Let's Talk Transfers

[5000+]

Open ported seem to have wider less peak powerbands. I wonder if this is mostly a result of port style or timing.

 

[Ironworker]

Nice saw randy, that thing screams.

 

[Ironworker]

Hey Randy do you do anything different as far as port work when doing a pipe saw.

 

[Redfin]

Whats a 660?

Sir if you dont know I cant answer. Heres another query. Thinking about the mains opening first, why the heck do the two port Stihls open intake first?

 

[smokey7]

I was wondering if time area had a effect in the equation. I always hear numbers but not much duration and rod angle stuff. Love to hear more

 

[jmssaws]

Sir if you dont know I cant answer. Heres another query. Thinking about the mains opening first, why the heck do the two port Stihls open intake first?

Push out exhaust?
I open them flat,I see no purpose in opening one side before the other.

 

[Mastermind]

Hey Randy do you do anything different as far as port work when doing a pipe saw.

No.....not really Numa. Just higher timing numbers.

 

[Backyard Lumberjack]

does the OPE have a thread on how to set up a degree wheel, complete with making TDC tool, setting the flywheel key for some ignition timing advance, and how to use it? with clarifications such as does the timing degree location get positioned from the top of the piston in relationship to the port? or from the top of the top ring? I see bits and pieces here and over at 'the park'... would be nice to not have to hunt all over for a definitive How To Degree Your Chainsaw Engine - A Primer. i am at the point where i would like to read one tread sorta like the Let's Tlak Transfers... i got some of the parts together, but need to see if i got the cylinder on in the right direction?... all these side pipe pix, kinda making me wonder if there is some add'l power from side facing exhaust... don't thing the spark plug cares where it is, and the piston is a piston...

i would like to check my port timing, blowdown and see where i am and if any tweaks in port timing could help me... i know need TDC tool, means to affix degree wheel to flywheel side and wire pointer... and that if about 1/2 key diameter on flywheel half moon... should get about 6-degrees add'l timing lead... all in one thread with pix would be nice...

044 needs a port timing thread

 

[Mastermind]

 

[Backyard Lumberjack]

"ask and ye shall receive!" Thank you ~

a thread would be nice, too... imo

 

[Mastermind]

OK.

 

[tree monkey]

this help at all?

 

[tree monkey]

 

[Red97]

this help at all?

Mighty fine thread sir.

 

[Motorhead]

Great reading material Gentelman.

 

[shorthunter]

To do what though? When a port cracks open it shoots it's wad.

it happens a lot slower then you think

The transfers most likely back flow before they ever flow fresh fuel up out of the crankcase. I believe that this is described in Jennings book

 

[jmssaws]

The transfers most likely back flow before they ever flow fresh fuel up out of the crankcase. I believe that this is described in Jennings book

What would be the purpose of a transfer?
How does fresh charge get on top of the piston?
Backflush through the fingers? Which would only work if you have fingers.

I've not read Jennings book though.

 

[srcarr52]

What would be the purpose of a transfer?
How does fresh charge get on top of the piston?
Backflush through the fingers? Which would only work if you have fingers.

I've not read Jennings book though.

It would only be temporary, as in the transfers would fill in with a little exhaust until the pressure of the cylinder is equalized with the crankcase and the flow is reversed expelling the exhaust before the fresh charge. It's not something you would want to have happen. I believe it was an example given of having too little blowdown period, or not having enough crankcase compression.

 

[jmssaws]

It would only be temporary, as in the transfers would fill in with a little exhaust until the pressure of the cylinder is equalized with the crankcase and the flow is reversed expelling the exhaust before the fresh charge. It's not something you would want to have happen. I believe it was an example given of having too little blowdown period, or not having enough crankcase compression.

Roger that.

 

[XP_Slinger]

Still enjoying the heck out of this thread! Can someone help me out with "blow down"? My simple, inexperienced mind defines it as the distance that the piston travels in degrees between the exhaust port opening and the upper transfer opening. Is this correct? And not enough blow down is basically the upper transfer opening before the pressure in the crank case is greater than the pressure in the cylinder causing exhaust to back feed into the transfers? If I've got it twisted somehow please advise. Thanks!