Water passages in head gasket

I have a 2006WR450 and have recently replaced the head gasket (because new piston, rings, timing chain) and whilst fitting it noticed the water passges in the head gasket where tiny (3-4mm) compared to the water ports round the actual barrel which where elongated - if I rememebr correctly where somewhere round 6x20mm. Also the head gaskets water holes didn't quite match up with the edge of the elongated barrel water ports. Not thinking too much about it I fitted it.

I have been riding it a while now and I find that it gets hot quickly and starts boiling when riding slow (walking pace) doing technical stuff (tree stumps, rocks, tricky uphills) - even in cool 15deg C temperatures. I know that the WR is supposed to be ridden at faster speeds to get proper cooling but my mind goes back to those tiny water holes in the head gasket.

What I'm asking is - has anybody else noticed this and would it be a good idea to drill out the 'tiny' holes to an elongated slot such that it matches the barrel ports more closely - or are the head gasket holes designed especially perhaps to build pressure or to regulate a particular flow and better not mess with it?

I know one is supposed to fit a new gasket everytime when removing it - could be be used and torqued up a 2nd time ?



Cape Town

South Africa

DO NOT alter the holes in the head gasket. They are designed to control and optimize the flow of coolant through the cylinder and head. Water enters the cylinder from the pump at the bottom front of the barrel. It then flows up and through the head and out. Looking at the gasket will show that the passages in the front are small, while those in the rear are larger. This is to force the water to flow around the cylinder to the back of it, then up and over the entire head dome before exiting. If all the holes were full size, the water could "take a short cut" up the front of the jug and out without circulating any fresh. cool water around the back of the cylinder, or more importantly, the head. The small holes in front are in fact only there at all so as to release steam from under the gasket.

And, no, you absolutely should not ever reuse a gasket that has been torqued completely once. I know it's been done, but nevertheless, it's a risky game to play.

The reason it heats rapidly at very low speeds is simple: no air going over the radiators. If you want to solve that problem, the best way is to address the actual issue of air flow by either 1), going faster, or 2), install a small fan or pair of fans.

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