...with the stock heads (85cc) and the .050" head gasket in the kit , yields a 10.2:1 ...but with a .030" cometic gasket ...will yield a 10.5:1

with the CVO heads ...yields a 9.6:1 ....

but remember ...these are cast not forged pistons !!!!
go ez !!!



110 bolt on cylinders and piston kit

 

well if I am running a 16 twin cooled limited with 10.2 stock and with PV , Canned FM Map 2-1-2 FM Header Rineharts
then why could I just add the 110 bolt on kit with the .050 gaskets to keep it at 10.2 to 1??
same map?
just run a few auto tunes?
?

 

is that just the piston/cylinder kit?

 

it says in the paper work for this kit ..that it fits both ...water and air cooled but
i believe that the twin cooled heads have a slightly smaller combustion chamber ...for a littler higher compression than the air cooled heads ...
here a couple pic's ..and just an opinion !!! .maybe hard to see with these pictures ...





water head



air head

 

yes ...cylinders and pistons only ....
part # 92500039 ...

 

interesting
I have a new take off set in a box I will look at today
Thats probably true for sure that the chamber is smaller
But by how much ?

I know my stock twin cooled 103ho compression ratio is 10.2 now

If those numbers above are for air cooled heads I wonder how much it would be raised over those numbers with the kit and 2 diff gaskets for the twin cooled heads

 

Your twin cooled engine is rated at 10:1 compression stock and is probably actually more like 9.8:1-9.9:1. Here is a calculator you can use to figure out your compression with any number of variables like chamber volume, displacement, head gasket thickness, etc. :

http://bigboyzheadporting.com/TwinCamComp.htm


An air cooled 103 HO has 85cc chambers for a nominal compression ratio of 9.6:1. Assuming everything except chamber volume is the same for the air cooled and twin cooled engines, your chamber volume would be 81cc.

Note that these are nominal figures. Even though the air cooled heads, for instance, are spec'd at 85cc, they often are larger, sometimes up to 88-89cc. That's why (at least on reason why) compression ratios are often lower than advertised.

 

if you have a set you can measure ...that would be cool ...need to installed an ACR ...and a spark plug ...level the head on a bench ...used some rubbing alcohol ...and a small syringe (ml 's same as cc's ) ....and see how much it takes to just reach the top ...
then post your finding here ...as a ball park figure ..!!!

 

If you're going to do this, I suggest taking a piece of plexiglass big enough to cover the gasket area of the head and drill a small hole in the middle. Grease the gasket surface of the head for a seal, and place the plexiglass over the chamber. Use the syringe to fill the chamber and measure the results.

Just pouring the alcohol in the chamber can give inaccurate results, as the surface of the alcohol will have a curve to it (miniscus) that will skew the results enough that your "ballpark" may not come very close to the actual volume. Bear in mind, a 2-3cc error (which isn't really a lot of volume and is an easy error to make) will make close to a quarter of a point compression difference in these engines.