Yamaha Genesis 120hp engine

Racer

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Here are some pictures of my Yamaha Genesis 120hp engine I installed in my Air Command.
The reason I chose this motor is there are so many things on this motor that come stock that I absolutely love.
This is a four stroke, water cooled, duel overhead cam engine with an excellent reliability and longevity record to back it up. The engine has a smooth wide torque curve that gives good even power without the unpredictable power band of a two stroke sled motor. This engine comes stock with a dry sump oil system and also has a divider in the center of the pan with two separate oil pickups, one on each side of the divider, that way it can still pump oil at a steep uphill or steep downhill angle. The oil pan is also "V" shaped so it can pickup oil even if laying at a severe angle in either direction, You almost cannot starve this engine for oil at any angle.
The crank shaft has a huge extra roller bearing at the end of the crank because in the snowmobile the variable clutch is supported and driven directly off the crank, It is beefed up a bunch.
This engine has altitude compensating carbs with coolant heat running through them to keep them from icing up. You can turn the coolant heat on or off manually. duel fuel pumps also stock.
It has a remote kill switch that you just hit down and it kills the motor, I mounted this on the opposite side of my gyro as the main ignition so now I can turn the gyro off from either side in case of an emergency.

I also have a digital dash that tells me everything from engine RPM, fuel level, to engine oil getting low, all engine warning signals etc. I can even get engine trouble codes. (Says on the trouble code now that my hand grip heat is malfunctioning)
For prop reduction I have a Rotax 3.0 to 1 "C Box" re drive on it with a new 68" Warp Drive HP-L hub and Prop blades on the way for it.

I have high hopes for this power plant but I must be honest with everyone, it was a big job transplanting this engine. Making a way for the C Box to attach to the motor in a strong way that will hold the power was a challenge. The flywheel I had to build to connect the engine power to the reduction box, the motor mounts and the exhaust system all cost me about $1,500.00 and I did most of the work myself.

Please note that I am not recommending, trying to convince, or trying to sell anyone on this engine, I am only sharing what I have done, that is all.
 

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Racer

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More Pics

More Pics

More Engine Pics
 

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Dean_Dolph

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None but enough kits in the garage to keep me busy the rest of my life!
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Todd, be careful with all that power! You may be flying out of a high altitude area and need it. But I hear experienced pilots questioning more and more the use of very powerful engines on light machines. I think torque roll is their biggest concern.
 

Racer

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Air Command CLT N7512X
That is one reason I went with this four stroke motor. Much smoother torque curve than a two stroke. Should be close to a Rotax 912 and there are a few Rotax 912's on single place Dominators.
 
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Timchick

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Looks great. Can't wait to hear the flight reports. Do you have a muffler on it or just pipes that point down?
 

Racer

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The engine came out of a 2005 Yamaha Vector snowmobile. I bought the whole machine and took out the engine, computer, wiring harness, dash, and some of the cooling system. I even took the ignition switch so I have an ignition key that I can take with me. I sold the chassis and everything else that I did not use.

Timchick, Here is a pic of the rest of my exhaust, it is all straight pipe but I made it so I can put a baffle in the exhaust tip if I need to quiet it down some more.
 

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Friendly

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I remember when you started this project, I hope for some great flying reports. Fuel use as well. Great effort on your part, to get it all done. Please post lots of info on this engine gyro combination.
 

GyroRon

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How much was the sled and how much were you able to sell it for after you stripped it?

Have you done any thrust tests with the engine and prop combo?

Have you considered replicating the conversion parts to sell to others?
 

Racer

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This engine gets 20 miles per gallon in the snowmobile so I am thinking I should get a really good gph in the air, I will let you know. The engine is known for its long life, in fact in the service manual the first valve adjustment is not due until the engine has 20,000 miles on it. I have had many people tell me these engines will outlast the sled that it came in by far. There was one weak link when these engines first came out, the timing chain tensioner spring was too weak and in extreme conditions the timing chain could jump a tooth, They have updated the tensioner with a stronger spring now and the problem is fixed, an easy fix by the way, only takes about 15 min to change. I changed mine out with a new one just to be sure. It also has a 12 volt magneto in it so you can run all of your accessories, strobes and whatever so there is no need for an alternator.
I will wait until I get my new HP-L Warp Drive prop before I do any thrust tests, I do not feel comfortable pouring the power on my standard prop, So for now I am just going over everything, making sure there are no leaks, nothing rubbing that shouldn't be while I wait for the new prop to arrive. Example Yesterday I confirmed that I will have to get a longer shaft for my pre rotator because when I go full stick forward it pulls up and touches my exhaust.

To answer Ron's question I looked long and hard and found the sled that you see in the picture for $3,000 then sold what I did not use for $1,000 so I have really only $2,000 in the motor and everything to make it run. But remember it did cost me about $1,500 to mount it and make it work so if you consider that into the pic I have about $3,500 in it the way it is mounted in my gyro not counting the re drive or prop.
To answer your other question Yes, I do have drawings of most of what I did if someone was really interested but I will admit I over engineered it to be safe, It is much stronger than it needs to be. I have found a source in Wyoming where I can buy as many of these sleds as I want for a pretty good deal. If anyone out there is thinking of this motor for themselves I will tell you that it was a much bigger job than I thought it would be and you would be pretty much on your own, but I will help out where I can. Let me say again, I am not trying to convince anybody or sell anybody on this motor, I am only sharing what I have done.
 

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scottessex

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I love it! I can't wait.....Yup snowmobile stuff is pretty hard to find around here.
 

Friendly

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Todd,
What is the weight of the engine, and weight of the total installation?
Is that a Dominator Tail on your aircommand?
 

chuter

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Really nice installation! That thing should be a rocket!

Hope it works out.
 

JEFF TIPTON

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Just a question. Should the pre rotator shaft under the exhaust need a shield to protect it from the heat?

Other wise I like it.
 

Racer

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Todd,
What is the weight of the engine, and weight of the total installation?
Is that a Dominator Tail on your aircommand?

The weight of the engine and carbs only is 118# I will add all the small stuff together when I get a chance but with fluids and everything I believe it will be about 145# all up weight for the running engine and everything to mount it.

Yes the pre rotator shaft is a issue but only where it makes the turn to go up the mast. When I tilt the rotor head forward it pulls it up and actually touches the exhaust, The prop moves the air enough even at Idle to keep the cable from getting hot. I will order a new cable that is long enough to stay away from everything.
 

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CLS447

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I love it too ! I just found this thread & I am very impressed.

Alot of talk about doing this & very little action..... YOU DID IT ! I wish you the best of luck in the rest of your testing & hope you get to fly her for a long time !

Keep us posted ...WOW !
 

Racer

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Hey, Thanks for the Hi Fives guys, I appreciate it.
I wish you could all come over and hear it run, The closest thing I can describe how it sounds it almost like a crotch rocket motorcycle, very smooth and attentive throttle. The next time your at a stop light and there is a kid next to you on one of these street racing bikes goosing his throttle, that is very close to how my gyro sounds
 

giro5

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Racer, did the rotax C box bolt up to the front of the engine or would you give a brief description on what you did to adapt it to the engine?
 
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