Originally Posted by Twin-Stack

Gluehand, I think a replacement for the Frog "clack valve" would have to be made from spring steel, as the original is quite rigid. This means that the whole valve is free to move forward under the negative pressure from the crankcase when the piston is rising. The reed valve (usually made from beryllium copper or similar) tends to be quite flexible, and even though retained by a circlip, can "bulge" in the middle to allow fuel mix to enter. BOB

Also known as the vibramatic one of the first new motors I ever owned ,most were 2nd hand and although I had mine apart from time to time I'm sure the edges weren't knife edged.

Originally Posted by olmod

Also known as the vibramatic one of the first new motors I ever owned ,most were 2nd hand and although I had mine apart from time to time I'm sure the edges weren't knife edged.

Here's a couple of photo's of the animal in the flesh. It says in the Engine Test of the 149 that the disc is shim steel, 0.005 in. thick. I think that, on examining it more closely, only one (the seal) side is ground. By holding a straight edge across the disc, I can see daylight on either side. BOB

Originally Posted by Twin-Stack

the disc is shim steel, 0.005 in. thick.

Maybe something like an 'old school' razor blade.... (thinking of potential 'raw materials' for making a disc..)

I can see a couple of ways to go about making it.
One way is to get some sheet metal around that thickness, maybe a little more thick. Then cut out several pieces. Then using two more thick washers or pieces, you could clamp them like a sandwich together tightly. Then using a milling machine and a rotary table, you machine the circle size to shape. The thin pieces in the middle ought to come out pretty good and useable with little or no lip or edge on them.

One could also chuck up a piece of steel round stock in a lathe and carve a piece or two out of it.

shim steel rough cut to oversize sandwiched between a sacrificial round bar and another between the tailstock centre on a lathe should do it, perhaps after cutting using a grinding head or emery taped to finish the edges while still chucked.

I have one ... it came from the estate of a flying colleague, it's an .099 with a tall vertical intake stack, like the old PAW 1.49 cc and 2.59 cc's.

It has a backplate held on by three machine screws. Will post a pic if anyone is interested. It's compression is gone to "compression heaven", but I plan on having a new piston made for it. Would love to run it.

I know nothing of KO engines. Does anyone know anything about them?

Originally Posted by fiery

I have one ... it came from the estate of a flying colleague, it's an .099 with a tall vertical intake stack, like the old PAW 1.49 cc and 2.59 cc's.

It has a backplate held on by three machine screws. Will post a pic if anyone is interested. It's compression is gone to "compression heaven", but I plan on having a new piston made for it. Would love to run it.

I know nothing of KO engines. Does anyone know anything about them?

Fiery, lets see it then. Didn't Adrian Duncan do an article on KO's ? If not, about all I know is that they were made by the Kondo brothers,who I think were speed flyers in Japan. If you go to the Vintage Glow Engines thread and look for the Global Engine Reviews (starting on page 23) you will find a few mentions of KO engines. BOB

Here 'tis. It looks sad, anodising long faded from head, but is cosmetically only a little marked, apart from prop driver (sigh, has the ever unappealing plier scars) and one oblongated mounting hole. Also missing screws from backplate and the comp screw is in another box somewhere. Sadly, P&L fit is toast. Will get it restored though.

Fiery, looks like it may have had an option for a second needle valve assembly, making it a two speed for RC.
It's a real shame when some one takes pliers to "bite" the engine parts. I get too agitated when I come across those and don't even consider them.
John

Well, i figure if it is dinged up from plier marks, and if it is fixable, it'll make a good runner as you can't mess it up much more, unless you crash it or something.

Is this a Diesel - if so, what is that thing on top of the cylinder ? BOB

To me that looks like a diesel and the arrangement on top apart from manual altering of compression would allow for in flight tweaking as well (through radio off course)

Originally Posted by Twin-Stack

Is this a Diesel - if so, what is that thing on top of the cylinder ? BOB

This is an engine made by Jan Garcic. You will recognise the shape on my website, there's a geared V-twin Garcic on there somewhere. Never seen this system on any engine, if selling it I am interested.

It's basically a throttle by controlling compression. Davis actually has a similar idea on their .049 head, which wasn't popular either.

Greg

Here is one you don't see too often. In case you are wondering but don't want to click, it's an Enya 41 4C Diesel. If I had not just bought the Webra T4-.90 I'd be trying to add this baby to my collection.