Chainsaw Porting Theory

[mdavlee]

Great reading fella's added a lot to my meagre porting knowledge.

Being just a backyard grinder with a love of dolmars, I have essentially just made the intake & exhaust wider, reduced the base gasket thickness (big ass red bull cans & copper spray). Being in oz have to deal with some hard as wood, so prefer torque of these saws.

Come across a little doozy of a problem (well self inflicted). May have seen a question I posted on the other site re a 166 dolmar cylinder a month or so back.

Cylinder is toast so I am getting it replated, I am also considering getting it overbored to 58mm (still waiting on 58mm piston to arrive).

Should I keep the transfers as they are (as overbore will make the transfers smaller as a percentage of cylinder wall area)? Use will be milling so I want the maximum possible torque not a screamer

Hope I haven't taken the thread to off topic.

9010 I'm guessing? It has been done. I think cooling was a small problem so being down there and your heat I would think porting the stock cylinder would be best.

 

[drf256]

Great reading fella's added a lot to my meagre porting knowledge.

Being just a backyard grinder with a love of dolmars, I have essentially just made the intake & exhaust wider, reduced the base gasket thickness (big ass red bull cans & copper spray). Being in oz have to deal with some hard as wood, so prefer torque of these saws.

Come across a little doozy of a problem (well self inflicted). May have seen a question I posted on the other site re a 166 dolmar cylinder a month or so back.

Cylinder is toast so I am getting it replated, I am also considering getting it overbored to 58mm (still waiting on 58mm piston to arrive).

Should I keep the transfers as they are (as overbore will make the transfers smaller as a percentage of cylinder wall area)? Use will be milling so I want the maximum possible torque not a screamer

Hope I haven't taken the thread to off topic.

Welcome, and nothing is off topic.

It seems that Dolly's have super tight cases. Hope the guys correct me if I'm wrong here, but I see larger bore jugs on the same case (6400/7900) running more blowdown because there will be proportionately less case volume to swept volume ratio.

So in your case, we'd really need your timing numbers to opine. I'd venture to say you'd want to keep your transfers physically lower than what you would expect to be optimal in your saw with the standard bore.

That's all I got. Hope someone jumps in to confirm the statement about dolmar transfers I made above.

 

[paragonbuilder]

Is there anything different to consider when porting an open port jug? Ive got a minty husky 66 I'm thinking of digging into.


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[srcarr52]

9010 I'm guessing? It has been done. I think cooling was a small problem so being down there and your heat I would think porting the stock cylinder would be best.

I put a 395BB cylinder on a 9010. Lots of work but it's a lot of fun. Cooling is a little bit of an issue but it was mostly because the AM cylinder had too tight of piston to cylinder clearance.

 

[Mastermind]

113cc.......and lots of RPM. What's not to love?

 

[lwhaples]

Awesome job! You surely post BIG when you post.

 

[exSW]

He he he,that's pretty cool.

 

[srcarr52]

113cc.......and lots of RPM. What's not to love?

The 50+ hours of work that it took me to do it.

Bad things will come to Nathan if he ever hurts it.

 

[paragonbuilder]

I put a 395BB cylinder on a 9010. Lots of work but it's a lot of fun. Cooling is a little bit of an issue but it was mostly because the AM cylinder had too tight of piston to cylinder clearance.

Man what a sweet sound that saw has! You can just hear the gobs of torque, and she is speedy to boot!! Great job. It's nice to see something different.


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[shorthunter]

Page 47 already and no in depth discussion about strato ports

 

[drf256]

Page 47 already and no in depth discussion about strato ports

Feel free to start a discussion on it.

I myself am trying to wrap my head around exhaust height and its effect on trapped volume and case volume/trapped volume ratio.

 

[Keith Gandy]

I put a 395BB cylinder on a 9010. Lots of work but it's a lot of fun. Cooling is a little bit of an issue but it was mostly because the AM cylinder had too tight of piston to cylinder clearance.

That bad boy is eatin some wood up!!

 

[Mastermind]

Page 47 already and no in depth discussion about strato ports

Let's hear what you have to say about it. I've noticed that you have nothing to add.....and only pop up to take little pokes. I've got no patience for that *B-S..... What do you have to add?

 

[Redfin]

The 50+ hours of work that it took me to do it.

Bad things will come to Nathan if he ever hurts it.

Very nice work man! What carb did you use on it?

 

[shorthunter]

Let's hear what you have to say about it. I've noticed that you have nothing to add.....and only pop up to take little pokes. I've got no patience for that *B-S..... What do you have to add?

You've got it wrong. I spent 20 pages trying to get my point across on transfer backflow. Been busy the last few weeks, popped in on this thread at the end of the week to see what had been going on. Noticed that there wasn't any discussion about stratos, thought I would rekindle the thread with a new topic

 

[Mastermind]

Well......let's hear what you have to say about strato ports.

 

[Magic_Man]

I have to say I don't know a damn thing about them. I own a saw with them, and it runs good, and that's about it. Lol

 

[drf256]

I have to say I don't know a damn thing about them. I own a saw with them, and it runs good, and that's about it. Lol

I'll second that, except for the ownin part.

 

[Mastermind]

My tolerance level might not be at it's all time high at the moment.

If I was out of line with you Brandon. I do apologize.

 

[shorthunter]

My tolerance level might not be at it's all time high at the moment.

If I was out of line with you Brandon. I do apologize.

I may have picked at JMS a little bit but otherwise I have been trying to contribute. As far as strato ports go this is a start. . . .