AndyW

My Feedback: (1)

Pictured is before and after on a Tanaka 26cc conversion from their TED 262DH powered drill. Dead nuts easy to do, all I had to do really, was to grind off the front flange bits. Also, I had to trim a bit of a groove to allow clearance of the mounting bolts. Plus the usual trimming of the flywheel and prop hub. I really like Tanaka's four bolt approach to everything. No oddball backplate mounting holes. The neat thing too is that you can bolt the Tanaka directly to your firewall, no mounting plate at all required.

On another thread I asked about the suitability of mounting a spring starter to the rear end. I flew a Quadra when they first came out and am only now going big again. If you look at my past postings, you'll see that I was/am heavily into 1/2A. I'm hoping you guys won't hold that against me. [X(]

Point is, getting whacked by a small engine is annoying. Not so a gasser, I'm speculating. Any advice in this regard?

AndyW

My Feedback: (1)

OK, now that I've annoyed everybody with super sized pictures, (don't know why that's happening) I'm going to do more of that and ask a stupid question. I assume that the smaller wire coming off the coil is meant to be grounded?

Antique

My Feedback: (4)

Check the drill, it was most likely connected to the kill button...Ground it and the engine stops...

AndyW

My Feedback: (1)

Thanks RC,

Can't check the drill, it is no more. Converted. But likely you're right. Ground would be the fact that the coil body is mounted to the frame. It's been a long time but boy am I ever looking forward to flying big again. Had a taste last fall on a Zenoah powered something and I got hooked. All these years and I had forgotten. Neat.

captinjohn

That Tanaka engine looks nice. Made In Japan. May have to try one. I re-done the photos .. Capt,n

AndyW

My Feedback: (1)

Cap,

Yes, the Tanakas have features that lend themselves very well to conversions. And unlike common, home use weedwhackers and the like, they're made to industrial standards. Used by lumberjacks, diamond drill operators and the like. The chrome work is thick and durable.

But, you get what you pay for and they do cost a bit more. I got lucky and got a used one (for diesel conversion) and a new one, (shown here) that's been converted but retained the gas fuel mode. This will be used as a bench mark engine to compare it to my other experiments which will include diesel and glow-on-gas operation.

All will be posted to YouTube as we go along. Will use this thread to record results.

Diesel pics attached.

For examples of my experiments on smaller engines, see, http://www.youtube.com/profile_videos?user=hopeso

I'm also making my own Biodiesel fuel and if the Tanaka works out, I have ambitions to convert my lawn mower to diesel and see if Biodiesel has a future cutting grass. Kinda nutty but fun to try.

AndyW

My Feedback: (1)

I'm also converting this one to reed operation. It won't be by adding a reed assembly at the side port intake, that has been plugged. The reed intake will be at the bottom of the case.

When I modify, no half measures, I MODIFY.

And as the pictures show, I'll be using a stock, RC throttle instead of the Walbro. This one is off of a K&B Sporster .60 and the bore of both rotary barrels is the same.

I'm very new getting back to big gassers so I don't know the latest. I noticed that the Walbro that came with the Tanaka has a rotary barrel along with a needle that restricts fuel delivery as the throttle is reduced. Very much like our RC throttles although the low speed needle appears not to be adjustable. Is this unusual or is this the norm these days?

AndyW

My Feedback: (1)

The latest run can be seen here.

http://www.youtube.com/watch?v=Q6DKts9o9pI

Now we're getting a proper 1600 to 7000 RPM on a Zinger 18 X 6. Still needs to be broken in.

However, it was found that the idle was a bit rich evidenced by the slight smoking on acceleration after a prolonged idle of ten minutes. So I went to lean out the idle and found that both the main and idle mixture is fixed on this engine.

The solution was to bolt on the carb from an OS .108 along with applying muffler pressure. It worked fine with nearly the same top end but idle wouldn't go lower than 2200 RPM. This may have been due to the below freezing conditions of the day with little chance to do much tweaking. If you look close, you can see frost on the OS carb.

Will try again when we warm up a bit.

foamcut

My Feedback: (40)

Andy,

Where did you get the reed valve and how did you determine the right size for your engine?

Thanks

AndyW

My Feedback: (1)

Foamcut,

Very little science was applied to that actually. The local, small engine shop gave me an old chainsaw engine that had reed valve induction. Don't remember the make. I pulled out the reed assembly and got a new rubber bracket, (holds the reeds) and went from there.

The reed assembly is from a 40cc engine so I'm assuming that at least I'll have no restriction on the intake side. Lots of reed volume to pull in the fuel.

The stock Tanaka's latest run using the .108 throttle can be seen here.

http://www.youtube.com/watch?v=z5fK1NWDLS4

Once I get the compression ratio sorted out, I'll be running this one first on glow and then on gas/glow and if it survives all that, on diesel.

AndyW

My Feedback: (1)

Here, http://www.youtube.com/watch?v=noH_SOBe0YE can be seen the case reed version of the Tanaka 26cc.

The stock cylinder had the head milled off and a new head button was made that is secured with long bolts that also holds the cylinder down. The head button carries an OS Turbo Plug.

The stock intake port has been plugged and a new, reed intake assembly has been installed to the bottom of the crankcase.

The carb is from a K&B .40 Sportster with a venturi bore of .34" as opposed to the stock bore of .45"

On the baseline, 18 X 6 Zinger wood prop, we are getting a solid, 7500 RPM. That translates into an extra .4 horsepower over the stock gasser on ignition.

We have shed nearly two pounds of ignition gear and gained power at the same time. Can't beat that.

However, we likely would gain that and more, if we could increase the compression ratio on the stock gasser. The real payoff with this conversion is the weight reduction.

Unfortunately, throttling didn't exist. Anything less than 3/4 throttle produced a flameout.

Flipping the engine to a sidemount configuration cured that, interestingly enough. We are speculating that at low throttle, engine suction was insufficient to draw fuel properly. Sidemounting provides for much easier fuel flow to the bypasses for delivery to the cylinder.

The plug is a P8, OS turbo plug. This is their cold plug and was tried in this case, simply because that's what we had on hand.

The head button was made to give us a compression ratio of 14:1 and this has proven to be about right. Decreasing the compression as an experiment will be tried but we don't anticipate any benefits. The runs today don't exhibit any overcompressed symptoms. More productive will be increasing compression to the point of getting some ping. Then we'll back off a bit and proceed to experiment with a bit of nitro (2-5%) along with various plug heat ranges and extra shims.

Pictured is the installation of an Enya, three needle throttle from their .60 which has a bore in the barrel slightly larger than the stock Walbro.

Throttling still wasn't perfect as we couldn't get less than 3K. The stock, ignition engine on gas gave a forever, solid idle of 1.3K So, as a side mount improved throttling, we reasoned that inverted might be even better. Unfortunately, it was pretty much the same as side mount.

Either the reed design itself isn't suited to this configuration, or a reed on the case just isn't a good idea.

Next up will be to install the reed assembly onto the sideport as per the stock arrangement.