Superjet won't rev in water

Ryan05

Ryan05

Location
Holland Michigan
I have a 1991 squarenose with a 701 in it.
Mods are:
B pipe
Head
Prop
Intake grate
Ride plate
X metal pole

I was out the other night for an hour jumping waves on Lake Michigan when my ski started to bog out, it would clear up for a bit, and then bog down again. After about 15 minutes I gave up and went in, on the way back, the ski would only hit low rpms and 1/4 throttle

I put it on the trailer and started it and it revs up fully, any ideas?
 
SJsforlife

SJsforlife

Location
Mobile,al
Check your e-box for water and test your stator. Check plug wires if they are old. Sounds like you have weak fire. Wouldn't hurt if you checked your fly wheel.
 
Pro-pulsion

Pro-pulsion

Location
Ontario, Canada
The first time this happened to me it was the coil. I tested the resistance of the secondary windings with the meter at the spark plug boots (one probe in each boot) to find it was way out of range. A new JetManiac coil and ran great after until the CDI died, a replacement CDI 2 years ago and no more issues there since.
 
hodges22

hodges22

Location
louisville ky
I'm sure These guys know what there talking about but one time the same thing as your saying happend to a friend and it would run fine out of water but bogging down in water .ended up been a head gasket was leaking cuz we pulled the plugs after putting it in the water and sure enough u saw water on plug .just my two cents .
 
Pro-pulsion

Pro-pulsion

Location
Ontario, Canada
There was only one other time this happened to me and you are not going to like it if it turns out to be correct. I had a 96 XP800 that did this very thing. Revved up on the trailer but when in the drink with a loaded up motor it would bog and puke. At first I thought electrical because certain times my battery light would kick on. I wasted loads of coin on parts. Later that fall I tore it down only to find the crank bearings were totally destroyed. It must have been defective bearings from the day it was assembled in the factory as there were only half the number of balls for the number of cage locations. Naturally the empty cage spots were blown to pieces on the outer bearings at the pto, there were zero signs of pieces inside the cases, it stayed totally contained at the bearing and seal. The result was when you put the power yo it, the crank would push down opening an air gap between the shaft and seal totally ruining all efficient carburetion ability.

You mentioned the ski is a 91, it could be worn out crank bearings or maybe it's just time to replace the seals. A crankcase pressure test will tell you that, either way, me thinks the seals don't owe you anything having a 25 year service life ;)
 
Pro-pulsion

Pro-pulsion

Location
Ontario, Canada
That sounds about right then. If there is an air leak anywhere from the throttle shaft down then you will have a tuning nightmare. Typically when they have an intake system air leak you will know by how it responds to sudden blips of the throttle. If after you give it a quick snap and it hangs on high RPM before coming down to the slowest speed it can on its own but fluctuates in idle speed, then you can safely assume that there is a leak somewhere. Now that you have that gasket found, it would be a very good idea to replace all the intake gaskets as a set.
 
SUPERJET-113

SUPERJET-113

GASKETS FOR CHAMP BRAP!
Location
Lake Havasu City, AZ USA
What does your spark look like? Is it bright white/blue or weak yellow looking? If your spark is weak it will run like crap under a load in the water.

Also when running in water do plugs look any kind of wet? Because if your head is leaking the slightest bit of water it will bog under a load in the water too.

Also I would go through your carb/carbs and check N/S, basket filter, and pop off.

Post a pic of the intake gasket cracks.. Also you did check the reeds?
 
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