Information for Pro-X owners!

[hondamancbr03]

Attached pictures of what i discovered after removing the head from my Pro-X 350PV motor....Before picture shows some serious blockage through a water jacket (All jackets had this issue), most import is the jacket in the picture is the one dirrectly above the exhaust. My repair only took about 10mins and well worth the time.

Thought this was worth sharing for those with Pro-X heads.....

[hondamancbr03]

After

[danhung11]

Is that part of the casting? This is a ProX head?

[hondamancbr03]

It was casting material from the mold...It's the Pro-X supercross head. The one in the picture was the worse but they all had casting that needed to be removed.

As you can see in the picture, my coolant flow should be much improved.

[C-LEIGH RACING]

That is ok to do in that hole, but dont do it on any of the others because the flow need to be slow on the intake side of the cylinder.

What would realy be nice, would be for the coolant to enter the cylinder under the exhaust port, flow around & exit out the head over the intake area.
Neil

[hondamancbr03]

That would be ideal....I did not change the casting I only cleared the casting material that squeezes out of the mold.

I felt confident that from what I found all areas needed cleaning....I'm running a dual pass and would like to actually take advantage of its abilities.

[All250R]

cbrman, if you have an oring'd cylinder, you definitely need to design the coolant flow around the stock head gasket restrictions. If you are running a gasket, the most important jacket area to radius in the head is the one with the widest gasket opening (because its the largest hole...).

Because the outlet port is not on the intake/cool side, it is very important especially to a highly tuned engine to keep these restrictions. However, the random casting flaws left in the head obviously are not the solution to the problem. I've used epoxy in these ports pretty successfully but an experienced engine welder would know how to keep warpage down and true it if it did for a more permanent type fix.

[hondamancbr03]

All250R,
The Pro-X cylinders are O-ring style and the head is cast to concentrate the water flow in the vital area, if you look at the water jackets on the Pro-X head it looks as if it's cast the same as a stock Honda head gasket. As you can see in the pictures there were no alterations to the size of the water jacket just merely cleaning the slag that was left behind by CPI after castings so the design they actually meant to cast will work 100%.....I see no logic in leaving casting slag in place with the belief it's helping the cooling of the cylinder/water.

I have found that most manufactures that mass produce items such as cylinders and heads do not put in the attention to detail we owners do.

[All250R]

Exactly. Was just trying to help. There have been a lot of cylinders run with "upgraded" heads that screwed up this coolant flow design so I thought I'd help if I could but clearly you dont need it.

[hondamancbr03]

Thanks I appreciate it....The post was mostly for the Pro-X owners that don't realize that there is a little trimming here and there that can improve on their purchase.

[C-LEIGH RACING]

Think about this,
all those jagged edges down in the jacket, are aiding in removing heat from the aluminum casting faster.
Air cooled engine have what, cooling fins & those little jagged edges down in the water jacket are ??.

Cold absorbs heat, so all those little edges will cool faster than a flat surface of the casting & more heat will be removed right where those casting edges are located.

What you did to that head was good, dont know if I've seen any other one with that much casting blockage.
Neil

[hondamancbr03]

Neil,
Unfortunately I remember working on those air cooled heads you speak of....I don't recall a bunch of casting slag hanging off the fins to the extreme of what I showed in my picture. Are air cooled engines porous? Yes! Do they have a texture to them to aid in the cooling? Yes! I agree with you on the air cooled subject and material surface to aid in cooling but I respectfully disagree with the large jagged edges being part of a design in water jackets to aid in cooling on a water cooled bike. It's a balance of slowing the water enough to cool the area but fast enough not to stay in place to over heat the water.

If you don't like the idea of smoothing areas that are subject to heat, how do you feel about people that polish their cylinders and heads?

I'm not sure how your last message relates to the main subject of merely informing Pro-X cylinder owners of bad castings to watch for? If you read my post, I never mentioned altering the flow into other areas or smoothing any areas in an exhaust port method.

[C-LEIGH RACING]

I wasnt saying what you did to that head was wrong, it was good, because out of the Pro-x heads I've seen over the years, I dont believe I've seen one with that much blockage in the passage way over top of the exhaust port.

Far as the jagged edeges, take a small light of some kind & look down inside the cooling jacket of most any of the Pro-x casting & theres little spikes sticking up everywhere as well as those in the passage ways where the o rings lay.

I dont know what to say about a cylinder being polished on the outside, if it makes any difference or not to the cooling of that cylinder. I dont think it would change any thing & do not have any facts to say if it would or not.
I do know, it makes no difference if it is pretty or ugly if it will win a race or not & most time pretty dont win races.
We've had our tail spanked many times, by a bike look like it couldnt pull its way out of a wet paper bag. Never underestimate just by the look of something what it can do.

Monday when I go to the shop, I'll check every Pro-x head & do your mod.
Neil