Super Jet Progressively worse no power issue, it's warming up Downunder, SJ needs to get wet !

[Spoony]

I've got an issue that has me stumped. 701 SJ, dual 46 black jacks, Riva Head, R&D wet pipe.

The ski has always been a bit of a pig down low (I just figured its the prop/pipe/carb setup), but once it comes on it hit nice and hard and went well. W

hat started happening, is the ski was taking longer and longer to come 'on pipe' but also somewhat limper and limper power wise once it did. It's now at the point where it wont come on power ('pipe') at all. It starts fine, revs fine out of the water just makes no power. Comp is still ok. The carbs are completely seperate in operation (individual pumps, feeds and pulse lines) so pulling a plug on each cylinder both run exactly the same with the same amount (lack) of power. Neither misses or, stutters etc.

I'm usually pretty good at nutting out issues but the progressiveness of this issue (ie getting worse) has me stumped. I've checked fuel lines, pulse lines, filters etc. But as everything is 100% individual for each carb I don't think it's that.

I'm thinking it's an electrical/electroinc issue. I don't think it's a simple spark issue, spark looks strong, new plugs don't help, and I've had breaking down spark issues before, they didn't symptom like this. Leads are MSD with MSD caps and Clips all fairly new.
I thought it might be timing related but I've got the flywheel off and mechanically the timing is spot on.

Could it be an issue in the Ebox? The over heat stuff has been pulled off eons ago, but maybe it's tripping, or something else? Probably the hardest stuff to dignose is possible ebox issues.


Any ideas would be heaps appreciated, I sort of stuck it away over winter and forgot about it while I had the drity to ride........... now I wanna get it in the water lol.

Cheers.

 

[XJCrawler]

I've got an issue that has me stumped. 701 SJ, dual 46 black jacks, Riva Head, R&D wet pipe.

The ski has always been a bit of a pig down low (I just figured its the prop/pipe/carb setup), but once it comes on it hit nice and hard and went well. W

hat started happening, is the ski was taking longer and longer to come 'on pipe' but also somewhat limper and limper power wise once it did. It's now at the point where it wont come on power ('pipe') at all. It starts fine, revs fine out of the water just makes no power. Comp is still ok. The carbs are completely seperate in operation (individual pumps, feeds and pulse lines) so pulling a plug on each cylinder both run exactly the same with the same amount (lack) of power. Neither misses or, stutters etc.

I'm usually pretty good at nutting out issues but the progressiveness of this issue (ie getting worse) has me stumped. I've checked fuel lines, pulse lines, filters etc. But as everything is 100% individual for each carb I don't think it's that.

I'm thinking it's an electrical/electroinc issue. I don't think it's a simple spark issue, spark looks strong, new plugs don't help, and I've had breaking down spark issues before, they didn't symptom like this. Leads are MSD with MSD caps and Clips all fairly new.
I thought it might be timing related but I've got the flywheel off and mechanically the timing is spot on.

Could it be an issue in the Ebox? The over heat stuff has been pulled off eons ago, but maybe it's tripping, or something else? Probably the hardest stuff to dignose is possible ebox issues.


Any ideas would be heaps appreciated, I sort of stuck it away over winter and forgot about it while I had the drity to ride........... now I wanna get it in the water lol.

Cheers.

Hows your compression?

 

[Spoony]

Comp hasn't changed from when it was running OK.

 

[Yellofury]

I had a similar problem and it turned out to be the flywheel key was breaking and allowing the flywheel to move. replaced the key and everything was fine. might check that out.

 

[Spoony]

Another good idea, which I also thought of, as it 'feel's, like a timing issue or something. Flywheel is off and the key etc looks ok.

 

[SXIPro]

Do you have a pair of stock 38s you could throw on just for giggles?

 

[WFO Speedracer]

Check your reeds, first pull the flame arresters and run the ski on the trailer, see if you have any blowback out the carbs, if you do the reeds are toast. I had a 1200 npv drive me absolutely nuts trying to figure it out, reeds looked fine, swapped the entire electrical system out, crankshaft seals, intake gaskets,rebuilt the carbs ets, I found several things wrong along the way, bad check valves in the carbs, broken intake gasket , bad spark plug wires. Ski wouldn't rev over 3500 RPM in the water, never even thought of getting in the powerband.

Nothing fixed the problem though, I happened to get another ski in here that needed an engine and this thing had to go. I swapped carbs and it did the same thing, so then I swapped the whole intake with reeds out and it was money, green money in large bills !

 

[Midlake Crisis]

I had a similar problem that turned out to be multiple exhaust leaks.

 

[Spoony]

SXIPro, sadly don't have stock carbs, and all mates have bloody Kwakas! haha. I'm good at stripping em down now so can have another look.

WFO, yeah I was thinking it could be reads. The carbontechs in there are not that old but it's always a possiblity. Given it's 1/2 in bits anyways I'll just pull the carbs and intake and have a look.

Midlake, yep, one of the first thought was that as I've had it before too where it just chokes on it's on exhaust. However a quick brrrrt with the lid off and no leaks can be detected (and it still has as much HP as a SuperCanoe).

 

[Maxumflux]

Reeds

 

[Spoony]

Ok, reeds are like new. Not a mark, chip or crack in one of them. Wish it was something so simple

 

[WFO Speedracer]

Mine looked great also, no chips, cracks, no standoff from the cages, they were not sealing at all, by looking at them you could not tell anything was wrong.

 

[Spoony]

Really? A few have a small amount of standoff/gap at rest. But nothing major. Will take a pic when I get home tonight and upload.

Why where yours not sealing? Lack of tension (ie they didn't snap shut like new) etc? Carbon Tech also?

I'd love it to be something as simple as the reeds but even though there is the odd minor standoff gap, I'm struggling to see how they could totall kill all power output. The ski will drag you through the water but is far to limp to get up on the plane & come on pipe.
It's so much better whens something simply & obviously just 'breaks' haha

 

[227]

Since we're all guessing here how sure are you of the stator? A while a go my ski had a slow developing power loss problem also. It would actually run great on the trailer but after I would launch and things got warmed up a little the ski would lose power and wouldn't run much more than an idle. Turned out to be a bad stator coil. When the stator was cold it would work correctly, however when it heated up is when it started acting up. Stators are tricky to test also. I have heard in order to test them accurately you need to put them in an oven and heat them up to around 200 degrees to get correct test readings. Just throwing it out there, hope you figure it out.

 

[WFO Speedracer]

Really? A few have a small amount of standoff/gap at rest. But nothing major. Will take a pic when I get home tonight and upload.

Why where yours not sealing? Lack of tension (ie they didn't snap shut like new) etc? Carbon Tech also?

I'd love it to be something as simple as the reeds but even though there is the odd minor standoff gap, I'm struggling to see how they could totall kill all power output. The ski will drag you through the water but is far to limp to get up on the plane & come on pipe.
It's so much better whens something simply & obviously just 'breaks' haha

I have no idea, stock reeds in perfect shape, no apparent flaws, damn thing drove me to drinking, well at least thats the excuse I am going with.

 

[Spoony]

227, a possiblity, flywheels off and ebox is appart so to pull the startor and 'cook it up' isn't a hard thing atm. 200deg, damn! sounds abit high though.

I'll have to try and find all the resistance specs for stators/coils etc to test all this.

WFO, haha I hear ya, working on it (read, scratching head) now means sinking many a can of JD, so it's not all bad!

 

[norcal ex]

baffle in the waterbox?

 

[Spoony]

Water box was cut open and the baffle tube re welded in not all that long ago, doubt it is that but will see how it flows water I guess.

I managed to do some electrical tests.

Coil lead resistance is in spec.

Ignition coil primary (feed) is hard to measure at 0.07 to .1 Ohm's but it's close (as good as my meter can do) so likely OK

The charge coil (stator for spark) measures at 440ohm, spec is 497 to 608 ohm, but from memory it tested at around this previously when the ski was going ok.

Pulser coil is in spec also.


I tried testing the CDI using the workshop manual (ie various colours to earth and to each other). Perhaps it's my cheapish meter but all but one reading measure way out of spec. The CDI does have some kind of mod from years back (ie back has been cut open and through the epoxy reseal I can see some kind of wire bridge put in, must be an old school mod).

However the out of spec on near all measurements indicate maybe it is CDI? I haven't found much info though with anyone else doing measurements on this, so it could just be a hard thing to measure. Manual does say 'the resistance values will vary from meter to meter'. But one would assume should be still within the fairly wide specs provided?

I don't really have access to a spare CDI to test. I figure replacing it with a MSD enhancer would be the go, but an expensive 'test' to find its not that. lol

 

[Penken]

Water box was cut open and the baffle tube re welded in not all that long ago, doubt it is that but will see how it flows water I guess.

I managed to do some electrical tests.

Coil lead resistance is in spec.

Ignition coil primary (feed) is hard to measure at 0.07 to .1 Ohm's but it's close (as good as my meter can do) so likely OK

The charge coil (stator for spark) measures at 440ohm, spec is 497 to 608 ohm, but from memory it tested at around this previously when the ski was going ok.

Pulser coil is in spec also.


I tried testing the CDI using the workshop manual (ie various colours to earth and to each other). Perhaps it's my cheapish meter but all but one reading measure way out of spec. The CDI does have some kind of mod from years back (ie back has been cut open and through the epoxy reseal I can see some kind of wire bridge put in, must be an old school mod).

However the out of spec on near all measurements indicate maybe it is CDI? I haven't found much info though with anyone else doing measurements on this, so it could just be a hard thing to measure. Manual does say 'the resistance values will vary from meter to meter'. But one would assume should be still within the fairly wide specs provided?

I don't really have access to a spare CDI to test. I figure replacing it with a MSD enhancer would be the go, but an expensive 'test' to find its not that. lol

but if not atleast you have an enhancer on your ski it´s not money tossed away it´s a good mod done by many others.

 

[feartheride]

Since we're all guessing here how sure are you of the stator? A while a go my ski had a slow developing power loss problem also. It would actually run great on the trailer but after I would launch and things got warmed up a little the ski would lose power and wouldn't run much more than an idle. Turned out to be a bad stator coil. When the stator was cold it would work correctly, however when it heated up is when it started acting up. Stators are tricky to test also. I have heard in order to test them accurately you need to put them in an oven and heat them up to around 200 degrees to get correct test readings. Just throwing it out there, hope you figure it out.

My friend had the exact same issue a couple years ago..

to bad for the lack of spare parts in your ride group..Around here people have buckets of spare cdi's,carbs stators reeds ect..or maybe I'm just a parts whore..actually come to think of it I am lol poles, total loss's and enhancers ect. ect.