If you can solve this one you win the prize - SOLVED

J..

J..

Location
Australia
Hi guys

I’ve lurked on this forum for ages now and have read virtually all the threads with running problems similar to mine. They gave me a lot of ideas to check and replace, but to date I have a problem with my SJ and I’m completely out of ideas what it could now be. I’ve been banging my head for months with this, if anyone has any ideas what could be causing this running problem you are a legend and I will be forever grateful!

So the problem is it has a consistent miss. Most noticeable round the mid upper rev range but present everywhere. It’s rideable, but consistently after about 10 mins it bogs, seems to go to half power just enough to get back to the ramp. When I flush it on the hose it comes good again till we repeat in the water next ride.

It would be quicker to list what I haven’t done toward this, but this is a list of things I’ve replaced or checked:

- virtually all the elec system has been changed for new and everything has been checked and re checked. I’m 99.9% sure this is not electrical, plus the clip below shows what looks like a strong and consistent spark

- fresh top end 2 hours ago

- stock and aftermarket heads fitted with various sets of plugs using both big and small gaps

- cylinders decked

- exhaust system checked, waterbox checked

- carbies swapped with almost new tuned and recoed pair

- tank valve checked, fuel system holds pressure and fuel delivery seems fine

- reeds checked, seem mint

This clip is running on the trailer where the miss can be heard:


This clip is after I brought it home yesterday and was flushing out:


The second clip is with a constant throttle, the varying revs are caused by the problem at it’s worst where the power seems to virtually cut on and off.

The funny thing, and what could be a clue to all this is right after that second clip I turned the hose on to flush and it cleared up back to running with just the plain old miss. Could have been a coincidence. Confusing :confused:

Seriously, I’m totally out of ideas. Does anyone have some clues that could be causing this voodoo magic?
 
TheBuzzard

TheBuzzard

Location
the jetski grave yard
does it miss when you dont have any water going to it? i had an sxr miss like that and it was the head allowing water to get into a cylinder. if the exhaust manifold gasket is leaking, it will miss also. that just happened to a local when a b-pipe was installed
 
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J..

J..

Location
Australia
Wow, heaps of replies, awesome! Australian forums pretty quiet in comparison...

Yes, always ride salt water but it's had a new ign coil, exciter coil, pulse coil, CDI, high tension leads and plug boots. Earth and continuity everywhere is fine. I'm pretty happy I've eliminated electrical seeing I can visually see a healthy continuous spark with the tester in clip 2. Never say never however.

It has the miss both in and out of the water but much more noticeable in the water and gets a little better if it dries out for a few days. Always present however.

Swapped between stock and aftermarket heads which you can see between the clips. New O rings, I'm sure it's not leaking.

I've checked the bottom end when the top was off getting bored and pistons last week. All checked out visually, crank was smooth as. Previously I had done a leak down test and it was all air tight.
 
MADMAT

MADMAT

Location
Ohio
KNOWN good CDI swap? Your description SCREAMS bad CDI to me.....but the video doesn't sound like the bad CDI's I have witnessed.
 
Quinc

Quinc

Buy a Superjet
Location
California
You might also disconnect your stop switch just for fun. I had an issue with both my msd enhancer and stop switch being intermittent.
 
WILKEY

WILKEY

SO FAR CHANGE SUCKS!!!!!!
Location
Va Beach."from the WOODZ not the damn hoodZ"
Take a bottle of saltwater with a fine tip sprayer and cut the lights out. Start the ski and spray your coil and see if you have fireworks poping off. When you say you get some ride time out of it then it bogs just makes me think coil. Also you say when it dries up makes me think that to. I could be wrong tho....... But it's worth a shot.
 
MADMAT

MADMAT

Location
Ohio
Oh yea forgot about that stinking tank valve! That has caused my ski to act really really weird while others here on the X have said they can tell zero diff with or without it......

I can tell the second mine pops off of the tank.
 
SuperJETT

SuperJETT

So long and thanks for all the fish
Location
none
To me it has to be ignition related, whether it's a faulty component or a running condition affecting something. When it's doing the missing, kill the engine and check the plugs immediately for water. You could have a small water jacket leak into a transfer port or other condition that affects the plugs which wouldn't show on the spark tester.
 
Dmac80sc

Dmac80sc

Site Supporter
Location
Here
Someone yell at me if I am wrong. IS there any chance it has to do with the over heat sensor? Would it cause problems if it is not taped up in the ebox and keeps grounding out from the vibration when he is riding?
 
Freakrider

Freakrider

X247
Location
Tampa Bay area
WILKEY said:
Take a bottle of saltwater with a fine tip sprayer and cut the lights out. Start the ski and spray your coil and see if you have fireworks poping off. When you say you get some ride time out of it then it bogs just makes me think coil. Also you say when it dries up makes me think that to. I could be wrong tho....... But it's worth a shot.
Click to expand...
Have done this idea also...good tip.
Is this a new oem coil ?
Have seen a WSM coil light up like a Christmas tree during this test.
 
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