Sandcast Cylinder Heads - Factory Port Jobs?

[vnz00]

Hi guys, another curious observation...

I noticed when I had the carbs off 1853 that the intake ports appeared to have had grinder marks on the inside where it appears the ports were hand smoothed.  At first I thought someone had the head off and done a home port job.

However after bead blasting 5528's head, I noticed similar work done on the intake ports/spigot junction too.  Close inspection revealed the guide bosses were shaped to taper into the guides too. 

Just wondering if I had to weld fill the ports and reshape the ports back to original as cast spec, or if it was a honda feature to make more HP for their flagship model

I'll post pics b4 the head goes back on...

[kmb69]

That's how they came from Honda. I was into drag racing these bad boys when they first came out. The first couple of stock 750cc class winners at NHRA events were disqualified at teardown for porting their heads. NHRA had some real issues for a while determining if any additional porting had actually been done. Don't weld your heads.

Keith

[Steve Swan]

Keith, what do you mean by "don't weld your heads?"

[kmb69]

Hi guys, another curious observation...

I noticed when I had the carbs off 1853 that the intake ports appeared to have had grinder marks on the inside where it appears the ports were hand smoothed.  At first I thought someone had the head off and done a home port job.

However after bead blasting 5528's head, I noticed similar work done on the intake ports/spigot junction too.  Close inspection revealed the guide bosses were shaped to taper into the guides too. 

Just wondering if I had to weld fill the ports and reshape the ports back to original as cast spec, or if it was a honda feature to make more HP for their flagship model

I'll post pics b4 the head goes back on...

Keith, what do you mean by "don't weld your heads?"

Steve was wondering if he needed to "weld fill" his ports. The answer is no.

[vnz00]

Hi guys thanks for the info. BTW was just joking about weld filling the head

I took some pics of the ports today. A great day working on the engine- we got the barrels on and head gies on next week (after difficulty trying to find a small hole head gasket).

My Yamiya no no. Pipes arrived this week too- they had them discounted.

Thinking about never starting the bike once she is back together- it's being built as a show bike so is there a need to carbon up new pipes and make all my new goodies 2nd hand?


Interested in knowing your thoughts on this. I know another member here has done the same

[Steve Swan]

Thinking i'm that member...  

[kmb69]

Thinking about never starting the bike once she is back together- it's being built as a show bike so is there a need to carbon up new pipes and make all my new goodies 2nd hand?

Interested in knowing your thoughts on this. I know another member here has done the same

It probably depends on how you assembled the engine. I was always taught to only put oil on the piston skirts and never above the oil ring on a new piston/cylinder assembly. This allows the rings to seat quickly to minimize cylinder glazing. At least 1 exhaust valve is always open so oxidation can occur rapidly in that cylinder especially if it is a freshly bored and/or honed cylinder without an oil film. If you oiled the cylinders prior to assembly you might be OK for a while. The factory always ran the engines in. They removed the spark plugs and sprayed inside the cylinders with a light film of a "grey" something that seemed to stick on everything. Don't know what they used but it was always visible on the plug threads. A new bike out of the crate always wisped smoke for a couple of minutes. The same stuff was sprayed inside the fuel tank. Part of our setup procedure was to rinse the tank with fresh gas to remove the preservative film.

Running the engine for some period does not render it a "2nd hand" bike in my humble opinion. The factory did it. My SOP is to put some old pipes on, run the engine some to make sure all is good, re-adjust the valves, and spray some preservative in the cylinders and the gas tank. Having said all of that, I have never taken one out of mothballs to inspect its condition over time.

Keith

[Riccardo]

Thinking about never starting the bike once she is back together- it's being built as a show bike so is there a need to carbon up new pipes and make all my new goodies 2nd hand?

Interested in knowing your thoughts on this. I know another member here has done the same

It probably depends on how you assembled the engine. I was always taught to only put oil on the piston skirts and never above the oil ring on a new piston/cylinder assembly. This allows the rings to seat quickly to minimize cylinder glazing. At least 1 exhaust valve is always open so oxidation can occur rapidly in that cylinder especially if it is a freshly bored and/or honed cylinder without an oil film. If you oiled the cylinders prior to assembly you might be OK for a while. The factory always ran the engines in. They removed the spark plugs and sprayed inside the cylinders with a light film of a "grey" something that seemed to stick on everything. Don't know what they used but it was always visible on the plug threads. A new bike out of the crate always wisped smoke for a couple of minutes. The same stuff was sprayed inside the fuel tank. Part of our setup procedure was to rinse the tank with fresh gas to remove the preservative film.

Running the engine for some period does not render it a "2nd hand" bike in my humble opinion. The factory did it. My SOP is to put some old pipes on, run the engine some to make sure all is good, re-adjust the valves, and spray some preservative in the cylinders and the gas tank. Having said all of that, I have never taken one out of mothballs to inspect its condition over time.

Keith

Sicerely i'e not m restored bik in my Home.
I prefer ride them.
Monthly, i make a medium range ride (about 35/40 mls) and i store the bikes when te engine and the pipes are hot after many miles riding at high rpm.
In this way the combustion cameras are carbon free and also the pipes.
r.