SX/SXi/SXi Pro Maiden voyage....not so good.......

[Jpass]

I took my new ski out last Saturday for the first time. It's a '91 650sx. I had a great time for the first 20 minutes until I decided to see what it was like to stop in the middle of the lake and then get back on. When I got back on, she wouldn't start. My buddy had to tow me back to the ramp.

We jumped it and she fired right up. I rode close by in case she died again. Good thing, 5 minutes into my second attempt the ski bogged and could only muster 3mph at WOT. Anything less than WOT would cause the ski to almost stall.

When I got back to the ramp the ski was smoking and I immediately removed the hood. I found the cooling line to the stinger from the head was melted off (the exposed nipple was the source of the smoke). The stinger was extremely hot to the point water from my hands was sizzling on contact with the pipe.

I had to replace the cooling line from the head to stinger, from the exhaust manifold to pisser, and the bilge line.

I have a question: In the pics you can see the way the stock tubing was routed (white tubing is replacement line). The owner added additional cooling to the rear cylinder head. This tubing hits a tee prior to turning 90 degrees to go down into the stinger while the fluid going straight thru the tee goes straight out the pisser. There was also a 1.5 seat just before the stinger nipple to reduce flow.

Wouldn't the water take the path of least resistance having the majority of the water go straight thru the tee and out the pisser as opposed to hanging a right and passing thru a restrictor and then into the stinger??? Is there a vacuum on the stinger that helps pull the water into it or does it create considerable back pressure that only adds in preventing water to make the turn at the tee?

See pics and thanks for the help.

 

[Jpass]

anyone?

 

[ger87410]

I'd route all the water from the head straight to the stinger and get rid of the tee.

 

[Jpass]

I'd route all the water from the head straight to the stinger and get rid of the tee.

I was thinking of removing the tee and adding a "Y" fitting to help evenly distribute the water flow.

Does anyone know if the pressure at the stinger nipple is negative or positive?

 

[ger87410]

Why are you hell bent on distributing the water across the stinger and a pisser? U think there's too much water flow for the stinger to handle?

I'd bet there's a negative pressure at the nipple.

Using a Y instead of a tee isn't going to do much. A simple test for this is to swap the pisser and stinger lines at the tee and test again. I'll bet you have the same problem. Either that or you'll fix it.
:haha:

 

[Jpass]

Why are you hell bent on distributing the water across the stinger and a pisser? U think there's too much water flow for the stinger to handle?

I'd bet there's a negative pressure at the nipple.

Using a Y instead of a tee isn't going to do much. A simple test for this is to swap the pisser and stinger lines at the tee and test again. I'll bet you have the same problem. Either that or you'll fix it.
:haha:

I'm not hell bent on anything. The ski was set-up this way from a very reputable shop. I simply want to keep the hose routing the same until I prove the system won't work the way it was plumbed. There was also a 1.5 seat inside the hose going to the stinger which may have reduced the flow to the point where there was insufficient flow at anything lower than WOT to cool the stinger enough to avoid heating up the stinger to the point it could melt hoses.

Since changing the hoses, I have not re-installed the resitrictor. I am taking it out tomorrow for a test run to see if the stinger gets too hot again.

I was also told by the mechanic that the ski needed the dual cooling at the heads because it ran a little hot.

Being that I have only had this a week and none of the intake or exhaust is stock, I am asking questions to see what my options are. My stock '88 has completely different cooling lines compared to this '91.

 

[ger87410]

I had about the same thing happen to me with my 550. My engine would overheat with the cooling lines setup how I got them. I was told it was setup by the best mechanic in the state.

I redid the lines how I thought they should be (with suggestions of course) and haven't had the slightest problem with overheating since.

Don't be afraid to change your setup from the way you got it.

I'm not sure why there's even a restrictor in that line anyways. Doesn't make sense to me.

 

[Jpass]

I had about the same thing happen to me with my 550. My engine would overheat with the cooling lines setup how I got them. I was told it was setup by the best mechanic in the state.

I redid the lines how I thought they should be (with suggestions of course) and haven't had the slightest problem with overheating since.

Don't be afraid to change your setup from the way you got it.

I'm not sure why there's even a restrictor in that line anyways. Doesn't make sense to me.

I agree. I am solely thinking about fluid dynamics and flow in regards to keeping this thing cool. My thinking is the tee is causing too much back pressure to have adequate flow to the tip of the stinger. At WOT this is probably not an issue, but I don't always ride it WOT. By removing the restrictor and adding a "Y" further upstream to make the split lines equal lengths to improve flow would help out greatly IMO????

It is a Mariner exhaust system. I do not know anything about it other than it's name. Not sure if it is a dry pipe or a wet pipe. I am assuming it is a wet pipe. I am concerned that if I remove the pisser line, than too much water will be in the stinger causing me to either lose performance or it may fill the exhaust too quickly possibly going back into the cylinders.

Keep in mind the ski is still on trial and if the cooling issue can not be cured, the owner will be taking it back. I want to run my changes by the mechanic who set it up, that way he doesn't blame me for any damage that may be caused by changing the cooling lines.

 

[ger87410]

I got a mariner on my 550. We eliminated the waterline going straight to the stinger without any problems. Now all my water dumps straight into the pipe or out the pisser.

Don't worry as much about waterflow efficiency. As long as there's good flow, the heat should be taken care of.

I don't think you can dump enough water from the engine cooling jacket into the exhaust to cause the water to backup and flood the engine. Maybe if you dump ALL the water into the exhaust and none out the pisser, but I'm not even sure then.

I don't buy the line about *needing* dual cooling. Dual cooling is almost always for reliability. It didn't sound to me like your ski was that modified.

 

[Jpass]

I got a mariner on my 550. We eliminated the waterline going straight to the stinger without any problems. Now all my water dumps straight into the pipe or out the pisser.

Don't worry as much about waterflow efficiency. As long as there's good flow, the heat should be taken care of.

I don't think you can dump enough water from the engine cooling jacket into the exhaust to cause the water to backup and flood the engine. Maybe if you dump ALL the water into the exhaust and none out the pisser, but I'm not even sure then.

I don't buy the line about *needing* dual cooling. Dual cooling is almost always for reliability. It didn't sound to me like your ski was that modified.

I know the entire engine has been rebuilt, but I have no idea, if anything, of what was done to the inside of it. I do know the carb is a 44mm with a Mariner intake. I also know the exhaust is not stock as well.

If you could post a pic of your exhaust system and cooling lines that would be great.

I was told it heated up quite a bit without the additional cooling, which is why it was added. If I were to restrict anything I would think I would put the resrictor on the pisser tube and not the stinger, but I am simply using logic and a little guessing.

I will add the "Y" and reroute the lines so they are more equal and see how she runs this weekend. If she is still hot, I will rstrict the flow to the second pisser to force more water into the stinger.

 

[madscientist]

how many water lines are going into the motor from the pump?

2 many exits and not enough going in.

 

[Jpass]

how many water lines are going into the motor from the pump?

2 many exits and not enough going in.

I think there are two. There is a new fitting on the left side of the pump.

I am going to put the restrictor just before the pisser to get more back pressure to feed the stinger. I'm taking it out tomorrow morning. I'll let you know how it goes.

 

[ger87410]

If you could post a pic of your exhaust system and cooling lines that would be great.

It's all torn apart and won't be back together till the weekend. Mine is like yours, but without the stinger line.

Oh, and no restrictors.

 

[Jpass]

It's all torn apart and won't be back together till the weekend. Mine is like yours, but without the stinger line.

Oh, and no restrictors.

I only put the restrictor back in cause it got a little warmer than I would have liked after about 5 minutes on the hose. A lot of water was coming out the pisser.

Like u said, I can't put too much water into the stinger.

 

[ger87410]

That's a very long time to be running your ski on the hose. There's a bearing that uses the water the craft is sitting in to keep cool. I forget the name.

 

[Jpass]

Today went just as bad. Ran it five minutes and checked the exhaust. It was HOT HOT HOT. I removed the line from the rear cylinder that went off the Tee to the pisser. So only the stock pisser hooked up with rear cylinder routed straight to stinger. Still ran hot. I put the restrictor in the pisser line from the manifold. This helped cool it further, but there's no way this is correct.

I will have to check and see if the lines are obstructed from the pump. Any other ideas of where to look?

I'll post pics in a bit.

 

[Jpass]

I removed the the ride plate and blew out all the cooling lines from the pump. Very small amount of sand (maybe 1/4 tsp). I also attached photos of the new plumbing that kept it coolest.

There's got to be a better way.

 

[sflsurfrider]

too much water going to the stinger will kill whatever bottom end snap you would otherwise have.

 

[WFO Speedracer]

You have something seriously wrong there if you are overheating with dual cooling.Better go back to the drawing board on that one,forget the fluid dynamics,its all about pressure and flow mostly flow,trying to get all fancy on the cooling lines will bite you in the arse every time.

 

[ger87410]

Could you be running lean?

What's your plugs look like?