Standard Enya .049-II engine vs. the Mikoken Enya engine -- What is different?

GallopingGhostler wrote:Besides the aluminum surfaces being polished and cylinder blued (a beautiful engine), the Mikoken engine cylinder top has been milled down to increase compression.

I did polish up the brass on the engine along with the aluminum head and prop driver.
The bluing of the cylinder was done by Mikoken and they also made the spinner for the engine.

All of the Mikoken engines that I have been able to acquire all have spinners on the crankshaft.

Yes, the cylinder top (aluminum head) has been milled down and a 1mm shim is between the crankcase and the cylinder.

Below is the look of the head from the inside:
On the right is the standard Enya .049 head, on the right is the Mikoken modified head



Standard .049 compression ratio is 8:1
With Mikoken head is 9.0:1

More details later.

Those are beautiful engines….. The carb’s look very well made….. Have you ran them both for comparison?

rdw777 wrote:Those are beautiful engines….. The carb’s look very well made….. Have you ran them both for comparison?

This is my 9th Mikoken .049 engine that I have acquired.

Currently, I have nineteen custom Mikoken engines.

I have run the standard Enya .049 with a Cox 6x3 prop on 5% nitro and got 17000rpm.
Another Mikoken .049 that I have run with the same prop and fuel (same day too) got 22000 to 24000rpm
Almost like the difference from a Cox Medallion and a Tee Dee.

By the way, there is one more major difference from the Enya .049 and the Mikoken engine (keep reading!)

Anyway, here are some more changes from the regular Enya .049 over the Mikoken engine:

We'll start with the crankshaft.
Mikoken made their own crankshaft. The threads on the prop end is M4x0.7 and not the Enya standard .049's M4x0.8.
So, you can get a standard M4 nut at the hardware store.
Also, Mikoken engines always have a spinner on the crankshaft.
That is an easy way to know it is a custom engine from Mikoken.

Another thing you'll notice with the Mikoken crankshaft is the hole for the fuel intake (it is round) and not square like the Enya .049 crankshaft and the Mikoken crankshaft counterweight is thicker.




Timing is the same, but the crank pin is 0.250mm farther away from the center of the crankshaft than the standard Enya's crankshaft.

With this change the bore is 10.5mm but the stroke is 9.9mm
The original Enya .049 bore is 10.5m and the stroke is 9.4mm

And making this slight change, Mikoken bored and modified the crankcase (just a little) to accept their crankshaft.
Enya's crank on the left / Mikoken crank on the right.
and notice the center hole on the Mikoken crank is smaller -- thicker wall on the crank for strength.



Onto the crankcase:
Enya just installs the crank into the crankcase --- no shims and maybe a thrust washer but not always.
Mikoken installs shims to reduce camshaft play, thust washer behind the prop driver and sometimes a shim between the crankcase and the piston cylinder.



Next on the case is the finish of the mating surfaces.
The place where the carb. assembly goes to is milled/lapped to a fine finish, whereas Enya does not bother with that.
The Mikoken photo is the 1st one
The Enya crankcase is the 2nd photo --- notice no thrust washer behind the prop driver on the Enya.




The back plate surfaces are the same on both of the engines.
Only difference is the screws used on the Mikoken back plate to tighten it to the crankcase.
The screws have a low head on them. The Enya screws heads are higher and stick up past the three mounting spots on the bck of the engine (by about 1mm or so)

Mikoken engine on the left side / Enya engine on the right



Next is the piston cylinder:
The top of the cylinder has been machined down about 1.0mm, along with the glow head machined down (see earlier photos)
Which increased the compression ratio from Enya standard 8.0:1 to 9.3:1

Mikoken cylinder on the left / Enya cylinder on the right



Now for the piston differences:
Mikoken did a bunch of work to lighten the piston (probably for the higher speeds it will produce?)
Inside you will see they tried to keep the piston weight down over the Enya piston (Mikoken made their own piston for this engine)
On the left is Enya's piston / on the right is Mikoken's piston -- see how the Mikoken piston skirt is thinner than the Enya piston?





The other thing to notice is the length of the piston as well.
The Mikoken piston is longer than the Enya piston.





Now the piston assembly inside the piston and how Mikoken kept it lighter than the Enya assembly.
The Mikoken assembly is 14 gram lighter over the Enya's assembly.





The assembled piston in the cylinder, screwed onto the crankcase.
On the Enya engine (that I am comparing with) at Top Dead Center the piston is below the glow head shoulder by 0.500mm
Whereas the Mikoken engine piston is at the shoulder of the glow head (just like a Cox engine piston)
Below is the Mikoken piston at Top Dead Center with a copper shim (one that was there with the engine .010")




This a comparison photo of the Enya and Mikoken engines at Top Dead Center to show the Enya is below the glow head shoulder.
The photo just did not come out clearly as many times I tried to take many different photos of it.
On the left is the Enya engine where you can see a shadow "ring" just below the glow head shoulder on the cylinder.



On to the carburetor assembly:

One thing noticeable is the hole size of the intake and the throttle drum on the carb.
They are slightly larger than the stock Enya carb.

See the photos below of the carb housing:
Mikoken housing on the left and the Enya carb. housing on the right.
Looking from the bottom, Next photo is looking down from the top.





Now the throttle drum:
Mikoken is on the right side and the Enya throttle drum is on the left.




Has anyone picked up what really makes this engine special?[

Let us look at the key points.

Custom made crankshaft which is 0.250mm difference from center of crankshaft to center if crank pin compared to the Enya engine
Measurement from bottom dead center to top dead center is 9.9mm.
1mm shim under the cylinder and above the crankcase.
Reduced glow head height and cylinder height.
Larger intake holes on the carb.

Now let us look at the Enya engine information:
Bore x stroke:  10.5 x 9.4
(c.c.)                .814   (c.i.) .0497
compression ratio: 8.0:1

Mikoken Engine data:
Bore x stroke: 10.5 x 9.9
(c.c.)                .857   (c.i.) .0523
compression ratio: 9.3:1

This is a custom made .051 by Mikoken --- that is what it was listed as when I purchased it.
This will go with the Mikoken Enya .10 custom made diesel and the other custom made Mikoken engines.

Here is the custom made Mikoken .10 diesel:






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All very intriguing and interesting-did Mikoken apply their expertise to other engine brands as well-or just Enya?

ChrisM
'ffkiwi'

ffkiwi wrote:All very intriguing and interesting-did Mikoken apply their expertise to other engine brands as well-or just Enya?

ChrisM
'ffkiwi'

They have their own website:

http://mokoken.driven.jp/index.html

You can get an engine specially made from them.
Or if you go to the bottom of the website, you may be able to get one that they are trying to sell?
It is a very interesting website

Very clear and precise overview and photos…. Was quite an impressive jump in performance!….Interesting to see what another country did that somewhat paralleled Cox…. I wonder what their main target was?… Looks suitable for 1/2A pylon

rdw777 wrote:Very clear and precise overview and photos…. Was quite an impressive jump in performance!….Interesting to see what another country did that somewhat paralleled Cox…. I wonder what their main target was?… Looks suitable for 1/2A pylon

Those Mikoken engines demand a good price.

On this engine:
The winning bid, auction cost (proxy buyer) and shipping to the USA totaled $237.74

Cheapest Mikoken engine I have won was $183.34
Each one is hand built and done with precision.

All of the ones I have are unique.