It seems pretty happy with the 18 x 8, though I agree that's a bit small. Once it's broken in I'll experiment with larger props. It runs nice and cool though. I did a lot of touch and goes with it as that's great for motor break in. Nice reliable idle and great response. I did some verticals with it, and did not notice any sagging. Keith said a lot of people use a 20 x 8 on this engine, and recommended around 7500 rpms as a good target. We'll see once I get some more time on it...

As for you torque comment, I don't understand why it wouldn't like to spin some rpms though. I usually run my Echo 23.6cc engines near 9000 rpms. Since this twin is made from Echo cylinders and cranks, why wouldn't it like high rpms as well? Of course with twice the displacement it will have more torque, but the port layout is the same as far as when/where the power curve is right? Is it because of the reed valve intake being restrictive??

That makes me think of another question. Other than tuning hassles, how would one of these run with twin carbs?? That would solve the problem of finding those no longer made reed valve assemblies. BTW do you have one of the BME twin blocks you would sell?

AV8TOR

I guess it really depends on the flying one does. 3D would want the bigger prop for low end power or thrust and the ability to pull hard from that point. Guess it is just finding the right power band for your flying style. A low grunt gear in a way. The prop is the flywheel and if the engine can handle the size of the prop (flywheel) at a lower RPM then that is where to go IMHO so long as you don't heat it up by lugging it. Even the big 61cc twin is like that. That thing darn near flew my test stand, err, grill when I ran it as it pulled so hard with that 22/8 prop. I have a few reed blocks but I need them for my yet to be finished projects. The reeds make for a smoother running engine too for what it is worth.

Tim

Tim, I wasn't asking about the reed blocks, I was asking about the engine blocks.

Also, about the 62cc twin. I believe something was mentioned about larger cylinders fitting that engine. Do you know what they are, and in what equipment they were offered?

AV8TOR

Sorry, I thought you meant the reed block. I have sold all but one of the engines I converted and I have it two cases left. For now I am hanging on to the cases but the last running engine??? I know there are other cylinders out there that would work but the problem is the pins in the case where the cylinder seats. Any of the other cylinders I have looked at would require new holes for the pins to match the cylinders. Not impossible but never took the time to try.

Tim,

Have you tried fitting one of the Mac25 cylinders to the BME case? I tried fitting a cylinder to a case and found that the mounting lugs line up after rotating the cylinder a few degrees. This would mean that the exhaust would not be exactly perpendicular to the crankshaft centerline. A custom exhaust header would probably need to be created. As long as the relationship between the ports, case, and piston skirt remain the same it might work. Unfortunately I don't have the equipment or skills to cut / weld a crankshaft or I'd try it myself.

I do have 2 40cc Echo cylinders I was thinking about putting on my 60cc twin.

I'll pull it out after Christmas and check it out.

My wife is tired of me buying my own Christmas presents [&o]

Foamcut I have looked at a bunch of cylinders over time. Most could work as the issue is in the pin on the case. I would need to look through the base gaskets I have and see how many fit the original cylinders and cross them to the bigger cylinder that uses the same gasket. Drill new holes for the pins and it would probably be OK.

This is just a general question im throwing out to anyone on this thread.like av8tor does anyone have or know of 1 BME twin case thats laying around not going to be used.If so PM me if possible.thanks for any help.

PM me also, I would really like to get my hands on a 100, 110 or 115 case, heck, even a small twin crankcase would work for starters. Tried calling and emailing BME for about a month now but no contact.

There is a guy in Colorado who did work for BME at one time.

Just US Machine
112 Factory St
Sterling, CO 80751
(970) 522-3763

He may still have some cases laying around. I had one from him but sent it back as BME had cranks made and I couldn't match anything up with the inside bores of that case. Cylinders were another issue. But maybe it will be a start for someone. He also does work for CH Ignitions, at least he used to.

I would like to know too. I want to make a twin.

Paul

KI8FR: How is that Homelite twin coming? There is a lot to figure out...RIGHT! Capt,n

I had a friend cut 2 blocks. Then he welded them to gather. Now he is looking in to a way to cut the block and have a way to bolt it back to gather with the crank in it. All of the ways he as to cut the thing will make the cut to big and it would have to take a shim or a very thick gasket to keep the block right for the jug. He said it will be a little before he can get it done. He is doing it at work in his shop but he can only have time to work in it on brakes and lunch.

I guess we will see how it works

The crank is going to be a little harder to do.

Paul

Happy Holidays!!

Just got back from flying the "Echo Twin/Giant Stik" combo again. But this time I had my new camera to take some pics!! (Sorry, I was alone so no flight shots....)

What a sweet little engine. I really enjoy it.

I know Captain is going to jump in here and ask, so....

1. Yes, it is Gas/Glow

2. Yes, I have hooked up an onboard glow system.

3. No, I don't use it after starting the engine. Turn the switch on, start the engine, turn the switch off, go fly. Period.

Merry Christmas!!

AV8TOR

Nice really nice.

What batterys are you using for the on board glow system?

Did you have to add any weight? If so where?

Thanks!

No, amazingly enough, the twin with it's mount, prop adapter, etc. weighed within one ounce of the Poulan 42cc single and mount that had been on the plane. It even has a smoke pump and tank in the front compartment too. With only heavy duty servos mounted in the rear, it balances just a touch aft of the c.g. specified in the manual. I do have the flight pack mounted towards the rear of the radio compartment under the wing though. The gas tank and the onboard glow battery are mounted right about on the c.g. I am using a 4500 mah onboard glow battery. Like I said, it is not needed for anything more than start up, but it is nice to not have to fool with hooking and unhooking two glow connectors. The plane flies so nice and light it doesn't even notice the slight additional weight. It lands very slow and light, and I don't use flaps. I had originally built it with flaps, but they weren't really needed and I found myself wanting a faster roll rate, so I took out the flap servos and hooked the flaps and ailerons together for full span ailerons. It's my favorite "knock around plane" now.

AV8TOR

I could not get my glow plugs to light with a 2 4500ma batteries in parallel
I wonder why? They were from Raido Shack.

Remember we talked about this before.

I have had very bad luck with batteries from Radio Shack. If you look in the review section on the batteries, (Radio Shack site), other people have been unhappy with them as well.

Try here: www.cheapbatterypacks.com Click on "Loose Cells" and then "Nimh".

I've gotten glow batteries from him, batteries for my starter setup, etc. Good prices, good service, good products from my experience.

AV8TOR

Commercial batteries used for cameras and portable electronics are not rated for high amp. They are usually rated for something like 0.5 - 1 A or so. I checked once D-size 9000mAh NiMh battery and I was surprised to find out that it was rated only for 1A. Not enough for glow plug. Cold glow plug (depends on type) may take up to 3.5A. Like AVI8TOR said, cheapbatterypacks has good high discharge batteries that work for glow. I bought ELITE3600 form my on-board glow (two cells parallel). Now I see they have ELITE4000SC - should be a better fit. I wouldn't bother with ELITE4500, not for that price.

BTW, I have one more hour on my CoroCub, still the same glow plug. Looks like keeping glow plug powered during the flight doesn't hurt it at all. Now I'm flying with APC 16.5x5W, the engine starts by flipping the prop most of the time in right direction (I finally figured it out) and gets more power every flight (now loops are much easier to do). I can repeat after AVI8TOR : It's my favorite "knock around plane" now.

Rysium.... Have you done any tests on standard two stroke glow plugs? My thinking is that in an application like yours, where the glow plug is powered all the time, that it would not be necessary to use a four stroke glow plug. I am also thinking that perhaps two stroke glow plugs might have a lower current draw. What do you think?

AV8TOR

Right now I don't know what plug I have as there is no symbol on it. It is long reach without the idle bar. I just checked other plugs I have and most of them take the same current. The highest current 4.6A was on some unknown brand with idle bar. A3 is taking 3.8A, A8 is glowing on 3.6A (the initial current is around 4.8A and goes down when the plug starts glowing). The lowest current I measured was on KB-1 and it was 2.6A. All these measurments were taken from fully charged two ELITE3600 connected in parallel.

I believe, there is no difference on the type of the glow plug used when the glow plug is powered all the time. I can take any used glow plug (it may have no platinium left) and the engine will run. As long as it is long reach and it has coil intact. The good thing is that I'm taking "burned" glow plugs from guys running glow engines and I can have many usefull hours in my Poulan. In most cases "burned" glow plug means it has platinium stripped out so it can not work without glow battery any more, but I don't care as I run glow power all the time. That makes my engine even cheaper in running - free glow plugs .

BTW, I messed up, as I thought I was posting in gas-glow thread [8D].

Ok, thanks Rysium.

AV8TOR

I spotted several 23.6cc echo engines (as per the owner) at a local small engine shop. Does anyone have one of the BME echo cases that they will not be using, that they would like to sell?

I've been looking for an inexpencive set of after market mufflers for my engine.

Has anybody came up with a good source?

Hi,

I just gutted, then cut short and capped my original mufflers for my twin. I've made numerous mufflers like this for my various conversion engines. They weigh the same, or often slightly less than an aluminum muffler because the wall thickness is much more with the aluminum.

In lieu of that, try www.wackerengines.com or www.lambertsrc.com. I'm sure either one could make you up a pair, especially if you send them a pattern of the exhaust exit.

AV8TOR