IS THIS ROTARY VALVE BAD??

[mejim707]

By the way in your other thread, that Rotary needs replacing and the surface on the engine said isn't all that bad. Good Luck.

Thanks for all the replies! I will be replacing the RV this Friday. I have a brand new one coming from SBT woohoo!

Honestly, I much rather working on the boat than a ski because of the space. The only issue is hanging upside down lol

But once I figure out this water issue, this boat with be a thing of perfection. I can't get over how often people come up and compliment the boat. It's a pretty sweet whip.

I'm going to pull the regulator off this afternoon and inspect it and rebuild it. I'll also check the fittings.

 

[etemplet]

Honestly, I much rather working on the boat than a ski because of the space. The only issue is hanging upside down lol

Exactly... that's PAINFUL !!

 

[mikidymac]

Low compression and too much rotary clearance will both make it really hard to start in the water with any backpressure on the exhaust but perfectly fine out of the water.

 

[mejim707]

Low compression and too much rotary clearance will both make it really hard to start in the water with any backpressure on the exhaust but perfectly fine out of the water.

True, but the cooling lines are causing this. And those shouldn't back pressure the engine right? Of course if the exhaust is filling with water then it will, and it will prevent starting.

The RV clearance is .0125 and the compression is 140 in both cylinders and it will start up when I clamp the water line coming form the pump.

So, since nobody has said otherwise, it seems that it's normal for the water flow regulator valve to pour water into the resonator. I have the regulator apart and it seems to be in perfect condition. But I don't think it seems right that the exhaust is filling with water but I'm not an expert and since nobody has said otherwise, this seems normal then.

 

[mejim707]

These are the hoses I need to pinch off to start when warm in water. I hear no signs of water pouring into the resonator until the boat has been run for a while then I shut it off. At the point I hear water pouring into the resonator as clear as day until I pinch off these hoses.

 

[mikidymac]

Given the excessive amount of hose in your picture from the pump I am sure that is intended to be routed up high so that water can't flow into the engine/exhaust with the boat in the water.

I would also assume that at idle the boats sit lower in the water than the skis and can push water from the lake into the engine whereas the skis the pump is partially out of the water at idle.

 

[Pedec]

My 97 xp kinda acts the same. If I leave it sit to long I need to hold throttle wide open for 5 -10 seconds to start sometimes. I contribute my problem to leaking needle and seat in carb I think. If I shut off hot it start right up in first min but 5-10 min need to hold wide open and crank a lot but does start. Maybe I have same problem as you. I have never listen for leaking water into exhaust or thought that could be the problem.

 

[TheYeti]

Sub'd for future reference if needed. Ya know, just in case. Good on ya for keep on it. It had me reading through the thread curiously

 

[Jtamaro]

I figured out my starting issue on water when hot!!!!!!!

The water regulator was allowing water to dribble into the resonator. And the main hose from the pump was also contributing.

A guy got stuck at the dock, and since I couldn't start the boat I was stuck with him blocked in. I took that time to track down the dribbling sound. I had hose clamps with me so I clamped off both the water regulator water hoses as well as the main water hose from the pump.

I then was like, screw it lets try to start with the hose clamps on and sure enough it fired up with no issues whatsoever! It was absolutely refusing to start the entire time until I clamped off those hoses and it fired up instantly!!! Of course I immediately shut it off since I wasn't going to run without water circulating. I took the clamps off and it fired up without issue!

I figured out why it wasn't starting! Now, I need to figure out why these hoses are causing this.

QUESTIONS:
Is the water regulator supposed to dribble water into the resonator while the boat sits?
Is the main water hose supposed to be held up and not laying in the hull?
Is there some valve or anything that should prevent water from bogging the exhaust out when sitting in water?

Any advice on how the hoses are supposed to be routed or if they're supposed to be elevated would be great. But at least now I know the cause!

I'm sooo stoked man you have no idea. I've been fighting with this issue for a very long time!

Glad you nailed it!

 

[mejim707]

Given the excessive amount of hose in your picture from the pump I am sure that is intended to be routed up high so that water can't flow into the engine/exhaust with the boat in the water.

I would also assume that at idle the boats sit lower in the water than the skis and can push water from the lake into the engine whereas the skis the pump is partially out of the water at idle.

I rerouted all the hoses and tied them in high loops. Looks a lot cleaner!

Sadly this didn't 100% resolve the issue as water still pours into the resonator. But, after spending time with it since, the water seems to be draining into the resonator back form the exhaust, through the head, into the lower hose on the water valve. So it's not actually coming in from the outside, it's draining from the exhaust through the head.

I'm not sure how to resolve that but this suggests there's a blockage somewhere else where the path of least resistance for the water to drain is back through the head into the resonator.

Is there a different place that the water should drain through form upper exhaust pipe instead of back through the head into the resonator?

I do see plenty of water draining out of the tail pipe through the weep hole drain from the lower drains on the cylinder cooling jackets when I take it out of water. So perhaps the cooling jackets are draining properly?

But this seems to be the only place where the upper portion of the exhaust would drain out, back through the lower drains on the cooling jackets. So if the water is instead coming back through the head into the resonator, this suggests that perhaps the cooling jacket drains are not draining freely enough?

 

[mejim707]

As an update, I did go ahead and replaced the RV with a brand new one from SBT. I ran into an issue where one of the bold holes was stripped because the previous owner used the wrong sized bolts, but I fixed that with a helicoil.

The new RV is in, everything is torqued to spec, and she purrrs! Pretty simple job to be honest.
1. Remove carbs
2. Remove RV cover
3. Mark old RV location with a sharpie
4. Remove RV and replace with the new one
5. In reverse order get everything back together torquing to spec and using Loctite where required.

Unless you have a stripped bolt, the entire job is about 30 - 40 minutes. Easy!