Rave valves?
- Thread starter Gray_rs
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purple_people_eater
New Member
from the seadoo manual,
RAVE SYSTEM OPERATION
For a 2-stroke-cycle engine to have high power capacity at high crankshaft speeds, a high
volumetric or breathing efficiency is required and the fresh charge losses must be minimized. The
result is achieved by opening the exhaust port early and utilizing the resonant effects of the tuned
exhaust system to control fresh charge losses.
When an engine of this design is run at a high speed, efficiency falls off quickly. The relatively high
exhaust port effectively shortens the useful power stroke and because the exhaust system is tuned
for maximum power, there is a large increase of fresh charge losses at lower speeds. As a result,
the torque decreases along with a dramatic increase of the specific fuel consumption. Higher
torque along with lower fuel consumption can be obtained at lower engine speeds if the time the
exhaust port is open is shortened.
Bombardier-Rotax has patented a remarkably simple system to automatically change the exhaust
port height based on pressure in the exhaust system.
Located above the exhaust port is a guillotine-type slide valve. This rectangular valve is connected
by a shaft to a diaphragm which is working against a return spring. Two small passages in the
cylinder just outside the exhaust port allow exhaust gas pressure to reach the diaphragm.
To the outside of the return spring is a red plastic adjustment knob. Turning the adjustment in or
out changes the preload on the return spring which, in turn, will change the RPM at which the
RAVE valve opens and closes.
RAVE SYSTEM OPERATION
For a 2-stroke-cycle engine to have high power capacity at high crankshaft speeds, a high
volumetric or breathing efficiency is required and the fresh charge losses must be minimized. The
result is achieved by opening the exhaust port early and utilizing the resonant effects of the tuned
exhaust system to control fresh charge losses.
When an engine of this design is run at a high speed, efficiency falls off quickly. The relatively high
exhaust port effectively shortens the useful power stroke and because the exhaust system is tuned
for maximum power, there is a large increase of fresh charge losses at lower speeds. As a result,
the torque decreases along with a dramatic increase of the specific fuel consumption. Higher
torque along with lower fuel consumption can be obtained at lower engine speeds if the time the
exhaust port is open is shortened.
Bombardier-Rotax has patented a remarkably simple system to automatically change the exhaust
port height based on pressure in the exhaust system.
Located above the exhaust port is a guillotine-type slide valve. This rectangular valve is connected
by a shaft to a diaphragm which is working against a return spring. Two small passages in the
cylinder just outside the exhaust port allow exhaust gas pressure to reach the diaphragm.
To the outside of the return spring is a red plastic adjustment knob. Turning the adjustment in or
out changes the preload on the return spring which, in turn, will change the RPM at which the
RAVE valve opens and closes.
purple_people_eater
New Member
to me that sounds more like a wear ring. check out your jet pump. i think that is your problem.
Where is that? Lol sorry don't know much about them, it makes like a shredding noise from the back when in the water, it's also like misfiring and goes threw plugs , I think I got had with it, all wanted to do was go out in summer aswell lol I should have tried it on the water,
artur3910
New Member
If u not going foward but your engine is working fine ( is going to max RPM) so that jet pump problem. Jet pump is on the back of ski, if jet ski is on trailer , look under the ski tru the intake gate almost in the end of ski , u can see wear ring from there and the impeller . Check if there is any space between impeller and wear ring. Have to be just a little , little about 1mm space. U can start the engine also and check if impeller is mowing if not so that will be drive schaft. That is long metal pice connect to your engine to impeller. If your engine mount a broken engine get l loose and drive shaft can go down.
http://m.youtube.com/index?desktop_uri=/&gl=US#/watch?v=SW3EiMdsopI
http://m.youtube.com/index?desktop_uri=/&gl=US#/watch?v=SW3EiMdsopI
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The wearing ring is part #3 in this drawing. They usually last about 10 years but if your riding up close to a beach on a regular basis, you can suck in large amounts of sand, which is abrasive, and wear it out faster.
You pull the pump, cut the old one out and put a new one in. You can order the part from here, at the Seadoowarehouse.
You pull the pump, cut the old one out and put a new one in. You can order the part from here, at the Seadoowarehouse.
BMANN06
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