Modding the Dolmar 7900

[HEAVY FUEL]

I didn't read whole thread, I'm guessin your running an 8 pin?

 

[parrisw]

this saw sounds a lot like my xpw ,lot of chain speed ,is that fir ? kind of hard to make out the bark

Yes its a type of Fir, some people call it Grand Fir, or Balsam. Pretty soft.

I didn't read whole thread, I'm guessin your running an 8 pin?

Yes, its 8 pin, with Stihl Semi-Chisel 28"

 

[tallguys]

Saw looks and sounds great:msp_thumbup:
I don't quite understand what you did, but it looks like it worked well.

I was thinking the same thing. :msp_smile: Whatever was done with that saw, was done quite nicely.

 

[parrisw]

I was thinking the same thing. :msp_smile: Whatever was done with that saw, was done quite nicely.

Thanks. Maybe I was just expecting more? I don't know. I believe the decoomp was leaking slightly, got that fixed. So well see next time out and when the ring seats in properly.

 

[Hedgerow]

Thanks. Maybe I was just expecting more? I don't know. I believe the decoomp was leaking slightly, got that fixed. So well see next time out and when the ring seats in properly.

What did the squish end up at Will? By the looks of that chamber, it should be puffing a ton!!!
Nice and compact...

 

[parrisw]

What did the squish end up at Will? By the looks of that chamber, it should be puffing a ton!!!
Nice and compact...

.020". Ya I thought it would be way high, but only hitting 185 now. Should come up though.

 

[Mastermind]

Y'all ever done a 7901?

 

[parrisw]

Y'all ever done a 7901?

If I'm Y'all, then no I haven't. Have you? Much different?

 

[Mastermind]

If I'm Y'all, then no I haven't. Have you? Much different?

Y'all can be anyone that answers...... :msp_wink:

I've got a new 7900 and a 7901 apart on my bench right now.

 

[parrisw]

Y'all can be anyone that answers...... :msp_wink:

I've got a new 7900 and a 7901 apart on my bench right now.

Sweet, like to hear more.

 

[Mastermind]

Sweet, like to hear more.

I'm taking pics for a thread.....

 

[166]

Y'all can be anyone that answers...... :msp_wink:

I've got a new 7900 and a 7901 apart on my bench right now.

I think you mean 7910.

 

[Mastermind]

I think you mean 7910.

Yeah......that's the one.

I finally got to it. Any ideas on the muffler?

 

[Hedgerow]

Yeah......that's the one.

I finally got to it. Any ideas on the muffler?

Yeah.... Replace it with a hollow can...
:msp_wink:

 

[Mastermind]

Yeah.... Replace it with a hollow can...
:msp_wink:

That's what we were thinking. I did wonder if it could work like an "expansion chamber". In that case I wanted to try it after the port work and compare it to the "can". :msp_wink:

 

[Hedgerow]

That's what we were thinking. I did wonder if it could work like an "expansion chamber". In that case I wanted to try it after the port work and compare it to the "can". :msp_wink:

By design, it's not so much an expansion chamber, as it is a septic system with lateral lines... It works to scrub exhaust for the dopes at the EPA, but kills HP... Remedy that thing Doc...
:big_smile:

 

[Mastermind]

By design, it's not so much an expansion chamber, as it is a septic system with lateral lines... It works to scrub exhaust for the dopes at the EPA, but kills HP... Remedy that thing Doc...
:big_smile:

I see. It sounds like you've played with these before.

 

[Hedgerow]

I see. It sounds like you've played with these before.

Nope... But the 7910 is on my list... I spent some time looking at the drawings of the new exhaust system...
And ran one while I was up in WI...
It would tell all if you ported it, and ran it for time with the bleed off chamber exhaust, then did your thing to the can, and ran it again... I'm betting minimum 10% faster time...
:monkey:

But hey, I been wrong before...

 

[Mastermind]

Nope... But the 7910 is on my list... I spent some time looking at the drawings of the new exhaust system...
And ran one while I was up in WI...
It would tell all if you ported it, and ran it for time with the bleed off chamber exhaust, then did your thing to the can, and ran it again... I'm betting minimum 10% faster time...
:monkey:

But hey, I been wrong before...

I'll be doing a thread on this thing.......we'll all get to see how it reacts to muffler mods.