044/046 rebuild pic. and video

[Grqnbech]

They all seem to have flow problems to the upper transfers.

I did see one big difference in the AM jug.

The walls in the transfers is alot thicker than in the stock jug.
Grinding some material away here and make the angle steeper would increase air flow.... right...?

 

[Stihlofadeal64]

Clean up your original cylinder and put in a new piston and rings, it will have more power that way than an aftermarket P&C setup.

+1 for me here. It looked like it was very week in the cut, struggling to maintain, no authority at all. Go back, with the OEM cylinder as has been suggested.

 

[buck futter]

My strongest hybrid was made with an 044 12 mm pin bottom end and a OEM 046 top end ported out to the maximum allowed by the stock piston plus raising the upper transfers to what was suggested by Brad , who had passed that info on to Randy. The carb has been modified a little also but that probably would not be necessary. I could not expect more from a performance package standpoint.

I have heard they are a stout saw, what numbers do you put in them?

 

[pioneerguy600]

+1 for me here. It looked like it was very week in the cut, struggling to maintain, no authority at all.
Go back, with the OEM cylinder as has been suggested.

In good stock condition that saw would walk away from that AM kitted saw, I have five of them myself and know them thoroughly. I also have built 5 of the 044/046 hybrids . First was just stock to stock, next was a ported 046 OEM top end and each one got a bit more port work until I hit the maximum on my last one. This one I will always keep, I couldn`t imagine more torque,RPM or performance from a package this size unless it was running nitro and a tuned pipe.

 

[pioneerguy600]

I have heard they are a stout saw, what numbers do you put in them?

I run Brad`s numbers, I am not sure he has put them out in the open forum but I will let him post them if he likes. Just a common courtesy, I got them from Randy (Mastermind)

 

[blsnelling]

I run Brad`s numbers, I am not sure he has put them out in the open forum but I will let him post them if he likes. Just a common courtesy, I got them from Randy (Mastermind)

Go for it. Post away. The key is unusually short blowdown and long intake.

 

[buck futter]

Go for it. Post away. The key is unusually short blowdown and long intake.

Thank you, here is a 460 I built quite a while ago. It was a blast, seems like a lot has been learned since then.

https://www.youtube.com/watch?v=9D4DHJUWV14

I have a couple of 044 and 440s around and some 046 tops, sooo....


regards David

 

[Adirondackstihl]

I did see one big difference in the AM jug. The walls in the transfers is alot thicker than in the stock jug.
Grinding some material away here and make the angle steeper would increase air flow.... right...?

You'll loose transfer velocity.
Not good.

Clean up your old 10mm cylinder if possible......or send it to me if youre not gonna use it...:msp_biggrin:

 

[splitpost]

what sort of compression has it got?
did you check your squish?
that muffler could do with more gutting

 

[rmh3481]

Aftermarket cylinders are great for learning the art of two cycle cylinder porting. If you have a problem its generally a less expensive lesson. Transfer port velocity has been mentioned and it is critical to the rpm that the engine will hold under load. Consider that you are working with an air pump. The more efficiently you can move air into and out of that pump, the more fuel you can burn and the more power that can be made.

You may want to do the time area calculations or you can plug your numbers into a computer program. You may also want to check the volume ratios between the crankcase, transfers and combustion chamber. You will need a degree wheel and port maps. Set your squish first. Here are a couple threads that may help;
http://www.arboristsite.com/chainsaw/85786.htm
http://www.arboristsite.com/saw-building-101/83777.htm

 

[Grqnbech]

I did open up the transfers some more. It got a little bit better.. about 4 sec. faster in the cut... but still having trouble holdning the RPM´s....
I will make a degree wheel, so I can see whats going on.

[video=youtube;tqKbpWKHTCU]http://www.youtube.com/watch?v=tqKbpWKHTCU&feature=youtu.be[/video]

 

[Grqnbech]

I did a little more tweakin´ to the saw
I cut 1mm of the base of the cylinder and made a popup piston.... I cannot tell you how much it raised the compression but it feels like alot... :msp_w00t:

opened the windows too...

I dont have a lathe so I grinded the popup.... :msp_rolleyes:

I found a 20" bar with full chiesel chain... cuts so much better....
[video=youtube;6Zmv4GeegVE]http://www.youtube.com/watch?v=6Zmv4GeegVE&feature=youtu.be[/video]

Next I will make a degree wheel and see if I can take the tranfers a bit higher...