Super Jet Superjet Running hot

[Vumad]

My build thread is in my sig. I use my SJ for surf, flat and racing. It's not set up for any one thing. I just changed it from all stock to fully limited.

I have a 2004 SJ stock motor, FPP pipe SJ manifold Kawi headpipe limited SJ chamber (top and middle closed, bottom open, can't adjust it), girdled head 180 psi, stock carbs jetted to spec, dual stage carbon reeds, reed stuffers, lightened stock flywheel, jetwork blue FCV (most open setting), MSD enhancer rev set at 8000, stator I think is still in stock position right about middle of available adjustment, various unrelated handling mods.

Cooling was as follows. Pump to manifold. Front line off head Tee to stinger. Back line on head to bottom of pipe. Front of pipe line connected to the other line from the head with a T (only one ADA pisser). Boat moved tons of water, threw it like 5' off the boat. Boat ran great through the RPM, 48mph on GPS in 1/4-1/2 mi drags, plugs nice brown color, no issues. No tach (have one now) so have GPS speed but no RPM.

Next ride I set up a small bouy course and got on it, maybe 1/4 mile track, about 4 laps. Came in to check, vapor rolled off the head, head pipe and chamber, not off waterbox. Hard sizzle on the 3 bolts that hold the head pipe to the manifold. No other sizzle.

Too hot, today I changed from 1 pisser to 2. Same cooling except the 2 lines don't rejoin, they get their own pissers. Water now thrown about 2-2.5' from boat from each pisser. Only rode a short bit, noted exhaust leak, I assume the other day I either split a weld or melted the coupler.

Everyone I have spoke to says single cooling should be enough for my boat. Jetmaniac, Xscream, various others, single cooling should be sufficient. What could be wrong with my boat? I am going to pull the stuff and find the exhaust leak. Hoping to resolve the issue while everything is out.

Any ideas? Is single cooling sufficient? Or is it only because most people are freeriders and single cooling is insufficient for extended WOT and racing. If I go to dual, should I do dual cooling or parallel. Help is appreciated. Probably going to end up switching to dual cooling but I don't want to mask a problem or over cool and damage something important.

Thanks

 

[ProSouth]

got access to a digital thermometer? like an infrared one that you point at something and it tells you the temp? so you can tell the temp differences between the exhaust and engine. was your b pipe used? theres an elbow that some people claim gets blocked, but dont think it would flow like your talking. when you had the head off to install ADA was everything corroded in there or look like a freshwater boat? just throwing out obvious dumb questions but... im kind of at a loss

 

[Vumad]

got access to a digital thermometer? like an infrared one that you point at something and it tells you the temp? so you can tell the temp differences between the exhaust and engine. was your b pipe used? theres an elbow that some people claim gets blocked, but dont think it would flow like your talking. when you had the head off to install ADA was everything corroded in there or look like a freshwater boat? just throwing out obvious dumb questions but... im kind of at a loss

My digital thermometer died (battery, cheaper to buy a new thermometer, lol). I'll have to get a new one. It was definately too hot if steam can roll off the head. My B-pipe was used, i've had it on my X2 for a few years. I know it's not blocked in the cooling passages, but I suppose it could be possible the bottom injection hole got blocked a little with the new paint. I'll check that. There was corrosion inside my motor but it wasn't bad.

I wonder if it has to do with the temps here. The air is 90* and the water is no less than 80*. JM and XS are both down here, but I don't think either of them race is lakes so shallow. Water is several degrees (like 10) warmer than most other bodies around here.

 

[tor*p*do]

go to a smaller restrictor?
if you are moving "a ton of water", there may not be enough dwell time to
properly transfer away the heat.
If the water flow in the motor is turbulent (hi velocity), heat transfer is far lower than if it is laminar (smooth, slower flow)
Also if you have single cooling, you should only run 1 pisser
1 inlet = 1 outlet

 

[tshank123]

Was this running cooler at one point, or is this a new build and you're not sure if this is normal or not. If this just showed up one day, I would be checking my line from the pump and make sure there is no blockage anywhere. If this is a new build, I would run dual cooling, but thats me.

 

[Vumad]

go to a smaller restrictor?
if you are moving "a ton of water", there may not be enough dwell time to
properly transfer away the heat.
If the water flow in the motor is turbulent (hi velocity), heat transfer is far lower than if it is laminar (smooth, slower flow)
Also if you have single cooling, you should only run 1 pisser
1 inlet = 1 outlet

I was running a single outlet. No restricters. The front of the cylinder combined with the exit from the pipe (which was fed from the rear cylinder) on a T, then exited a single 8mm ADA pisser. I added the second pisser yesterday (front of head to pisser/stinger, rear of head to pipe then pisser), but I was unable to test since I had an exhaust leake. I'm heading out now to check for the leak, I'm assuming it's from the coupler.

Was this running cooler at one point, or is this a new build and you're not sure if this is normal or not. If this just showed up one day, I would be checking my line from the pump and make sure there is no blockage anywhere. If this is a new build, I would run dual cooling, but thats me.

It was all stock. I just put all of the mods on it at once. It has only been in the water a few times since. The time it over heated was the 1st time I was really racing around with it. Previous times, I had only held it WOT for about 15 seconds.

Any chance this could be a timing issue? I think my timing is factory with a MSD ignition. I did not move my stator and I am guessing the 1st owner did not either. It was right in the middle of the available adjustment.

My computer was acting up earlier but is working fine now. Here's a pic when I took the stock head off. There was some corrosion in the jacket but nothing serous.

 

[Vumad]

Chuckie of team scream (Supertune here) said it was because I had 2 lines going from the head but only one of those went to the pipe. Single cooling should have one line from the head to the pipe, then one pisser after the pipe. He said that stole too much cooling from the pipe. He told me that I should have had the 2 fittings on my ADA head T or Y back together and both feed the pipe, then from the pipe to the one pisser/stinger.

Basically, I had a single cooling supply with a dual cooling discharge. The pipe overheating made everything else over heat.

I'm willing to accept this as an answer. Everything else seems perfect, it's a reasonable explanation and no one else has provided any other cause. Besides, Chuckie has a pretty good rep for knowing his .

My pump and manifold are now tapped for dual cooling, but I don't want to lose my stock bilge, so I'm not sure if I just want to plug the pump tap, Y them together and just increase the pressure through the one line, or just do dual cooling and give up the siphon bilge. Something about giving up that stock insurance policy concerns me.

 

[ProSouth]

awesome. glad you found the problem and an easy solution.

 

[Poizen]

two fitting on the head one t pipe and one to pisser on single cooling wont make run super hot

thats how mine is set up and its not even sizzleing yet need to heat it up more

what i do have tho is a valve tap on the 2nd head fitting to restrict the water

 

[tshank123]

You can still run the siphon bilge and add a cooling line. Its not real difficult. Dual cooling is the solution!

 

[Vumad]

two fitting on the head one t pipe and one to pisser on single cooling wont make run super hot

thats how mine is set up and its not even sizzleing yet need to heat it up more

what i do have tho is a valve tap on the 2nd head fitting to restrict the water

But are you running in 90 degree water with a 90 degree air temp? In either case, you are still sending a lot more water to the pipe than I was. Wish you would have mentioned that sooner. A number of people mentioned 2 pissers, no one mentioned running restrictors. I knew better. It's my fault

You can still run the siphon bilge and add a cooling line. Its not real difficult. Dual cooling is the solution!

How? The only way I know is to add a 3rd line, and that is not happening. My hull is minty. I plan to keep it that way. It's dual cooling with 2 electric bilges or single cooling with one electric one siphon.

 

[Poizen]

But are you running in 90 degree water with a 90 degree air temp? In either case, you are still sending a lot more water to the pipe than I was. Wish you would have mentioned that sooner. A number of people mentioned 2 pissers, no one mentioned running restrictors. I knew better. It's my fault

by 90deg do you mean deg F because if you do thats roughly 32deg C i live in Africa we get up to 40deg C or 104deg F regular on a summers day even some winters


but yes single line cooling is fine for you just put a tap gate in you 2nd pisser line that way you can control the flow less or more quick and easy this is what i did

you can see just below my tank water trap is the valve its just a normal stainless ball valve with custom made handle

 

[tshank123]

How? The only way I know is to add a 3rd line, and that is not happening. My hull is minty. I plan to keep it that way. It's dual cooling with 2 electric bilges or single cooling with one electric one siphon.

You would have to run a 3rd line, which is pretty easy, but if your not willing to drill a hole in it then you cant do it.

 

[jeff32]

I hate when things dont run