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Carb synchronisation done - SMOOTH!!!
Posted: Mon Dec 30, 2013 7:49 pm
by Turbo
hey all,
I subscribed to the rotax-owner.com site and have access to all the videos and technical info etc etc
I watched a video on carb balancing -- carried it out when I serviced the engine, and it has made a world of difference!!! If I switch one of the mags off, the engine RPM drops as normal but the engine does not run any rougher at all! The sound of the engine is smoother and the power delivery is much stronger and the overall engine sound is much smoother and there are absolutely no vibrations at all!
Rotax recommend balancing the carbs every 75hours..... I bet you never knew that -- check this out
http://www.lightsportaircraft.ca/volume ... webcast-3/
anyways I have purchased carb balancers and have all the fittings, and valves for the 912/914 engines - if anyone needs help - shout.
Re: Carb synchronisation done - SMOOTH!!!
Posted: Mon Dec 30, 2013 7:58 pm
by AWACS
Hey Chris,
You're right...I think most of us did not know about the 75 hr interval...
Will contact you in Jan '14.
Cia!
Re: Carb synchronisation done - SMOOTH!!!
Posted: Mon Dec 30, 2013 9:20 pm
by Turbo
You welcome boet -- anytime. as per the video - ill help you setup the carbs - it was setup by Glen recently, but I went over them again and made small changes to the benefit of the engine --- there are many other interesting things about the Rotax engines, both 4 stroke and 2 stroke on this site, that will greatly benefit everyone flying with these engines.
Re: Carb synchronisation done - SMOOTH!!!
Posted: Tue Dec 31, 2013 7:22 am
by mulderpm
Hey Chris,
Did not know about the 75 hr interval but anyway I did mine with a vacuume balance gauge and the results were remarkable. EGT's were closer, engine ran smoother and started easier. Also, there is less uneven tourque on the middle of the crank, therefore reducing the risk of crank failure! I checked the settings using a mechanical mechism, two pencilles under the slides, and found it to show balance as well. So, since then I check the balance using this method and my EGT's are less than 10 deg apart at max. I do this every 100 hrs. Usually no adjustment is required.

This method does not allow for uneven wear of the carbs
I believe......If you look after your Rotax it will look after you
Great advice Chris.
Enjoy....fly safe.
Re: Carb synchronisation done - SMOOTH!!!
Posted: Tue Dec 31, 2013 12:39 pm
by Turbo
hey Mulderpm -
I did notice that the two CHT gauges were perfectly in line with one another after the balance -- meaning that both sides of the engine are running at the same mixtures ....
if one runs leaner than the other, the lean running bank will show higher CHT readings, and the same goes for the EGT readings.
Re: Carb synchronisation done - SMOOTH!!!
Posted: Tue Dec 31, 2013 2:39 pm
by mulderpm
Turbo wrote:I did notice that the two CHT gauges were perfectly in line with one another after the balance -- meaning that both sides of the engine are running at the same mixtures .....
The Rotax, or any twin or multi pistoned engine with multiple carbs is just two or more engines joined together at the hip (crank). If one piston (engine) gets more fuel (carb slide higher) than the other it works proportionately harder, dragging the others along via the crank....eina
Great advice Chris....keep those carbs balanced.
Please also see thread,
viewtopic.php?f=13&t=20640&hilit=carb+b ... g&start=15