1988 waverunner 500 overheating

[bashr52]

I recently bought an 88 waverunner and have had nothing but issues with it. After almost sinking due to a cracked intake grate, water in the tank, fuel pump going bad, etc I pulled the engine. I went through and replaced all the gaskets, had the head milled .03, installed a set of power reeds, ported and smoothed the factory exhaust, and converted to a new SBN carb with a primer setup. The engine runs like a top now, but overheats after only a minute of running it. I've been trying to tune the carb with the thing backed into the water on the trailer, and I can't even get it off the trailer! I am getting a good stream of water from the pump, and I installed a pisser in the wash port, and there is a good stream coming from that, even at idle. Somehow water is not being circulated. I did pull the enigine again, strip it down, and flush/blow out all the water passages and verify everything is free and clear. When I was actually able to ride it before the teardown, it never had an issue with getting hot. I could run it for 20 minutes or so and still be able to hold my hand on the head. Now after only a minute or so of it idling on the trailer inthe water, its so hot water will boil instantly if it touches the head.

I pulled the pump hose off the engine, and hooked up a temporary line to the inlet and blew air through it. I can hear it bubbling what water is left in the water box, so I know it is passing through with no obstructions. I'm at a loss at what to do next

[bashr52]

Re: 1988 waverunner 500 overheating

I think I may be on to something. I pulled off the exhaust hose to the water box, thinking that perhaps there was an obstruction in there causing extra back pressure on the system. First there was only a little water coming out, then the flow picked up to a decent stream. Head was still getting hot, so on a whim I felt the water flowing out the exhaust. It was as cool as the water going in! It appears what is happening is the water is simply bypassing the head/cylinders, and just exiting out the exhaust. Now the question is, why and where could it be crossing paths?