Hi Everyone:
I've recently purchased a Seadoo Challenger 1800 and brought it to the dealer who tuned up both engines, rebuilt carbs, etc. to make sure the boat is running properly. Both engines have plenty of power and run very smoothly.
Since i've never jetboated before and only drove inboard boats I wasn't sure what to expect and I'm curious as to a few things I'm experiencing.
The issue is on the port engine if I apply full throttle to both engines the RPM consistently increase (and the boat accellerates) till about 4500 RPM at which point the RPM on the port engine jumps to over 7000 RPM almost instantly and makes a high pitch spinning sound almost like its spinning in air. I also loose thrust at that time. Is this what cavitation is and has anyone experienced his before? I checked carbon seals and they're not leaking water so I think they ar in great shape.
Seems like everytime I have this boat at the dealer I'm $1,000 lighter so I wanted to get some ideas or things to check before taking this into the dealership. Any ideas of what the most obvious/main culprits are on this boat which I can easily check or any water tests I can do to further narrow down the problem?
Also - a couple of other questions:
i. My starboard side has the wrong impeller pitch on it. The jet pump was seized so I replaced it with one from a jetski whic had a differnet pitch on it and i havn't had a chance to swap out the impellers. Could imbalanced jet pump output cause this behaviour?
ii. I know there is supposed to be a seal between the jet pump and the boat mounting but i can't find this seal in the parts diagram anywhere. I've verified on my boat there are infact no seals there - does anyone know on this boat if there is supposed to be a seal between the jetpump and the hull?
iii. I see a lot of aftermarket impellers on eBay - are these worth the $$ over factory or at the lower end (tubing, skiiing) are the stock impellers more than enough?
Many thanks in advance for all your experience and input.
I've recently purchased a Seadoo Challenger 1800 and brought it to the dealer who tuned up both engines, rebuilt carbs, etc. to make sure the boat is running properly. Both engines have plenty of power and run very smoothly.
Since i've never jetboated before and only drove inboard boats I wasn't sure what to expect and I'm curious as to a few things I'm experiencing.
The issue is on the port engine if I apply full throttle to both engines the RPM consistently increase (and the boat accellerates) till about 4500 RPM at which point the RPM on the port engine jumps to over 7000 RPM almost instantly and makes a high pitch spinning sound almost like its spinning in air. I also loose thrust at that time. Is this what cavitation is and has anyone experienced his before? I checked carbon seals and they're not leaking water so I think they ar in great shape.
Seems like everytime I have this boat at the dealer I'm $1,000 lighter so I wanted to get some ideas or things to check before taking this into the dealership. Any ideas of what the most obvious/main culprits are on this boat which I can easily check or any water tests I can do to further narrow down the problem?
Also - a couple of other questions:
i. My starboard side has the wrong impeller pitch on it. The jet pump was seized so I replaced it with one from a jetski whic had a differnet pitch on it and i havn't had a chance to swap out the impellers. Could imbalanced jet pump output cause this behaviour?
ii. I know there is supposed to be a seal between the jet pump and the boat mounting but i can't find this seal in the parts diagram anywhere. I've verified on my boat there are infact no seals there - does anyone know on this boat if there is supposed to be a seal between the jetpump and the hull?
iii. I see a lot of aftermarket impellers on eBay - are these worth the $$ over factory or at the lower end (tubing, skiiing) are the stock impellers more than enough?
Many thanks in advance for all your experience and input.
