Super Jet 650 Superjet Overheating Need Help!

[kawa js550]

Hi, I am helping a friend get his 650 superjet to run but it keeps overheating after 5min of riding. I went through all the hoses and I know for a fact there is good water flow all the way to the pisser. The only problem is water barley or doesn't come out of the pisser when riding. Im thinking that all the water is just going to the water box and not the pisser. I do not believe it is a temp sensor because when I threw water on the motor it sizzles off right away. I checked the plugs and it doesn't seem to run lean. Do I need a flow restrictor or flow control valve? Also its pushing about 170psi and I think he is running regular, could that be the problem? Here is the picture of the pipe, I thinks its a Coffman Sizzler. I just checked the plugs again and it seems to be running pretty rich. Could that cause overheating?

 

[SteveC]

I might be blind, but I don’t see a path for water out of the head. Presumably it goes in the exhaust manifold, out the head off to the right of what is shown in the photo, and into the bottom of the head pipe. Is that right? Any chance there’s a blockage in the cylinder set limiting where water can reach? Meaning, water can flow through but not actually reach a big portion of the internal surface area. Just brainstorming...

 

[mikidymac]

As Steve said we will have to be able to see the rear of the engine and how the water gets from the head to the pipe.

 

[kawa js550]

Here is a better look at how it is routed

 

[SteveC]

If it were me, i would check the engine water path by hooking a hose up to the line from the pump. If water flows generously out the pisser and exhaust, then suspect the pump isn't getting water to the engine. If the hose trick doesn't flow nicely, step through feeding the hose water straight in at points and looking at the output flow, trying to isolate a clog. Diagnosing is hard: best wishes!

 

[kawa js550]

I just hooked it up to the hose from where it comes out of the bulkhead. Ran it on the hose for 10 min and it had good water flow and a solid stream to the pisser. I hooked the hose up to the other end (from bulkhead to pump) and was a powerful and solid stream. So what it is leading me to believe is the pump isn't picking up water good enough to the motor. Also I noticed smoke coming from the water box, so it has a exhaust leak that will need to be fixed. I thought that maybe thats why it was running like crap, but that doesn't explain the overheating and steam coming out of the exhaust when riding.

 

[kawa js550]

In the next week im going to take it to the lake and see how it does with the hood off and if it runs good then ill know it just needs a new waterbox.

 

[orangefinger]

with this set up I would run dual cooling would not be a bad idea... ( not a must ) but still not a bad idea

push water backwards from bulkhead thru pump make sure there is nothing clogged , your water will always be very hot on this set up because you are running
thru engine then into head pipe, your overboard line appears to be smaller so you are running the rest into the water box , in order to push more water overboard you should have the line going to the waterbypass overboard same size 3/8's and slightly restrict flow to waterbox .

The vent nipple is in the west coast head and oem yam heads for a reason to avoid air bubble within and allow for proper water distribution within head chambers,
if u stay with single cooling I would open that line and let that go overboard, which furthermore allows more water in.
Check your compression make sure you are running the proper octane .

 

[r6487]

at the tee I always run straight across top of tee, from headpipe to pisser and make waterbox portion make the 90 turn, and as above all lines same size.

 

[kawa js550]

Think I found the problem.... Opened up the head and had a bunch of sand and pebbles in the cylinder jacket. I covered up the cylinders and blew out all the sand and pebbles with a air hose. Also the head gasket looked like it was going bad. This should fix the problem. I already ordered dual cooling stuff so if it still runs hot I have that to help out.

 

[mbrick]

Nice find, definitely need to make sure all of the passages are clear given that much sand.

I agree with orange you may need the small vent line on the mag side of the head to be connected.

Let us know how it goes when you get it back together. With the OEM head gasket GroupK recommends checking the head bolt torque after a few hours of running to make sure its still at spec.

 

[kawa js550]

I routed all the cooling like you guys said and put it on the hose and it seemed to run pretty cool. Obviously its going to be different in the water though so we will see. If it still overheats then that means the exhaust manifold is clogged up and at that point I will just pull the motor and dual cool it.

 

[kawa js550]

Took the ski to the lake today. The thing rips, but then it got hot. Got home and pulled of the head and exhaust manifold. Exhaust manifold had sand in it just the like cylinder jug so im going to clean that out. While the manifold and head are off im tapping a second fitting just in case cleaning out all the ports doesn't work. I plan to run a T the manifold to try and even the cooling. If it still overheats then ill tap the pump and finish the dual cooling.

 

[kawa js550]

Dual cooling was the fix!