---------------------------------------------------------- RotaxEngines-List Digest Archive --- Total Messages Posted Thu 03/03/11: 7 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 04:53 AM - Re: Bing Type 64 Carb. Idle Mixture Setting (Thom Riddle) 2. 05:47 AM - Re: Re: Bing Type 64 Carb. Idle Mixture Setting (Hugh McKay) 3. 06:12 AM - Re: Bing Type 64 Carb. Idle Mixture Setting (Roger Lee) 4. 06:16 AM - Re: Bing Type 64 Carb. Idle Mixture Setting (Thom Riddle) 5. 06:56 AM - Re: Re: Bing Type 64 Carb. Idle Mixture Setting (Hugh McKay) 6. 08:03 AM - Re: Bing Type 64 Carb. Idle Mixture Setting (Roger Lee) 7. 08:39 AM - Re: Re: Bing Type 64 Carb. Idle Mixture Setting (Hugh McKay) ________________________________ Message 1 _____________________________________ Time: 04:53:43 AM PST US Subject: RotaxEngines-List: Re: Bing Type 64 Carb. Idle Mixture Setting From: "Thom Riddle" Hugh, If you are happy with the balance/synch of the two carbs but not happy with the idle mixture, then any adjustments you make to one idle mixture should be done to both. Once you get the two idle mixtures to where you are happy, then you should check the synch again. It should not change much, if any, as long as you make the idle mixture adjustments equal on both carbs. If I may ask, what triggered the need to make idle mixture adjustments? -------- Thom Riddle Buffalo, NY (9G0) Kolb Slingshot SS-021 Jabiru 2200A #1574 Tennessee Prop 64x32 Don't accept your dog's admiration as conclusive evidence that you are wonderful. Ann Landers Read this topic online here: http://forums.matronics.com/viewtopic.php?p=332606#332606 ________________________________ Message 2 _____________________________________ Time: 05:47:02 AM PST US From: "Hugh McKay" Subject: Re: RotaxEngines-List: Re: Bing Type 64 Carb. Idle Mixture Setting Thom, Some time ago I had a rough engine problem which was finally traced to a broken wire at one of the modules. In the course of trying a number of things to find the problem, one of the things I did was to re-set the idle mixture. I closed the idle mixture screw on both carbs and then backed them out the 1.5 turns per Rotax. Unfortunately I did not index the original position of the screws so I don't know exactly where they were set by the factory (i.e. 1.5, 1.8 ,or say 2.0 etc). Anyway, my plugs have a black velvet coating on them every time I change them, and the inside of my exhaust is black and sooty. My reading has reading on this has indicated that my idle mix setting is too rich, so I am going to try and readjust them per the Pro Carb Shop procedure. Any suggestions? Hugh G. McKay III, P.E. Senior Consultant Worldwide Engineering Inc. 4090 North NC Hwy. 16 Denver, NC 28037 Ph. 704-661-8271 Fax 704-483-5466 email hgmckay@bellsouth.net http://www.wwegeo.com -----Original Message----- From: Thom Riddle Sent: Thursday, March 03, 2011 7:50 AM Subject: RotaxEngines-List: Re: Bing Type 64 Carb. Idle Mixture Setting Hugh, If you are happy with the balance/synch of the two carbs but not happy with the idle mixture, then any adjustments you make to one idle mixture should be done to both. Once you get the two idle mixtures to where you are happy, then you should check the synch again. It should not change much, if any, as long as you make the idle mixture adjustments equal on both carbs. If I may ask, what triggered the need to make idle mixture adjustments? -------- Thom Riddle Buffalo, NY (9G0) Kolb Slingshot SS-021 Jabiru 2200A #1574 Tennessee Prop 64x32 Don't accept your dog's admiration as conclusive evidence that you are wonderful. Ann Landers Read this topic online here: http://forums.matronics.com/viewtopic.php?p=332606#332606 ________________________________ Message 3 _____________________________________ Time: 06:12:16 AM PST US Subject: RotaxEngines-List: Re: Bing Type 64 Carb. Idle Mixture Setting From: "Roger Lee" Hi Hugh, The factory setting is 1.5 turns. You can tweak these some and clean up the idle mixture. It will not effect any thing above idle. The black dry velvet can be normal and only happens at idle. When you are cruising then this does not happen. Because of the way the air intakes are setup you can have a slight difference between sides on the mixture. You actually can just tweak one side if need be and it won't hurt any thing. The black velvet won't hurt a thing and you shouldn't be at idle for long periods anyway. Most of the time your engine is well above that so it isn't a factor so the other option is to just leave it alone. My plane will have it sometimes and other times it doesn't, plus it may move from one plug to another. It is a small item and not one that I would worry too much about. -------- Roger Lee Tucson, Az. Light Sport Repairman - Maintenance Rated Rotax Repair Center Home 520-574-1080 TRY HOME FIRST Cell 520-349-7056 Read this topic online here: http://forums.matronics.com/viewtopic.php?p=332616#332616 ________________________________ Message 4 _____________________________________ Time: 06:16:42 AM PST US Subject: RotaxEngines-List: Re: Bing Type 64 Carb. Idle Mixture Setting From: "Thom Riddle" Hugh, Just make small adjustments, no more than 1/8th turn (45 degrees) at a time, on both carbs, from the original 1.5 turn starting point. Run the engine and check again. Keep in mind that these affect only the mixture at idle speed or slightly above idle speed and that at idle, they must be fairly rich to come off idle smoothly without stuttering or balking. The plugs will show black sooty appearance after extended idle periods even when it is adjusted perfectly, because it must be somewhat rich at idle. The color inside the exhaust tip reflects more accurately the normal cruise speed mixture, and should be less black and more gray in color. If you run the engine under less load than recommended (too little prop pitch or too slow rpm) then the exhaust color may be black. If you have EGTs installed, the normal cruise temps should be approximately 1,470F with a max of 1,560F. In my experience with prop pitched properly, the 912UL will have the proper EGT readings above 4800 rpm or so with gradual drop off below that speed range. -------- Thom Riddle Buffalo, NY (9G0) Kolb Slingshot SS-021 Jabiru 2200A #1574 Tennessee Prop 64x32 Don't accept your dog's admiration as conclusive evidence that you are wonderful. Ann Landers Read this topic online here: http://forums.matronics.com/viewtopic.php?p=332617#332617 ________________________________ Message 5 _____________________________________ Time: 06:56:08 AM PST US From: "Hugh McKay" Subject: Re: RotaxEngines-List: Re: Bing Type 64 Carb. Idle Mixture Setting Thom/Roger, Thank you for your counsel and advice. My exhaust is certainly not grey. It is black and sooty! My prop pitch is is 15 degrees which gives me 5100 Static rpm. The following three tests were run to set my prop pitch: First Test Pitch 17.5 degrees rpm 4600 Second Test Pitch 16.5 degrees rpm 4900 Third Test Pitch 15 degrees rpm 5100 I have been happy with the pitch at 15 degrees. When I cruise I keep the engine rpm between 5200 to 5400 rpm. Under this condition (cruise) I am not at WOT. On take off (WOT), my rpm is around 5100. I still think I am too rich because of the black sooty exhaust. Hugh G. McKay III, P.E. Senior Consultant Worldwide Engineering Inc. 4090 North NC Hwy. 16 Denver, NC 28037 Ph. 704-661-8271 Fax 704-483-5466 email hgmckay@bellsouth.net http://www.wwegeo.com -----Original Message----- From: Thom Riddle Sent: Thursday, March 03, 2011 9:13 AM Subject: RotaxEngines-List: Re: Bing Type 64 Carb. Idle Mixture Setting Hugh, Just make small adjustments, no more than 1/8th turn (45 degrees) at a time, on both carbs, from the original 1.5 turn starting point. Run the engine and check again. Keep in mind that these affect only the mixture at idle speed or slightly above idle speed and that at idle, they must be fairly rich to come off idle smoothly without stuttering or balking. The plugs will show black sooty appearance after extended idle periods even when it is adjusted perfectly, because it must be somewhat rich at idle. The color inside the exhaust tip reflects more accurately the normal cruise speed mixture, and should be less black and more gray in color. If you run the engine under less load than recommended (too little prop pitch or too slow rpm) then the exhaust color may be black. If you have EGTs installed, the normal cruise temps should be approximately 1,470F with a max of 1,560F. In my experience with prop pitched properly, the 912UL will have the proper EGT readings above 4800 rpm or so with gradual drop off below that speed range. -------- Thom Riddle Buffalo, NY (9G0) Kolb Slingshot SS-021 Jabiru 2200A #1574 Tennessee Prop 64x32 Don't accept your dog's admiration as conclusive evidence that you are wonderful. Ann Landers Read this topic online here: http://forums.matronics.com/viewtopic.php?p=332617#332617 ________________________________ Message 6 _____________________________________ Time: 08:03:22 AM PST US Subject: RotaxEngines-List: Re: Bing Type 64 Carb. Idle Mixture Setting From: "Roger Lee" Hi Hugh, With the rpm numbers you give sounds like you are little under propped. What do you get at WOT flat and level? It sounds like you may be close to 5700 WOT? It won't hurt anything, but you'll loose a little cruise speed and fuel economy. -------- Roger Lee Tucson, Az. Light Sport Repairman - Maintenance Rated Rotax Repair Center Home 520-574-1080 TRY HOME FIRST Cell 520-349-7056 Read this topic online here: http://forums.matronics.com/viewtopic.php?p=332635#332635 ________________________________ Message 7 _____________________________________ Time: 08:39:07 AM PST US From: "Hugh McKay" Subject: Re: RotaxEngines-List: Re: Bing Type 64 Carb. Idle Mixture Setting Roger, I never fly WOT while cruising. I will fly today and open her wide open and check the rpm. I will let you know. Hugh G. McKay III, P.E. Senior Consultant Worldwide Engineering Inc. 4090 North NC Hwy. 16 Denver, NC 28037 Ph. 704-661-8271 Fax 704-483-5466 email hgmckay@bellsouth.net http://www.wwegeo.com -----Original Message----- From: Roger Lee Sent: Thursday, March 03, 2011 11:00 AM Subject: RotaxEngines-List: Re: Bing Type 64 Carb. Idle Mixture Setting Hi Hugh, With the rpm numbers you give sounds like you are little under propped. What do you get at WOT flat and level? It sounds like you may be close to 5700 WOT? It won't hurt anything, but you'll loose a little cruise speed and fuel economy. -------- Roger Lee Tucson, Az. 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