650/X-2 650 overheating, can't figure it out

[whennotsailing]

Cannot for the life of me figure out a 650sx, it runs good for 15 - 20 minutes then gets hot and only idles (I presume fuel is boiling). Get back to the ramp and let her cool and all is good again. Engine has good compression and did a leak down test on it, it held a vacuum for well over and hr without the needle moving.

Cleaned entire head, jug, exhaust, mani, etc. I found a bit of sand inside the jug and thought I for sure had the problem solved, but that was to no avail.

Ski hadn't run in years but fired right up and runs great til it gets warm. Has all the goodies on it, milled head, intake and exhuast mani, carbon fiber reeds, Coffman exhaust.

Only thing I can think of is plumbing, water is fed in through exhaust manifold through head then into head tube, (has a pisser with a bypass) from there back to waterbox. (see pics). Is it possible all the water is getting through manifold and not making it through jug thoroughly ? Flow restrictors somewhere maybe ?

Other thoughts ?

 

[rwilliamtaylor]

check your cooling lines from the pump. If you had sand in the water jacket, i bet the cooling line is plugged or partly plugged. use compressed air to blow them out.


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[stagesrt4]

if fuel is boiling then you have some serious issues

how well is ski pissing?

how long does it take to start pissing



my buddies that like to beach their skis have a tendency to clog their cooling lines with sand pretty often....

 

[stagesrt4]

just looked a pic

you should upgrade the pisser line n fitting that exits the hull

 

[Vumad]

Pisserine and fitting look normal. The blue one looks like it goes to the pisser and its a normal size. Grey one looks smaller but it goes to the stinger and is probably giving plenty considering most of us are running flow restrictors.

I'm not sure why you'd believe your gasoline is boiling. Your gas isn't even near anything hot.

Splash water onto everything when it gets real hot like that. What sizzles/boils the water? Pipe? Head? Waterbox?

If you are not steaming water off any of those parts, heat is not the issues.

Block off that crank case drain next time you have your motor out.