniac offers for all of his motors I believe. They run about $200 plus shipping and other fees. A new OEM crank would set you back $600.

There are writeups on how to pressure test a motor. I don't believe you could do such a test on just your case. You will have to reassemble it before you can do a leak down test. Just google leak down test and you will find the necessary steps. JetLabs @DAG just came out with a very nice leak down kit, there are other options.

You can try to save money on your electronics by reassembling the ski to test, but I'd hate to spend a bunch of time cranking a fresh motor. Some people like JSS as Ksarge said. I have never used JSS. You can do research on their reviews and products. Google Jet Ski Solutions.

Don't send your carbs out. Just buy a pop-off tester and rebuild them. A pop-off tester will set you back about $50, but it's worth it. Only buy genuine mikuni carb parts. Rebuild kits for the 38sbn are about $50 and the needles / seats are about $25, so expect to pay about $150 to rebuild both carbs. The mikuni tuning manual is free online and there are videos about how to rebuild carbs. Its not a big deal. Just make sure they are cleaned, synced and pressure tested both ways (leak and pop-off). A product called Chem-Dip works very well for soaking corroded jets, or you can use carb cleaner. Use nylon wire, not metal wire, if you need to clean out a passage. You will have to tune if you do a pipe, but a stock motor and pipe is 130/70@52 (although I am running my stock blaster at 42psi). Keep your stock airbox for surf riding.

Don't D-cut your plate. Do it later if you need the nose to ride higher.

Don't buy stock reeds. A broken metal reed can damage a motor, but a composite one shouldn't. Dual stage fiber reeds are inexpensive (not the carbon).

Personally, even though I just gave a very long response to answer most of your questions...

I don't think you should do most of the mods you said. Just fix the engine, carbs and electronics, install a bilge. Get the ski running strong all stock and put it in the water. Get out, meet people, try different pole lengths, different ride plates and sponsons, different foot holds. Look for a fair deal on a pipe and buy a Jetmaniac demo head.

I missed a lot of time riding on projects, and when I finally stopped messing with projects, I had an injury that prevented a lot of riding. Get that thing running good, enjoy what is left of the season, bring it to Daytona and worry about the rest of your list when you get home from that event.

 

[MadFish]

Thanks for the reply guys! Those resources should get me started in the right direction. @Vumad, I don't like tearing things down multiple times so i figured that this was the best time to reinforce the hull. I don't plan on having in back in the water until spring since there is only a month or so left in the riding season here in Michigan. I broke 2 poles and multiple engine mounts in my 650sx jumping waves during storms so I feel it needs to be done, especially since my son has back flips on the agenda. As far as Daytona goes... it looks like a blast, but being a fresh water guy the shark issue is something I'd need to get over! :0

@ksarge91, I'll take your advice on the ride plate. I saw it mentioned in the mods thread and wasn't for sure what the benefit was. When I raced we always used extended ride plates so I was curious. I'll also be getting in touch with John as well... THanks!

 

[iangdesign]

If you don't want to break the bank on the ski, you can always track down a donor ski and yank the engine. Prices are gonna start dropping on skis now that fall is here and winter is coming.

 

[MadFish]

If you don't want to break the bank on the ski, you can always track down a donor ski and yank the engine.

I was looking into used engines and skiis, but I'd rather make sure that things are done right the first time.

Keep your stock airbox for surf riding.

Is this better for low end performance and does it relate to exhaust back pressure?... just curious.

 

[Roseand]

I was looking into used engines and skiis, but I'd rather make sure that things are done right the first time.



Is this better for low end performance and does it relate to exhaust back pressure?... just curious.

Helps keep water out of the motor.

Sent from my SM-G920V using Tapatalk

 

[Zero Client]

I second a doner ski. While two wrongs won't make a right, you'll probably find the second/doner ski gives a ton of rebuild bounty for not so much. Even if you drop to a 61x single carb - don't worry it'll be about the same. Score a $500 701 parts ski on a single trailer and you've got your money made very easily.

That being said, I had a friend run a crusty crank which he let sit in wd40 for a few days before build- and it lasted 2 years. Options.

Sbt rebuilt crank for $200ish but are ehhhh
Wsm new cranks are $400ish

 

[ksarge91]

X2 on a donor ski. If it sat in water I'd bet the starter/bendix are on their last legs if not shot already as well.

That being said if it were me I'd just rebuild it since you're not out much to begin with and you'll know you have a solid platform once finished.

Jetmaniac sells rebuilt OEM cranks for $249 and your core will get you $35 back. $214 for a rebuilt OEM crank ain't bad.

http://www.x-h2o.com/index.php?thre...iseco-pistons-gaskets-crank-seals-etc.142081/

 

[DirtTOwater96]

Hows this build goin.