SkiDaddy
Just Havin' Fun!
- Location
- Orange City, FL
I found this at GropK:
"While testing props and nozzles one morning, we were making repeated, long, smooth-water passes turning consistently 7250 rpm. About 2 hours into that testing, the test rider encountered a few ripples at peak speed that set the nose bouncing a bit…. But he still maintained full rpm. Suddenly, the boat surged a couple of times (obviously from air bubbles getting in the fuel pickup of a 1/3 full tank)… but he still maintained full throttle. After about 2-3 seconds of the intermittent surging, the engine shut down. Back at the shop we found a scored rear piston…. obviously from air bubbles entering the fuel lines while running the engine at full rpm.
We realized that we needed to re-define the term “pump gas safe”. As long as our F800 had a full tank of fuel, it was totally “pump gas safe”. However as soon as the tank got under half full, the occasional air in the fuel line, from rough water riding, could easily create piston-killing detonation in mere moments. For any closed course race boat, it is impossible to keep air from entering the fuel pickup tube…the only thing you can do is eliminate those air bubbles before they reach the carb….so we did.
The solution was to install a pulse-pump fuel-air separator. With the separator mounted, we were able to run the tank to less than a half gallon at peak rpm with no detonation or surging at all. The only down side of the separator is that when you run out of gas…. you are “out of gas”… there is no notice. Just the same, we figured this inconvenience is better than a scored piston. We made a simple aluminum-strap bracket to mount the remote pump & chamber on top of the battery (worked like a charm). For any modified closed course or freestyle “pump-gas” boats (like our F800), we strongly recommend a fuel/air separator to avoid damaging a piston when fuel levels get low."
Are they just pushing sales of their seperator or is this really an issue? I know I ride sometimes until the ski starts hesitating when landing from waves (from running ~low~ on gas & fuel sloshing in the gas tank). Then it's to reserve & ride back to the ramp/beach. I'm not holding it WOT across a lake very much or anything.
However, I definately don't want to toast another piston.....:aargh4: :aargh4: :aargh4: :aargh4: :aargh4: :aargh4: :aargh4:
"While testing props and nozzles one morning, we were making repeated, long, smooth-water passes turning consistently 7250 rpm. About 2 hours into that testing, the test rider encountered a few ripples at peak speed that set the nose bouncing a bit…. But he still maintained full rpm. Suddenly, the boat surged a couple of times (obviously from air bubbles getting in the fuel pickup of a 1/3 full tank)… but he still maintained full throttle. After about 2-3 seconds of the intermittent surging, the engine shut down. Back at the shop we found a scored rear piston…. obviously from air bubbles entering the fuel lines while running the engine at full rpm.
We realized that we needed to re-define the term “pump gas safe”. As long as our F800 had a full tank of fuel, it was totally “pump gas safe”. However as soon as the tank got under half full, the occasional air in the fuel line, from rough water riding, could easily create piston-killing detonation in mere moments. For any closed course race boat, it is impossible to keep air from entering the fuel pickup tube…the only thing you can do is eliminate those air bubbles before they reach the carb….so we did.
The solution was to install a pulse-pump fuel-air separator. With the separator mounted, we were able to run the tank to less than a half gallon at peak rpm with no detonation or surging at all. The only down side of the separator is that when you run out of gas…. you are “out of gas”… there is no notice. Just the same, we figured this inconvenience is better than a scored piston. We made a simple aluminum-strap bracket to mount the remote pump & chamber on top of the battery (worked like a charm). For any modified closed course or freestyle “pump-gas” boats (like our F800), we strongly recommend a fuel/air separator to avoid damaging a piston when fuel levels get low."
Are they just pushing sales of their seperator or is this really an issue? I know I ride sometimes until the ski starts hesitating when landing from waves (from running ~low~ on gas & fuel sloshing in the gas tank). Then it's to reserve & ride back to the ramp/beach. I'm not holding it WOT across a lake very much or anything.
However, I definately don't want to toast another piston.....:aargh4: :aargh4: :aargh4: :aargh4: :aargh4: :aargh4: :aargh4:
