Newbies GUIDE to GIANT SCALE GAS ENGINES GUIDE TO GIANT
Contents
1. Setup Smoke It works great and looks like a million but most folks don t mess with the mess 21 Spark plugs These are not glow plugs They need ignition sources They have to be properly gapped They should not be oily looking fouled or have shiny metal flakes on the porcelain ANY of these things are symptoms that something else is wrong 22 If your engine doesn t take throttle hesitates the low end is probably lean If it takes throttle but bogs down coughs sputters etc it is low end RICH NO doubt about these Properly adjusted gas ser carbs operate very well Poorly adjusted ones will make you insane 23 If you have been flipping until your arm is ready to fall off go back to the first post on this thread SOMETHING ain t right All of these engines need air gas compression and ignition Given all of them in the proper portion and time these engines ALWAYS start If they do not SOMETHING IS NOT 24 Gassers vibrate Period Firewalls must be STRONG and pinning around their circumference with wood dowels or epoxy nails is a good practice Pulling the engine box off an ARF is easier to do than you think 25 Your engine will probably require standoffs Measure your ARF from intended prop spinner back plate to firewall Deduct the overall mounting length of your engine plus 1 8 Whatever is left is the standoff You can buy metal ones or make your own out of hardwood dowels whatever BUT they have t2. is that the MAJORITY of time it s OUR failure to seek read and heed qualified guidance We re just too proud since all of us have had chainsaws and weed eaters since we were kids They all work the same NOTIN www rcaer com support rcaer com Page 6 of 6 Tel 888 239 8593 Giant Scale Engines and Products that Surpass Expectations
3. filters USE FILTERS Note If a two line system is used make sure the tank is not lower than the fuel er you use If it is the fuel will run out of the line back into the tank and then you have to pump the fuel back to the carb and there will be air in the line Making the first start after fueling a little harder 1b Pulse Lines MANY gassers have a piece of Tygon fuel line running from a fitting on the crankcase or intake adapter to an inlet pipe on one of the sides of the carb This line is NOT for gas It must not be kinked It cannot have holes If not hooked to the pulse line on the carb the carb will not pump Ever When in doubt call the manufacturer Most of them ship their engines with the pulse lines already properly connected Sometimes they even have manuals with pictures in them that MAY show this line and its fittings 2 Every engine with a Walbro or clone carb MUST HAVE their Low and HIGH speed needles re adjusted from factory settings to get GOOD performance EVERY ENGINE 2a Walbro carbs and other similar have PUMPS Rocking the prop back and forth or flipping it with fuel will PUMP the head full Spark doesn t work under fluid The tank can be a long way from the carb and that s okay As you rock the prop watch the air bubble fuel move up the line If the bubble isn t moving the pump isn t pumping Get the pump wet inside somehow Fact 3 Breaking an engine in on the ground is generally not a real good i
4. RC Aero Products LLC Newbies GUIDE to GIANT SCALE GAS ENGINES By Bob Pasiorello This is a living document that will be updated whenever the need arises Many of these hints are common sense based upon years of experience They are not hard to learn not difficult to remember and easy to use These hints will make your RC flying safer a lot more funner So aS a newbie to Gas Some things in general that you must keep in Mind and Learn About Doing The following guides are not in any particular order GUIDE TO GIANT SCALE GAS ENGINES 1 All tank and plumbing accessories must be gas rated Dubro brown color stoppers are the standard Yellow Tygon is widely used Clear tubing is crap All fittings need to be secured over their attachment barbs All smooth brass tubing needs some kind of bump solder blob or barb to keep Tygon on as it swells in use BEFORE it gets rigid and brittle with age NORMAL 1a Klunks and filters gotta have em someplace Klunks in the tanks that are like the little Walbro felt clunks in your weed eater work REALLY well Sordo more exotic ceramic particle filters Gotta have a klunk Gas should be filtered in the jug too before it gets INTO your airplane And yes tanks only need two lines vent to atmosphere and line to carb You can use a tee with a fuel dot to fill and drain the tank It will work forever You also can use three lines but that gets a little more complicated Use
5. ch accidently while flying 34 Tygon tubing of the type mostly used for gas engine in model airplanes degrades over time Check the tubing on any airplane you have acquired especially at the ends The piece of tubing inside the tank that is attached to the clunk and dipped in fuel will likely get hard in a year loose its flexibility and could be the source of fuel draw issues if not checked 35 OIL It is vital that you protect a gas ser with the RIGHT kind of internal oil film for operation Too little oil and it will die a quick and horrible death Too much oil and you plugs and airplane covering will look ugly It is never a good idea to use an oil that intentionally introduces abrasives to wear in an engine Let a proper amount of good oil do that during FLYING Everyone has their preferences some are based on experience some on knowledge and even fewer on BOTH Ask the person with BOTH what they recommend ALWAYS pay attention to what the company that is providing WARRANTY on your engine says about oil Do it their way or be prepared to fix the engine yourself for ANYTHING even remotely oil related www rcaer com support rcaer com Page 4 of 6 Tel 888 239 8593 Giant Scale Engines and Products that Surpass Expectations RC Aero Products LLC 36 KILL SYSTEMS Gassers because of their power and usually size of airplane SHOULD have some sort of a kill device either mechanical or electrical In general most folk
6. dea Use the manufacturer s recommended oil ratio for starters get a couple tanks or less through the engine to make sure everything is okay then go fly the damm thing so it will have SOME form of cooling air over it 4 Spark plug cap fittings usually fit very tightly if they are the push on type and you will have to push HARD It s normal If the plug cap isn t on correctly it will not run right EVER And you ll get unreliable starting running and radio interference all not good things www rcaer com support rcaer com Page 1 of 6 Tel 888 239 8593 Giant Scale Engines and Products that Surpass Expectations RC Aero Products LLC 5 Prop drilling if you have a jig use it If you don t use the prop washer as a guide and try to get straight holes ALWAYS balance a prop before using it 6 Most carbs will require you to modify the throttle arm to be user friendly for our pushrod ball link setups Get over it It s the way it is Use a short servo arm to attach to the crappy little plate they supply on the throttle butterfly shaft Use ball links and very rigid pushrod setups with GOOD servos 7 Remove and toss the stop screw on the throttle arm plate then unhook the little spring that pulls the butterfly closed unless you want your throttle servo under constant load tension Do NOT REMOVE THE SPRING 8 Electronic ignitions work wonderfully if they are getting power Use a reliable battery with the voltage rating and millia
7. gth Install You will be very close to perfect Tweak the ATV end points as needed you perhaps will need to adjust the Throttle trim authority again but you will be very close to a good linear setup If it isn t like you want it THEN setup the Throttle curve function but not until after all the mechanical stuff has been taken care of 38 Using Stuff NOT from the Manufacturer in general unless you have a field full of qualified and experienced gas helpers make your FIRST gas ser install exactly like the engine manufacturer tells you to do it This helps you in several ways 1 you ll be doing what the folks who will WARRANTY the thing have said to do 2 if you have to call them for help they will know how your system is setup and it will be easier on both of you for troubleshooting 3 sometimes stuff that folks buy as add ons to make things better easier neater really do NOT and then as a new user you have inadvertently placed unknown variables into the why doesn t this work equation It is just really easier the FIRST time to do it the easy way and follow the instructions as much as that advice may seem counter intuitive to our knowledge and reason 39 If you have read this thread this far please go back to the start and remind yourself of the basics When things don t go well most of us immediately begin jumping on device or component failure The sad truth and am absolutely including myself in this
8. ing past the switch on the hub crankcase to figure out when to send the spark to the plug It only knows when the magnet has passed it ALL of these work the same way Rotating the hub magnet past the hall sensor switch means that the IGNITION WILL FIRE THE PLUG if it has power Many people with injured fingers thought an ignition was OFF when it wasn t and found out by casual flicking of a hot prop The ED department visit usually costs more than an engine AVOID this always Treat a gas ser with an ignition attached as if itis HOT 100 of the time 9 In general anew carb will not pump if it has been dry for awhile Period Get some gas into the thing by normal priming close the choke flip through a few times ignition on throttle at high idle Engine pops starts dies open choke flip till starts RESTRAIN you AIRPLANE while doing this ALWAYS 10 These gassers need GAS Not some other kind of make believe fuel If yours has ethanol it will be okay 95 of our engines will do just fine on regular unleaded 87 octane pump stuff They also have to have OIL Nearly all of these need about 30 or 32 1 ratios for their first starts That s 4 oz to a gallon Easy to remember Won t hurt the engine Use a good quality oil for 2 strokes If in doubt call the ENGINE seller about ratios and types 11 No Metal to metal from the servo to carb Use nylon rod and sleeve 12 Place the Rx as far as practable away from the CDI as possible 13 Wh
9. mp hour rating that the manufacturer recommends WHY Because if you toast the ignition from incorrect battery usage YOU WILL BUY THE REPLACEMENT If they say nothing go with a 4 cell 1100mah NiCad or NimH or a 5 cell system on a GOOD regulator Not recommended for newbie s Get some experience with this area Always use a switch and setup throttle so you can kill it Generally speaking there are good ignitions and there are cheap ignitions but not so much Good and Cheap Ya gets what ya pays for on this one 8a Ignitions all have three chunks of wire ONE the spark plug lead also contains the ground and must make contact with the outside of the plug hex where your socket wrench grabs the plug It can t have holes or cracks and should always be prevented from rubbing on ANYTHING TWO Power usually a female battery type connector with a red and black or red and white wire connector This is where the OUT of your switch provides power to the ignition NEVER get the red and other color mixed up ever THREE the sensor pickup usually a black white red or similar wire that connects to the thing that is mounted up near the prop hub on most engines This is the hall switch and picks up the rotation of the prop hub by sensing a magnet when it rotates past the face of this switch ALL three wires have to connect and the polarity of these three wires can never be wrong either The ignition senses the magnet rotat
10. o mount real solid like Find sources of long 10 32 hex head bolts split washers flat washers fender washers and nylon insert Locking nuts USE them It is a BAD plan to have an engine come loose 26 Allow exit area You cannot avoid it You either make holes to let LOTS of air out of your cowling nose or you cook your engine Period If you are able to do it direct air by dams or ducting directly over the fins of the engine THEN to the big exit area If you hover or do strenuous 3D skip this step and you ll cook the motor probably seizing it up at a low altitude hover by overheating thereby crashing your airplane ALSO 27 Props the most important accessory for your engine Bad props give sucky performance break easily or disappoint you in their performance Any good prop of the manufacturers rated size will make you a happy gas ser 27a Prop Balancing probably an oft ignored and vitally important thing for gas ser guys A good balancer is essential A bad balancer is a waste of money prefer the Dubro Spin balancer very sensitive Blades are balanced by lightly spraying the back of the blade with clear spray lacquer lightly until blades balance If blades are balanced but moves anyway check the hub Put the prop on the balancer with blade vertical Release blade Watch top blade if it falls LEFT as you re looking at it www rcaer com support rcaer com Page 3 of 6 Tel 888 239 8593 Giant Scale Engines and Pr
11. oducts that Surpass Expectations RC Aero Products LLC then the RIGHT hub needs weight and vice versa Weight on the hub is the curly Velcro ca d in place a few drops of thick ca then kicker Recheck balance Keep at it until the prop remains motionless wherever you position it on the balancer THAT is perfect balance Takes about a half hour on a 22 more on bigger DO IT 28 RPM readings Nearly meaningless for one user to compare to another user Even if using the same prop Carbs are very sensitive and being off the sweet spot by 1 16th turn on the H needle can make a big difference in tach readings Plus most tachs are semi accurate part of the time and light angle sensitive all of the time Unless you know me and how tune my altitude air density oil mix ratio type of oil and heat temperature my peak rpm is of no consequence to you except for ball park and it s a helluva big park Most 50cc gas sers and above should be somewhere around 7000 with the stated prop from the manufacturer Larger displacement lower peak rpm That s how it goes 29 Frequently check your ignition battery voltage Under load if possible An ignition battery that is losing its guts will create bizarre unreliable and misfiring engines 30 If your engine was fine yesterday and today it s NFG then something changed Find what changed and fix it Don t jump to conclusions and speculate Work through the systems Start at the tank work thro
12. oo black Friday don t fly on this day 14 If it isn t running right on the ground it will NOT improve in the air ADJUST IT And do that ONLY after it is at its normal operating temp www rcaer com support rcaer com Page 2 of 6 Tel 888 239 8593 Giant Scale Engines and Products that Surpass Expectations RC Aero Products LLC 15 More prop does not mean more power It means more load and generally that isn t a good thing EVERY prop change on EVERY engine will need re adjustment PERIOD 16 If someone helps you and things get worse with your engine get a different helper ALWAYS 17 Mufflers nearly all of them are NOT they are exhaust cans with diverter outlet tubes They are usually louder than you think If you want quiet you need a canister period Not necessarily for newbies 18 Install mufflers with no gasket use a thin film of Permatex High Temp Permagasket on the face of the muffler flange Put RED permanent or high temp Loctite on the screws and tighten them Tightly 19 If you have to use a Pitts muffler brace the canister part to the engine firewall with a bracket or strap of some kind Tighten the muffler to the engine exhaust THEN install the strap canister attachment Don t do it the other way 20 Smoke is not for a newbie If you must smoke get help with it as you ve instantly doubled your plumbing complexity tanks added weight electronics etc If you have to have it post here on How to
13. s agree that a transmitter operated kill switch is a good safety device If airborne with a typical large tank your throttle servo fails or disconnects you either land hot and break something or fly around risking killing batteries If you have a switch to flip that chokes the engine or removes power from the ignition YOU can decide when to land safely a Choke Servo this involves hooking up a choke servo to an extra channel and assigning to a switch or lever on the TX that closes the choke when you actuate it Overly rich with air cutoff the engine will die quickly Pros and cons to this system b Electronic Kill Device this involves an electronic switch that is operated by a spare RX channel activated by the TX that cuts off power to the ignition module These are nearly always installed after the on board separate ignition switch and before the module in the power lead Usually optically coupled electronic switches they don t induce any harmful interference when properly installed Lots of these available If going this way ask around your area or on RCU to help make your decision Whatever you do please ALWAYS consider the safety benefit of being able to shut off your gasser when YOU want to It is a vital element of overall RC safety IMO 37 Throttle Linkage Trim and Adjustment Our carbs are really intended to be nearly full on a majority of time not to be continually varying them in the middle range which is o
14. t describe mine as it is consistent repeatable and reliable Use a Servo arm where the take off or ball link attach point is about 5 8 from center of shaft Purpose of that distance is to ensure that you ll be close to needing 100 ATV on both ends of the throttle channel making the clicks of throttle less profound You don t want big differences per click anda longer arm will be too much Shorter arm requires too much ATV diddling and introduces mechanical expo which may not be in the correct direction On the Carb use an arm with the ball link take off point at 3 4 from shaft center This permits more rotation of the arm and helps solve sensitivity issues mechanically at the carb Walbro carbs are www rcaer com support rcaer com Page 5 of 6 Tel 888 239 8593 Giant Scale Engines and Products that Surpass Expectations RC Aero Products LLC HORRIFICALLY non linear and overly sensitive Now with both arms installed set your ATV to about 90 on both extremes Open the carb arm to FULL THROTTLE where it hits the mechanical full throttle stop and move throttle stick to FULL throttle Measure the straight line distance between the centers of the ball link attachment points Now go to full CUTOFF low throttle and low trim and rotate the carb arm to FULL CUTOFF Measure that straight line difference If not the same as the full throttle length take the average Create a Carbon fiber or stiff metal pushrod of EXACTLY that len
15. ugh the plumbing Start at the battery work through to the plug start at the servo work through to the butterfly Only a VERY few and special engines are actually sold with Gremlins built into them Usually they have already been owned by someone who couldn t find and kill the gremlin so you got it Think of a finicky motor as a PC virus there is a solution you just have to find it 31 When you have a new engine buy a new correct spark plug And as soon as you can afford it a Spare Ignition and a Hall Sensor switch Spare carb if you aren t a carb tweaker Carb rebuild kit whether you are or are not Buy replacement prop bolts and be sure to use split and flat washers so the prop washer doesn t get all boogered up Many manufacturers don t know about this yet so they don t include screws long enough for thick hubs and spinner back plates much less the split and flat washer It is worth investing in 32 Buy extra metric screws and ball drivers NEVER trick yourself into believing that a 10 32 is the same as a 5mm They ain t 33 ALWAYS provide for some form of emergency engine ignition cutoff At a minimum install an external switch that cuts off power to the ignition Better yet add to that an internal ignition cutoff that is connected to a spare channel on your radio Optical remote cutoff modules from SmartFly or other providers work really well Make sure the assigned switch is out of the way so you do not hit that swit
16. ur main usage So to get things right it s important maybe VITAL to properly setup the mechanical and electrical setups of the throttle and carb arms Here s what suggest Method A Basic Approach Full DOWN throttle trim is cut off closing the carb completely This is the full ATV adjusted on the bottom end set this by fine tuning the ATV so the control rod isn t binding the servo but the throttle plate is completely closed Middle detent throttle trim is the landing and taxi trim setting That is determined by a couple of things that inter relate First in the System setup screen set the Throttle trim authority to 50 It is far too sensitive otherwise for a gas ser Then assuming that you ve set the carb arm length to be slightly more than the servo control arm take off length the half trim should be where the plane will sit motionless when engine is fully warmed up Finally set the Throttle Curve function ONLY if you cannot get the low end sensitivity linearity mechanically Reason suggest that is that the mechanical rotational and linear geometry of the arms can go a long way toward getting it right Finally the full trim is the hot restart setting because my carbs tend to be leaner on the low end soa hot restart needs just a bit more travel Method B The Real Deal Now the real deal is to get the correct pushrod length There are again many opinions on these mechanical setups but I ll jus
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