This is a 62t / 61x 781 big bore JM motor, with dual 38s, MSD Enhancer, MSD coil, and lightened flywheel, running 188 psi. Ok, long story short. Rode Daytona free ride, and at the end of the ride, noticed a little break up at top end. Got back to shop and flushed out . This Saturday, went to the river to ride, and within 5 minutes, was back on the trailer confused. Took off from the ramp, ski was breaking up and got worse. Then all of a sudden, the ski shut off and would not refire. Took the ski back to the shop and ran a compression test, 188 and 188, so no issue there, even took the head off. Did notice a little fuel leak at the slave carb on the inlet side. Rebuilt carbs, and re installed. Lake test came up with the same result, 5 minutes of breaking up, then shut off with no restart. Did get 1 backfire out of it after letting off the start button. So I have compression, and fuel, so I am starting to lean towards an ignition issue. Any of you engine gurus have an idea on where to start with the ignition issues? The flywheel was off Saturday, and stator looked ok, but looks can't always see the issue. I did do an old fashioned spark test, which is showing a weak intermediate to weak spark at best. Both MSD coil and enhancer are a year old. On a side note, the ski fires up and revs on the trailer, but in the water it breaks up, and after a little heat, shuts off. Ski will fire up when it sits for a while. Any advise or preveious experience with a GREMLIN like this little bastard would be greatly appreciated.
A nasty little gremlin
- Thread starter Prickster
- Start date
- Location
- Great Pacific Northwest
Not sure if you just removed the carbs off the intake OR removed the whole intake but I would check reeds. I had a reed cage come unbolted and my motor ran exactly like you are describing. Reinstalled with loctite and all was fixed. Reason I mention this is that you said it had fuel leaking (not sure if it was back up through the air filter or not. Mine had a lot of fuel sputtering back up the air filter when the issue happened). could be ignition but wanted to chime in with my similar experience with a motor acting this way. Hope you can figure out the issue.
Yes sir, removed the carbs from the manifold, then dropped my bore scope down to make sure reeds and cages were fine, which they were. The fuel leak was on the slave carb (carb without the fuel pump) on the inlet side of the carb on the plate, that turns into the return line to the tank.
cookn
Kamikaze
- Location
- where you live
The msd coils have been known to be an issue, try an oem coil to eliminate that
Quinc
Buy a Superjet
- Location
- California
Do you have spart after it happens? Failing electronics get worse with heat. Check that your ground wire is still connected to the block etc.
No doubt, seems the MSD coils have been getting worse and worse over the years. I have a complete back up set of electronics, so I will swap the coil first I guess.
Quinc, I cant answer that honestly. I was so bent when this happened, I went totally backwards on checking things the right way. I would say, and I am pretty confident, that the spark is non apparent after the shut downs. But on a side note, I took a shot from the electrical system when I grabbed both plug wires to move them while I was still on the start button. Felt like my girlfriend punched me in the arm, which is pretty weak. Didnt even make me jump, which I am pretty sure it should have. The spark seems to be in and out, with varying intensity.
- Location
- central florida
Yes, do eliminate the MSD coil- even if that is not the problem. Most likely the charge coil of the stator got "tired". Check it's resistance with a meter. If brown wire to ground is about 500 on a 62T stator, it won't work with a MSD enhancer, though it may still work with oem cdi
Great, would you happen to know what the resistance is if it a 61x instead of a 62t? MSD coil is going in the garbage.
Quinc
Buy a Superjet
- Location
- California
Start with checking your grounds, then testing your stator, oem coils, then cdi.
That sounds like the new game plan. Thank you Quinc for the help and info on this problem. I am getting rid of the MSD coil for sure, and have a new 61x stator ready to go. I hope it's not my MSD enhancer since it is less than a year old, but I have gotten 1 before that had a bad rev limiter adjuster???
- Location
- central florida
I checked 3 61X stators found loitering on one of my shelve
s, one was 342 ohm, the other 2 were 350. Here's a pic from a '95 SJ shop manual:Damn, you are the man. Thank you for the info, and I am running into the shop right now to take a swing at it. Waiting on JM to get back so I can grab a new coil from him tomorrow.
Now you see why I was asking when you were getting back, and I know you have a Yami/Saki coil in blue for me, LOL.
long beach local
long beach local
- Location
- Az
I had similar issue trying to tune a rebuilt 760 yesterday it just would not rev out on top end chased my tail with jetting ,screw adjustments etc. It felt like it was hitting the rev limiter, cutting out and carb adjustments were not helping. It has a rebuilt ocd coil, a supposedly tested stator (a few years back) , and a new 1 year old MSD enhancer. I swapped out the entire E-box with a stock 62T CDI with a JM yamasaki coil and it runs goods now.!! I blame the new MSD enhancer but its my second one that has gone bad on this motor with the same Stator. I am now wondering if this stator charge coil is MY Gremlin? hmmm I have another clean stator in the drawer think i will swap it out too. Thanks for the tips guys with any luck that enhancer is still good.
Doubt the MSD enhancer was bad. Usually they work or they don’t.
long beach local
long beach local
- Location
- Az
long beach local
long beach local
- Location
- Az
Leaking stupid salt water