500 KX500 PF


Staff member
I know that some people might think that I am doing R+D for free and getting ripped off. I don't see it that way. My motivation is to get the part I need, and I am getting help from Jerry with the laser cut pieces. Also, I'm not going to go into business to sell this new part, so I might as well share the idea and the possibility of Jerry making it for sale to help out the guys that may need this part, but lack the means to make it.


The world needs more people like that. :thumb:

It's looking good. :ride:
Now for the cooling of the beast.....

The 500 has a series cooling circuit, and the 250 is a parallel cooling circuit. I need to use the 250 system since it fits the chassis (just like stock!:busted:). I'll describe how each system flows, starting at the water pump inlet.


Water pump inlet, to wp outlet, to right side of jug, up through jug to head, out of head on the left side, to bottom of left rad, from top of left rad to top of right rad, from bottom of right rad back to the water pump inlet. This circuit is in series since the coolant flows through one radiator, then flows through the other.


Water pump inlet, to wp outlet, to rear side of jug, up through jug to head, out of head on the top rear WITH TWO OUTLETS going to the top of each rad, through both rads to the bottom of both rads, and back to the water pump inlet. This is parallel since the coolant flows through both radiators at the same time.

Just in case anyone thinks I am belittling them by spelling out the differences between series and parallel, remember that there are some people that just never knew this. It's for thier benefit. So :P.

Next post has pics!

Pics! Whoooo!

The water pump inlet manifold from the 250 is wider than the 500, from bolt-to-bolt....


So, I welded up the holes to relocate them:


Then, I milled and drilled: Note: KX500 heads seem to be a purer alloy than KX250 water manifolds, based on the way they weld. I need to fix these pits:


In order to move the bolt holes in, I needed a smaller bolt head. Hello, Allen!


The factory bolt was too fat:


Here are pics of how things will lay out. I still need to make a wye to split the coolant between the radiators for the parallel arangement I want. That wye will split the coolant flow in half between the head and the top of each radiator.




The manifold looks a little vulnerable to damage. Is there a skidplate with a wing on it for some additional protection, or is that on your list of things to build / modify?