New member needs help with exhaust water injection

I have a 2000 kawasaki zxi1100 pwc that Ive swapped a 1992 honda cbr600f2 engine and transmission into. It is up and running , connected to stock jet pump drive via a 3 ujoint drive shaft with carrier bearings and safety loops. Im almost done with it. The exhaust Im making it too complicated I think. Do I inject water into the exhaust to help cool it and keep the temps down or do I in case the manifold pipe and seal it and have water being pumped through it and out to a water box before exiting the hull? Truing to find out the strategy behind this is proving to be quite difficult. If I inject water into each primary tube of the exhaust how much water do I have it solenoid controlled by a thermostat? Or could I just have it plumbed out of the bike motor cooling ports through the exhaust I don't know I'm very eager for some input from the pros here. My header pipe is a crude mock up for proof of concept at the moment. I can upload pics if needed.

 

Pics needed, old and new, focused on exhaust system.
Do I understand that you have put a motorcycle engine into a jet ski?
And gone down to nearly half the displacement of the original?
My advice would be to mimic the original exhaust system’s configuration.

 

Do PWC's use a dry sump to enable the oil pump to provide oil at all attitudes of running? I am assuming a wet sump on the Honda as Wiki said that on one model they increased the depth of the sump.
Just curious as to constant oil pressure with the severe operating attitudes that PWC's often operate.

As the engine is enclosed, you should find a way to cool the exhaust manifolds which normally done with a water jacket as
1) you cannot risk injecting water anywhere near the exhaust valves, a sudden stall, back fire etc could cause water to go directly into the cylinder
2) you do not want to risk the high temperature in the engine enclosure from the manifolds.

On larger inboard/jets/props the riser and manifold are normally water jacket cooled ( unless bobtail/open engine mount) and the cooling water injected into the exhaust is done after the apex of the riser, normally just before the exhaust pipe/hose. One to keep the hose from starting a fire, ( a story here but omitted) in the hose as well as cooling the exhaust gas.

 

What kind of heat exchanger have you installed?

 

How did you go with this mate? There would be more than a few challenges to overcome, with possibly the hardest being turning the impeller fast enough.

 

Kawasaki R&D spends a great deal of time and money to design a product that is well engineered to perform the job it is intended to do….
Does the motorcycle engine have some advantages over the stock motor?