Makita EA3601...the most intriguing saw to date

[wcorey]

My seat o’ the pants take on it…


It seems the primary set of reeds that lets the strato air in is simply another way of doing more or less the same thing as the cutaway piston timed design.
The charge passes across/through the lower transfers and then down the passages in front the crank case, instead of through the piston passages and around the sides of the cylinder.

The secondary reeds being outgoing from the crank case just loop right back in to the middle of the strato tract at a different time in the cycle, when the piston is on its way down.

So at that point that section of passages have a different function, it’s all air/fuel mix by then and goes up and out the upper transfers instead of across the lowers and down.
One last bit of charge into the combustion chamber and from a rearward direction.

Maybe one last squirt to keep the charge velocity going at a time when the crank case pressure is relatively low near the bottom of the stroke where a more conventional design would be losing it.(and taking advantage of the correspondingly low pressure in the combustion chamber).
Though it's so small it's hard to imagine the velocity maintaining all that way...

I'll probably read this again in the morning and wonder what the hell I was thinking, lol...

 

[Terry Syd]

What would turning the reeds around achieve that removing them wouldn't?

The secondary reeds presently feed OUTWARD from the crankcase. If you were to mount them so that they fed INWARD to the crankcase (with the appropriate porting), then instead of two reeds feeding the crankcase - you would have four reeds feeding the crankcase. The more fuel/air you can stuff into the crankcase, the more fuel/air you can pump up into the cylinder from the crankcase.

I still don't understand why those reeds are flowing out from the crankcase. The crankcase pressure should be uniform throughout the crankcase. We'll just have to wait and see what blocking off the secondary reeds does to the powerband and develop a theory or two to explain it.

 

[paragonbuilder]

The secondary reeds presently feed OUTWARD from the crankcase. If you were to mount them so that they fed INWARD to the crankcase (with the appropriate porting), then instead of two reeds feeding the crankcase - you would have four reeds feeding the crankcase. The more fuel/air you can stuff into the crankcase, the more fuel/air you can pump up into the cylinder from the crankcase.

I still don't understand why those reeds are flowing out from the crankcase. The crankcase pressure should be uniform throughout the crankcase. We'll just have to wait and see what blocking off the secondary reeds does to the powerband and develop a theory or two to explain it.

I'm still confused. The first set feeds the second set, so to me it is just an unnecessary restriction. I think it would need a separate feed to achieve what you are thinking.
It looks to me like the second sets function is to force the fresh air through the long lower tract as opposed to just entering the case immediately. Then to equalize the fuel air charge on the down stroke, the reeds open and the fuel air comes from both sides of the crankcase up through the lowers to the cylinder.


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[ajschainsaws]

Interesting what is the piston like is it different at all are the ring spacing and skirt length critical on this set up

 

[paragonbuilder]

Interesting what is the piston like is it different at all are the ring spacing and skirt length critical on this set up

I don't have an extra crank, so I won't be able to check that til I tear it down for mods.



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[Dub11]

Video of it running?

 

[paragonbuilder]

Video of it running?

There are some earlier in this thread @166 posted. I'll have some later today.


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[Dub11]

Nice ! And I'll look back.

 

[Duane(Pa)]

I presume it has a spur? What chain is this feller running?

 

[paragonbuilder]

I presume it has a spur? What chain is this feller running?

Yes it has a spur.
Comes with 3/8picco semi safety chain

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[paragonbuilder]

Just picked up a couple 63ps chains for this little guy!


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[fordf150]

Just picked up a couple 63ps chains for this little guy!


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Want to test some chain while your videoing the saw?

I have Archer 63PS clone chain i can spin a loop of and send your way to compare with the real deal.

 

[paragonbuilder]

Want to test some chain while your videoing the saw?

I have Archer 63PS clone chain i can spin a loop of and send your way to compare with the real deal.

Yes sure why not!


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[paragonbuilder]

Fueled and ready to go make it's first cuts.

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[Philbert]

Attractive little saw!

Philbert

 

[paragonbuilder]

Here it is.
First off I forgot it had a primer bulb, so it probably would have started better if I primed it.
Also I rarely run a saw this small so I'm probably pushing it a little too much...

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[paragonbuilder]

It seemed to be tuned just above the rev limiter. But I can't get it to 4 stroke lifting in the wood. At least to my ears.
Unfortunately I don't have the carb adjusting tool for this Saw... so I'll probably see if I can get them out and slot them for a screwdriver.


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[paragonbuilder]

Here it is in 5" maple

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[paragonbuilder]

I'm going to go cut with the tach and see what I think


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[Terry Syd]

What would turning the reeds around achieve that removing them wouldn't?

The first set feeds the second set, so to me it is just an unnecessary restriction. I think it would need a separate feed to achieve what you are thinking.

It may be that blocking the second set of reeds is the easiest approach to modding, perhaps even widening the reeds to get a bit more area. However, with an extra set of reeds sitting in that engine just waiting for someone to figure out how to make use of them, Crikey, I can't get them out of my mind.

Like you said, if the first set of reeds feeds the second, then the reeds are in SERIES and will cause a greater restriction to flow. What we need is to have the reeds running in PARALLEL so there is less restriction. Your comment about having a separate feed for the secondary reeds is what needs to be done.

I don't have one of these engines sitting in my lap to mull over, so I'm left with abstract ideas that might not even be close to what is workable. Here's the way I envisioned a possible set-up. There is that 'soap dish' contraption under the reeds. Perhaps all that can be removed and a simple plate put under the primary reeds to feed the cylinder. Then the space under the plate could be used as a channel to feed fresh air to the reeds on the case.

Once we can figure out a separate feed of fresh air for the secondary reeds, the mod should come together fairly easy.