Solo 665/Dolmar 7910

[Mastermind]

Mind if post up some numbers with ya?

Hell no......please do. Let's get this thread started rockin.

 

[wildroamer]

The 7910 jug just works better on this chassis than the 681 jug....

Now you're just trying to make me feel bad...

 

[MustangMike]

OK, so you like the 7910 jug on the 681 better than the 681 jug.

But why is the 681 chassis better than a 7910 chassis???

 

[Mastermind]

I said for me........

It's not really easy to use the 7910 jug without machine work.

 

[Mastermind]

OK, so you like the 7910 jug on the 681 better than the 681 jug.

But why is the 681 chassis better than a 7910 chassis???

Longer stroke.

 

[Deets066]

Longer stroke.

1 mm ?

 

[Hedgerow]

Longer stroke.

Harrumph..
And more leverage.

 

[awol]

Yeah, 38mm........

 

[Hedgerow]

I've not checked the compression........my gauge says everything is blowing about 200psi. I don't trust it much these days.

I'll share my theory. Remember......it's just a idea of mine.

From the squish band down to the roof on the exhaust port is about 25mm. I see this a lot in really strong saws.

If you set this saw up at 102° or so it's way lower than that. So, I started thinking that the "power stroke" was actually too long in this case. So......I started at 98° then 97°......then 96°. I also raised the transfers as I went up. Now.....the intake floor is at 81°. That's a little too low on many saws.......but this saw has a really tight case. So......with a 81° intake, I felt like I could take all the other numbers higher to match it. Does this make any sense?

Have you tried even higher yet?
These saws, if set up properly can still run good with insanely high exhausts.

 

[Mastermind]

Have you tried even higher yet?
These saws, if set up properly can still run good with insanely high exhausts.

If it gets any stronger I'd be surprised as hell. I think that it would start going backward.

The unlimited saw advanced 35°past stock is holding 12,400 - 12,600 in the cut in that same wood.

 

[awol]

So if length of stroke dictates exhaust height to an extent, I wonder how an 064 would run with 180 degrees of duration????

 

[Hedgerow]

If it gets any stronger I'd be surprised as hell. I think that it would start going backward.

The unlimited saw advanced 35°past stock is holding 12,400 - 12,600 in the cut in that same wood.

Send me one..
I wanna run it in the 5 cube at the Linn races..
I bet it would do well..

 

[Four Paws]

So if length of stroke dictates exhaust height to an extent, I wonder how an 064 would run with 180 degrees of duration????

Would be interesting to cc both the 064 case and the 7900 case.

 

[Mastermind]

So if length of stroke dictates exhaust height to an extent, I wonder how an 064 would run with 180 degrees of duration????

There's more at play here.......I'm still trying to understand it.

 

[Mastermind]

Send me one..
I wanna run it in the 5 cube at the Linn races..
I bet it would do well..

I'm waiting on a brake handle to put mine together.....when is the event?

 

[Mastermind]

So if length of stroke dictates exhaust height to an extent, I wonder how an 064 would run with 180 degrees of duration????

I've got a 064 jug here that Dennis Cahoon ported years ago. 90°/110°/82°

 

[Hedgerow]

I'm waiting on a brake handle to put mine together.....when is the event?

I believe July. Muffler saws on gas.
Mean work saw and good chain will get the job done I think.

 

[Hedgerow]

I've got a 064 jug here that Dennis Cahoon ported years ago. 90°/110°/82°

If DC eats a banana...
Just eat the damn banana.

 

[Mastermind]

I believe July. Muffler saws on gas.
Mean work saw and good chain will get the job done I think.

I'll send you mine.......it will be a few weeks. I wanna really get it dialed in.

 

[Miller Mod Saws]

The first one of these 665s I did I ported just like a 7910. I cut the squish band and set the numbers at 100/128/81 netted unbroke in 230 comp. the dolmar was actually stronger with these numbers. So the next one I wanted a little less comp so I put dual 7910 base gaskets under it. Which raised my intake to 79. Netted 220 comp. Then I did 98/126 mains 128 secondaries with the 79 intake. There was a huge improvement there. I remind you I'm giving you the cliff note version. So I tore down the other one took it to 98/126/81. Saws were almost impossible to tell apart but I felt the 79 intake was a tad stronger. With a little encouragement from randy and Mike lee. I tore the 81 intake saw back apart. Epoxied the intake back up to 79. Recut the squish and put a 2° angle on it to drop my comp a little. Netted 210 not broken in. And went 96/124/79. And i really like this saw. I'll run ya threw some of my test here in a bit.