Replacement Rave Housing

[bigJake]

I melted a plastic rave exhaust valve in 2 hours use (not the first one to melt, usually just the threads disappear) I have new o-rings installed so that's not the issue. There seems to be excessive play if I wiggle the rave so I'm assuming the housing and/or valve stem are worn but every site I've checked, OEM housings are not available. All I'm finding are Chinese aftermarket from Titan and JSP. I posted previously if anyone had tried the Titan and replies were that the metal was too soft and they wore out quickly. Anyone know of GOOD aftermarket or where to find OEM? Offhore Marine lists one for $50 but does not specify the brand. UPDATE: OffShore Marine tells me their housing is made by WSM. I have no idea if that means it is any good or not?

I only put on a few hours a year so the cheap $25 ones might be adequate and just replace as necessary vs $100 for OEM.

I also plan to switch to the aluminum caps.

Also, wondering if there is a specific size bolt or something that should fit snugly in the housing hole that I can use to verify if the housing is really worn or if it's just the valve stem?

I've never put anything around the base of the bellows, I just noticed the parts diagram calls for Dow Corning 111. Can I just use Super Lube Synthetic Grease?

 

[mikidymac]

I know @etemplet has been putting bushings into the OEM housings to refurbish them.

I would not put anything on the bellows as it can cause them to slip off.

 

[bigJake]

yea I saw he mentioned he was going to try that. @etemplet was that successful? Could I ship you 4 housings off my skis to do?

 

[etemplet]

I have not done any of the housings yet because I believe the root cause needs to be eliminated and bushings shouldn't be necessary. Rebushing housings is not something I want to get into doing. I'm sure a local shop or machinist could help you out with that. The rattling of the blade is causing the premature wear and destruction of the piston. I want to figure out why some do it and some don't. I'm wondering of the MAG Rave is more prone do destroy itself than the PTO. Strange.

 

[bigJake]

I have not done any of the housings yet because I believe the root cause needs to be eliminated and bushings shouldn't be necessary. Rebushing housings is not something I want to get into doing. I'm sure a local shop or machinist could help you out with that. The rattling of the blade is causing the premature wear and destruction of the piston. I want to figure out why some do it and some don't. I'm wondering of the MAG Rave is more prone do destroy itself than the PTO. Strange.

I usually do, but can't say that I always keep strict track of Mag vs PTO when I take them off to clean, so mine may have been intermingled at some point. When I had them off in the spring I had a couple spare Raves so tried to pick the ones with the best looking shafts. All mine have slightly worn shafts just below the blade.. (even ones with only 20-30 hours - I replaced the originals with slotted raves on one of the skis a few years ago). Just my guess, is that the shafts wear which then maybe allows them to wobble a little in the housing which then wears the housing. That's just a totally uneducated guess. I've had several caps melt over the years and never really documented which ones melted, which in retrospect would be good to know. The first few times I thought it was just the o-rings which I have replaced every couple years when they get hard. But the latest melted with only about 2 hours use and a new o-ring so I'm assuming housing/shaft wear. For what it's worth, this one that melted is PTO. (But that rave may have previously been in the MAG side at some point)

 

[burtshaver2021]

I wonder, might be worth calling around for a used set of housings ?

 

[bigJake]

I wonder, might be worth calling around for a used set of housings ?

Yea, I was wondering about that. @Minnetonka4me or someone else who parts out skis, may have a used set, but it's hard to say if a used set is going to be more or less worn than my current set. And I don't know if my problem is housing or rave shaft wear or probably a combination of both. That's why I was wondering about a simple way to measure current level of housing wear with say a specific diameter bolt or dowel. I don't have a micrometer but was thinking mabe a drill bit gauge could be used to get a rough measurement of shaft wear on the rave. hmm, might be able to use drill bits to roughly measure the hole in the housing if anyone knows the size in a new housing to compare against?

 

[burtshaver2021]

I have a 96 GSX here that I don’t mind taking the rave valve off and measuring the housing, don’t really want to take it off my 97 or 99 GSX just because I’m riding them and with my luck I will wreck the gasket or something. Also couldn’t hurt to make a call to @Minnetonka4me and get a price on the housing with guillotine. He will stand behind any used parts. If you want that measurement from my 96 let me know and I will get it tomorrow

 

[bigJake]

I have a 96 GSX here that I don’t mind taking the rave valve off and measuring the housing, don’t really want to take it off my 97 or 99 GSX just because I’m riding them and with my luck I will wreck the gasket or something. Also couldn’t hurt to make a call to @Minnetonka4me and get a price on the housing with guillotine. He will stand behind any used parts. If you want that measurement from my 96 let me know and I will get it tomorrow

yes please. How will you measure, do you have a bore gauge or something? I wonder if I can rent something from an auto parts store to measure mine.

 

[burtshaver2021]

yes please. How will you measure, do you have a bore gauge or something? I wonder if I can rent something from an auto parts store to measure mine.

I have a dial bore gauge but I don’t think that will fit, I will probably try and use my micrometer to measure the inside diameter and if that doesn’t work I may just try insert something like a drill bit and then measure that, maybe wrap the drill bit in blue painters tape if I can’t get the exact size of drill bit. We will figure something out,

 

[etemplet]

I did all that measuring and testing. I'm a machinist by trade and have a lathe at home I bought brand new rave housings and in a couple hours run time they were worn worse than the stock housings I removed the first time. The housing fit is getting hammered by the rave valve shaft due to wobble. Housing to valve shaft clearance new is about (.005") I believe the stock housings from Seadoo are a harder grade of aluminum. That's why my plan was to machine some brass bushings or better yet find some bushings (oilite stock would be great) at the local hardward store.

I melted only ONE piston and it took about 4 minutes and only 40 seconds at full throttle. I felt it go. I modified a rave blade and slotted them myself. The cutter was a tad larger but I didn't care at the time. Anyway, the piston failed because when I installed the rave housing I didn't check to make sure the shaft was moving freely. That is what I am attributing the failure to on my end. The gasket was not exactly in position and caused the valve to hang up. Hot gas on the piston and it melted quickly. Never had that problem again. I check for free movement meticulously every time I install a rave valve.

I have slotted raves on the problem ski right now and I don't feel like cutting and measuring a new set of raves for the ski to determine if the slots are an issue on the 1996. I'm more tempted to do some alumium welding on the rave blade to increase the size so they can't rattle as much but that can create other problems. Big problem is these engines are small and not many gurus are going to spend time troubleshooting.

I do wonder about the engine cylinder itself. Does that slot inside the cylinder become worn? (These engines have so few hours on them I can't see that being a problem) I have measured those slots in the cylinders and the measurements are all over the place. The RFI raves fit a great deal tighter in the slots than the 787 carb.

I have 4 aluminum pistons I bought. I'm gonna install one on the Mag cylinder and see how it works out. If it holds up better than the plastic (1 day on the water) I'll leave it all alone.

I can tell you the wear on the valve shafts is insignificant. Couple thousandths isn't tearing up pistons. The housings I replaced had (.015") and a bit more clearance.

Just my 2 cents. If ya'll want to work on this count me in. I'll play.

 

[burtshaver2021]

yes please. How will you measure, do you have a bore gauge or something? I wonder if I can rent something from an auto parts store to measure mine.

Am I measuring where I have the screw driver?

 

[burtshaver2021]

The hole in the housing where the guillotine shaft slides measured .3970 and the shaft measured .3905 Hope this helps? On mine that’s a clearance if .0065

 

[bigJake]

I did all that measuring and testing. I'm a machinist by trade and have a lathe at home I bought brand new rave housings and in a couple hours run time they were worn worse than the stock housings I removed the first time. The housing fit is getting hammered by the rave valve shaft due to wobble. Housing to valve shaft clearance new is about (.005") I believe the stock housings from Seadoo are a harder grade of aluminum. That's why my plan was to machine some brass bushings or better yet find some bushings (oilite stock would be great) at the local hardward store.

I melted only ONE piston and it took about 4 minutes and only 40 seconds at full throttle. I felt it go. I modified a rave blade and slotted them myself. The cutter was a tad larger but I didn't care at the time. Anyway, the piston failed because when I installed the rave housing I didn't check to make sure the shaft was moving freely. That is what I am attributing the failure to on my end. The gasket was not exactly in position and caused the valve to hang up. Hot gas on the piston and it melted quickly. Never had that problem again. I check for free movement meticulously every time I install a rave valve.

I have slotted raves on the problem ski right now and I don't feel like cutting and measuring a new set of raves for the ski to determine if the slots are an issue on the 1996. I'm more tempted to do some alumium welding on the rave blade to increase the size so they can't rattle as much but that can create other problems. Big problem is these engines are small and not many gurus are going to spend time troubleshooting.

I do wonder about the engine cylinder itself. Does that slot inside the cylinder become worn? (These engines have so few hours on them I can't see that being a problem) I have measured those slots in the cylinders and the measurements are all over the place. The RFI raves fit a great deal tighter in the slots than the 787 carb.

I have 4 aluminum pistons I bought. I'm gonna install one on the Mag cylinder and see how it works out. If it holds up better than the plastic (1 day on the water) I'll leave it all alone.

I can tell you the wear on the valve shafts is insignificant. Couple thousandths isn't tearing up pistons. The housings I replaced had (.015") and a bit more clearance.

Just my 2 cents. If ya'll want to work on this count me in. I'll play.

etemplet,
Can you tell me what this set is in the first picture? Found it in my dad's garage after he died. He was not a mechanic or machinst, just a pack rat so don't know why he would have had it. Best I could figure out is that the rods all seem to attach together for measuring depth of something? Also found the old micrometer, should I be able to use that with Burt's idea of blue tape around a drill bit to measure the diameter of the hole in my housings? I have to get it back from my brother next week when we go to Hilton Head.

 

[bigJake]

View attachment 64004The hole in the housing where the guillotine shaft slides measured .3970 and the shaft measured .3905 Hope this helps? On mine that’s a clearance if .0065

thanks Burt, I have to get a micrometer to measure mine,

 

[burtshaver2021]

thanks Burt, I have to get a micrometer to measure mine,

I was able to use my cheap micrometer from Canadian Tire to measure the bore, I had to measure from the side the valve goes on though, wouldn’t reach from the other side. Even though it’s not a precision instrument I think it would be more accurate than my original idea with the blue tape which after thinking about it I don’t think would be very accurate at all.

 

[burtshaver2021]

This is what I used to measure with.

 

[bigJake]

View attachment 64007This is what I used to measure with.

Looks like I can get one like that at HF for $23
6 in. Digital Caliper with SAE and Metric Fractional Readings

 

[etemplet]

etemplet,
Can you tell me what this set is in the first picture? Found it in my dad's garage after he died. He was not a mechanic or machinst, just a pack rat so don't know why he would have had it. Best I could figure out is that the rods all seem to attach together for measuring depth of something? Also found the old micrometer, should I be able to use that with Burt's idea of blue tape around a drill bit to measure the diameter of the hole in my housings? I have to get it back from my brother next week when we go to Hilton Head.

Sure that's a set of inside micrometers. You need the outside micometers to measure the length when transferring. You'll get really close but not spot on. Those mics likely won't go smaller than 1.5" The rods go on th end of the barrel to get the correct range. I have a couple of sets and that is what I use to measure cylinder bores.

The single is a Zero to 1" outside micrometer. Good to have. Measure drills, dowels, pins, etc... If you get a set of telescope gauges you can measure the bore of the rave housing. You probably won' have much use for the inside set and they don't bring much money these days.

I have full sets that go up to 6" on the outside but I still play machinist. LOL Some of us old guys can get a size with calipers and transfer to micrometers by feel.

 

[etemplet]

My question to solve the root cause is this; Is the vibration low frequency, high frequency, or thrust. I'm not sure side to side motion is pulling the theads out of the rave piston. It only to my ski 1.5 hours to pull the threads out of a good piston. Hmmmm.... I actually love this kinda stuff. LOL I have a way to stop it but I want to find out what's going on .

 

[bigJake]

It might be a couple weeks before I get a chance to measure the housings to determine best way to proceed. Will reply back when I get those readings. Thanks.

 

[bigJake]

@etemplet @burtshaver2021 @mikidymac OK, I'm back from vacation and my $5 set of digital calipers arrived.
Assuming the calipers are fairly accurate, I measure the hole in the housing to be 0.3937" (10 mm) and the ends of the guillotine shaft at 0.389764" (9.9 mm) but the center of the shaft that rubs agains tthe housing measures 0.38189" (9.7 mm) for a clearance of .0118" (0.3 mm).
I'm thinking I'll just order the aluminun caps for now and monitor things next season. Thoughts?

 

[etemplet]

I've never seen a shaft under .391" The housings always wear excessively. Steel shaft VS Aluminum housing. I'd replace the valve. That's too much clearance. I'd like to see a picture of the valve stem. That wear tells me the housing bore is harder than the valve stem or something abrasive got in there.

 

[bigJake]

I'm not sure how much credence we can put into the accuracy of the measurements from my $5 Chineese made calipers.
As a test, I measured a 13/32 drill bit with the calipers. 13/32 = .40625" = 10.31875mm
The calipers measured the drill bit at 10.1mm = .397638" A varaince of .008612.
Of course the drill bits are probably made in China too so we don't know how accurate the size on them is either.
If we can assume the drill bits are correct size then add the .008612 variance to the valve stem measurements that gives .398364" on the ends and .39058 on the worn part of the stem. Pretty close to being inline with your expectation.

 

[burtshaver2021]

I'm not sure how much credence we can put into the accuracy of the measurements from my $5 Chineese made calipers.
As a test, I measured a 13/32 drill bit with the calipers. 13/32 = .40625" = 10.31875mm
The calipers measured the drill bit at 10.1mm = .397638" A varaince of .008612.
Of course the drill bits are probably made in China too so we don't know how accurate the size on them is either.
If we can assume the drill bits are correct size then add the .008612 variance to the valve stem measurements that gives .398364" on the ends and .39058 on the worn part of the stem. Pretty close to being inline with your expectation.

Although I agree that it is possible that the calipers may not be accurate I would hope that the scale would at least be accurate. What I mean is, if the caliper were off by .001 then hopefully it would always be off by the same .001 and at least we would know if you have the proper clearance? Or maybe not