Ski runs like crap when the tank is full, but it runs better when empty?

Roseand

The Weaponizer
Site Supporter
Location
Wisconsin
So I glassed up my waterbox, changed my cooling routing around. Two into mani, one head outlet to pisser, other to bottom of headpipe, top of headpipe to stinger with straight end of tee going to stinger with a fcv, and right end to a cold fusion adjustable pisser so I can get enough pressure to my head pipe.

Spent a couple days messing with my b pipe screws and finally got it very snappy for bottom/midrange power. This is all being done on a small flat water Lake, pretty much just me on the lake. Spent a couple hours constantly hitting my wake over and over again, and it was perfect. No bog or loading up, extremely snappy and was just how I wanted it to be.
Was happy with my tuning so I decided to start working on stabs, etc. Note:I lm only running one bilge pump right now.
Ski would get a little water in the carbs but would clear out and get snappy pretty shortly after. Now onto where it's really noticeable :
Launched it where I usually do most of my riding. Lots of huge boat wakes, etc. After I did a big stab and went under, I definitely had a bilge full and you can tell when a little water gets in the carbs and it takes a little bit to clear out, but this time it was different. This feeling is extremely similar to bad plug wires or cavitation due to a little bit of clogged weeds in your intake. Right after your bilge pump stops pumping and you peg it, it feels like water in your carb/bad plug wires and it just isn't snappy until you peg it for a few seconds and then blip it out a few times and it gets significantly better. However, there was a time earlier today that it still just wasn't snappy and had that same feeling when climbing up the face of a wave. It wouldn't get any better and I took it to the pier, popped the hood, inspected everything, pulled off fuse cover and it was dry inside. Checked plug wires, let it be for like 1/2 hour and then buttoned it all back up and went out. After about 5 minutes of hitting my own wake, it finally started running perfectly again.
Whenever I do stabs off of boat wakes it's like inevitable for a little bit of water to get splashed in the carbs so it takes a quick peg run, then a couple blips for it to be snappy again. This I find to be not all that weird especially since I'm running a single bilge right now, and even with a modded hood a deep/inverted stab takes in water..
But seriously, why after getting wet inside of the engine bay, my ski ran crappy and didn't have much snap at all? When hitting a boat wake it just felt really funny, and I'm not positive what it is but it's a feeling like water in carb/plug wires/cavitating but it didn't go away that one time. Coil is a season old ocd one so I know it's not that, but it's weird because it ran close to perfect for the last hour I was riding it and chasing boat wakes.
Sorry for the book, but I'm just a little confused on what's going on with my ski, because sometimes it's something normal and sometimes I know it's doing something it shouldn't.
Having to do A little bit of clearing up and blipping is normal after a trick since water and combustion don't really mix.. But how long should that take to clear up?
All of these scenarios produce the same kind of feeling I'm talking about like bad plug wires/water ingestion/cavitation. IMO they all feel similar to me, since it's not like a bog or hesitation, it's more of it just doesn't have the snap and all the power it should have.
This never happened when I was constantly just hitting my own wake the other day, keeping rpms up, etc. And it ran perfect for the last part of my ride even though I was doing similar stuff.
I don't know exactly how to explain it and I apologize if I'm talking in circles. I know it's not just water getting splashed in the carbs all the time, but it's a similar feeling, but very intermittent.
It's just confusing and there's so many different variables.. Carb/motor is freshly rebuilt and it rips hard when it's running perfect.. When it's running good, if you hold it like mikuni says for 1/4 throttle and like 30 seconds, then peg it, there's no bog/hesitation
EDIT: Is it possible that after more impacts/sudden movements/weird angles that my needle leaks excess fuel, possibly due to incorrect popoff pressure? It's a brand new needle & seat but I replaced the spring with what's recommended from factory pipe...I never tested the popoff. I'm running stock flame arrestor with one screen, which was what jetmaniac recommended in his b pipe jet/spring kit.
Any help is highly appreciated..
 
Last edited:
Location
Stockton
Any possibility of a baffle coming loose inside that repaired water box? I'am not sure it has baffling, but my former Rn's water box had a broken baffle and it gave me intermittent symptoms. You ride a lot you've said, could your plug wires need trimming back ?

I tried to test the adjustment on the flow control while I was camping but all I got was this, feels like 3 psi, when I blew thru with my mouth it was like trying to blow up a ballon initially. Had an unrelated cooling issue so no water was flowing in the line, so no throttle opening/flow info
 

Roseand

The Weaponizer
Site Supporter
Location
Wisconsin
Any possibility of a baffle coming loose inside that repaired water box? I'am not sure it has baffling, but my former Rn's water box had a broken baffle and it gave me intermittent symptoms. You ride a lot you've said, could your plug wires need trimming back ?

I tried to test the adjustment on the flow control while I was camping but all I got was this, feels like 3 psi, when I blew thru with my mouth it was like trying to blow up a ballon initially. Had an unrelated cooling issue so no water was flowing in the line, so no throttle opening/flow info
Hmmm! I never even thought of that. I'm serious, when I was constantly jumping my own wake on a calm lake, my ski would rip so hard no matter if I was going from idle or whatever. But now that I'm getting it really wet and thrashing it, I get intermittent symptoms..
I'd say I've got around 5ish gallons of oil through it already and I've only had to cut one plug wire back due to a broken terminal, but that's like probably 70ish hours of riding so maybe its time? I dunno. It's just so wierd because sometimes it's absolutely perfect..It does load up sometimes in idle/nowake zones, but i doubt it would load up that much from the 1 second it's at idle after a trick..
 
Location
Stockton
I had the baffle issue and broken plug wire strands at the same time. Before I realized those issues, I first found voltage leaking out my plug wires when they got wet jumping and what not. Now I wonder if the leaking voltage was caused by the high resistance of the broken strands
 

Roseand

The Weaponizer
Site Supporter
Location
Wisconsin
Ahh okay. That'd be awesome if that's all it is. I've been getting that weird feeling when I pin it up a wave for a while though, like it's needed to clear itself out for it to be snappy again, not like a bog of hesitation though..Just lack of power/hookup.
If it's fuel related, what would cause similar symptoms to this? Because if I'm hitting my own wake and constantly keeping rpms up and giving it hell, it's always perfectly snappy.
 
Location
Stockton
My baffle issue didn't cause a bog or Hesitation like the plug wire did. Intermittently it wouldn't get completely on the pipe, lake of power some, like it needs to be cleared out, that's actually what I thought was going on, to much fuel, to little fuel or something, I'd feather the throttle in and out repeatedly, cruise a bit and try again.

I've only had one needle and seat go bad, it stuck shut. Your internal filter are clean and clear?

That's strange it only happens going up the face of a wave, so nose up tray low, for a bit, hmm
 

Roseand

The Weaponizer
Site Supporter
Location
Wisconsin
Interesting!
I'm not sure what my internal filter looks like, but I've already replaced two inline fuel filters and I'm on my third one right now. They always seem to pickup crap. I pegged my ski WOT for 10+ seconds and pulled the plugs and they looked perfect so I think you could say I'm getting enough fuel and no cloggage.
Well up a wave is when I really notice it, because that's when I need the most snap. It's like it loads up in the mean time before I'm about to hit a wave. Like after circling around and needing to kick in my holds.
Its so weird!
 

Roseand

The Weaponizer
Site Supporter
Location
Wisconsin
Yeah. If it's a fuel issue, it loads up after jumping/tricks..or waiting to hit another wave. Brand new needle & seat, popoff spring, etc. So I'm curious what that could be if it is that. 701 61x with 44mm carb and factory pipe recommended settings, and when it's running properly it seriously hits super well.
 
I had a cdi go bad once that caused some odd intermittent issues. wouldn't rev quite right, slap a wave and it would run decent again.
 

Big Kahuna

Administrator
Location
Tuscaloosa, AL
Check your hood liner and sealing areas. My hoodliner is seperated, if I land a certain way sometimes water splashed in. Also check your plug wires, it will have the same effect. When you jump and land it jars the wires. when you are going straight trying to clear out, the wires are not bouncing any more and making connection.
 

Roseand

The Weaponizer
Site Supporter
Location
Wisconsin
zack thought a broke a reed last week. fuel lines got loose sucking air. similar issues.
Reeds are oem metal ones red loctited on, only ingested water once and they remained fine afterwards.

Good points @Big Kahuna! My hood liner was glassed in by me but the way I pound it, I wouldn't be all that surprised if it's messed up. I'll cut back my wires again for sure..
I feel like I had two issues going on that produce identical symptoms.
If my ski occasionally loads up to the point it needs to clear up, what part of the fuel system would it be? Needle opening too soon at lower throttle positioning? I mean my low speed screw probably is a little rich, but after a wave or something I don't really ever idle more than a couple seconds at a time..
 

Roseand

The Weaponizer
Site Supporter
Location
Wisconsin
Haven't had a chance to ride so I can't say yet. Tomorrow I might have time to cut my wires back.
I'm still waiting on a response on what could be wrong if it's something fuel related too. Just curious right now..
 
Top Bottom