MillerModSaws and the PS-7910

[drf255]

View attachment 404433 I marked out what I'm gonna do with the base but the side of the lower trans is still in thought process. Really leaning towards squaring the rear up like the front. Raising it the amount I took off the base and come out from the base square. So let's here some comments here.

I got a comment.

Really nice farking porting going on there. Clean stuff.....

 

[Andyshine77]

Keep in mind.......this is a 7910. The ring pin will end up in the transfer port if they are widened too much.

Where is the pin end? it's not centered with the intake port?

 

[Mastermind]

Where is the pin end? it's not centered with the intake port?

Nope........off to the side.

 

[Andyshine77]

.021"

I don't suggest it, but I've seen .010" on a few 7900 work saws. I like .017-.020 myself.

 

[MillerModSaws]

On the intake I did very little. I squared squared the corners up just a bit and widened just a little and I mean a little. I didn't do much more than knock the nikasil overlap off. And then smoothed the intake tunnel up getting rid of all the ridges. It's sitting at exactly 80° right now.

 

[Andyshine77]

Nope........off to the side.

That sucks.

 

[CR888]

l think these saws run well stock....but that aint exactly any help here. Well engineered jugs.

 

[MillerModSaws]

Where is the pin end? it's not centered with the intake port?

Here it is. Lol.

 

[Andyshine77]

View attachment 404561
Here it is. Lol.

I liked that post, but I don't really like it.

 

[Mastermind]

IMHO widening the uppers is a mistake. They will scavenge better if they aren't overly wide.

 

[MillerModSaws]

IMHO widening the uppers is a mistake. They will scavenge better if they aren't overly wide.

These are not widen. If they are it's just from cleanup.

 

[Mastermind]

These are not widen. If they are it's just from cleanup.

I could see that.

I normally just take them out to edge of the factory bevels.

Now on a 562XP.......I wrap em on around. The transfer flow comes in at a different angle on those though.

 

[Hedgerow]

View attachment 404561
Here it is. Lol.

It just wouldn't be a Dolmar project if them bastards didn't make it difficult...
Looks like good work so far...

 

[LegDeLimber]

Do you still have that resonant chamber from inside of the muffler?
If so, could you measure the volume of it?
Would prefer in CCs if you have something like an oil ratio cup.
Looks like you could hold it like I rotated your pic and depending on how wide,
I guess you would put your thumb or a piece of cardboard or a port blocking plate etc...
at the blue arrow and fill with water.

then one more request, please sir.
Could you post photos of it from the directions of the 3 red arrows.
Maybe a scale/ruler laying alongside would be just awesome.

 

[Four Paws]

What good is more power to pull a long bar when you can't oil it? We should be discussing how to port the stingy Dolmar oiler.

 

[Andyshine77]

IMHO widening the uppers is a mistake. They will scavenge better if they aren't overly wide.

It's more about direction of the charge than area IMHO.

 

[MillerModSaws]

Do you still have that resonant chamber from inside of the muffler?
If so, could you measure the volume of it?
Would prefer in CCs if you have something like an oil ratio cup.
Looks like you could hold it like I rotated your pic and depending on how wide,
I guess you would put your thumb or a piece of cardboard or a port blocking plate etc...
at the blue arrow and fill with water.

then one more request, please sir.
Could you post photos of it from the directions of the 3 red arrows.
Maybe a scale/ruler laying alongside would be just awesome.

I already threw it away. However I will try and remember to do this when I do the second saw for you.

 

[redfin]

What good is more power to pull a long bar when you can't oil it? We should be discussing how to port the stingy Dolmar oiler.

Have you modded one Josh?

 

[jar944]

What good is more power to pull a long bar when you can't oil it? We should be discussing how to port the stingy Dolmar oiler.

No porting involved but doubling the oil output has been figured out
http://www.arboristsite.com/community/threads/dolmar-makita-oil-pump-upgrade-modification.264696/

 

[jar944]

It's more about direction of the charge than area IMHO.

Which is why IMHO kickers on the intake side of the B ports will help scavenging.