piston movement/noise

[dave916]

Did you knife edge it yourself?
Most tuned cylinders Could have loads more work done [radius bottom tranfers, cylinder matched to cases,casting flaws removed ,exhaust polished etc.
 Loads of other factors could also vary a cylinder ;slighty differant port timing from factor {the vary by few degree}, a plated cyclinder will usually lose a few hp to orginal
someone could have removed base gasket surface {I have A Cylinder with .08mm removed from bottom {more low down power}

the most current  RSA cylinder aprilia which I   shows the complete opposite of knife edging.
 but there is no argument that the RSA aprilla motogp is the pinacle of current two stroke development.
you would be crazy not to follow in there footsteps,
 300 cylinders a year Between casting and dyno took about 3 months
3-4 cylinders a day
 There were 2 dynos working every day.
 over last decade of two stroke development

Most good tuners dont show there work online , here one kx540 cylinder that looks pretty good {no knife edge]
 LOOK at the work on intake side,/ radius bottom cylinder /, intake ribs removed/ radius bottom tranfers/ rear case ports enlarge

[sandblaster]

The cylinders that I have seen aren't online.
They are ones that I have had pass through my shop.
I did all the work myself.
I used the same cylinder in totally stock trim other then a plate job.
What I did wasn't a knife edge but more of a symmetrical laminar edge but close enough for this conversation.
I cleaned up the transfers, intake bridges, boost ports, floor ports, cylinder to case match, casting flaws removed, and polished the exhaust port.
The degree wheel shows that the cylinders timing is dead nuts on stock specs or as close to dead nuts as my eye can see which is why I use a HUGE degree wheel and my reading
So, any of these things I did could help gain a few HP.
The pics of the Aprillia cylinder are dramatic but if I'm looking at it correctly they are trying to move the flow further around the cylinder while maintaining the correct cross section so that they do not loose velocity.
I wouldn't Knife edge that cylinder as I wouldn't think it would gain much and in fact might loose some HP.
Until I see dyno numbers specific to the K5 that disprove the practice I will continue to clean up my cylinders as I am very happy with the results.
But then again I'm stubborn 
Oh... I'd like to see more pics of that K5 cylinder 

[dave916]

{{" l cleaned up the transfers, intake bridges, boost ports, floor ports, cylinder to case match, casting flaws removed, and polished the exhaust port."]}
 Do nothing only knife edging to a stock cylinder is probadly the only way to prove the point

I have no personal experance on the matter , only that two stroke tuning has change since the late 90s , the info is now out there due to no more two stroke in moto gp
 My tzr250  motor with the early 90s tuning {shown in pic early} was the sweetest twostroke i have every driven,

{[ " "" I will continue to clean up my cylinders as I am very happy with the results."""]} nobody is saying dont clean up cylinder it was the knife edging shown on the first pictures

50bhp from  125{Probably more than a few 500  these cylinder are $$$ second ones are around 5k  



 

[alward25]

My Team Green Cylinder, runs much stronger than my other engine without porting.

[dave916]

Of course its going to run stronger its got loads of work done, {loads of work on intake side} cant see exhaust
it looks more like a narrowing  of the areas than pure knife edging in the early sandblaster photes

If aprilla had  stuck with the 90s porting way, would the have won so many world titles in the later years?
looks like they should have asked a team green mechanaic to show them and saved millons

Moto gp titles
250 cc class
1995, 1998, 1999, 2002, 2003, 2006, 2007, 2008, 2009
125 cc class
1996, 1997, 2002, 2003, 2004, 2006, 2007, 2008, 2009, 2011

[Mike Grant]

https://www.google.ca/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&cad=rja&uact=8&ved=0CCYQFjAB&url=http%3A%2F%2Fwww.macdizzy.com%2Fwings.htm&ei=yCezVOPXJ8_yoATk2oLQDg&usg=AFQjCNGyR5XBu7UWu4lT80iafjZtjGIxUA&sig2=CX44JGrM-N2QB18u4r5Www&bvm=bv.83339334,d.cGU

[sandblaster]

My Team Green Cylinder, runs much stronger than my other engine without porting.

Any idea what your exhaust port timing is?

[alward25]

Stock, for now

[sandblaster]

Stock, for now

Well... pump it up till she glows in the dark....
Then I wanna ride it