RE: Echo BME twin
 

Hi Ralph,

Go to echoincorporated.com. Scroll down R/H side of page to technical info. That will ask for a model # ie. srm-2100, hc-2400 cs-440. Open the operators manual, Page to contents, then to tech. data page for spec of that model.

RE: Echo BME twin
 

Try this http://www.echo-usa.com/documentation.asp Then this http://www.echo-usa.com/oot/docs/HC2...T1E_031903.pdf Capt,n

RE: Echo BME twin
 

Okay guys I have made diligent effort here.

I have 6 echo engines and 3 different piston sizes.

Please tell me, what is the diameter of the 23.6 engine?

Will the 4 bolt cylinders fit the two bolt cylinder flange?

RE: Echo BME twin
 

ralphbf: Take APART the 2 engines you want to ex-change cylinders on, it will not hurt anything. You will then see what will work. Who knows...maybe the 2 bolt cyl will go on the 4 bolt base, and just use the 2 bolts for attachment. You can put some blue-ing on cyl base to see how the ports match. If close you can rework them untill they match. Maybe you can use one cyl with the matching piston and see if the small end of rod (of other engine) will match. Lots of stuff you can try without hurting anythig. Put some chewing gum on top of piston to see if squish clearence is close enough! Have fun. Capt,n

RE: Echo BME twin
 

Hello ralph

the cylinder bore of the 23.6cc engine is 34.0mm. the bore of the 21.2 engine is 32.mm. The stroke for 23.6cc down to 21.2 is 26.0mm. Hope this helps.

George

RE: Echo BME twin
 

Thanks George

It helped a lot.

I may have all of the parts now, or at least I know where to get them.

RE: Echo BME twin
 

I WIN!! :D

AV8TOR

RE: Echo BME twin
 

You won on gas/glow...what about spark ignition!!!! Capt,n

RE: Echo BME twin
 

Not much to that, except more money and weight... ;)

It handles very nice. Started on the third flip. No vibration whatsoever. Can't even see the gas jiggle in the tank, nor feel vibration on the test stand at any speed. With only 10 minutes on the engine and no fine tuning, a quick full throttle blast showed 6500 rpms with that big old 20 x 10 wide blade APC prop. After about 25 minutes of easy running I shut it down, and it restarted on the second flip of the prop. It's going to be a keeper!!

Thank god it starts so easy by hand flipping.... I have a gear reduced starter rigged up to a 16 volt high amp nicad pack. It turns my Poulan 42cc over easily and fast. I later tried to spin this twin over to injest some after run oil with the starter, and it won't turn it!!

AV8TOR

RE: Echo BME twin
 

Sounds like you got a winner there. I see in your photo you have the Glow Power on about as many amps as plug will take. Did you un-hook glow completely? How was the Idle without glow drivers on? Thanks capt,n

RE: Echo BME twin
 

Yeah, I let it run for a while with the glow power on, and then disconnected it. Good catch on seeing the glow power was on for the photo! I was wondering whom, if anyone would notice that.

It ran fine without glow power; just like my other engines. They will often idle just a hair slower with the glow power on, and this one is the same, though it idles quite slow without glow power as well.

I really wasn't sure how it would run without the glow power on, as I put some old non-idle bar Fox plugs I had in it for break in. I've noticed that often times with these Gas/Glow jobs that they will "eat" a glow plug on break in due to the tiny metal particles shed during the initial break in. That's why I put some old "disposable" glow plugs in it to start. After another tank of fuel, I will change over to the OS or Saito 4 stroke plugs that I normally use. I expect then it will handle even nicer and run smoother; though I have no complaints at this point anyway... It might also pick up a touch of power as the hotter plugs will advance the timing somewhat.

So be warned everyone... If your new engine starts acting "flaky" after a while when first run, change the glow plug. You will find that the glow plug looks fine, but it has been contaminated by tiny metal particles and it's bad. Put a new plug in and the engine will start acting normally again.

Cool project and I'm REALLY happy with the engine.

AV8TOR

RE: Echo BME twin
 

Looks great. Did you get any pictures of the welded crank? Was sit welded all the way around or tacked? Also noticed no bearing in front of the case or behind the prop hub. Any reason one way or the other. What carb did you use? All I have left to move to the new house and shop is the lathe and mill. Maybe I can get to mine in a while. We will see.

RE: Echo BME twin
 

Hi,

No, I didn't weld all the way around. I stopped on each side before I got to the pin as I didn't want to overheat that area.

As far as the front bearing, it bothered me a bit that it left so little of the crank sticking out to attach a hub. After studying it I thought that while it would be somewhat stronger with the third bearing, I didn't feel it was necessary. I mentioned it to Keith and he also thought it would be ok without it.

Carb is a 13.5mm venturi that I had here. I'll get the number off it if you want.

AV8TOR

RE: Echo BME twin
 

Yea that would be fine on the number. Just wondered if you had to modify it any for glow fuel. What mix do you run in it?

RE: Echo BME twin
 

Ok, I'll get back to you on that number. I'm running our standard Gas/Glow mix of one part 10% oil & 10% nitro glow fuel mixed with two parts of high test gasoline. I didn't have to modify the carb, though the needles are turned out quite far. In fine tuning I will likely raise the regulator level just a touch. This then flows more fuel and you can run the needles closer to original settings. I find that on some carbs you need to do this for Gas/Glow operation, some not.

Note to anyone thinking of running Gas/Glow: I always treat my Gas/Glow engines just like a glow engine after running. I run the carb out dry of fuel, and then use after run oil in the engine. It's important for several reasons.

AV8TOR

RE: Echo BME twin
 

av8tor1977: What oil do you like to run in for keeping things inside nice? Thanks Capt,n

RE: Echo BME twin
 

I've been using nothing but straight automatic transmission fluid as an after run oil in my engines for.... well, more years than I care to admit, and it works super! I have glow engines that are 25 years old, never been rebuilt or taken apart, and still run like new. But I am a stickler for always running the engine dry, and then injecting auto trans fluid when done for the day.

Ran the twin some more today. Just keeps getting better. I put OS four stroke glow plugs in it. (Just as I suspected, my "break in" glow plugs started to break down and not work properly.) Had it idling down to 1500 rpms without glow heat on. 1600 is more reliable though. Top end is up to 6600 now with that APC 20 x 10 prop.

Here's a "twin hint" for you guys though. At one point after shutting it down, it didn't want to restart. My glow panel showed a normal meter indication. After trouble shooting for a bit, I decided to take both glow plugs out and check them with the glow power at the same time. They weren't glowing!! The battery had dropped just enough that there wasn't enough current going to the plugs. I grabbed my other flight box, hooked up, and in two flips she was running again.... Something to keep in mind.

AV8TOR

RE: Echo BME twin
 

Just for grins we have the CHEXL 10mm twin ignition with Computer timing and shielded caps for $100. Just in case somebody wants to play with spark plugs.

RE: Echo BME twin
 

Just might have to do that one of these days soon Terry, for a comparison if nothing else. (I might also be moving to a place that would make it hard to find my special glow fuel... ) That's a good price for a twin ignition!

AV8TOR

RE: Echo BME twin
 

We it looks like I have a joint effort going.
Mine should be done by next weekend and 2 friends of mine are building one.
We haven't received their cases yet. but we are doing the cranks for all of the this week.

I'll have $100.00 in mine with the 23.6cc cylinders and they are building with the 21cc.
It looks like they will only have to buy the rear bearings, so they will have about $80.00 in theirs.

I hit up 3 echo shops and got 6 engines for free and purchased one for $30.00.
All of the cylinders were good, a couple were excellent.

I know some of you have theirs running.
Any problems? What size prop and how many RPM's

This is turning out to be a fun build.

RE: Echo BME twin
 

av8tor: How is the twin runing? How much time on it now, and how powerfull is it? Thanks Capt,n;)

RE: Echo BME twin
 

I haven't had time to run it much more, but it runs excellent. I'm getting 6700 with an APC wide blade 20 x 10, but I think I will prop it down some to let it rev up a bit more. The 23.6cc singles seem happier spinning up over 7500. Keith said a lot of people liked a 20 x 8 on their twins. It will idle reliably at 1600 rpms. I'm running Gas/Glow, and no problems.

One hint though.... At one point it mysteriously didn't want to start. Long story short I found that my field box battery got a little low, and it wouldn't light both glow plugs. It would light one just fine, but not both. So if you are going to run your twin on Gas/Glow, make sure to check with the glow plugs out that your equipment will make them both glow nice and orange. Other than that, starts are usually one or to flips. I haven't used a starter on it yet.

Also, it will end up that the carb regulator cover and it's hole will be facing forward. This can cause tuning problems due to the ram air from the prop, and later from the slipstream. Solder a small 90 degree brass tube into the regulator cover pointed into the carb opening to avoid this potential problem. If your engine is going to be cowled, run a hose from this tube into the fuselage to sense static air; not pressurized cowling air.

Good luck,
AV8TOR

RE: Echo BME twin
 

Hey Ralph, could you post a few pictures of your cranks? Still trying to get my new home in order then I will get back in the shop to organize that. Then I can get back on my own engines.

RE: Echo BME twin
 

So far we have only drilled out one, but I will post as we go.

But it should go pretty fast from now on.

RE: Echo BME twin
 

I ordered 2 more today and had a nice little talk with Keith.
He said these twins liked RPMS below 7500 and the smaller port cylinders
may not be that big of a factor.

Right now I have 3 sets of cylinders 23.6 large ports, 21 large ports and 21 small ports.
So in the next couple of weeks I should be doing a lot of testing.

It looks like the average cost will be about $100.00 running on Gas / Glow.