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Mastermind Meets The Dolmar 7910

Mastermind

Mastermind

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Here she is.....a brand spanking new 7910. Ain't she a beaut??????

I'm finally getting caught up a little and can get out of the shop early enough to do a thread.



I've had this saw for a few weeks now. I've done a lot of thinking about it....wondering just how much different it was than the 7900.

Notice the muffler deflector is different.



I like the brace.....I feel that it was needed on the 7900.



The decompression valve is in a different place....



The coil is a new and different color.......I've not checked the limit yet.



The new slab sided light weight piston is on board.

 
bryanr2

bryanr2

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hmm. what happened to the Johnsered 2188 thread we were promised in Brad's 390 thread.:msp_sneaky:

And it's about time you did a thread- good reads have been scarce. Been making do on usual AS Drama.
 
Mastermind

Mastermind

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Everything looks the same here except the decomp....



7900 on the left.......7910 on the right.



Yeah we are porting it so the squish band has been cut.



A few shots of the stock ports.





Here's where it gets different......

 
Majorpayne

Majorpayne

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hmm. what happened to the Johnsered 2188 thread we were promised in Brad's 390 thread.:msp_sneaky:

And it's about time you did a thread- good reads have been scarce. Been making do on usual AS Drama.
What happened with the Echo twin you were going to do?
 
Mastermind

Mastermind

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It's fairly straightforward to dissect the muffler. Just heat and uncrimp the bottom and up the sides a bit.



Then it just slides apart.......with a little bumping and stuff.



There's nothing to support the flange after removing the crackpipe thingy......so we made a steel support and brazed it to the back half of the shell.



Then we bolted it to the reshaped exhaust flange and matched it to it.





Now we fix this.....

 

166

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The 7910 is rev limited to 12,800. I have both 7900 & 7910 cylinders here and they look identical except for the deco valve and the exhaust. I have tried using a 7900 muffler on a 7910 and it does run more like a 7900 with that exhaust.

The major changes from the 7900 to 7910 are the cylinder, muffler, crank, & coil.
 
Plan-b

Plan-b

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Here's where it gets different......

[/QUOTE]

That looks to be a reverberation ridge.
 
Last edited:
Mastermind

Mastermind

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Tennessee
In these pics those screws look huge. They don't block the outlet the way they appear. The deflector is 15mm deep and 40mm x 40mm the whole area under it is open and screened.







Ported jug........y'all have seen plenty of those.





 
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