Green Sky Adventures, Inc.
  Ph 352 475-5625  Fax 501 643-1087 Email   mail@greenskyadventures.com
Engines
Instruments
Propellers
Micro Mong
Zippy Sport


FREQUENTLY ASKED QUESTIONS
TECHNICAL SERVICES
What is the engine weight installed and ready to run? Electric Fuel Pump: "My fuel tank is approximately 20 to 25" below the 700e carbs. Would I need a electric pump?"
Yes The engine comes standard with a pneumatic fuel pump which operates from pressure pulses. If the fuel supply is below the level of the carburetors, a backup electric pump must be installed.


Hearing different stories about the power and idle speeds...

Idle speed is between 1800 and 1950. Most we have seen like to idle smoothly around 1900. A lower inertia prop might allow lower. For instance, our Kitfox with an Ivo In-flight Adjustable will idle nicely at very low rpm, ...like 1400. We like to think this, in part is because of our mount, but at flat pitch and low throttle setting, the propeller puts very little load on the engine. Our Zippy Sport with a very steep pitch 2 bld 64 inch prop likes to idle around 1900.
What would be your recommended propeller?


Power Nothing is absolute. Much of our data comes from tests with  GSC Systems propellers. The number values may be different with other propeller designs but the principal is the same. Also, performance difference between Rotax 2.62 type C and E gearboxes vs the 2.58 type A or B is insignificant. Power output of the HKS 700-e is just off that of a Rotax 582. The challenge for some, especially PPCs is how to convert that power to static thrust. For instance: A Trike owner replaced a 50 HP Rotax 503 3.47 E box engine with a 60 HP HKS 700-e and 3.47:1 ratio. He used the same large diameter Ivo 3 blade propeller. Without adding pitch, the HKS could easily over rev. ...A clear indication of increased power. Eventually he was able to crank in enough pitch to load the engine with a resulting take off and climb similar to the 503, but with much faster cruise speeds at low rpm. Static thrust was not substantially improved because the extra pitch to load the engine made the prop less efficient for producing static thrust.
HKS vs Rotax. The propeller doesn't care what turns it. So it is a matter of Diameter, Pitch, Speed, and the variations in efficiency. Our Rotax experience suggests a 2.58 or 2.62 ratio gearbox on a Rotax 503 is best configured to produce static thrust with a 60 inch 3 blade propeller. If a two blade is used, and pitch is increased to load the engine, static thrust will suffer. So a two blade either has to be longer or turn faster.  To achieve equal or better static thrust, than the 60" x 3 bld prop and 2.62 ratio, but with  two blades, and the same ratio, 68 inch diameter is near optimal. Another possibility is faster prop speed. A 60 inch two blade can work just as well as a 60 inch three blade on a 503 if it's turned faster using the 2.238 ratio. So, if the non variable is 60 inch propeller diameter and the goal is to increase static thrust by adding 10 HP, results will be far from linear. In testing Rotax 503 vs 582 using 60 inch three blade propellers, the 30 percent increase in Horsepower resulted in less than 10 % increase in static thrust.
The HKS with 2.58 and 64 inch GSC Tech III prop will produce nearly identical thrust as a Rotax 582 with 2.62 and 60 inch GSC Tech III prop.


What's the deal with the oil hoses and fittings?

You will make up the individual line from bulk length of hose. The AN-10 fittings are barbed on one end and require no special tools to assemble. Once a specific length and fitting angle are determined, we generally freeze the fitting, and warm the oil line. Joining the line and fitting is pretty much a continuous one shot deal. If the line is pushed on only part way, it is very difficult to start again and push it fully in place. It is basically impossible to remove without cutting the line. If you have to do this, be careful not to mark, or otherwise damage the fitting.
I thought the exhaust pipes came with the nut (for the EGT probe) already welded on.  Mine don't have them.
Small hose clamp senders are used for EGT. The factory pipes are Stainless, so you could TIG weld bosses if desired, without much discoloration of the pipe.


Why are there no mounting bolts for the engine? Can I order them from you?

The mounting bosses on the HKS are well above the lowest point of the engine (the crankcase sump). The length of bolt will be determined by the individual application. The universal plate that is available stands off a minimum of 9/16 inch. This can mount with bolts as short as 50 mm. With longer spacers, obviously longer bolts are required. An important detail, is the thread pitch. HKS and Rotax both use 10 mm diameter fasteners for mount attachement, but he HKS is a 10 mm x 1.25 fine pitch vs 1.5 coarse pitch for the Rotax. These metric bolts are generally available locally.  If that is not option, let us know what length you would like, and we'll get some for you. We generally have a variety of lengths in stock.


Is it true: If the battery dies the engine will quit?

The HKS uses a DC CDI. This type of ignition allows a full advance curve, without which the engine would be very mediocre in most respects. It must have 12 volts DC from an outside source to start. Once running, a dead battery will not effect engine operation because the integral alternator will provide power for ignition. The concern, then becomes one of wiring. Output from the charging system needs to be on the line side of the circuit which powers ignition. This way, regardless of battery, cable, or master switch condition, primary power is uninterrupted. In the event of a charging system failure, ignition is dependent on battery.
I know the muffler needs to be shock mounted...Do the exhaust pipes need to be secured to the engine (other than
at the exhaust ports)?  It looks like they might twist/turn/vibrate and break the weld...Has this ever been a problem?
 
Generally, this has not been a problem, but it has happened. Securing the exhaust pipes to the engine may actually do more harm than good. Naturally, the individual engine installation can effect the outcome, but the stock systems have been well proven. Particularly, the Type II as used on the Flightstar. It has 2 slip joints to a collector, then a ball joint to muffler, and a final vibration dampened attachment to the airframe structure. Of course, in pusher application every reasonable precaution should be made with safety restraints on anything that might depart the aircraft forward of the propeller. Green Sky Adventures, Inc. manufactures alternate exhaust systems designed around specific HKS / Airframe installation packages. Besides "Best Fit" for the particular installation, there are other benefits to such a system. We use a readily available industrial muffler, and build up head pipes generally from Mild Steel U-bends (Stainless can be used). Field repairs or replacement may therefore available locally, eliminating any possibility of extended lead times for specialty OEM parts. Our systems have proven durable, with equal performance, good sound, and comparable or less weight.  
Can the HKS700 E  operate on oxygenated gas ? This is the only type available here in northern Illinois?
The engine and carburetor components are compatible with present oxygenated fuel. If percentages increase, it is logical to expect a possible rise in exhaust gas temperature which can be compensated with larger jets.  Other components in the fuel system may or may not be tolerant. ...Gaskets, o-rings, rubber seals,  fuel level senders, tank floats, etc. ??? If in doubt, though more expensive, 100LL Aviation Fuel would be a good choice. Lead contamination of the the oil in the HKS is not the concern that it is with Rotax 912 because of the design of the oil system.
What is the Standard Equipment that comes w/ the HKS 700E? Challenger: How involved is taking off the wings for trailer transport if the HKS is mounted on the topside as with the Green Sky top mount solution for Challenger? What is the advantage of using an oil thermostat? Which additional fittings would be required to mount the thermostat? Why a 19-row oil cooler as opposed to the 25 or 16 row? How effective is the Carb Heat Probe?  Is it used similar to a Carb Heat on a conventional airplane?  I read a little on the HACman mixture control.  It seems pretty nice and a good tool if you are flying at altitude.  Is there any additional instrumentation required with this installation? What are the DC toggle switches for? In particular, what hardware does not come with the Challenger Mount? Is the remote electrical accessory connector kit the same thing as a wiring harness? Are the oil filters proprietary or are they readily available locally? Are there air and oil filters included? Are there recommended accessories that are added cost? Possibly the most important question would be the cost.  How much will it cost me? What oil is recommended for the engine?  The PSRU gearbox, if separate from the engine? What fuel is recommended? Do you have a firewall forward package available? .Is 1000 hours reasonable for TBO? What does a TBO rebuild consist of? Can the rebuild be accomplished by a person with good mechanical skills ( I have rebuilt several auto engines including a VW and Rotax 582 with success What is the cost of parts for the rebuild? Are machine shop services required or special tools?  If special tools, are they available? What is the Cost for Green Sky to do a rebuild? I bought a hks 700E with serial no between 100301 and 100600 I would like to know the tbo of this engine Did I BUY A GOOD ENGINE IT IS BRAND NEW
 
 
 
 
 
 
 

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