Dolmar 6100 and 7910 muffler mod questions

[Miller Mod Saws]

Try to use a diamond burr if possible

Diamond burrs are slow. Lol. That's what I finish with. Tonight's work in progress!

 

[Adirondackstihl]

Diamond burrs are slow. Lol. That's what I finish with. Tonight's work in progress! View attachment 39517

I believe he was referring to the port chamfer, that's why I suggested diamond.
A stone ball can chip the plating.

 

[Miller Mod Saws]

I believe he was referring to the port chamfer, that's why I suggested diamond.
A stone ball can chip the plating.

Ahh I gotcha! Lol. Smart thinking. Lol.

 

[Adirondackstihl]

Ahh I gotcha! Lol. Smart thinking. Lol.

Jeesh......
Gotta teach you errthing
*eye roll*

 

[Miller Mod Saws]

Jeesh......
Gotta teach you errthing
*eye roll*

IKR! My kids say the same thing. Lol

 

[SOS Ridgerider]

I uncrimped the mufflers tonight and started cutting the unneeded stuff outta there. On the 6100 there is a thin shield sandwiched in between the two halves. Is it necessary to reinstall it? Doesn't seem like it's doing much... It's the middle piece in the photo. Also, how much should I enlarge the exhaust outlet? On the other ones I've done, I've pretty much kept it as big as I can go under the stock deflector.


And here's the SLR outta the 7910. I assume I cut off and reuse the flange? Braze it in there maybe?
I'm going to copy the extra exhaust hole in the front, like @Adirondackstihl showed in the photo. Do I keep the stock hole the same, or still enlarge it?

 

[mdavlee]

I make the original bigger and add a 1/2x7/8" or so hole and weld a deflector over it.

 

[SOS Ridgerider]

I make the original bigger and add a 1/2x7/8" or so hole and weld a deflector over it.

On the 7910?

 

[Miller Mod Saws]

I uncrimped the mufflers tonight and started cutting the unneeded stuff outta there. On the 6100 there is a thin shield sandwiched in between the two halves. Is it necessary to reinstall it? Doesn't seem like it's doing much... It's the middle piece in the photo. Also, how much should I enlarge the exhaust outlet? On the other ones I've done, I've pretty much kept it as big as I can go under the stock deflector.
View attachment 39543

And here's the SLR outta the 7910. I assume I cut off and reuse the flange? Braze it in there maybe?
I'm going to copy the extra exhaust hole in the front, like @Adirondackstihl showed in the photo. Do I keep the stock hole the same, or still enlarge it?
View attachment 39544

On the 6100. Trash it. And then donloke you normally do. Just open up under the stock defector.
On the 7910. yes tac weld the spacer/flange back in. Then before you put it back together. Those little bends that help you center that spacer flange in there. Well grind those out so your muffler inlet is the same of as the flange ID That will line the muffler up pretty close to the cylinder exhaust port. And I add a second port like mike lee does. But since your saw will still be stock ported. Opening up under the defector will be sufficient.

 

[SOS Ridgerider]

I make the original bigger and add a 1/2x7/8" or so hole and weld a deflector over it.

On the 6100. Trash it. And then donloke you normally do. Just open up under the stock defector.
On the 7910. yes tac weld the spacer/flange back in. Then before you put it back together. Those little bends that help you center that spacer flange in there. Well grind those out so your muffler inlet is the same of as the flange ID That will line the muffler up pretty close to the cylinder exhaust port. And I add a second port like mike lee does. But since your saw will still be stock ported. Opening up under the defector will be sufficient.

That's great information and help!! The willingness to share knowledge and expertise is fantastic, and very much appreciated! Thank you! For me saws are for fun and firewood, and this makes it that much better!

 

[SOS Ridgerider]

Both saws are back together. I checked tune this morning. I tached them to right below the rev limiter wot, but they still seem fat in the wood. I want them to run and perform the best they can, but I don't want them lean either. Can I safely tune them so they clean up under light load in wood, and not be worried about running too lean?

 

[mdavlee]

You'll be on the limiter to tune them right. It is a little harder to tune that way but they do run better for me with the limited coil

 

[SOS Ridgerider]

You'll be on the limiter to tune them right. It is a little harder to tune that way but they do run better for me with the limited coil

Thanks. I'll take another look Saturday morning at the CT GTG. I'm sure there'll be plenty of wood there. Lol.

 

[mdavlee]

Should be able to get it dialed in there.

 

[Miller Mod Saws]

This is why I like the 7900/6421 coil. While it's still limited. It allows just enough more rpm over the 12800 7910 coil that it makes them easier to tune. But that's my opinion. Lol.

 

[SOS Ridgerider]

This is why I like the 7900/6421 coil. While it's still limited. It allows just enough more rpm over the 12800 7910 coil that it makes them easier to tune. But that's my opinion. Lol.

I asked that question a while back, in a different thread, if it would be beneficial to use that coil. Never got a good answer, so I didn't think more about it. I have a 6421 so I could just swap the coils for tuning, then swap back. I'm sure we'll get it taken care of tomorrow, though. There's gonna be guys with a lot more experience than me there, and I'm sure they can give me some pointers.

 

[Adirondackstihl]

This is why I like the 7900/6421 coil. While it's still limited. It allows just enough more rpm over the 12800 7910 coil that it makes them easier to tune. But that's my opinion. Lol.

13,580 right? .......I know I'm close

 

[Miller Mod Saws]

I asked that question a while back, in a different thread, if it would be beneficial to use that coil. Never got a good answer, so I didn't think more about it. I have a 6421 so I could just swap the coils for tuning, then swap back. I'm sure we'll get it taken care of tomorrow, though. There's gonna be guys with a lot more experience than me there, and I'm sure they can give me some pointers.

Won't work. The flywheels are different. If ya swap neither saw will run. I know it sucks. Lol. You'll go just fine with the 12800. Especially since it's not ported YET! Lol.

 

[Miller Mod Saws]

13,580 right? .......I know I'm close

13500ish is where they normally hit. Everyone seems to be a tad different.

 

[SOS Ridgerider]

Won't work. The flywheels are different. If ya swap neither saw will run. I know it sucks. Lol. You'll go just fine with the 12800. Especially since it's not ported YET! Lol.

Ah! Didn't know that. Yeah, I'd love to get that 7910 ported. And the 6100. And the 5105. And the 421. Lol.