Help identifying what's been done.

[eric_f]

Hi all,

I recently acquired a '91 SN SJ. I can tell it's had some work done but I don't know what. I'm trying to figure it all out and could use some help with it.

Things I know:
- Engine case is marked 6m6.
- Cylinders are marked, with what I believe to be 61x.
- Compression is around the 170psi mark.
- Exhaust is a Coffman's pipe - are these any good?
- Has a side exhaust port added.
- Running single cooling but has 5 pissers.
- The impeller looks to be stainless steel, so I think it's aftermarket. But I'm not sure how to tell. I can't find any markings on it.

The questions I have so far are:
- The cooling... what the hell has been done here? The lines coming into and out from the exhaust manifold look to be correct, but the 3 ports that have been added into the head confuse me.


At the front of the head, there is a little port that's been blocked off, next to it is the "clear" hose that tees into the black hose coming off what appears to be the stock port. Then both of those feed the two aluminum pissers. Beside the spark plugs is 2 more ports that have been tapped in and each one of those feeds the 2 black pissers under the hood. All 4 of them feed the tray to keep my feet warm
The side pisser has barely any water coming from it, so I'm a little worried about the volume of water available.
Is this "correct" and is there anything I should be doing differently?

- Can anybody identify the cylinders from this marking? Is this the right place, I can't find anything else.


Any help is appreciated, I'm sure I'll have more questions.

Cheers,
Eric

 

[kevbo]

Looks like a 650 case with a 701 cylinder. Somebody modified the head and got a little pisser happy. I would get a newer stock head and do away with all that nonsense. The pipe is very good. You have an old modified ski that has not been maintained. It needs to be disassembled and inspected/overhauled.

 

[mthomps]

Sounds to me like someone went crazy on the "hot hands mod" and went for a "hot toe mod" as well.

How well does it run?

Give more details about how it's routed so guys like kevbo can help us all learn something

 

[eric_f]

Looks like a 650 case with a 701 cylinder

That's what I'm thinking, I just don't know how to verify this 100%.

Somebody modified the head and got a little pisser happy

Agreed. However, the warm water on the feet is really nice. My local lake is really cold and the warm water is something I wish every ski had

Some more history, the ski was my uncle's, and the last time he rode it was around 2010. It sat parked until last year when my dad and brothers picked it up. They spent some time tinkering and got it running. It runs well and has lots of power. They ran it all last year and this year as-is until they ripped an old hull patch apart. They didn't know how to patch it properly so I took it. I got it all patched up and was running yesterday until I broke the engine to the midshaft coupler. So now the engine has to come out to fix that and while I'm at it I can do more investigation.

Give more details about how it's routed so guys like kevbo can help us all learn something

Here is my crappy drawing of how the lines are run
As you can see, the orange line hooks to the stock port as well as the front-most port and tees into the two pissers.
The green line runs from the front cylinder directly to one pisser, and the blue runs from the rear cylinder to the other pisser.

 

[kevbo]

I guess I never thought of riding a jetski in frosty water, some people apparently do. This hobby has many different kinds of people from various backgrounds. I suppose its most economical to run it till it blows, I would pull it apart and catch up all the maintenance.

 

[TheBuzzard]

If the intake manifold is cast 6m6, then its 650 cases. All cases 650, 701, 760 are cast 6m6 on the bottom but you cant see that with motor in. 61x cyl same as all superjet, blaster , wr3 gp, vxr pro. Whatever. Until the motor is in pieces, you wont know what else has been done as far as porting. If they are 650 cases, they had to be hogged out for the 701 sleeves to slip in. I see no reason to start changing anything. It's been that way for 20+ years. 650 reeds are 3 screw and 701 are 4 screw, if you pull the intake off

 

[eric_f]

Thanks for the information

Now that I have to remove the engine... breaking the coupling is not how I imagined ending the season, what is a must in regards to inspection/fixing. I'm thinking rebuilding the carb, checking the midshaft housing since I'm there anyway. General cleaning and reinforcement. I think there is a small exhaust leak around the waterbox, so fixing that up.

 

[mthomps]

In the north here a lot of guys re-route pissers to their handlebars in the fall and early winter. They bypasses your pisser(s) usually. Never heard of someone running pissers with hand and foot warmers but if it runs well maybe just leave it alone until you want to go bigger.

Some guys ride with ice on the great lakes. With the right body gear you can do it.

That said your coupler failure is either a 30 year old part failing or an engine that's not properly aligned. Check your bedplate bolts and see if they are still tight. If not that explains the coupler failure.

6m6 650's are the most conservative and reliable jet ski engine ever. It's all low end/mid and piss poor top end. (An engine builder told me that)

6m6/61x Frankensteins, 61x single carb 701's, 62t/61x, and strait 62t's from couches are all almost just as reliable stock.

I have a stock 6m6 minus electronics with a protec pipe and perfectly tuned carb on the bench that has crisper response than a bone stock 61x. No its not fast, it goes about 34 mph and the bored exit nozzle doesn't help.

Only went bigger after I stripped a driveshaft and said why not. New ported 61x motor is way stronger but its that "on the pipe" feel and not very linear. It's just different.

Sorry for the rant my point was just that if it runs well consider not changing it until you want to upgrade

 

[eric_f]

Thanks mthomps rant posts like these are typically full of useful information

I don't plan to change anything right away besides what's broken, I more want to understand what's been done so I can make informed decisions. The SuperJets are new to me, I've been riding 550 Kawis for a long time, but never really had to work on them. This is the first ski where I've got control of what happens.

I haven't checked the engine alignment yet, but I had planned on doing so before removing the engine to see if it's an alignment issue or just old parts and a hard hit on the water. Thankfully it stayed intact enough for me to slowly ride back to shore

Now for the real question. Is it worth changing to an aftermarket coupler or just replacing the broken piece and keep running stock?

 

[smoofers]

Thanks mthomps rant posts like these are typically full of useful information

I don't plan to change anything right away besides what's broken, I more want to understand what's been done so I can make informed decisions. The SuperJets are new to me, I've been riding 550 Kawis for a long time, but never really had to work on them. This is the first ski where I've got control of what happens.

I haven't checked the engine alignment yet, but I had planned on doing so before removing the engine to see if it's an alignment issue or just old parts and a hard hit on the water. Thankfully it stayed intact enough for me to slowly ride back to shore
View attachment 416422
Now for the real question. Is it worth changing to an aftermarket coupler or just replacing the broken piece and keep running stock?

It depends on how much you want to spend. The quickest way to get back on the water is to replace with a used OEM coupler. If you want to go with aftermarket couplers, you'll need a new (or used) '94+ midshaft too. The '90-'93 superjets have a smaller diameter thread on the midshaft than '94 to current. All of the aftermarket couplers fit the '94+ midshaft threads. Other than threads, the rest of the dimensions are the same. The midshaft bearing housing for the '90-'93 series is also different than the '94+.

 

[brapperdoodle]

Just to mention it, verify proper coupler alignment when you re-install the engine!

 

[eric_f]

Just to mention it, verify proper coupler alignment when you re-install the engine!

Thanks. I've read about it a bunch, but this helped show the process nicely

 

[mthomps]

Doesn't the 94+ midshaft have a different bolt pattern? I cant remember.

 

[Chad24384]

Yes, it has a larger bolt pattern.

 

[kevbo]

Im not too sure about threads being smaller. Ive used the same ADA couplers on three 1993s and newer Superjets. The 93s did have a smaller housing.

 

[smoofers]

The '90-'93 SJs used a 6R7-51323-01-00 shaft, which is no longer made. Everything '94+ uses a 6R7-51323-02-00 shaft.

 

[eric_f]

I've read through this thread Midshaft Talk and from what I understand, the '90-'93 have a smaller housing, smaller threads, and a thinner shaft. So aftermarket couplers aren't compatible. But what I haven't figured out is am I able to install a newer midshaft into the smaller housing, essentially upgrading to the larger shaft and ability to have aftermarket couplers, or am I limited to stock replacement only?

 

[smoofers]

I've read through this thread Midshaft Talk and from what I understand, the '90-'93 have a smaller housing, smaller threads, and a thinner shaft. So aftermarket couplers aren't compatible. But what I haven't figured out is am I able to install a newer midshaft into the smaller housing, essentially upgrading to the larger shaft and ability to have aftermarket couplers, or am I limited to stock replacement only?

Yep, all you need for aftermarket couplers is the larger shaft.

 

[eric_f]

So I pulled the engine today and found a few things that bring up new questions... isn't that always the way.

On the Midshaft talk page, it says "There is a hose with a zerk fitting on newer SN and all larger 701/760 housings". This tells me that the older, smaller midshafts don't have this fitting. Well, my midshaft does have this hose, so I'm confused if I have the newer, larger housing or if somebody added this. I also don't know if the shaft has been replaced with the newer size, I haven't been able to find the dimensions to measure against.



But, I found the reason the coupler broke is from a wobbly engine. I'm assuming at least one of the mounts is broken. I don't think that metal piece is supposed to be separate from the base of the mount? The two back ones are like this, the metal piece is off and the two fronts are almost there. If the mounts need to be replaced, does anybody have any suggestions of which would be best? Stick with OEM, or are there some after-market ones that perform better?

 

[orangefinger]

your uncle had cold feet ( orange lines ) your uncle had cold legs ( blue and green lines ) ...that all , are there any more lines going up to the bars/grips ?