The parent thread to this thread is "Tiger King 27cc Engine Making Waves". Some very good
questions and observations were posted in the parent thread and I hope everyone will copy
and paste any and all pertinent statements which have already been made into this thread.
TIA. Naturally, new material is welcome also.

This is such an interesting topic it deserves it's own thread. I've had a question about
this same topic so I'm not about to pass up this opportunity to ask it.

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I'm convinced that CY places a stippled surface on the crown of it's pistons. I have no
idea why they do it.

Please see the photos. Two pics of the stipples - one with natural light and one with flash.
The third pic is the internal surface and it it is easy to see how much smoother this raw
cast surface is as compared with the crown.

There are only two observations I can make about the effect of the stipples:

- when I use gasoline, combustion deposits stick to the stipples readily and form a dark,
coated spot on the pistons crown

- when I use camp fuel, there are no deposits which stick to the crown

If anyone has any guesses or conjectures as to why CY thinks these stipples are beneficial,
I am very curious to read your thoughts. TIA

CC,

I'm not sure why CY or Zenoah made pistons with crowns like this. Maybe it has something to do with the casting process. All my pistons are very smooth on top & there are no combustion deposits or vapor trails to be seem after many hours of running, mostly at WOT. There are also no deposits on the head buttons & no death ash beneath the piston's crown after running the engines under load at WOT. I believe this may have something to do with the lubricant used. I get the same results with Coleman fuel & a 50% mix of gasoline plus methanol.

JA

CC,

I found this paper in my library pertaining to ceramic plasma coating of pistons by Mike Hammer. Interesting read about how much coating to apply, where is the best situation to use coatings, how to run the engine after applying coatings, are coatings best for air cooled or water cooled engines, etc. ( www.strappe.com/plasma.html)

JA

Embee does all my coatings, the coatings allow you to run a longer fuze on the engine

I know I'm new to this forum and do not wish to step on any bodies toes. I have to ask JA why the use of the white fuel with gas&methanol (and I'm assuming blenzall)?

Whitefish, I believe that it is not a coating on the piston, I believe that it is the surface texture that is on the permanent mold which is coated with a spray on releasing agent to protect the molds surface. It can be smoother, just up to the person in the die coating department.

Sorry. I guess I didn't type that correctly. I meant white fuel with 10 0os of oil or gas plus 50% methanol with 10 ozs of oil.

JA

I have never had an issue with carbon building up massively on HP2@8oz and 110 race fuel. Only a thin layer is left after hard running to display the flow patter. A very usefull tool when porting. Piston crown and chambers are always micro polished.

bn2o wrote:

>Whitefish, I believe that it is not a coating on the piston,

The term in the thread title "Surface Treatments" was selected to be all encompassing.
Every form of crown configuration whether it be stippled, polished, coated, dish top, flat
top, etc. is welcome and can be covered here.

There was no suggestion made in post #22511 that it is or might be a coating. The stipples
displayed in the pics are formed from the cast piston's aluminum. Sorry I did not make that
clear in the original post.

>I believe that it is the surface
>texture that is on the permanent mold which is coated with a spray on releasing agent to
>protect the molds surface.

I agree. It is in the permanent mold. The mold maker is adding that surface texture to the
mold - the question is why do they spend the extra time?

>It can be smoother, just up to the person in the die coating department.

I'm convinced they want it stippled like that. The six CY pistons I have here all have the
same texture (stipples) on the crowns. Also, the third pic in the original post proves how
smooth they can cast a surface (piston interior) when they want to. That is the CY logo
showing in the third pic also – a single dot with double crescents – AFAIK, all CY pistons
have that logo in the casting.

SRI Motorsports:

Congrats on first post to MGB. Welcome aboard!

Combustion Deposits On Crown: When I discovered that camp fuel left no deposits in the
chamber and also blows the sludge out of the exhaust (from burning gas) I went over to
the naptha side and never came back to gas. Add to that the wife never tells me my toy
boats stink anymore so I'm really not left with much choice.