YAMAHA RX-1 (140 HP) install in Kitfox 5

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Posted (edited)

I'll repost Steve Henry's  worksheet here below and should have mine weighed here in a few weeks to see how much I lost from the subaru.  Hoping for 40 or 50lbs.

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Edited by Yamma-Fox
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Posted

What is the weight of the Yamaha? 

If too heavy (200+) you will most likely need to balance out with weight on the tail.

A friend put a Subaru on his MK4 and had to add weight at the tail wheel to prevent it from being too nose heavy.

John M

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Posted

What is the weight of the Yamaha? 

If too heavy (200+) you will most likely need to balance out with weight on the tail.

A friend put a Subaru on his MK4 and had to add weight at the tail wheel to prevent it from being too nose heavy.

John M

The post above yours shows all weights to 1/2 a lb! Maybe your browser doesn't open the pictures. Here is what it says:

Header 7 lb,  muffler 6 lb, motor mount 6.5, oil tank coolant tank and radiator 8 lb, electrics hoses nuts and bolts 5 lb, Apex engine, throttle bodies and Skytrax gearbox 144 lb, airbox and filters 2 lb, total 178.5 lb

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Posted

Got the round cowl fit up.  Did a kind of boot cowl thing over the original.  Plenty of room in the round cowl for the Yamaha! 

Next is the float install.  Getting things ready for that:

 

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Posted (edited)

Nice job. What kind of door latch is that? How about a picture of lower mount area.

New plane for me, not real nuts about the door latch.  Works great, but it is a little tough to get to and open from the cockpit  in a hurry (egress).  On the to-do list to modify.

 

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I know this is an old post, but I am curious what tubing OD and wall thickness you used for the main tubing (see red arrow in the pic). I am also curious what thickness you used for the flanges (other red arrow in the pic). 4130 I assume, right?

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Edited by Supermotive
mispelled word

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Posted

RX-1 IGNITION :

Been waiting for the mount to come back from the welder, so I've been digging into other things on the plane.

One is wiring ignition power to the ECU.  There is a single wire for that and I believe it is the only power source to the ecu, making it critical to keeping the engine running.

I decided to power it from two sources, each switched and CB protected.  One source will come directly off of the engine magneto (alternator coil), prior to the main fuse for the charging system.  The other power source will come from hot battery direct. I will put a surge protector on the magneto side in case the engine's voltage regulator were to fail.

I will also will diode protect each power source to prevent backfeed if I get down to one source (example that if the magneto were to fail I would want to switch the master off to conserve the battery, but would not want my panel being fed backwards through my ignition hot battery wire).

So that is my plan.   Any electrical engineers out there (or just people smarter than me!) please speak up if you see me going wrong!

I know this is an old topic, but I am an Electrical Design Engineer, and I would be willing to take a look as any of your electrical circuits.

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Posted (edited)

QUIETING THE BEAST:

Probably the biggest downside IMO with going Yamaha is that they are known to be loud.  Probably has to do with the 8500 rpm thing but typically they are known as "screamers".  I really wanted to fix that.

The exhaust I "temped up" is quieted by use of 2 mufflers inline - a steel 17" glasspack and my 2011-14 Suzuki gsxr 1000 muffler.  Also helping quiet it down is the extra length of exhaust pipe, and having the outlet of the rear muffler well behind the seats /doors.

The upside:  it is far quieter even than the snowmobile (which is quiet).  So quiet that in full power runup I couldn't even detect ANY exhaust outlet noise over the prop /gearbox / engine noise up front.  Not even when standing outside and behind the plane.  The difference is now like a stock Goldwing compared to before where it had a bit of that "sport bike with an aftermarket can" thing going on.

Downside is added weight along with the aerodynamic and "asthetic" loss of an exterior routed system.  That's acceptable for me in my quest for quiet and I couldn't get the gsxr muff under the cowl anyway.

Here's a video and it seems loud here but that probably is because there is nothing to compare the sound with.  I will post another someday taking off and doing a fly by with another plane to compare better with.

Edited by Yamma-Fox

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Posted

Here's a pic of my temporary  (UGLY!) test setup.  The green circle is my glasspack and the blue is the gsxr muffler.  I think the quiet I accomplished is in that the first muffler knocks down the sound and the second takes the rest out... down to what I'd call "Toyota quiet".   Really all that is left now is prop-engine-gearbox noise and that in itself ain't "quiet" but at least I got rid of the exhaust noise!

Next is to clean it up in a permanent routing.

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Posted (edited)

FIRST FLIGHTS!

(Just reposting here after the server problem.  I Like to keep this thread updated for those that don't do Facebook and also as a backup for what I post over there.)

Below is a video of my first flights and some other pics.  But first I'll post a copy of my write up of impressions after 3 days of flying:

IMPRESSIONS OF THE YAMAHA AFTER 5 HOURS FLYING IT:

I'll start off by telling you that (being a 100% Yamaha enthusiast) I am gonna set aside that admitted bias and be as entirely impartial as possible here.

So with that in mind I'll start off with the cons:

"Re-sellability":  The Yamaha is an unknown to the majority of people and I would assume it might take some time and education for a buyer to be comfortable with buying a plane with an owner built Yamaha (different story entirely for one done from a name reputable builder such as Wild West or Edge Performance).  To that end I have no plans to ever sell this plane.

Insurance:  If you SPECIFY that you have a Yamaha you will find it very difficult to find a policy, as is true for many other auto conversions and lesser known power plants.  I unfortunately am "self insured".

Noise level:  It really is NOT louder than any other engines in it's class, but it has a different tone that seems to travel farther.  My two inline mufflers bring it down much more and I'd call it quieter than the average plane with a gearbox.

RPMs:  You gotta do your research on how well these motors do in snowmobiles and sportbikes, or have owned one, and also have to fly it for a couple hours to get used to it in a plane.  At first it admittedly is strange.  Once you get used to that you will find it (as anyone who has owned one will attest) to be an unbelievably smooth and sweet running engine that just loves to hum along at 7.5-8.5k cruise and loves even more to scream a little when you call for it!  Simply put:  It was built to do it and it has proven to do it well.

Now the Pros: (In no particular order)

Cold start: (in my case with a centrifugal clutch) Two days here my start was at about +5F after sitting out on the ice with no preheat or cowl blanket.  Fired right up and purred along.  Again, It is a snowmo engine and was built for that.

Extra power:  I am flying a plane built around the 80 HP 912 and on floats it would fly well with a 100 HP engine.  Flying the RX-1 I have chosen to fly prop pitch derated to about 120 HP static and I'll typically take off with that, level off quickly and pull flaps and throttle back to approx 100 HP (SWAG) and climb out at about 800fpm (@1150lbs and 20F).  When I "punch it" in the climb I am getting more like 130 HP due to ram rise RPM and solo in  the cold weather at Vy it climbs steeper than I need.  It is just SO nice to be able to pull power and climb VERY well at approx 70% of what the motor is desinged to do!

Cost per HP:  I'm at a little under $9k for everything (less my time) and including a new prop and have capability of 140+ HP with a simple prop pitch change.

Run Quality:  Absolutely the smoothest running and most throttle responsive recip I've flown.  Even down at idle when you tap the throttle it is right there..  push it all the way and it'll snap you back in your seat.  40 to 90 mph happens quick!

Not a drip of anything:  Besides the initial start "burp off" of my coolant overfill this thing has not dripped one drop of anything.  That is obviously great on many levels but to me mostly in that if I ever see even one drip I know that I need to for sure track it down and figure it out.

Ok that is off the top of my head here now and I'm forgetting some things but overall I think you can see that I have most definitely NOT been disappointed!!

 

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Edited by Yamma-Fox
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