Super Jet Running out of ideas... Superjet issue

///M3

///M3

Location
DC
Edit: Ski is now fixed and rips. ATP Epic CDI was bad. OEM cdi swapped in and issue is gone.

Ski ran perfect all last summer until the last ride. Ski started bogging down and sounded like it was running on one cylinder. At full throttle it is very limited and only goes about 30mph. It is NOT bouncing off the rev limiter. When cruising around 15-20 mph steady throttle it will sporadically choke and then catch itself back up. Out of water on the stand it does not run properly either. When revving and holding down full throttle out of water it won't rev up to high rpm's.

videos:
video 1
video 2
video 3

701 62t
170-170 compression (ATP head)
ATP Epic ignition
B-Pipe
135/70 jets
1.5 n/s
1.5 turns highs/1 turn lows
Stock F/A w/ 1 screen each

things i have tried/fixed:

- tested carb popoff, 40psi both carbs
- bypassed fuel filter & selector
- brand new OEM s/s
- two different sets of carbs
- new fuel line,
- tank vent is good and working
- OCD oem rebuilt coil
- swapped and tested w/ OEM cdi
- checked reeds and look okay
- tested stator

stator results:
charge coil - 527 ohms / 68 volts while cranking
pulse coil - 14 ohms / 3.4 volts while cranking
 
Last edited:
JetManiac

JetManiac

Stoked
Site Supporter
Vendor Account
Location
orlando
My first thought was the epic, many have been down that rabbit hole before, but you said you swapped to oem cdi. Is oem cdi still in it? Or the epic?

Next would be to try to different stator on electrical side or new charge coil on yours. Also consider a leak down test on motor.
 
///M3

///M3

Location
DC
JetManiac said:
My first thought was the epic, many have been down that rabbit hole before, but you said you swapped to oem cdi. Is oem cdi still in it? Or the epic?

Next would be to try to different stator on electrical side or new charge coil on yours. Also consider a leak down test on motor.
Click to expand...

I reconnected the epic since the oem cdi didn't fix the issue. I forgot to mention when running the ski out of water on the trailer yesterday I was getting a bunch of exhaust smoke in the engine bay. Could not pinpoint where but it appears from front by waterbox. I already had the waterbox out and found no holes and didn't hear any rattling inside. Hoses are also good and everything was very tight. Would a bad waterbox cause the ski to run like this even while out of the water?
 
JetManiac

JetManiac

Stoked
Site Supporter
Vendor Account
Location
orlando
///M3 said:
I reconnected the epic since the oem cdi didn't fix the issue. I forgot to mention when running the ski out of water on the trailer yesterday I was getting a bunch of exhaust smoke in the engine bay. Could not pinpoint where but it appears from front by waterbox. I already had the waterbox out and found no holes and didn't hear any rattling inside. Hoses are also good and everything was very tight. Would a bad waterbox cause the ski to run like this even while out of the water?
Click to expand...
If the smoke is coming from inside, then you have an exhaust leak and need to find it. An exhaust leak or intermitent exh leak will cause all kinds of running issues. If on the water and you have skills, crack the hood and see if that makes it run better.
 
Citizen

Citizen

Location
Coeur D' Alene, ID
JetManiac said:
If the smoke is coming from inside, then you have an exhaust leak and need to find it. An exhaust leak or intermitent exh leak will cause all kinds of running issues. If on the water and you have skills, crack the hood and see if that makes it run better.
Click to expand...
Def sounds like exhaust leak, all the symptoms.
 
///M3

///M3

Location
DC
I found this old post and this is exactly what my ski is doing. Unfortunately they said it was the primer causing the issues but I do not have a primer or choke.

Super Jet - Can't seem to figure out what is wrong with this superjet (WITH VIDEO)

This is my buddys ski, not Mine. The ski used to run like a champ. Babyscream engine. 2nd time bored out since the original build. It ran amazing up until the first 10 min we were in Daytona. For the previous 5 days before, we rode the Gulf and the ski ran top notch. Not even a hiccup. We drove...
www.x-h2o.com
 
Citizen

Citizen

Location
Coeur D' Alene, ID
///M3 said:
It runs identical out of the water without the hood on, I figured exhaust leak would only be an issue with the hood on.
Click to expand...
Yep if it runs the same with hood off it's not exhaust, easy to test for sheared flywheel. Take a sharpy and draw a line on flywheel to case, then crank it. If the lines dont match up your ring gear may be slipping. Had this happen a few times.
 
Big Kahuna

Big Kahuna

Administrator
Location
Tuscaloosa, AL
Bypass the primer if your have one on there. I had issues years ago, had Tricky helping me, he finally noticed it. Air getting sucked into the fuel lines from the Primer "T".
 
///M3

///M3

Location
DC
Big Kahuna said:
Bypass the primer if your have one on there. I had issues years ago, had Tricky helping me, he finally noticed it. Air getting sucked into the fuel lines from the Primer "T".
Click to expand...

Sorry, just updated original post, i dont have a primer and i also tried bypassing petcock and fuel filter directly from tank to carb. same result
 
///M3

///M3

Location
DC
Citizen said:
Yep if it runs the same with hood off it's not exhaust, easy to test for sheared flywheel. Take a sharpy and draw a line on flywheel to case, then crank it. If the lines dont match up your ring gear may be slipping. Had this happen a few times.
Click to expand...
Can you explain this test some? I’m confused how this works. If you crank the motor, doesn’t the flywheel spin, thus it wouldn’t line up with where you made the mark on the case? Sorry if this is a dumb question
 
Citizen

Citizen

Location
Coeur D' Alene, ID
///M3 said:
Can you explain this test some? I’m confused how this works. If you crank the motor, doesn’t the flywheel spin, thus it wouldn’t line up with where you made the mark on the case? Sorry if this is a dumb question
Click to expand...
I didnt type that out well sorry. So not really looking for a sheared key, cause all that does is index the flywheel. It doesnt hold it in place. What you are testing for is the ring gear spinning on the flywheel. So draw a line on flywheel and onto ring gear. Then put cover back on and bump the starter. If the lines no longer match up your ring gear is moving on the flywheel, causes all sorts of issues.
 
You must log in or register to reply here.
Top Bottom