Blowing up ride plate ??

[burnrubber]

Keep hearing about blowing off ride plates while doing a quick fire up in the driveway ???????

Sounds like a huge hype ??

All my friends have never " blown one off " in the driveway .

Always value advice here from the helpful guys here , but just cant seem to grasp this concept as being a reality -- unless someone is reving a massive recless 1100 rpm for some lame reason and they deserve some consequence.

Sport jets dont have a rubber impellor - their self draining - ---- 30 seconds in the driveway shouldent hurt anything .

If ime way out of bounds then let me have it .

 

[Painlesstom]

Re: Blowing up ride plate ??

Just because you don't understand something doesn't mean it isn't so.... trust me. You may very well get away with a quick start in the driveway, it is possible provided there is NO fuel or fumes in the chamber above that ride plate. If the motor doesn't start immediately you'd better not try again. If you crank and crank and it finally fires off, that fuel in the chamber will detonate and the resulting backfire will bend the ride plate out of the way for the pressure to escape. Then your ride plate is leaking exhaust gas and your pump is cavetating and you can't figure out why you won't go over 10mph at 5000rpm... Then you must remove the ride plate and bend it back if you are capable, or just buy a new one for a couple hundred bucks and another fifty for a new gasket. Grasp the concept now, it will cost you $$$ later if you don't..

 

[burnrubber]

Re: Blowing up ride plate ??

Hi Tom
Thank you for the well explained definition and nature of this .

111 veiws of this "Topic" and you are the only reply?
My boat has a fan and hoses that provide fresh air to my engine compartment to clear away fumes , but it is not for the fumes trapped in the area we are
discussing, i get that.
I wander how loud the explosion could be , is it like a car backfiring or more of a gun shot type of blast.
Also , i read an older post relating to this , and he implied that a garden hose hooked up could stop the detionation problem,
but i know gasses can still ignite under water so ime not sure if the running water thing is a guaranteed stop for this or
if it still can go boom ?
Winter is taking hold here, water is geting coooold , fish are biting good but i sure miss that warm swimming water !
Happy boating

 

[smclear]

Re: Blowing up ride plate ??

You might want to consider posting your question here;

http://www.greenhulk.net/forums/

Greenhulk is a forum dedicated to personal watercraft. The folks on here are absolutely great and most really do know their stuff. But they are predominately focused on boating, not pwc's. In fact, pwc's are looked down upon by a high % of folks here.

 

[Painlesstom]

Re: Blowing up ride plate ??

I would sound like a muffled pop, like popping a bread bag in the next room through a closed door. Using the dealer flush kit would prevent this from happening, it adapts a garden hose to the hose fitting on the base of the motor / pump plate, NOT the little fitting on the top of the thermostat housing! It's a tricky kind of situation as you cannot use full pressure from the hose or you could force water past old gaskets and fill your motor. The jet pump doesn't provide allot water pressure for cooling, lots of volume. So while holding your hose aimed in the air the water should only come out a couple inches high in it's stream. I built a shut off valve that adapts the water hose to the inlet hose, this allows me to turn the spigot on enough to set the flow then I close the shut off valve I made, hook it up to the pump hose and turn the water back on from my valve. Then I can start the motor and not worry about a thing. Just be sure to turn the water on BEFORE you start the motor or you just defeated the purpose of doing it all, just remember no pressure. So now that the water is on and the motor is running, make sure you don't rev past 2000 rpm. There is enough water to keep things cool up to a high idle but revving without load is bad on these motors, your steering and drive cables run through the exhaust chamber and while out of the water can be prone to heat damage. you can also look under the boat at the ride plate and if you see any water dripping out around the where the ride plate and the hull or the intake grate meet then you have things to fix, Water should ONLY come out at the rear of the ride plate and behind the intake grate.

I've spent hours reading about sportjets on here when I first got mine and found allot of invaluable information, It appears though that all of those helpful people have moved on. These sportjet boats got a bad rap because of poor maintenance and people who owned them didn't understand how they worked enough to use them properly. The safest thing for these boats for the average person is to just never attempt to start it out of the water, it opens a can or worms most people don't understand or can't handle and there doesn't seem to be many marine mechanics who know much about these either. They are actually very simple, you just have to understand it's "rules".

 

[burnrubber]

Re: Blowing up ride plate ??

Great description and wisdom Tom
I am trying to get used to this unique boat. I have always had propellor boats and jet skis , but never a jet boat like this .
Only had it out 1 time ,maby 10 minutes , i knew when i bought it there was a problem in the pump so i am prepairing for the repairs needed.

Did you notice the strange but negative reply above from " smclear" ??

He seems to say nicely that we shouldent be using this site ??

I have been a member of green hulk for years and i like being a member here too.

There is room here for all of us and it isint hurting him one bit . Weird comment from him.

 

[Painlesstom]

Re: Blowing up ride plate ??

I believe smclear was simply stating the obvious about what kind of help to expect around here for pwc. I've noticed that not many people post anything that helpful in that department anymore around here and this forum is mainly used by boaters with "real" boats. Our boats aren't popular, you don't see them in allot of driveways and I doubt I'll ever see one on the water with me. They are like Harley Davidsons Buell sportbike... It's not a sportbike and it's not a Harley.. kind of a bastard bike that doesnt' fit in anywhere well but it is a blast to ride and has a small following... We don't have a jetski but it's not a full fledged boat either and is again something in between that most people aren't going to like or know much about... So he was just trying to point you to a place that could potentially show more support for this type of craft. But, if you search the pwc section for sport jet, you will have many old posts with solved problems that you can learn allot from. Hours of education there so enjoy.

 

[e-spin]

Re: Blowing up ride plate ??

Not a proud moment for me, but I can assure you that it is possible, even likely, that you will eventually blow your ride plate up, with a spectacular ,4th of July worthy, BANG!. Brought the wife up from the far end of the house to see how dumb ***** had bought it. I have yet to assess the total damage, but I was able to observe the front of the plate hanging down about an inch and the seal just hanging there. My hope is that I can remove and straighten the plate and save the seal. Obviously I was part of the crowd that found the whole premise at least unlikely. Where does all that back pressure come from!!!

 

[emoney]

Re: Blowing up ride plate ??

e-spin, thanks for sharing that. I think there are a LOT of people who don't believe the whole "Don't start your jet out of water" advice, so you're not alone. Hopefully, your repair will be painless and not very expensive. Anything spent on a mistake is a hard lesson to learn but by sharing it "with the group", maybe someone else will be able to avoid the same. Again, thanks.

 

[Daley]

Re: Blowing up ride plate ??

I too made the same progression as many when I bought my boat. I figured that it's so simple, nothing could go wrong - quite the mistake on my part! After spending a considerable amount of time here, learning from knowledgeable helpful folks, I'm confident that I at least understand the 'whats' and 'whys' of my sportjet. To answer e-spin's question about where the backpressure comes from, consider the fact that when the boat is in the water, the jet cavity is filled with water - therefore there's no way for fumes to build up in there. When sitting on the trailer, that cavity is filled with air. Starting out of water, the cavity fills with un-burned fuel, and being a 2-stroke that fuel *will* ignite. This ignition has little room to escape through the intake grate (and even less out the jet nozzle), so the force of the resulting explosion has to do something to make room for the rapid expansion of gasses - so it MAKES room - by forcibly moving things out of the way. The weakest link here is the ride-plate, so we end up with stripped bolt-holes, bent ride-plate, damaged gasket, unhappy neighbors and money spent on repairs vs. fun on the lake.

I get the feeling that people don't like 'em because, as Tom so eloquently pointed out, it's somewhat of a hybrid - not as popular as a full-fledged boat or a real PWC. His very accurate analogy clearly illustrates the small following these boats carry, and with that comes a limited understanding (and therefore limited acceptance).

Don't get me wrong - I *love* my SJ! It's a blast on the water, easy as heck to maintain/store/trailer, and doesn't cost an arm and three left legs. I consider myself fairly mechanically-inclined, so fixing things is relatively simple. The only problems I've run into are the things I didn't know or understand, and the assumptions I made due to that lack of knowledge. Now that I've read the informative posts of others with experience (both professional and driveway-mechanics), I know more of the "rules" - and I follow 'em. That equates to less money spent on repairs and more time on the water.

It's a great little boat. Understand its little quirks and unique requirements, and it'll give you plenty of fun on the water!

 

[slag]

Re: Blowing up ride plate ??

Still don't believe it. Owned over 20 jetskis/seadoos/tigersharks, you name it over the course of 7-8 years and never had it happen. The backside of where the rideplate is sealed to is open air. Any blast would blow out the back end and there wouldn't be that much unburnt fuel to create an explosion to begin with.

 

[Painlesstom]

Re: Blowing up ride plate ??

Still don't believe it. Owned over 20 jetskis/seadoos/tigersharks, you name it over the course of 7-8 years and never had it happen. The backside of where the rideplate is sealed to is open air. Any blast would blow out the back end and there wouldn't be that much unburnt fuel to create an explosion to begin with.

You don't have to believe it, it's a proven fact that has been experienced by many that own a SportJet. The backside of "our" rideplates are NOT open to the air like you think. The rideplate is really the part that completes the "muffler" on these boats, any blast will, and has, blown the ride plate away from the hull. It isn't a matter of believing, own a SportJet and don't follow the rules.. You'll see, Murphy's law applies to everyone. lol

 

[aksor]

Re: Blowing up ride plate ??

There is always non believers till it happens to them! If your lucky it will just bend your ride plate, else it will blow it right off and it can also damage your fiberglass hull.

 

[e-spin]

Re: Blowing up ride plate ??

A picture is worth a thousand words!

The good news is that the mounting hardware looks ok (not stripped) but the Lube (fill/drain) cap and hardware went for a ride. Hoping it can move without damage but haven't removed ride plate to see.

 

[slag]

Re: Blowing up ride plate ??

You don't have to believe it, it's a proven fact that has been experienced by many that own a SportJet. The backside of "our" rideplates are NOT open to the air like you think. The rideplate is really the part that completes the "muffler" on these boats, any blast will, and has, blown the ride plate away from the hull. It isn't a matter of believing, own a SportJet and don't follow the rules.. You'll see, Murphy's law applies to everyone. lol

Well, stupid me, thats what I get for not reading the entire posts. I didn't see that this was a sport jet only phenomenon. Sorry for the misunderstanding.

 

[aksor]

Re: Blowing up ride plate ??

That looks exactly like my rideplate when i bought my boat a few 2x4 pieces and a mallet straithened it right out.

 

[e-spin]

Re: Blowing up ride plate ??

Just an update
1) replaced the stater, This needed to be done when I realized output to Battery was and must have been low. Old stator had several, what I assume were shorted winding Jumped to by pass them.( glad I replaced stator)
2) removed blown up ride plate, still bent, but waiting for running engine before attempting to straighten and replace ride plate, in case it blows up again.
3)Have battery checked and charged since starter is not turning well and while there are feeble starting sounds I am way out of turning speed check.
4) remove starter and open case. Magnet inside are broken and broken parts loose(These are fairly large loose pieces(2"x2"))
5) I have 4 partial starters(2 from the neighbor) one may have magnets in tact otherwise I'm SOL. Seems like I have plenty of good bendix units now. The cheap one I bought (with the broken magnets) always had POS bendix units and it was all I could do to get one to work. Now , thanks to my neighbor, I think I have at least 2 very good ones.

My next move is to try to cobble together a starter and get it mounted. Assuming it's turning good I will be back to my original problem
Which was very low RPMs and a intermittent spark on 3 problem. Kinda hoping that a fully charged battery may solve some of this, since I think there is a good chance that the battery had gotten depleted over time since charging has been flaky forever and I didn't ness.charge it since I assumed it was getting charged. Any way, once I get the engine running I will try to straighten the ride plate and replace it.

 

[smclear]

Re: Blowing up ride plate ??

I believe smclear was simply stating the obvious about what kind of help to expect around here for pwc.

This is exactly my point.

@ Burnrubber


"He seems to say nicely that we shouldent be using this site ??"

I said nothing like that, I just stated you might have better luck posting this question on a forum that is dedicated to jets

"I have been a member of green hulk for years and i like being a member here too."

So have I. Great people on both sites.

"There is room here for all of us and it isint hurting him one bit . Weird comment from him. "

Is it weird that I try to steer you in a direction that could provide more responses to your question?

 

[Anders67]

Re: Blowing up ride plate ??

Once mine ingnited fumes after the cyl. exhau. ports.

It sound like a 12 gauge shotgun, but it did not bend something.


But it was loud !!!!!



Regards. Anders

 

[Painlesstom]

Re: Blowing up ride plate ??

Once mine ingnited fumes after the cyl. exhau. ports.

It sound like a 12 gauge shotgun, but it did not bend something.


But it was loud !!!!!



Reards. Anders

And this happened on a Sportjet?