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Old 07-22-2019, 10:08 PM
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Originally Posted by RCAddiction View Post
As dshriver mentioned above, the 40cc twin is going to be comparable to a 35cc single, and not close to a 50cc single like DA50. For a given displacement, a 2 stroke twin is typically much smoother but also less powerful than a single. The VVRC 40cc twin is a great option for 78-80" aerobats, but you may be disappointed in a 85"/50cc airframe.
I understand that the twin overall will give up some overall power if used within same RPM range because you are giving up torque as a result of a shorter stroke crankshaft but not able to take advantage of tge short stroke with more RPMs because its a airplane motor needing a specific RPM range for a given prop. I was just speculating maybe compression ratio and port timings were optimized within RPM range within target output being a factor in better power output. I build and modify small engines for a living in my machine shop and fully understand the dynamics. I was just hoping for something I dont have to build myself. I dont want to have to go that route.
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Old 07-23-2019, 07:26 AM
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After doing more research I came to the conclusion that I would need a 60cc twin if I was going this direction. This would add about a 0.75lb or a little less but would gain a little bit over 1hp then a 50 or 55cc single. Hard decision.
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Old 07-23-2019, 07:40 AM
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If you are going to build the 85" Extra do your self a favor and buy the DA-50. The only alternative I would consider would be a DLE-55. EF designed the plane specifically for the DA-50. The guys at EF really know what they are doing.

If your heart is set on the VVRC 40, then I'd strongly recommend the 78" Extra V3 or the 74" Laser V2. The 40 would be fantastic in either one.

If you really want a twin, look at a DA-70 in any of the V2 90" class planes. The DA-70 is one of the best engines available today in any size.
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Old 07-23-2019, 11:41 AM
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Originally Posted by dshriver View Post
If you are going to build the 85" Extra do your self a favor and buy the DA-50. The only alternative I would consider would be a DLE-55. EF designed the plane specifically for the DA-50. The guys at EF really know what they are doing.

If your heart is set on the VVRC 40, then I'd strongly recommend the 78" Extra V3 or the 74" Laser V2. The 40 would be fantastic in either one.

If you really want a twin, look at a DA-70 in any of the V2 90" class planes. The DA-70 is one of the best engines available today in any size.
I Have a 92" EF Edge540 coming and a 91" SkyWing ARS300 coming this week. I have a New EME 70 twin going in one and undecided on the secound one. I might just go with a DA 70 for one of them but want to see how this EME behaves first. I have a first Gen "DL50" thats been sitting new since 2009 which I just did some mild port work to that was going to go into the 85" EF Extra but I just love the twins.
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Old 07-23-2019, 04:54 PM
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Originally Posted by RCAddiction View Post
Tom, what do you suggest as max or appropriate ground and in-the-air rpm for this twin. Is it lower than a 40cc single? I run 20x10's on my Brison 40cc single.

Ground vs Air - my DA100L runs a 28x10 Mejzlik on the ground at 6450-6500rpm, but according to my telemetry yesterday, in the air it unloaded to as high as 7440rpm.I was a bit surprised it went up that much. And it's still running somewhat rich, going by the still black-ish plugs.
I like to keep the static on the ground RPM's around 6800 or less. As you know it will unload in the air but if you keep it no more than 6800 on the ground it will be fine. I suggest a 21 X 8 propeller.
Thank you
Tom
Valley View RC
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Old 07-23-2019, 04:58 PM
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Can you let me know where you tried to purchase this engine? Valley View RC is the only importer of the 70cc twin and we have the latest in stock? See link below.
https://www.valleyviewrc.com/new-rcg...win-gas-engine
Please read the reviews.
Thanks
Tom
Valley View RC

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Originally Posted by Cycletech View Post
I ordered one of these motors last week and was sent a refund yesterday. Was told that updates to cylinders and cranks are being made and wont be available untill next month or so. I have two more planes to build and one is getting a fresh EME 70 so Im hoping that by the time I get to the third plane that needs a 70 twin that the updated VV-70 will be available. I REALLY want to compare them against eachother from fresh out the box. One will be in a 92" EF Edge 540 and the other a SkyWing 91" ARS 300. I have never had any motors from EME or VV RCGF. This EME looks greqt out the box and Ive heard good things about it. From those with experience with these two manufacturers How would you compare then up against eachother?
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Old 07-23-2019, 05:01 PM
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Originally Posted by Cycletech View Post
I Have a 92" EF Edge540 coming and a 91" SkyWing ARS300 coming this week. I have a New EME 70 twin going in one and undecided on the secound one. I might just go with a DA 70 for one of them but want to see how this EME behaves first. I have a first Gen "DL50" thats been sitting new since 2009 which I just did some mild port work to that was going to go into the 85" EF Extra but I just love the twins.
No disrespect meant guys but this is a thread for the VVRC 40cc twin.
Thank you
Tom
Valley View RC
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Old 07-23-2019, 09:22 PM
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Originally Posted by denney47 View Post
I like to keep the static on the ground RPM's around 6800 or less. As you know it will unload in the air but if you keep it no more than 6800 on the ground it will be fine. I suggest a 21 X 8 propeller.
Thank you
Tom
Valley View RC

Thanks, Tom. Helpful as always.
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Old 07-23-2019, 10:51 PM
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Quote:
Originally Posted by denney47 View Post
Can you let me know where you tried to purchase this engine? Valley View RC is the only importer of the 70cc twin and we have the latest in stock? See link below.
https://www.valleyviewrc.com/new-rcg...win-gas-engine
Please read the reviews.
Thanks
Tom
Valley View RC
Please forgive me Tom it was the 120cc motor and not the 70cc. Got too much going on at once and got mixed up! I kept talking About the 70 but meant the 120 for something else.
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Old 07-26-2019, 01:08 PM
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Both engines have the same power and uses the same propeller. We do the service on both engines at our service center. I would not suggest one over another but my favorite is the "Classic"
Thanks
Tom
Valley View RC
www.valleyviewrc.com

Thanks for the detailed explanation Tom. After thinking about the choices I decided to go with the Classic.

I just placed the order. The extra 12% discount ValleyView offered today on the Classic twins helped make up my mind

I look forward to receiving and running it.
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Old 08-23-2019, 06:03 AM
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Hi

What are the options for quieting those baby down? I'm using money in a H-9 Cessna.
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Old 08-23-2019, 07:00 AM
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Hi

What are the options for quieting those baby down? I'm using money in a H-9 Cessna.
Maybe something custom from Jtec? They’ll make you anything you want.
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Old 08-23-2019, 12:22 PM
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Hi

Jtec. Thanks. Hadn't thought of them. I'll give them a call. I ran this baby again yesterday. Half hour with the starter, then 3 more runs hand-flipping. Never had a gasser this smooth.
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Old 08-25-2019, 08:48 PM
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HI

I bought a VV 40cc twin last winter and set it up in a Goldwing Pitts Biplane. One of the guys in my club has this combo and it seems to work well. I have only tried to fire it up for break in twice and had a bear of a time.
A few weeks ago I brought it to the field and couldn't hand start it. Spent about 25 min flipping it before someone with a heavy duty starter realized and took pity on me. It took some effort but it did fire up with the starter. The engine would only run in the mid range and full throttle and would not idle. I ran it for about 15 min.

Today I tried to fire it up at home. Same thing. Couldn't get a pop for the first 20 min of flipping. Even with a new battery I couldn't get my starter to help me out. Finally I reset the needles to what is prescribed in the instructions (they were out a bit further than called for). With the throttle open just a bit I was able to get a few pops out of it after that. Often a few flips with the choke would produce a pop and then a pop or two with the choke off. It almost seems to fire and kick backwards but I'm not sure if that is what is happening. I moved the timing forward a little and it seemed to help but my arm was shot by that time. The timing is back to the factory setting (based on witness marks).

I have flown glow for many years and have experience with gas engines outside of RC (lawn equipment, chain saw, etc.). The firing/pop tells me that that ignition is producing spark. I'm not sure if it's at the correct ignition timing though. I am using a 30:1 mix for brake in. It is getting fuel to the carburetor. After a few flips with the choke closed a bit drips out when I open it. Basically I'm at the point of looking for suggestions. Could he electronic ignition be missing the pickup most of the time? Is the timing off? Something I'm missing?

Thanks,

Carl
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Old 08-25-2019, 09:43 PM
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Mine likes to start with a little bit of throttle - is it possible that yours is set too low? Another possibility is the low end is a bit lean. Have you pulled the plugs to confirm consistent spark and to check plug color? If none of that helps I’d look at the carb- check the filter screen and tubing.
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