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Old 01-10-2017, 06:28 PM
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Default Weight Rotax 912 vs Yamaha YG4

Just to clarify the weight issue and since no weight breakdown of the YG4 and ancillaries that compares directly with the Rotax 912 is available, here is my best estimate:
YG4 naked 125lbs
C box PSRU 17.6lbs
Oil tank, connections, hoses 5lbs?
Sprag or roller clutch 3lbs ?
Adapter block to PSRU 5lbs?
Carbs, intake manifold 8lbs?
Exhaust 8.8lbs
Air box 2.9lbs
Air Filter 0.7lbs
Radiator 4lbs
Oli cooler 1lb
Regulator rectifier 0.2lbs
Total installed weight as compared to Rotax listing seems to be 181.2lbs. This seems a lot but maybe my guestimates shown with question marks above are off. The remainder are Rotax. Please everyone feel free to correct.

Rotax official listing:
124.7lbs / 56.6Kg
Exhaust System 8.8lbs / 4.0Kg
Air Box 2.9lbs / 1.3Kg
Air Filter 0.7lbs / 0.3Kg
Liquid Radiator 2.2lbs / 1.0Kg
Oil Radiator 1.1lbs / 0.5Kg
Regulator-Rectifier 0.2lbs / 0.1Kg
Installed Weight 140.6lbs / 63.8Kg


So why the difference? The Rotax list includes carbs, intake manifold and oil tank. The naked YG4 doesn’t. This accounts for 17.6+adapter? +oil tank?= >20lbs
The YG4 is a great engine but people should know that it will be over 20lbs heavier when comparing apples to apples. Actually the best comparison will be two identical aircraft with the two engines installed.
Finally here are some weights posted on the facebook Yamaha Aircraft Engines page by Morten Wiik.


Kudos to Teal, Greg and the other dedicated individuals who have worked on converting the Yamahas.
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  #2  
Old 01-11-2017, 05:56 AM
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Can the Yamaha make up for the added weight by its added HP over the 912?
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Old 01-11-2017, 08:33 AM
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Probably yes, especially when the weight is known.

Last edited by dinoa; 01-11-2017 at 08:37 AM.
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Old 01-11-2017, 08:40 AM
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You can never make up for added weight with extra horsepower, you just end up with a more powerful heavy gyro but it's still flys like a heavy machine, no amount of power or blade area can get it back flying the way that a light weight machine can .
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Old 01-11-2017, 09:11 AM
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This is true! Norm, What kind of machine are you working on these days?
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Old 01-11-2017, 09:34 AM
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Norm is right. nothing beats a light nimble gyro. I was talking about power to weight ratio independent of it's application.
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Old 01-11-2017, 02:28 PM
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Jerry, I have been working on a very light weight ultralight machine that can carry more than its fuelled weight with good performance without sacrificing any comfort or convenience features while still being less than 254 pounds empty weight, I'm getting there but I had a head transmission explode during testing so I have to build it a little stronger, I don't want to give up my zero roll take off feature so the transmission and fixed spindle head with automatic collective is important to me, this machine is not a copy of any previous machine from this planet or another planets that I have lived on but it is built using the limited materials that we have on earth.
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Old 01-11-2017, 05:03 PM
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Photo of the head, Norm?
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Old 01-11-2017, 05:26 PM
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WHOA, horsie! Before you go out on a limb and announce what "people should know" -like that a YG4 weighs 20# more than Rotax, installed - you should get your facts straight first.

Arm-chair supposition and desk-top calculations are not the same as putting the stuff in a box and actually weighing it all.

Buddy, I weigh EVERYTHING I use to install a YG4 on an aircraft, and each and every time it weighs 165# complete, sans muffler.

That includes PSRU, radiator, hoses, connections, the Mohawk SS exhaust which is well over two feet long, electricals, oil tank, EVERYTHING the engine needs to run properly.

I have read the official Rotax-linked web claims that their 80HP 912 weighs 165 lbs installed. So what? 80 HP vs 143 HP? [NOTE: <Error, I should have been talking about the 914, not the 80HP 912. My bad>] Hell, let's be generous and call it 100. $20,000 for a new engine vs $15,000 for a new YG4i? How about $12,000 for a used 912 vs $3000 for a used YG4? Wait, are we talking about a $30,000 914 non-certificated turbo that BARELY puts out 115hp for a few minutes before it turns into a grenade and you gotta cut it back to 100HP? Oh yeah, now THAT engine, installed, weighs 185# (Rotax claims) like you are talking about.

So just to be fair, and to compare apples-to-apples, let's us just put a 20 lbs turbo kit on a YG4 and guess what? We get 240HP, dude, at the SAME weight as that wimpy, overpriced, Rotax you are comparing the bullet-proof Yamaha to.

Certificated schmercifacted, shyaaa. Which one of the 912's is really certificated? Which ones are not?

Can any of them match - let alone beat - the durability, power, AND WEIGHT of a Yamaha 3 or 4 or Apex FI????

No. It is a moot point.

Dino, what you have said above is pure conjecture. Now I know what Donald Trump feels like. Next time, pick up the phone and call me first, or write me an email, before you make wild claims and "inform" people of bogus news and fabricated "facts" like this that concern me.

In closing, ya'll might wanna check out a thread I just opened regarding the ill-advised use of Rotax C boxes on YG4 kits.
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Last edited by NoWingsAttached; 01-12-2017 at 05:08 PM.
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Old 01-12-2017, 04:02 AM
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Quote:
Originally Posted by NoWingsAttached View Post
WHOA, horsie! Before you go out on a limb and announce what "people should know" -like that a YG4 weighs 20# more than Rotax, installed - you should get your facts straight first.

Arm-chair supposition and desk-top calculations are not the same as putting the stuff in a box and actually weighing it all.

Buddy, I weigh EVERYTHING I use to install a YG4 on an aircraft, and each and every time it weighs 165# complete, sans muffler.

That includes PSRU, radiator, hoses, connections, the Mohawk SS exhaust which is well over two feet long, electricals, oil tank, EVERYTHING the engine needs to run properly.

I have read the official Rotax-linked web claims that their 80HP 912 weighs 165 lbs installed. So what? 80 HP vs 143 HP? Hell, let's be generous and call it 100. $20,000 for a new engine vs $15,000 for a new YG4i? How about $12,000 for a used 912 vs $3000 for a used YG4? Wait, are we talking about a $30,000 914 non-certificated turbo that BARELY puts out 115hp for a few minutes before it turns into a grenade and you gotta cut it back to 100HP? Oh yeah, now THAT engine, installed, weighs 185# (Rotax claims) like you are talking about.

So just to be fair, and to compare apples-to-apples, let's us just put a 20 lbs turbo kit on a YG4 and guess what? We get 240HP, dude, at the SAME weight as that wimpy, overpriced, Rotax you are comparing the bullet-proof Yamaha to.

Certificated schmercifacted, shyaaa. Which one of the 912's is really certificated? Which ones are not?

Can any of them match - let alone beat - the durability, power, AND WEIGHT of a Yamaha 3 or 4 or Apex FI????

No. It is a moot point.

Dino, what you have said above is pure conjecture. Now I know what Donald Trump feels like. Next time, pick up the phone and call me first, or write me an email, before you make wild claims and "inform" people of bogus news and fabricated "facts" like this that concern me.

In closing, ya'll might wanna check out a thread I just opened regarding the ill-advised use of Rotax C boxes on YG4 kits.


I was waiting for you to chime in, thanks
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Old 01-12-2017, 04:22 AM
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You may recall we've been along this road several times before - some salient points in this previous RWF thread

http://www.rotaryforum.com/forum/showthread.php?t=44131
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Old 01-12-2017, 06:56 AM
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It's not conjecture or bogus or fabricated. It's what's been gleaned off the web by people willing to publish what each component weighs so anyone can do the math.

NoWings, if you weigh everything then let's see it. Not altogether, but each component individually. It will help your future clients evaluate what is and is not included in "installed" weight so they can make a better comparison.

Everyone is waiting for a Rotax alternative. Let's see if this is it.

Last edited by dinoa; 01-12-2017 at 12:48 PM.
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Old 01-12-2017, 07:04 AM
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double post deleted

Last edited by dinoa; 01-12-2017 at 11:34 AM. Reason: double post
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Old 01-12-2017, 03:59 PM
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Dino

Spring scales are most accurate in the middle of their range, it is safe to say that on the lower end of the scale they will be off significantly. Let's call it one pound to make a point.

Let's say we use a digital bathroom scale - which is still a spring scale - to weigh 15 light objects individually. Together those 15 weighed objects' weights added together are off by 15 x 1 = 15 lbs.

If I just weigh everything together in a box, deduct for the box weight, and get enough junk in the box to get the scale as far into its midrange as possible, then I probably only have 1# of error to deal with, if that, total.

I have weighed multiple YG4 kits all-up, they have all been the same: 165 lbs w/o a muffler, give or take a pound or two.
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Last edited by NoWingsAttached; 01-12-2017 at 04:15 PM.
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Old 01-12-2017, 04:24 PM
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Here is a Rotax weight/Power matrix
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Last edited by NoWingsAttached; 01-12-2017 at 05:06 PM.
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