Rave valve with no diaphragm? Pics

[Seadoo rxdi]

So, I am cleaning my valves today on 03 rxdi. 87hrs. All the information I keep finding about rebuild kits include a diaphragm. Mine does not have a diaphragm just a spring. Is this normal?

Also, I noticed that there is oil inside them. Looks like the rubber oring is damaged.

Besides all that, how can I tell if these are operating normally? I have a hand held vacuum pump and pressure pump. Could I hook the vacuum pump to the vacuum nipple or something?

 

[Sportster-2001-951C-Stock]

The DI version of the 951 uses a piston to actuate the RAVE instead of the low pressure diaphragm. You will find these specific details and much more in the factory service manual, it's well written and worth it's weight in gold!

Dunking the RAVE blades in a plastic baggie with oven cleaner will dissolve the gunky carbon right off.

The RAVE assembly exploded view can be found here:

Rivamotorsports.com's 2003 Sea Doo PWC RX DI N. AMERICA (VIPER RED) [6123] Parts List

 

[Seadoo rxdi]

The DI version of the 951 uses a piston to actuate the RAVE instead of the low pressure diaphragm. You will find these specific details and much more in the factory service manual, it's well written and worth it's weight in gold!

Dunking the RAVE blades in a plastic baggie with oven cleaner will dissolve the gunky carbon right off.

Thank you for clearing that up.

Would I also be able to find out how to test these things in the manual? Or would you happen to know?

 

[Sportster-2001-951C-Stock]

Well, the air pump produces 100psi, maybe start low, like 25 and see if that moves it. If you attach your vacuum pump to the nipple you can pull a vacuum and see if there;s a gross leak but that won't move the piston.

I think the thing to do is buy a repair kit if there is one, or the individual rubber seals separately. Original manufacturer parts are the best you can get. aftermarket may not be the same quality.

Then just put it back together like it was, it should be good as new.

I assume the ski was running fine beforehand, right?

 

[Seadoo rxdi]

I have a box of different sized universal o rings so I went ahead and replaced the bottom one only until the rebuild kit with all of them arrive. This o ring only seems to serve one purpose, to keep oil/exhaust fumes from entering the raves.

I pushed the piston all the way in and held it, then took my thumb and held it over the vacuum port on the valve. The piston does not return to the down position until I remove my thumb. That must mean its working properly I'd assume?

The ski was running decent..It use to hit about 6800rpms on wot around 56 to 58mph GPS. However I have recently lost a few hundred rpms. It is now only hitting 6600 sometimes 6700. But I think it is due to sucking up debris. I am currently replacing the impeller and wear ring and hoping this gives me my rpms back. The impeller is pretty knicked up.

It looks like my raves are screwed all the way down. Is that how it comes from factory? Thinking about taking a flathead to the lake with me and unscrewing them a bit and see how it does.

 

[Sportster-2001-951C-Stock]

I think you'll be fine with replacing the one damaged o-ring, Viton is the preferred elastomer as far as I know. It looked like there was a thin wire around the blade shaft? If yes, that's not what I expected to see... unless some other seal with wire reinforcement disintegrated? I'm not sure.

Anyway, Yes, if covering the port with your finger results in a hermetic seal I agree, the piston seal isn't leaking appreciably. Some small leak is nothing to be concerned with but what can happen is if the leak is large, too much exhaust can travel past the piston and burn plastic parts.

As you can see, the closer to the heat source, the more punishment the parts receive. And yes, the rubber seal on the blade shaft is intended to block hot exhaust gasses from entering the upper section while the blade is in the open position. While the blade is in the open position, maximum heat is being generated, thus the shaft seal (just an o-ring, I believe) helps to keep hot gasses from traveling up inside the body and causing damage.

Thus if it's only the one o-ring that's damaged, a replacement that's capable of withstanding the environment (Kalrez and Viton come to mind) will suffuce as long as the blade travels to the open position as intended. If for some reason the blade doesn't open properly, that o-ring receives more punishment b/c it's directly exposed to heat, it's not up against the body where heat is lower temperature.

Hopefully this explanation makes sense, lol.

If you see some parts damaged by heat, then do so. These elastomers will have to be replaced eventually due to the environment and trouble occurs if they're degraded and allow exhaust into the upper section. For instance, the plastic parts may be burned.

The blue button is the adjustment. The service manual I believe, suggests the correct position but if nobody has moved it just leave it as is. These aren't so critical as the other engines b/c the other engine rely more on spring tension where as the 951's the RAVE will either be engaged or disengaged by the MPEM computer.

The plastic piston is threaded onto the blade shaft fully till it bottoms, using finger torque should be sufficient and using a wrench to over tighten can damage the threads so not gorilla tight on that one, tight enough it won't work loose is the goal.

 

[Sportster-2001-951C-Stock]

I wouldn't be overly concerned with chasing a few hundred RPM as long as performance isn't suffering in some notable aspect, but that's me. That is, environmental aspects can cause RPM to vary some and as you suspect, dings or even a slightly bent impeller blade might impact RPM to this degree.

Might also consider a cylinder compression check, as the engine ages some power loss can be anticipated.

If one or both RAVES are malfunctioning, you'll experience definite performance issues, perhaps 1,000 RPM or more. This can also lead to early plug fouling b/c combustion temperatures will be insufficient for the plugs to self-clean carbon deposits.

Never attempt to burn stale fuel in any marine engine, the more high strung the engine, the more this rule applies.

 

[mikidymac]

I wouldn't be overly concerned with chasing a few hundred RPM as long as performance isn't suffering in some notable aspect, but that's me. That is, environmental aspects can cause RPM to vary some and as you suspect, dings or even a slightly bent impeller blade might impact RPM to this degree.

Might also consider a cylinder compression check, as the engine ages some power loss can be anticipated.

If one or both RAVES are malfunctioning, you'll experience definite performance issues, perhaps 1,000 RPM or more. This can also lead to early plug fouling b/c combustion temperatures will be insufficient for the plugs to self-clean carbon deposits.

Never attempt to burn stale fuel in any marine engine, the more high strung the engine, the more this rule applies.

Great info as usual Sportster.

I always like fresh fuel and stale causes headaches.

I know you like technical stuff and found something interesting from one of the masters Harry Klemm at Group K as far as our engines being "high performance" as you say "high strung". I always though as our engines as high output but basically he is saying per cc PWC engines are pretty low performance and is why they don't show issues with minor air leaks that would kill a dirtbike instantly. A 250cc motocross bike makes the same power as a 650cc PWC so per cc we are really low on performance by comparison, that and we have a constant cold water supply. Just thought you might find it interesting as I never looked at it that way. I do know that Seadoo typically makes more power per cc than Yamaha or Kawasaki.

 

[Sportster-2001-951C-Stock]

For sure, we don't want no stinking fuel, lol.

RE: Motorcycles it's true on the surface but consider the lazy loafer motorcycle engine comparison doesn't account for the high duty cycle and torque load. I imagine they never come close to burning the 12~14 GPH of fuel consumed by a constant duty cycle engine pushing upwards of 1200lb+ through water.

It's one thing to tout horsepower but torque has to be considered as well.

Honda BF 40 - 50 - 75 - 90 - 115 - 135 - 150 - 225 - 250 hp Outboard Fuel Consumption Chart GPH MPG Test & Specs | Portable 2.3 - 5 - 8 - 9.9 - 15 - 20 hp

 

[Seadoo rxdi]

Hmm very interesting read sportster. I appreciate that info. Makes perfect sense. There were no wires wrapped around the shaft. U may be looking at the torn up o ring I'd assume.

Now, there is one thing I noticed while I had the raves out and ima bit scared but it could be normal..

I found a few water droplets down in there around where the valves sit on the head and also on the piston and rings. Absolutely no signs of rust or anything of that sort. Rings look great and the ski runs like top, fires right up every time. Idles perfect...should I be concerned or is this normal condensation?

 

[mikidymac]

For some unknown reason the 951 engine gets moisture in the cylinders. It is always a good idea to fog the cylinders after every run on a 951.

 

[Sportster-2001-951C-Stock]

I too suspect condensation. But keep an eye on it and fogging oil really is a serious consideration if you're going to put it away for more than a couple days.

Also, if have you been running it in the driveway with a garden hose for cooling water, I avoid this if possible. I fire mine up just briefly when out of water, probably no more than 30 seconds. Can't do that with an outboard or stern drive but jet ski you can.

Running on the hose injects the exhaust system with water, which can get sucked back into the cylinder. Short startups can produce traces of water vapor as hydro-carbons in fuel combine with oxygen during combustion.

 

[Seadoo rxdi]

I do run mine on the hose in the driveway for just a bit maybe 2 minutes before I hit the lake. Mostly to make sure its running correctly.

Any recommendations on a good fog oil from you pros?

 

[mikidymac]

There is no reason to run it on the hose to get ready for the lake and especially that long. You risk overheating the driveshaft seal.

Just fire it up dry at the house give it a little rev and done, you know it runs.

For fogging oil I like the Klotz FogOn but any will work.

 

[Sportster-2001-951C-Stock]

I do run mine on the hose in the driveway for just a bit maybe 2 minutes before I hit the lake. Mostly to make sure its running correctly.

Any recommendations on a good fog oil from you pros?

Basically whatever works for you is fine. I always seem to have a ton of outboard 2-stroke oil hanging around and it's made for the specific environment so I put it in a windex type bottle and spray away when the need occurs.

A couple minutes running on the hose might be rough on your carbon seal but traces of moisture for a short period of time won't do any damage. Obce you launch and fire it up that moisture get burned off quickly.

It's the case of sitting around for weeks with moisture trapped inside the crankcase that causes cylinder wall and bearing rust pitting. If you don't plan or have a concrete plan to use it in a few days, then go ahead and fog it. The price you pay is risk of fouling plugs vs internal corrosion.

Always keep a spare set of known good plugs on hand, fresh new ones is best. And for winter storage, leave the old used plugs in until after spring startup then install the shiny new plugs once the heavy fogging oil is cleared out.