Reading flow pattern

[georgieboy]

Hi all,
today lifted the jug off my bike and made a picture of the piston crown and cilinderhead.
The exhaust side is top.
I have a squish gap issue. It reads 1.65mm (0.063 inch).
But i want to ask you about the flow pattern.
Which side is flowing more?

 

[georgieboy]

Wauw....
quite in here.
There was a time that the mods forum had the most discussions and debates.
Times change.

 

[76GMC1500]

That's a lot of carbon, what kind of oil are you running?

 

[georgieboy]

76, Hi.
I did that on purpose to get a good showing flow pattern ;)
So you guys cld comment on that.
ps:i know it is rich.

 

[76GMC1500]

I've always heard modern oils burn to cleanly/have too much detergent to give a good flow pattern on the piston crown.

 

[georgieboy]

That is why i runned it rich ;)

 

[Rich Rohrich]

The only useful thing you can read from those pictures is how horribly rich (and slow) this engine is running.

Until you sharpen up the jetting you won't read much of value by looking at the piston crown or cylinder head.

 

[76GMC1500]

There is a burn pattern on the crown on my old piston. I couldn't tell you exactly what I did to get it. I Scotchbrited most of the old carbon off and ran the bike for a short time before I decided the piston was trashed and replaced it. I haven't pulled the head on the new piston yet so I couldn't tell you how that one looks. I've never had any carbon whatsoever on the underside of the head, you probably shouldn't either.

 

[georgieboy]

I already said it was rich jetted.
My question was about the flow, but nobody wants to say anything about my flow pattern :(

 

[Rich Rohrich]

My question was about the flow, but nobody wants to say anything about my flow pattern :(

That's because it is MEANINGLESS until you get the tuning correct.:bang:

When you sharpen the jetting you speed up the rate of combustion as well as increasing the piston crown and combustion chamber temperatures. The scavenging will be influenced by these changes and with it the pattern that is left behind.

You are wasting your time, and by association our time by chasing your tail here. :coocoo:

 

[georgieboy]

Ahh Mr Rohrich, i knew in the end i wld recve an answer that i cld live with.
Sorry i wasted yr time, but since the only comment was: yr jetting is rich and for the rest no explaination with it, i assumed that nobody read my question in the first place.
So scavenging is related with temperatures. I thought that scavenging was related with motor-layout and rpm's.

 

[Rich Rohrich]

I thought that scavenging was related with motor-layout and rpm's.

Scavenging is related to that as well. It's a complicated process that can be influenced by a lot of seemingly insignificant things.

 

[georgieboy]

Ok won't take anymore of yr time to debate flow patterns.
Will look at the bigger picture and solve the richness in combination with getting the ports open symmetrically. Leave it with that... for now ;)
Thnks for yr patience.

 

[Rich Rohrich]

Will look at the bigger picture and solve the richness in combination with getting the ports open symmetrically. Leave it with that... for now ;)

It's definitely a system and there are a lot of interactions that need to be considered. Going at it in a step by step way will get you the most useful info.

Eric Gorr and I flowed hundreds of cylinders on a special flow bench setup we built. Over the years using this equipment to try and balance transfers had some value, but only if the time/area and the rest of the scavenging process is optimized as well. Dwelling on flow patterns alone makes for some interesting nights in the shop but aren't likely to show much on the racetrack. ;)

 

[georgieboy]

That is why i stay away from doing something drastic to a nice looking cilinder and head, other than matching everything together ;)
But i agree it is tempting to do something real cool like changing the angles or so.
Anyway, thx for the replies and help.
You surely advised me good with that decel knocking topic.

 

[bclapham]

It's a complicated process that can be influenced by a lot of seemingly insignificant things.

arent most things in life! :yell:

 

[Rich Rohrich]

arent most things in life! :yell:

So it seems. :nod:

 

[mtk]

Stick to something simple then, like women. ;)