One for Lozza

[HuskyPete]

it's all in the head says Stevie.



Before

[Mike52]

What,s the deal with the chatter marks 67 ?
Have they been done on purpose ?
If so why ?
Won,t they cause pinging ?

[Lozza]

Who's Stevie?OK for a first attempt. Maybe he did it on a wood lathe Mike

[HuskyPete]

Stevie is VMX Magazine Steve "The Works Mechanic"  the head was one he had done for some guy at Diamond Dons, when i took the photo i asked about the cnc machining marks and he said it would help the swirl He welded up the head and re machined as shown

[Lozza]

Stevie is VMX Magazine Steve "The Works Mechanic"  the head was one he had done for some guy at Diamond Dons, when i took the photo i asked about the cnc machining marks and he said it would help the swirl He welded up the head and re machined as shown

Swirl eh he's a comedian as well, where's he find the time.

[vmx42]

Swirl eh he's a comedian as well, where's he find the time.

If only he had called it a Vortex Generator then all would be good. 

[090]

If you guys ever ventured into the Maico section you would see the blog of Doug who has had a couple of bikes done this way. His latest project is a 74 450 resto. http://ozvmx.com/community/index.php?topic=18418.0

[Bamford#69]

Hi,
Whoever did that head job was a clever bugger
 started with an 68/69 CZ 5 stud head and turned into a 74 6 stud head,.

[zorroz]

Hi,
Whoever did that head job was a clever bugger
 started with an 68/69 CZ 5 stud head and turned into a 74 6 stud head,.

It's not even the same heads b4 & after?

[090]

That is what he is implying. I would assume that both heads are there side by side for a comparison as the combustion chamber differences are what he is highlighting. Picky bugger 

[TeeBone]

Wasn't that in VMX mag a few issues back in LPB's column? I seem to remember it from the Stasiefski works files. Certainly a more efficient squish dome~

[BultacoMacca]

I thought I read somewhere that if your existing transfer ports aren't "aimed" at a new centred squish chamber modification then the results wont be significant as you hope.
True or not?

[Lozza]

Hmmm yes and no, by the time the squish starts to work transfers are closed long ago, and aim of the transfers are everything

[Mike52]

If you take a close look at a 4 stroke inlet passage you,ll see that it is built on an angle to give the gas a bit of a spin. The gas does a swirly sort of thingy.
Is a 2 stroke the same?
If so then those bumps would stuff it up wouldn,t they.
I spent a bit of time ,when I was younger, playing with 4 stroke heads and porting.
You had to retain that angle on the inlet or you LOST h/p.
Also you had to round off any sharp bits or pinging was a certainty.
I,me probably living in the past but those bumps just look wrong to me.
The shape of the chamber looks fine to me , it,s just those bumps.

[cheapracer]

Is a 2 stroke the same?

The shape of the chamber looks fine to me , it,s just those bumps.

Yup but the gas flow doesn't follow the floorline to such a degree it will make any difference.

Those bumps won't do a thing, they are certainly not sharp enough to develop hot spots and they may actually be of benefit by creating a little surface turbulence and able the charge to be burnt more effectively mind you taking your jumper off and lowering your gross weight would probably have the same effect on performance.