850 Cylinder head

Hi All,

I'm about to search a second hand 850 cylinder head. Is there one RHx better than others in terms of pure quality (no porosity, no weak point...) not performance?

Thks for your help,

Laurent

laurentdom said:

Hi All,

I'm about to search a second hand 850 cylinder head. Is there one RHx better than others in terms of pure quality (no porosity, no weak point...) not performance?

Thks for your help,

Laurent

Click to expand...

RH10

RH10 has better inlet guide support, as for porosity that is still a lottery with all 850 heads. Sellers know the RH10 is preferred so expect the pricing to reflect this.

I use RH 10 .
But nothing wrong with using the RH 4 850 head .
Just don't get too experimental with it .
Enjoy .

Thks gents. I'll focus first on RH10.

found this:
"In the Norton Commando article in December 2006 Classic Bike magazine on page 73, Roger Meyers states, that porous cylinder heads are not unusual on 850s. He goes on to say that oil will weep from the front of the casting above the gasket..."

"Yes the article is just repeating an incredibly old fact that the castings were typically porous.
Some processes called for something like a rosin dip that sealed similar casting done...
In addition all Commando heads and cases were painted to possibly to seal them up.
I learned about this in the late 80's when I was stripping gasket goo off the gearbox outer cover with methylene chloride type stripper and found it was also eating the "paint/coating" off the inside of the cover...
I use (all aproximate) 1 part hardware store radiator silver/aluminum paint, with 1 part acrylic enamel silver, with 5-10 parts thinner and a touch of isocyinate hardener. When this is sprayed on, it is almost not noticeable that it is there. Which is what I want.....a clean aluminum finish that doesn't corrode and turn dark."
Dave Comeau