Mastermind
Work Saw Specialist
I have notes in the shop with stock numbers.......but I didn't get them on these 7900 jugs. I've got a solid plan on those saws. No reason to measure stock numbers on them.
Small carb.....
Makita 6401 to 7901 Plus porting the 7900 and the Solo 681
- Thread starter Mastermind
- Start date
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I have notes in the shop with stock numbers.......but I didn't get them on these 7900 jugs. I've got a solid plan on those saws. No reason to measure stock numbers on them.
Small carb.....
Terry Syd
Addicted to ArboristSite
The 7900 jug shows what happens when a big bore is put in a smaller cylinder, the transfer tunnels run close to the bore and there is a tighter turn (and perhaps less cross section) for the transfer flow. The Solo appears to have addressed the porting problem and moved the transfers out from the bore. - A 5% increase isn't going to come from a 2 millimetre increase in stroke.
I was thinking my next big saw would be a 7900/7901, but that well designed Solo jug now has me thinking about the Solo.
Can the 681 jug be used on 7900 cases and still be able to use the increased area in the lower transfers?
Mastermind
Work Saw Specialist
I open both, but the Solo needs less work.
The Solo has the windowed piston. I wish I had a slab sided piston.........I bet it would help.
Yes, but you'd have to cut about a mm off the base. That would change the timing numbers enough that you'd need to rework the exhaust and the transfers.
Deets066
Firewood hack
Got a little excited there and forgot they were made by different manufacturers lol
Mastermind
Work Saw Specialist
Solo and Dolmar designed the 7900 together. They share many parts. The jug will bolt right on.
Deets066
Firewood hack
Yeah I just looked at some pics of the solo, looks a lot like the dolmar
Will any of these saws be coning to Kentucky next weekend?
Mastermind
Work Saw Specialist
I don't think they sell the spacer anymore- but I think I goofed. I think the spacer was for mounting their own big bore kits on the 6400/6401/665 lower, and that's what they were selling for a while. If I remember correctly, the spacer had slotted mounting holes. I actually have one in storage somewhere.
CapitaineHaddoc
European Westcoaster
That's a nice thread Randy, thanks for sharing. Do you think you'll have the time to record some vids from thes saws when done?
jeff taswelder
ArboristSite Operative
Sty57
Tree Freak
I have a questionOK, now we're gonna look at how we cut the squish.
I've got a bunch of different plates made up with different bolt patterns for different saws. All you need is a 4" x 4"x 3/8" or thicker steel or aluminum plate, or some all thread.
Now, this is sorta important.........you need a pivot point under the jug.
Some washers and nuts, and it's ready to go in the four jaw.
Wouldn't it be easier to make the base plate out of round stock instead of square? Wouldn't you be able to use a Three Jaw chuck if that all you had?
Sty57
Tree Freak
How do you decide how much to take out of the Squish Band?Once all the indicating is done, cutting it takes maybe 5 minutes max. I also cut the cylinder extensions while the jug is mounted.
Then slick it up with a diamond burr.
MillerModSaws
USE2COULDBESPONSER!
Awesome work randy! Have your ever put the solo crank in a 7900?
MillerModSaws
USE2COULDBESPONSER!
Is the solo rev limited just like the 7900? 
drf255
BAD CAD
So the Dolmar uppers were just as narrow in height as the Solo ones before grinding?
Or is that your point, that smaller tighter uppers make more power?
The work is beautiful.
Or is that your point, that smaller tighter uppers make more power?
The work is beautiful.
Sty57
Tree Freak
Do you take out just enough to clean up the Squish band and then cut the base to bring down the Squish?
I have a stock OEM 7900 jug sitting on a shelf, would You like me to snap some pictures for comparisons with the 681 jug?The Dolmar has had some relieving done on the right hand side. Making this comparison was an after thought.
Interesting thread.
