Some frequently asked questions and answers follow. If you do not see an answer to your question, please send a note to webmaster @ rotaxrick.info:
- What is the maximum cruise RPM for your Rotax 503, 582, 618, and 670 engines? All RPM listed below are at full throttle straight and level flight:
503 is 500 RPM below the maximum RPM
582 is 700 RPM below the maximum RPM
618 is 800 RPM below the maximum RPM
670 is 1000 RPM below the maximum RPM. A 670s power is equal to a 582s maximum cruise power at 1300 RPM below its maximum RPM
In 90% of the engines that fail, the damage that caused the failure happened while the engine was running at full power.
- Which is better, the Rotax Gray Head or the Blue Head?
PROS for the Blue Head
Less likely to have a cold seizure
Controls the water temperature much better and if not below freezing you do not have to cover the radiator.
Blue Head CONS
If the thermostat fails they usually fail in a half open and half closed position. On a Blue Head that makes at least 80% of the coolant bypass the radiator, and will allow little time to land before the engine fails.
A Gray head with a broken thermostat as above will only require a power reduction to stay at a safe water temperature. When Rotax first came out with the 582, they did not install a thermostat, because without one, there is no chance of a thermostat failure. So why did they install the thermostats later? Without a thermostat, the steel cylinders (with cool water passing through them) could not expand as fast as needed to keep up with the fast expansion of the aluminum pistons. This results in a cold seizure, which is why we use ceramic top pistons. They deflect the heat from the piston and let it expand much slower.
A Gray Head with a ceramic top piston is as cold seizure proof as a Blue Head is with OEM pistons. A Blue Head with ceramic topped pistons is very hard to cold seize.
PROS for the Gray Head
Simple bullet proof design.
Can have the normal thermostat failure and be ok to get you home safely.
CONS for the Gray Head
When flying in cold weather you may need cover part of the radiator.
A slightly longer warm-up is required.
And how does this relate to the 670? All said, the 582 is far more likely to cold seize than a 670. We have NEVER had a 670 cold seize.
- How do I break in my engine? If it comes out of our shop, we already did the 1 hour break in. All you need to do is run it on the ground 20 to 30 minutes to check out your installation.
Once your’e ready to fly, warm it up an extra long time. This is very important on a new or freshly overhauled engine. The Rotax engines use a cast piston that will shrink .001 to .0015 in the first four hours. On new snowmobiles, a computer retards the timing to limit the horsepower. This is why it is really very important to extend the warm up period on overhauled or new engines.
On liquid cooled engines you can fly at different RPMs every 5 minutes. Avoid touch and go manuevers. A few climbs for 1 minute at 300 RPM below max RPM, followed by reducing the power to idle, and a 30 second to 1 minute glide will help the pistons size down.
For non Rotax Rick customers, PLEASE do not use the Rotax break in chart. We used to use that chart with a timer on many factory new gray and blue head engines. However, after we completed the one hour Rotax break in we would remove the exhaust and inspect the cylinder bores and cross hatching through the exhaust port. We found big band streaks with little to no cross hatching. If using the chart, where it says full power run the engine 300 to 350 rpm’s below maximum RPM.
CAUTION On an air-cooled 503 touch and go maneuvers are a NO NO. The cylinder will shrink in size on the downwind, base and final approach. When you apply full power on the takeoff, the aluminum piston will outgrow the much cooled cylinder and scrape off your cross hatching or even seize.
- What is the proper way to start a 2 cycle engine? You should have a plunger primer installed. Not the inline bulb type. The primer that goes into the carburetors.
If you fly in an area where you do a lot of cold weather flying (below 40 degrees) you may want to use enrichment chokes, which keep the engine running after the plunger primer starts it.
Depending on how cold it is you may have to pump it 2 or 3 times.
The throttle needs to be cracked. How far? About where it would be when the engine is completely warmed up and idling at 3500 rpm. The carburetor slides, if watching them, would move up about the thickness of a nickel (.090).
Crank the engine. Once it starts give it a slow 1 or 2 more pumps on the plunger primer. If you have the chokes, no further pumping will be needed. Chokes are not need above 40 degrees.
Once started, advance the throttle to 2500 RPM. Adjust your seat belts, check your control movements and taxi out to the run up area. The steel expands much slower than the aluminum piston, which is why you need .003 to .006 piston to cylinder wall clearance. The aluminum piston will swell much faster than the steel. Ceramic topped pistons deflect a lot of heat from the piston to the exhaust. Once you’re at the run up area, advance the throttle to 4500 RPM. If any lower RPMs are used you will not heat the steel cylinder walls and expand them. Heating the water is one thing but really the cylinder walls is what counts. That’s why we use ceramic top pistons.
Run it at 4500 RPM while you do your mag and fuel pump check. I recommend 4 minutes at 4500 RPM depending on the outside air temperature. After the 4 minutes I would run it at 5000 RPM. for one more minute (in a matter of seconds it will be at 6500 rpm). This really helps expand the cylinders. After warming it like this DO NOT idle it again before takeoff. If you are delayed, like an aircraft is landing, keep your engine at the 4500 RPM.
During take-off, use full throttle until the wheels are off the ground. If there are no obstructions reduce the power around 300 RPM. If an engine has a problem it would generally show up at full power. That’s the reason for going to full power. Climb to a safe altitude and reduce power to the desired cruise RPM and speed. Remember, 90% of the engines that fail, the damage that caused the failure happened when the engine was running at full power.
What is the safe maximum cruise RPM? On a 503 it is 500 rpm below its maximum RPM that it can reach straight and level. On a 582 it is 700 rpm below maximum straight and level. On a 670 it is 1000 rpm below max straight and level RPM.
What is the TBO on my engine. On the liquid cooled Rotax engines, the TBO is 1500 gallons of gas. Running a 582 at 5 gallons per hour equals 300 hours. The same 582 running at 2 1/2 gallons per hour is 600 hours. Being that the 670 burns around 1 GPH less than a 582, it therefore has a higher TBO. The 503 is a different engine and I feel it should be overhauled between 300 and 450 hours depending on its age, the oil used & the storage condition.
- For the exhaust Y manifold, do I install 8 screws to connect the exhaust to the cylinders, or do I just install 4 screws, 2 screws each cylinder? On a 582 I prefer to use 2 bolts on each side just like the 503 does. Rotax sends 6 bolts with a new engine package. The problem is if you install the 3rd bolt, it may hit the flange and you could get a leak. They do sell a stud and nut kit for this situation, but 1 on each side is fine. On a 670 you want to use all 4 screws in each side.
- Does it matter which side of the engine has the coolant expansion tank? The expansion tank needs to be on the side where the water comes out of the cylinder head (right where the thermostat is). The inlet side (the other side) sucks. The outlet side (where it should be) is under pressure. If you remove your radiator cap and look in the center of it, you will see a small round piece with a small spring. This is there for when the engine cools, as it creates a vacuum. It then sucks water out of the overflow tank and fills the coolant system to the top. We want the expansion tank large enough so when the engine is cold it still has at least 1 inch of water in it. When it’s as hot as it ever gets it should still be 1 inch below the radiator cap. Your radiator cap SHOULD open at 18 lbs. Let’s say it’s broken, damaged or worn out and as a result it takes 45 lbs to open it. SOMETHING is going to blow. On an engine with the expansion tank on the wrong side, it will cause the inner cylinder head o-ring to fail or the cylinder base gasket to blow out.
- With the two fuel pumps in this system (one pulse and one electric), should they be installed in parallel or in series to the carburetors? On your fuel system, the order of components should be: the flow out of the fuel tank, to a fuel filter, then the primer pickup line, the Fawcet fuel pump, then the pulse pump, then a fuel filter in each line from the pulse pump to the carburetor(s). You must use the 2 to 4 psi Fawcet fuel pump in your system. That, plus the pulse pump will provide 9 psi. The floats in your carburetor(s) will take that pressure without any problem. DO NOT run it parallel . Run in series with no bypass. SIMPLE IS BEST.
- The recommended fuel for these engines says only use Avgas in emergencies if unleaded fuel is not available. The reasons given for this is that Avgas will cause lead deposits on the spark plugs and increased carbon deposits on the pistons/rings. Yet you say Avgas LL100 is the best fuel to use. Why? For the same reason it is the only allowed fuel in general aviation aircraft. It’s handled carefully (no filling hoses dragged across the ground) and it has traceability. Also you are sure of it having the correct octane and it does not go stale or turn into turpentine. It also mixes and stays mixed with 2 stroke oil. Now in regards to the damage it does to your engine. The so called experts say it’s bad, but how many engines did they ever tear down and inspect that ran nothing but 100LL for 400+ hours? I have overhauled over 720 engines to date, and i’ve seen many that ran nothing but 100LL Avgas.
- Why green antifreeze instead of orange Dex-Cool coolant. Dex-Cool was in use on my engine before – Green antifreeze has silica in it. In the old cup style seals used in all the grey head engines, the silica would cut a grove in the rotator shaft and seal contact area. Because aircraft run at a higher water temperature this caused even more pressure then snowmobiles ever saw. Dexcool was the answer. NO SILICA! The problem is, if you have a head o-ring fail it will be like glue on the cylinder walls and will take out the lower rod bearing as the piston is pushed through it. The ceramic water pump seal does not mind silica at all. It may even help polish the ceramic surface . Use only the green antifreeze.
- What is with the bearing failures I hear about? – Customers are calling me to see if they have bad bearings in their engine. We started rebuilding crankshafts in February 2011. The first 10 crankshafts we rebuilt used the WSM rebuilt kit, supplied with Japanese Nachi bearings. Prior to using them, we studied the bearings and inquired at several bearing outlets. We found no negative information about the Nachi bearings. Nothing but praise. The 7th engine we modified with the Nachie bearings had a failure on the rear main bearing (not to be confused with the lower rod bearing’s perfect record). We subsequently replaced the bearing, the magneto piston, and all the seals and gaskets. The customer continued to fly this engine for 2 more years. None of the other 9 engines using the Nachi bearings have had any reported problems. It’s well known there can be many other explanations for such a failure, including premix, water, debris, etc. Sense June 2011 all 475 plus crankshafts rebuilt by Rotax Rick have used nothing but the German OEM brand FAG bearing. We have never had a single lower rod bearing fail. This is by far the #1 biggest reason for an engine out on a Rotax 2-stroke engine. Any bearing can, and they do fail. Too many factory crankshafts with 125 or less hours have failed, due to the lower rod bearing. Whether you buy a new factory crankshaft or one of our custom crankshafts is up to you. But our custom crankshafts have a far better record!
- Is this the same issue with pin bearings? – The pin bearing is used on the much higher horsepower Rotax 618 aircraft engine. They’re also used on the 670 series engines that produces up to 132 horsepower. The pin gives you assurance that the bearing will not rotate in the crankshaft. Their cost is much more and they’re very easy to install by putting a small slot in the case half where the pin rests. We believe they are a good addition to your engine.
- What is the problem with this guy who is operating an alleged Rotax Rick website? – This is a very frustrating situation where the free speech of the internet can sometimes confuse people into questioning what is right and wrong. While we have resisted getting into a back and forth debate with that site’s owner, our silence could be interpreted as shying away from the truth. To help provide a more accurate sense of what is real versus not real, we have decided to jump in and offer a series of responses to the many unsubstantiated accusations on that site. Should you wish to see these responses, please CLICK HERE.
- What kind of warranty does Rotax Rick provide for his engines? – Engines traded in and modified by us come with a 1 year warranty. Full engines purchased from us come with a 2 year warranty. IF there are problems, we will get it right.
- What are RAVE valves? – The Rotax Adjustable Variable Exhaust (RAVE) system is part of the secret to adding more power and efficiency to the engine. The current 500 series engines (e.g. 503 and 582) do not offer the RAVE technology. RAVE valves are located above the exhaust manifold. They open the exhaust port larger as the engine RPM increases. As RPM increases, pressure increases, and the valves open. Their purpose is to TIME THE EXHAUST WAVE (THAT IS AT THE SPEED OF SOUND) TO THE SPEED OF THE ENGINE’S PISTONS FOR CORRECT PORT TIMING. AS THE PISTON SLOWS DOWN, THE EXHAUST WAVE IS STILL AT THE SPEED OF SOUND AND IF IT ARRIVES TOO SOON IT WILL BOUNCE OFF THE CYLINDER WALL AND THEN BACK OUT THE EXHAUST PIPE, WASTING GAS AND THE TURBO PRESSURE THIS WAVE GIVES THE 2 CYCLE ENGINE. THE TUNED EXHAUST IS LIKE A 2 STROKES CAMSHAFT. WHEN THE RAVE VALVE IS IN THE LOWER RPM RANGE DOWN POSITION, YOU GET A FAR LONGER POWER STROKE .
- Why don’t you like oil injection? – The oil pump can just fail. There is no way to inspect it. It’s sealed. One (1) out of five (5) oil injection pumps removed have the bottom of the gear melted. This causes the nylon gear to have no pressure on it and I have seen the flat spot on the gear, round out. A test of a brand new 582 Blue Head determined that the oil:fuel ratio was first 51:1 ratio, and then 91:1 ratio, with the last test 81:1. The outlet on the pump has a check valve in the banjo bolt fitting. If that check valve fails, that cylinder only gets 60% of the oil. So you’d still be burning 80% of the oil that you should and may not notice the difference. When the cable lever is in the up position, you’re hopefully at a 50:1 ratio, but when it’s down you’re at 120:1. This means at start up where the engine could use a little extra oil you’re possibly at 120:1. Same thing on shut down, If the pump is working perfectly it’s pumping 50:1. These engines need 40:1. So you would still need to add oil to the gas directly. At shut down with a 40:1 ratio, you should cool the engine down, then rev it to 3500 rpm. Pull the primer out and give it a big pump, then quickly a second pump. Now you coated your engine parts with oil. This was in the 532 manual before oil injection was used.
- I can’t get that exhaust to mount properly on a Rans S-12. What gives?
- The bracket mounts you got may have worked on one S-12, but not all of them. You may need to possibly drill new holes in them or even weld/attach with bolts an extension on to them.
- Since the exhaust can move up, down, in and out with one bolt in place (may require some bending of the bracket at the engine attach point), your goal is to end up rotating the entire exhaust up and away from the engine, and thus from the wing’s material also. Put the top bolt in place as it was shipped (previously bent or not), and then rotate the entire exhaust out and up on that one attach point (not so easy, and not so clean, just be careful bending that attach point). Once your angle is where you want it, you would need to now somehow extend the bottom bracket with a new piece of steel (adding it on to the current bracket). We’re talking 5+ inches of extension possibly to overlap on the existing bracket, extend beyond that bracket, and to allow you to rotate the entire exhaust to a desired position. Your creativity, cutting, and/or welding skills would help here. I removed the bend at the end of the bottom bracket and simply added on a longer straight piece. You’ll have to cut off that bend (the attach to engine point) on the bottom bracket and create a new one at the end of the extension you are building.
- Take a piece of steel, drill 2 holes to match the existing bracket’s hole diameter (the bend you cut off); drill two holes in the existing bracket; and attach the extension with bolts to the existing bracket so that it overlaps (for strength) and it is longer to now reach the engine with the exhaust in the position you want. Two holes where the extension connects to the existing bracket will keep that extension from bending in the future. Don’t tighten anything down at this point.
- Now you have to figure out how long exactly that extension needs to be and how you will re-create the bend at the end for attaching to the engine. Don’t bend the extension piece to make it work, as it will vibrate and break off later. Welding is pretty much a requirement for this last piece (the bend). Be totally sure you have the right angle in the bend to lay against the engine’s attach point. Weld it on as appropriate.
- Now with some additional bending and fighting, you can get BOTH brackets to lay up against the engine while keeping the exhaust as far away from the wing skin as possible.
- Take it all off and paint as needed with black hi-temp paint for rust protection
- Again, this is a fighting, bending, lots of scrapes on your hands kind of venture. It is nice that you don’t have the skins on the wings yet.
- Now, CONSIDER whether you need to protect the skin on the wing from the heat coming out of the exhaust at the closest point to the wing. I didn’t, and paid the price of a hole in my wing’s skin. So order some race car firewall insulating material that you will stick right on the wing to deflect any heat that might try to burn or melt the wing cover. The material is silver and it looks and sticks fine on the wing. Trust me, I know. Google “firewall insulation engine” for choices out there. You should need a 1’ square piece I would think to protect the wing.