^^ okay, oversimplified thingy worked very fine with me.
So the whole cycle should be efficient right?
Any calculations to mod CR, for the 90 octain petrol?

The thing you're supposed to take away from this explanation is that there is no easy way to know what modifying the CR will do to your engine. It might boost power or just cause massive knocking and destroy it. (The other things that I skipped over were things like octane, combustion chamber shape, squish zones and lots of more things I don't understand.)

My suggestion: don't go there. Leave it to people like Joel, who understand all of it, have a workshop for testing and can afford to blow a few engines while testing.

Also proper application of a K&N air-filter, a real performance exhaust (not the fart cans from the local mechanic) and properly rejetting the carburettor will gain you power far more easily than mucking about modifying your compression ratio. But it has to be done right, mess it up and all you're left with is a noisy bike that will destroy itself quickly.

That's what i thought after so much of googling.. Its all trial & error method (go slow & learn kinda)
btw, I'm not onto any DIY mod (at least now) just started this thread out of curiosity & for some theoritical know how.

lets not stop here, somebody plz put up definitions of static & dynamic compressions.

Yeah, plz dont stop here guys & gurus, keep pouring your knowledge..
My small push start to this ailing thread:-
what to do to prevent detonation/pinging (caused due to raising CR) when high octain petrol or octain boosters are not available... Does mixing 2t with petrol in small quantity help say 0.5ml or 1ml to a liter?? I guess 2t in petrol will bring down the temperature in combustion chamber, hence preventing pinging?? Am i right here??

2t oil in a 4t engine will most likely foul your spark plug soon.

Preventing knocking / pinging... Probably stuff like:
Jetting the carb such that it always runs rich, but there's limits to how rich you can run, plus it will kill your mileage.
Retarding ignition timing till the knocking stops, but that will likely cause a drop in power.

All in all, nothing you can do on the move.

but I've used 2t in hunk, ratio was 0.5ml to a liter. It didn't caused any problem, electrodes turned super black but no fouling observed.
Did it to counter overheating... We were on highway with temperature hovering around 45'c. And oem 10w30 oil did no good to us.

Kennedys DynoTune- Dynamic Compression Ratio Explained

my two cents on CR ( in layman's term )

As far as simple science it's the ratio of x parts of AIR to 1 part of fuel i.e if You take CR as 9:1 then it's 9 parts of air to 1 part of fuel burnt. Generally the CR is under 10 :1 in most Desi Engines owing to the quality of fuel ( Note : 89 - 91 Octanes) and economical factors.
So if we bump up the CR in our engine we would need better quality fuel ( Octane <91) or else it would cause knocking and loss of performance and vice versa.

Note by : I ain't and engineer or a tech guy so If I am wrong at any point kindly take a note and correct me .