rotax

Here you will find a fairly complete resource for all the popular Rotax engines valid as of April 2006.

Time Between Overhauls (TBO) for Rotax Aircraft Engines

	Rotax 2-Stroke UL Engines	Rotax 4-Stroke UL Engines
	Rotax 2-Stroke UL Engines	912UL	912 ULS	912 ULSFR	914UL
300h / 5 years	All
600h / 10 years		≤ 4,152.666 SI-26-1994 to 1200h
1000h / 10 years					≤ 4,418.103 SB-914-027UL to 1200h
1200h / 10 years			≤ 4,427.532 SB-912-041UL to 1500h	≤ 4,429.714 SB-912-041UL to 1500h
1200h / 12 years					≥ 4,418.104
1200h / 15 years		≥ 4,152.667 ≤ 4,404.717 SB-912-041UL to 1500h
1500h / 12 years			≥ 4,427.533	≥ 4,429.715
1500h / 15 years		≥ 4,404.718

Example:
You have an 912 ULS engine with a serial number of 4,427.116. In the 912 ULS column, you'll notice that the serial numbers which are inferior or equal to 4,427.532 have a TBO of 1200h / 10 years. You will also notice that the TBO can be increased to 1500h when the instructions contained in service document SB-912-041UL are followed. You can find these service documents on
www.rotax-owner.com

	Carburetors	Intake Silencer	Main Jet	Idle Jet	Needle Jet	Jet Needle	Needle Clip	Air Screw Turns
Rotax 277 UL	1	No	148	45	2.72	8L2	2	1
Rotax 277 UL	1	Yes	140	45	2.72	8L2	1	1
Rotax 377 UL	1	No	165	45	2.70	8O2	2	½
Rotax 377 UL	1	Yes	155	45	2.70	8O2	2	½
Rotax 447 UL	1	No	165	45	2.70	15K2	2	½
	1	Yes	155	45	2.70	15K2	2	½
	2	No	135	50	2.70	6G1	3	1
	2	Yes	128	50	2.68	15K2	2	1
Rotax 503 UL up to #3785371	1	No	180	45	2.74	8G2	3	½
Rotax 503 UL up to #3785371	1	Yes	158	45	2.74	6H2	3	½
Rotax 503 UL after #3785372	1	No	185	45	2.72	15K2	3	½
	1	Yes	165	45	2.70	15K2	3	½
	2	No	158	45	2.70	11K2	2	½
	2	Yes	148	45	2.68	11K2	2	1
Rotax 532 UL 582 UL	2	No	165	55	2.72	11G2	3	1
Rotax 532 UL 582 UL	2	Yes	145	55	2.68	15K2	2	½
Rotax 618 UL	2	No	160 PTO 170 MAG	50	2.68	9M10J	2	1
Rotax 618 UL	2	Yes	135 PTO 145 MAG	50	2.68	9M10J	2	1½

Adjusting Rotax 2-stroke Aircraft Engine Bing Carburetors to atmospheric conditions

The fuel/air mixture the carburetor provides to the engine varies with air density. Air density fluctuates with ambient temperature and altitude above sea level.

It is sometimes possible to adjust the mixture by changing the position of the needle clip, but for great variations in atmospheric conditions, a change of main jet is necessary.

J₂ = (D₂ / D₁) X J₁

D₁ = Original density factor
D₂ = New density factor
J₁ = Original main jet
J₂ = New main jet

Refer to the chart below to find density factors.

	m	0	500	1000	1500	2000	2500	3000	3500	4000
°C	°F/ft	0	1600	3300	5000	6500	8200	10000	11500	13000
-30	-22	104	103	101	100	98	97	95	94	93
-20	-4	103	102	100	99	97	96	95	93	92
-10	14	102	101	99	98	96	95	94	92	91
0	32	101	100	98	97	95	94	93	91	90
10	50	100	99	97	96	95	93	92	91	89
15	59	100	99	97	96	94	93	92	90	89
20	68	100	98	97	95	94	93	91	90	88
30	86	99	97	96	94	93	92	90	89	88
40	104	98	96	95	94	92	91	90	88	87
50	122	97	96	94	93	92	90	89	88	86

For example: your mixture was perfectly adjusted with a 158 main jet to fly at sea level and a temperature of 20ºC, but you decide to use your engine in a region at 1500m above sea level and a temperature of 30ºC. What main jet will you need?
J₂ = (94 / 100) x 158 = 0.94 x 158 = 148.52
The result is rounded to the next available larger main jet, in this case 150.

Rotax 4-stroke Aircraft Engine Bing Carburetor Configurations

		Main Jet	Idle Jet	Needle Jet	Diffuser	Jet Needle	Needle Clip	Air Screw Surns
Rotax 912 UL		158	35	2.72	961200	961215	3	1½
Rotax 912 ULS		155	35	2.70	961202	961215	3	1½
Rotax 914 UL	cyl. 1/3	160	35	2.72	961200	961215	1	1½
Rotax 914 UL	cyl.2/4	164	35	2.72	961200	961215	2	1½

Rotax

Time Between Overhauls (TBO) for Rotax Aircraft Engines

Rotax Aircraft Engine Bing Carburetors

Rotax 2-stroke Aircraft Engine Bing Carburetor Configurations

Adjusting Rotax 2-stroke Aircraft Engine Bing Carburetors to atmospheric conditions

Rotax 4-stroke Aircraft Engine Bing Carburetor Configurations