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Makita EA3601...the most intriguing saw to date

Terry Syd

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I worked my way, second by second, through the video to try and figure out how they consider this to be a 'strato' configuration. The video left me with even more questions.

Apparently, they have decided to dump the fresh air charge at the bottom of the crankcase (the opposite to what we are used to) so that the intake charge coming in from the carb can 'somehow' push the fresh air ahead of it into the cylinder. I'd need some time with this cylinder to get a feel for what is really going on.

Here are some observations that I think will be important for modding. If you look at the picture of the carb and the strato butterfly, it is clear that the carb is a LOT SMALLER than the strato butterfly. The carb appears to have a venturi that is less than 50% the area of the strato opening.

That's good, we can use that. Then we come to the first set of reeds and they are very good size, probably have even more area than the 6100 has.

But then we come to a SECOND set of reeds (WTF?) Why would they put a second set of reeds in series with another set of reeds. There must be more to this reed configuration, like separate conduits to the forward or back transfers, otherwise the second set of reeds would just be adding a restriction to the flow.

I'm waiting for a build thread on this saw where all the questions about internal flow have been resolved. Then we can start figuring out how to make that flow even larger.
 

paragonbuilder

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I worked my way, second by second, through the video to try and figure out how they consider this to be a 'strato' configuration. The video left me with even more questions.

Apparently, they have decided to dump the fresh air charge at the bottom of the crankcase (the opposite to what we are used to) so that the intake charge coming in from the carb can 'somehow' push the fresh air ahead of it into the cylinder. I'd need some time with this cylinder to get a feel for what is really going on.

Here are some observations that I think will be important for modding. If you look at the picture of the carb and the strato butterfly, it is clear that the carb is a LOT SMALLER than the strato butterfly. The carb appears to have a venturi that is less than 50% the area of the strato opening.

That's good, we can use that. Then we come to the first set of reeds and they are very good size, probably have even more area than the 6100 has.

But then we come to a SECOND set of reeds (WTF?) Why would they put a second set of reeds in series with another set of reeds. There must be more to this reed configuration, like separate conduits to the forward or back transfers, otherwise the second set of reeds would just be adding a restriction to the flow.

I'm waiting for a build thread on this saw where all the questions about internal flow have been resolved. Then we can start figuring out how to make that flow even larger.

I'll be looking for insight Terry as i dissect this saw. I'm sure I'll have it apart a few times. Please feel free to offer insight and ask questions as I progress. I'll tag you when I get the saw and start the build thread.


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Simondo

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I worked my way, second by second, through the video to try and figure out how they consider this to be a 'strato' configuration. The video left me with even more questions.

Apparently, they have decided to dump the fresh air charge at the bottom of the crankcase (the opposite to what we are used to) so that the intake charge coming in from the carb can 'somehow' push the fresh air ahead of it into the cylinder. I'd need some time with this cylinder to get a feel for what is really going on.

Here are some observations that I think will be important for modding. If you look at the picture of the carb and the strato butterfly, it is clear that the carb is a LOT SMALLER than the strato butterfly. The carb appears to have a venturi that is less than 50% the area of the strato opening.

That's good, we can use that. Then we come to the first set of reeds and they are very good size, probably have even more area than the 6100 has.

But then we come to a SECOND set of reeds (WTF?) Why would they put a second set of reeds in series with another set of reeds. There must be more to this reed configuration, like separate conduits to the forward or back transfers, otherwise the second set of reeds would just be adding a restriction to the flow.

I'm waiting for a build thread on this saw where all the questions about internal flow have been resolved. Then we can start figuring out how to make that flow even larger.
Just so as i can understand where you are with this Terry.
The configuration of carb and stratto intake are opposite to normal , the carb ....intake.... ( i assume ) "Seems" the bigger one but changes further down the tract.
 
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Terry Syd

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Yeah, I'm referring to VENTURI size, not the size of the opening to the carburetor. For example, on my modded 450 I have a carb with a 13.5mm venturi and a strato butterfly of 13.5mm. The combination of those two areas is equivalent to running a 19mm carb on a 50cc engine. - The thing just howls (the transfer port work took weeks to complete). A stock 450 has peak power at 9,000, this thing likes to cut between 12,000 and 12,500 rpm. I use the 13,000 rev limiter as my 'dull chain indicator'.

I still don't know where the flow is in this Dolmar. I thought that the reeds would flow into the transfer port closest to the carb/strato. Then I saw the picture in post #35 where the light shows the FRONT transfer area and the bottom of the crankcase joined together. OK - how does the strato air flow get to that area? I don't see any passages that would allow the strato flow to move from behind the cylinder to the front.

Here's another problem I have in conceptualizing this 'strato'. You need to have the transfer tunnels filled with fresh air in order for it to be a strato. That way, when the transfers open, it is the fresh air that enters first and starts pushing the exhaust out the exhaust port. - So, how does this engine get the fresh air up in transfer tunnels?

Maybe the answer may lie with another look into those transfer tunnel covers. Perhaps there is another passage in there that joins up with the strato reed valves.
 

ajschainsaws

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i put it in the wrong thread simon typical but I do like watching his videos and good for you too see this 7910
 

fordf150

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Im chuckling to myself a bit here .....The amount of interest in a 35cc saw compared to the usual bigger cc saws . Who would have thought it :)
Its the design not the size that has people interested. At least thats the way i see it.

Its not often that we get to see something new in the chainsaw world, usually its just small design changes, porting changes, assembly changes that come with new saws....saws from the today are virtually unchanged in basic design from the 80's other than strato and autotune. Not true for this, Makita/Dolmar threw the book in the trash and came up with something that resembles absolutely nothing we have seen before, and it seems to work well. The question is, will this same system be used on bigger saws....say a 50cc....or bigger?
 

Simondo

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Its the design not the size that has people interested. At least thats the way i see it.

Its not often that we get to see something new in the chainsaw world, usually its just small design changes, porting changes, assembly changes that come with new saws....saws from the today are virtually unchanged in basic design from the 80's other than strato and autotune. Not true for this, Makita/Dolmar threw the book in the trash and came up with something that resembles absolutely nothing we have seen before, and it seems to work well. The question is, will this same system be used on bigger saws....say a 50cc....or bigger?
Yea... it wasn't meant as a dig at anyone. Im just used to reading a lot of enthusiastic threads on the mid to upper end of the cc classes rather than the smaller saws.
I don't believe with the amount of R&D that has gone into this saw you are looking at a 1 off . They had to start somewhere and i guess they feel the 35cc saw with good power, build and price has a broad appeal ...very common size in Europe for all sorts of folks. Its Launch season for Stihl,Husqvarna as well ...Roll up, Roll up and come take a look.....Stalls for the future designs are being set out :)
 
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JMoney

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Just to muddy the waters some more. Looking at the top (intake side) of the reed block we see one seed of reeds coming from the strato intake of the air filter, simple enough, but when we go to the cylinder side things get complicated.

There are two smaller ports without reeds. Do these ports go into the transfers via the piston (like a conventional strato)?

Then we have the two larger ports with reeds and cowls. The cowls seem to be protecting these reeds from flow through the smaller ports. The reeds seem go go through the case.

Does anybody else think that they may be using the dual reeds as a sort of impulse / vacuum driven air pump to increase the pressure and / or volume of clean air in the transfers.
 

Terry Syd

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Its the design not the size that has people interested. At least thats the way i see it.

Yep, there's heaps of potential in this design. Most importantly, the reeds will allow for more bottom end torque. So let's say that after playing with this thing we end up with a saw that has the top end power of a 40cc engine. That's nice, but what if we end up with a saw that ALSO has the low end power of a 50cc saw.

I think such a lightweight saw would appeal to a lot of users.
 

Terry Syd

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This design still has me stumped, I finally figured out the first picture of the cylinder still had the base gasket on it and the second picture had it removed. That clarified how the fresh air got to the transfer tunnels. But bugger me if I can figure out how that freaking reed block works.

It even looks like the strato intake may have a plastic restriction to the diameter of the flow into the strato valve. If so, that might just have to come out.

The 6100 has a flow problem over the piston from the way the transfers enter the cylinder. This design may have avoided that 'tongue' pattern by sweeping the transfer flows in from the front of the engine instead of up alongside the cylinder.

Yep, this is an intriguing design!
 

Terry Syd

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Now I can see the strato entrance to the crankcase (the 'square' kind of hole), but bugger if I can figure out what that hole in the case is for that sits under the reed block. - I still can't figure out how that reed block works...

It looks like Dolmar has taken the trend towards long horizonal transfer tunnels to a new level. Heck, the tunnel for the mixture from the carb goes all the way to the bottom of the cases, around the front of the engine and then towards the back of the cylinder. It will be interesting to see how much blow-down this engine has. The long tunnels usually indicate a short blowdown so as to be able to use part of the residual exhaust gases to get the flow moving in the cylinder before the strato/mixture starts entering. The result is less mixing with the residual exhaust gases in the cylinder.

I wonder what the venturi size is on that carb. It looks pretty damn small to me. I'd be looking for a bigger carb before I touched that intake port with a Dremel. What model carb is it? There must be larger ones that could be adapted.

This engine is looking better all the time. If we figure out how to eliminate the various EPA tweaks the factory always ends up having to use and build it for power, this design could become Dolmar's primary design for all their saws.
 
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