Blowdown time for a 125cc

[georgieboy]

So i made a portmap and measurred the blowdown time.
It came to 25 degrees with PV open. 11 degrees when closed.
The exhaustport sits at 30mm from TDC and the mainports sitting at 41mm.

Does this engine favor more crankcase compression to speed up the scavenging due to the low blowdown time? If so what wld be the best option to acieve this?

I can imagine that this wld be called a lowend engine.
Am I right saying this?





Or is it

 

[Jman271]

What bike is this for? Bore, stroke con rod length?

 

[marcusgunby]

LOL normally this is georgieboys project from hell- Husky Cr125:)

 

[Jman271]

Runaway!!!!!

 

[georgieboy]

Chiodi became champion of the world on it.
But you are right i am suprised about that too :laugh:
I know that Deansfastway and cujet did some modification to it, but can you comment on the engine with the provided data.
Conrod length 105.8mm
Bore the famous 54mm
stroke (yes u guessed right) 54.5mm
Exh opens (PV open) 30mm
Transf open 41mm
I did some grinding to the intake traject. Made it a Honda intake traject, nice and smooth and wide.
I just like some comments on the engine, so maybe with the next piston change i dare to do some jug work.
I assume with this short scavenging you need a good pipe?

 

[marcusgunby]

You want one like this??? LOL

 

[georgieboy]

I have no access to yr piccie, so everybody have a laugh accept me :) (i assume yr pulling my leg, don't you)

 

[marcusgunby]

Hmm seems like you cant enjoy what others see-worth the subscription just to find out?

 

[Pete Payne]

georgieboy,.
Also what is the deck height of your engine?

 

[georgieboy]

0.8mm according to the ringwear. The crank is at this moment at the dealer's for new bigend. Also ordered a new cilinderhead as the previous one was smashed by broken bigend. So i don't know for now the squish but it must be excessive.
Bear in mind that I need the must lowend i can get from such a small engine, with moderate topend.

 

[georgieboy]

analog and digital ignition

stumbled on an other issue.
In earlier days this Huskie 125 was equipped with analog ignition and comes now with digital ignition.
The difference is that a digital ignition works with a chip?
And so is programmed for a certain ignition curve as analog is always linear ignition?