pro design cool head failure

[sameltoe]

So...what do you guys run?? I guess I relly don't know, but who else makes heads? Esr?

[Jerry Hall]

So...what do you guys run?? I guess I relly don't know, but who else makes heads? Esr?

Why not just run an OEM head that has the "right" modifications done to it.  The engine does not care if it is a billet head or anodized or made of unobtanium.


The engine wants a the right shape combustion chamber with the right piston to head clearance.  It needs a volume that will give the exhaust pipe the exhaust temperature it was designed for.  The cylinder wants the head to control the coolant flowing through it in a manner that will cool the cylinder, the combustion chamber and keep the spark plug base temperature correct for long hard runs.

The engine wants a head design that will compliment the rest of the engine.  The engine does not care if the optimum head design it gets is the result of millions of dollars of research and testing or the design was purely accidental.

[udontknowme]

rk tek makes a head. never tried it though

i dont see much point in using aftermarket unless your wanting a dome profile that cant be accomplished with the oe head

if you want to chop up alot of blank inserts for experimentation then aftermarket would be handy

[rsss396]

One appeal is the o-rings cut are in the head so its a bolt on upgrade to close the very large squish on 250r motors, plus I prefer o-rings over head gaskets. Its also much easier to chuck up a coolhead dome in a lathe to cut then it is to setup a factory head on a plate.
If Pro-design would just stop putting the cooling fins on the domes and left more material for strength then they would not have the problems they sometimes have.
The lower compression heads are thinner due to more material cut away for the larger combustion area and heads that are run under frequent detonation conditions are the ones failing.
The other coolhead down side is the water passages are not sized to direct flow like the factory gasket does,so filling the water passage on the head with epoxy and sizing them like a factory head gasket is a worth while effort

[udontknowme]

http://phatheadracing.com/trx250.html
http://2strokeheads.com/

i like orings but on the other hand i never had a problem with a gasket. im sure all the aftermarket stuff will be full open design. its probly not a bad idea to 'partially' plug off the frontal area. you can see on this head the rear is open and front is pretty well plugged

[chrisr]

http://phatheadracing.com/trx250.html
http://2strokeheads.com/

I ran across the phathead racing billet heads one time on a different board.  I always wondered about them.

[etccb]

The esr head body has the passages cut to flow more to the ex side and less on the intake side. The intake side may still be larger then what some may want to see but they have addressed coolant flow on thier oring heads.

[rsss396]

http://phatheadracing.com/trx250.html
http://2strokeheads.com/

i like orings but on the other hand i never had a problem with a gasket. im sure all the aftermarket stuff will be full open design. its probly not a bad idea to 'partially' plug off the frontal area. you can see on this head the rear is open and front is pretty well plugged

Trx250r's have water inlets on the rear of the cylinder so it's best to restrict flow on the intake side and improve flow over the exhaust port where cooling is most important.

[udontknowme]

yes of course. i didnt take into consideration the water path. the pic shown water goes through the case and to the exh bottom very first thing then to cylinder rear. 250r sounds like the opposite

[udontknowme]

i never seen this kind of insert before. looks like some sort of copper or brass alloy mixture. does anybody know of it ?