Makita 6401 to 7901 Plus porting the 7900 and the Solo 681

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Did you have a good day?

I did. Thanks for asking........you are true and dear friend.

You can see the 1mm thicker flange for the longer stroke on the 681. I'd like to find another one of those saws.

I'd already cut the bases on the 7900 jugs, but you are right Brad. The thicker base is very noticeable.
 
Thank you for sharing...

Gots a question or two.

What size boring bar you you use?

Do you take the squish band just to the edge of the bore? or go just a bit past? larger than the bore .002-3?
 
No one really asks many questions anymore.....
That "nub" on your flat plate when you're cutting the squish. Is that just a bit of loose round stock?
The new lathe is in and turning. I have to pluck up the courage to cut a squish band one day soon.
Would you suggest a 550 or an oe346 is a better candidate for a hack?
 
That "nub" on your flat plate when you're cutting the squish. Is that just a bit of loose round stock?
The new lathe is in and turning. I have to pluck up the courage to cut a squish band one day soon.
Would you suggest a 550 or an oe346 is a better candidate for a hack?

That's just a piece of 1/2" drill rod. I've got a few in different lengths.

The 346 will give you more experience with the port work. The 550s I do just get a little work on the exhaust and the uppers. The rest is all machine work.
 
That's just a piece of 1/2" drill rod. I've got a few in different lengths.

The 346 will give you more experience with the port work. The 550s I do just get a little work on the exhaust and the uppers. The rest is all machine work.
Upper transfer shape still leaves me scratching my head.
It's most of the reason I read these threads at the moment, trying to get my head around flat vs tapered, roof shape, direction, what works for different saws and perhaps why.
 
The 681.



Now a 7900.



See the differences in the lower transfers?
So what your thoughts on the lower transfer?
The uppers look wider on the solo

What numbers did the doom are have.

Why do the have so much intake timing and low transfer and exhaust numbers
 
Randy,

Do the opened up lower transfers on the Solo? And would doing that to the Dolmar help??

What piston is the Solo running ? Open port or slab side? What would the effects be putting the closed slab side Dolmar piston in the Solo if it's the open piston.

Just thinking out loud....
 
The Solo 681 would easily have the highest BMEP of any saw on the market. While many only consider a saw from the major two, its mind boggling what gets left behind. A 576/461 would not touch an 'off the shelf' solo 681 without significant modification. The difference l like between the 7900/681 lies not only in extra zip of the 681 but a host of little imorovements in minor detail all over the saw. lts not untill you get both saws on a bench together for this to be evident. Thanks again M/M for reviving this place and keeping it alive!
 

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