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View Full Version : SeaDoo XP sluggish, sort of. Also battery help.



CragarShinoda
03-18-08, 10:49 PM
Hello,
I have heard so much about the XP being Snot fast, but mine seems fairly sluggish. It is faster than my buddy's 1996 GTi, but not by much. I expected it to be a LOT faster. Throttle response was not at all what I expected either. I was reading about wear rings being replaced and pepping the ski up a TON!, sould this be my issue? It has good compression, and runs a little on the rich side I think, but not too rich. Also, when I leave the battery hooked up overnight the battery will drain down. I replaced the battery and the new one does the same thing. I have a RacePak digital tach, but that is all that is hooked to the battery, and the tach has a switch that I can turn it on and off. Any ideas? Thanks!

CragarShinoda
03-18-08, 10:53 PM
I almost forgot, the ski came with a clear ring. I was told that if the wear ring is damaged it will turn brown, (due to water being in it). The ring has no brown in it, is there any other damage that can occur to these rings other than water penetration?

seadoosnipe
03-18-08, 11:11 PM
That thing running the 951, it should throw you off the back. You said your wearing ring is clear, so it seems that your not having a wearing ring issue. Your also talking about how sluggish it is....
When's the last time you cleaned the RAVE valves?
On this model 951 (947cc), the RAVE valves are controlled by the MPEM (multipurpose electronic module). The MPEM measures two factors to control the RAVE valves: engine speed and it’s rate of acceleration. To open the RAVE valves, the MPEM activates a solenoid which directs the positive pressure from the crankcase to the valves. A check valve on the pressure line eliminates the negative pressure from the crankcase.
The RAVE valves directly direct the "get up and go" of the ski. If I were to tell you what these valves were in lamens terms, I'd explain it like this. For what ever an engine breaths in, is only what it can breath out. That's what dictates performance and speed, in any engine. It does'nt matter how much carb or injector you put on the intake, it will only go as fast as the exhaust system can exhaust it. Well, the patented (by Rotax) RAVE (Rotax adjustable Variable Exhaust) is a guillotine slide valve in the exhaust system, that when at idle, is closed. Your exhaust ports are smaller. When you start to speed up, you build more pressure in the cylinder, this pressure is sensed and the RAVE begins to open. This allows more exhaust gas to exit the engine, which in turn, lets you breath in more gas. At WOT (wide open throttle) the RAVE will be wide open, opening your exhaust system diameter an extra 3/4 (hypothetical) inch to allow the gas to exit faster. This, in turn, creates more horsepower.
If this system is sticky, or doesn't work, the engine will run like crap!....If the RAVE is stuck open, then your horsepower will be greatly reduced because your exhaust system is not allowing any back pressure on the cylinders.....causing your compression to be lower than necessary to have high engine torque.
I bet I confused the hell out of ya!.........Look into your RAVE valves.....I bet they need cleaned. There is a thread in the boat section somewhere I did on cleaning them. Although the 787 is a different horse power engine, the RAVE's look similar. You can go to that thread to check what dirty ones look like and what cleans ones look like. http://www.seadooforum.com/showthread.php?t=936

CragarShinoda
03-19-08, 12:57 AM
Wow! Information overload! Seriously though, I will check the RAVE valves tomorrow, weather permitting. Thanks for the help! Here's praying for crapped up valves! :)




That thing running the 951, it should throw you off the back. You said your wearing ring is clear, so it seems that your not having a wearing ring issue. Your also talking about how sluggish it is....
When's the last time you cleaned the RAVE valves?
On this model 951 (947cc), the RAVE valves are controlled by the MPEM (multipurpose electronic module). The MPEM measures two factors to control the RAVE valves: engine speed and itís rate of acceleration. To open the RAVE valves, the MPEM activates a solenoid which directs the positive pressure from the crankcase to the valves. A check valve on the pressure line eliminates the negative pressure from the crankcase.
The RAVE valves directly direct the "get up and go" of the ski. If I were to tell you what these valves were in lamens terms, I'd explain it like this. For what ever an engine breaths in, is only what it can breath out. That's what dictates performance and speed, in any engine. It does'nt matter how much carb or injector you put on the intake, it will only go as fast as the exhaust system can exhaust it. Well, the patented (by Rotax) RAVE (Rotax adjustable Variable Exhaust) is a guillotine slide valve in the exhaust system, that when at idle, is closed. Your exhaust ports are smaller. When you start to speed up, you build more pressure in the cylinder, this pressure is sensed and the RAVE begins to open. This allows more exhaust gas to exit the engine, which in turn, lets you breath in more gas. At WOT (wide open throttle) the RAVE will be wide open, opening your exhaust system diameter an extra 3/4 (hypothetical) inch to allow the gas to exit faster. This, in turn, creates more horsepower.
If this system is sticky, or doesn't work, the engine will run like crap!....If the RAVE is stuck open, then your horsepower will be greatly reduced because your exhaust system is not allowing any back pressure on the cylinders.....causing your compression to be lower than necessary to have high engine torque.
I bet I confused the hell out of ya!.........Look into your RAVE valves.....I bet they need cleaned. There is a thread in the boat section somewhere I did on cleaning them. Although the 787 is a different horse power engine, the RAVE's look similar. You can go to that thread to check what dirty ones look like and what cleans ones look like. http://www.seadooforum.com/showthread.php?t=936

scooper77515
03-19-08, 09:28 AM
I felt the same way when I first got my ski and joined this forum. But buy the book, listen to the guys here, and you will find that it really is all a simple machine.

I got mine running tip-top form for around $400, and the bike was GIVEN to me because the previous owner gave up on it!!!

mkov608
03-26-08, 09:25 AM
That thing running the 951, it should throw you off the back. You said your wearing ring is clear, so it seems that your not having a wearing ring issue. Your also talking about how sluggish it is....
When's the last time you cleaned the RAVE valves?
On this model 951 (947cc), the RAVE valves are controlled by the MPEM (multipurpose electronic module). The MPEM measures two factors to control the RAVE valves: engine speed and itís rate of acceleration. To open the RAVE valves, the MPEM activates a solenoid which directs the positive pressure from the crankcase to the valves. A check valve on the pressure line eliminates the negative pressure from the crankcase.
The RAVE valves directly direct the "get up and go" of the ski. If I were to tell you what these valves were in lamens terms, I'd explain it like this. For what ever an engine breaths in, is only what it can breath out. That's what dictates performance and speed, in any engine. It does'nt matter how much carb or injector you put on the intake, it will only go as fast as the exhaust system can exhaust it. Well, the patented (by Rotax) RAVE (Rotax adjustable Variable Exhaust) is a guillotine slide valve in the exhaust system, that when at idle, is closed. Your exhaust ports are smaller. When you start to speed up, you build more pressure in the cylinder, this pressure is sensed and the RAVE begins to open. This allows more exhaust gas to exit the engine, which in turn, lets you breath in more gas. At WOT (wide open throttle) the RAVE will be wide open, opening your exhaust system diameter an extra 3/4 (hypothetical) inch to allow the gas to exit faster. This, in turn, creates more horsepower.
If this system is sticky, or doesn't work, the engine will run like crap!....If the RAVE is stuck open, then your horsepower will be greatly reduced because your exhaust system is not allowing any back pressure on the cylinders.....causing your compression to be lower than necessary to have high engine torque.
I bet I confused the hell out of ya!.........Look into your RAVE valves.....I bet they need cleaned. There is a thread in the boat section somewhere I did on cleaning them. Although the 787 is a different horse power engine, the RAVE's look similar. You can go to that thread to check what dirty ones look like and what cleans ones look like. http://www.seadooforum.com/showthread.php?t=936

Does this mean that skis equiped with RAVE the compression should be checked with the throttle closed?

CragarShinoda
03-26-08, 04:25 PM
Also on the same line as compression, I have always checked the compression on a car when the motor is warm... how do I do it on a ski? Will it make a big difference if I check it cold, or do I need to have the ski warm before I check the compression again? I hate to start it out of the water, and will probably forget to take the gauge to the lake next time I go.

seadoosnipe
03-26-08, 05:50 PM
I've always checked compression on a cycle cold and a 4 cycle, by starting once for about 10 seconds then shutting down. The reason is the oiling. With the oil coating the rings and cylinder walls, your getting a better reading close to what your actually running when the engine is hot. Because a thin film of oil, will change the pressure, if there isn't any prestent. In a 2 cycle, spinning the engine over several times allows the fuel/oil mix to be present, so it doesn't have to run. In a 4 cycle, you need the oil pump to coat the engines components, so it can run for several seconds, to coat the cylinder walls with oil.
The raves, aren't really adjustable during a compression check. On the 787, the engines compression is what variates the slides of the valve. On a 951, the raves actually are ported with air line tubing, attached to a solenoid. So, the raves have no affect on the compression test. Just leave them as they are.