DrZoos Posted January 3, 2014 Share Posted January 3, 2014 Hi guys my idle is way too high and 100 hourly coming up. I will of course refer to Rotax manual, but just wondering where you guys have your idle set at please. Thanks in advance. Mine idles at 1750 if i hold the knob, 1880 without holding it. The rotax manual says min 1400 rpm My POH says green arc 1400-5500rpm and yellow arc 1000-1400rpm red arc 5800rpm Im planning on 1450rpm or so but interested in your thoughts. Link to comment Share on other sites More sharing options...
metalman Posted January 3, 2014 Share Posted January 3, 2014 2000 rpm, but I never just let it sit there and bang away in the gearbox , always taxi at 2200-2300 and warm up at 3000 Matty Link to comment Share on other sites More sharing options...
crashley Posted January 3, 2014 Share Posted January 3, 2014 My idle is set to give about 1400 rpm minimum during flight not sure what that equates to on a ground run I will check and let you know rotax manual states 1400 to 2500 until oil is warm I set throttle at about 2100 - 2200 for warm up as It will bang on the clutch if the revs are too low Link to comment Share on other sites More sharing options...
DrZoos Posted January 3, 2014 Author Share Posted January 3, 2014 Mine starts and runs perfect now, very very smooth. But i thought my idle was too high. Its fine for taxiing most places, just a bit of extra braking near the hangers thats all.. I run mine at 2000-2500rpm during warm up. But im more concerned with how low to take the idle. I dont want to take it down much if its going to be problematic, but i would like it lower. Wow matty 2000rpm seems high. Are you on grass most the time ?? Im on Bitumen or bitch a man 99% of the time so it rolls pretty quick with not much throttle. Link to comment Share on other sites More sharing options...
metalman Posted January 4, 2014 Share Posted January 4, 2014 Grass and gravel, I also have pretty draggy tyres so it will roll along nicely without brakes while taxiing, and it'll sit there no brakes at idle, I've actually had it stop on me by pulling a bit hard on the throttle on final, it's possible to bend stuff if your a bit heavy handed , it might actually idle a bit lower than that, 1800 maybe, I very rarely let it just idle Matty Just had a look at one of my utube vids,,, 1800 on the ground,,,,like I said I very rarely just let it sit there idling Link to comment Share on other sites More sharing options...
DrZoos Posted January 4, 2014 Author Share Posted January 4, 2014 Anyone else got any figures they are running. Link to comment Share on other sites More sharing options...
Guest Maj Millard Posted January 4, 2014 Share Posted January 4, 2014 Matty is correct, I start mine up and warm up at 2000 for bit, and then go to 2200. Don't sit at low idle too much. Being a taildragger I like my idle botto stop set at minimum 1750-1800, things are happy there, and your not getting any backlash in the gearbox. About the only time it sees 1750 however is coming over the fence getting set up for landing....Wear a set of pads out if you have to, they are a lot cheaper and an easier maintenance task than a gearbox overhaul.......Maj.... Link to comment Share on other sites More sharing options...
DrZoos Posted January 4, 2014 Author Share Posted January 4, 2014 Thanks yeh i might just look to get 1750 without holding it back. Link to comment Share on other sites More sharing options...
Guest Maj Millard Posted January 4, 2014 Share Posted January 4, 2014 Some 912s are happy to idle at 1400 or so, but mostly the 80 HP ones, and I've even seen the odd one quite happy at 1200. I don't think the 912uls is even close to run in until around 400-500 hrs, and they just keep getting better from there on. So if your only looking at at an engine with only 100-200 hours on it, and expecting it to purr, your wasting your time, best thing you can do is go and fly it some more. The higher compression 912uls will never idle as good as the lower compression 80 hp anyway, IMOP.. I have operated some 912Uls with well over 2000 hours plus on them, and then they are super- smooth like a little turbine. My own 912 ULs should turn the big 800 hrs in the morning if the WX cooperates. It's been very reliable and keeps getting better. Will Probabily do the trip again to Temora this year, and possibly a trip to the Kimberlies in August from Townsville..................Maj....... Link to comment Share on other sites More sharing options...
Mriya Posted January 4, 2014 Share Posted January 4, 2014 I have also found that props make a difference. A Tecnam P92 Echo Super that I maintain used to comfortably idle on the book figures of 1400rpm (others in this thread have already covered the problems with leaving the engine running for extended periods <2000rpm) when the original 2 blade GT propeller installed. However once this was replaced with a 3 blade ground adjustable Bolly prop the idle needed to be set higher as it would not happily idle at anything less than 1700rpm. Also a VH registered Flight Design MC aircraft, that we maintain, with a Neuform 3 blade ground adjustable prop also needs to be set at +1700rpm. 1 Link to comment Share on other sites More sharing options...
Guest Maj Millard Posted January 4, 2014 Share Posted January 4, 2014 Props can make a lot of difference to setting idle. The lighter weight carbon fibre props have very low- inertia and generally need to be run at higher RPMs for smoothness........Maj.... Link to comment Share on other sites More sharing options...
Downunder Posted January 4, 2014 Share Posted January 4, 2014 912ULS..... Factory set to 1800 but found idle on final a bit too fast. (Prefer a glide or just off idle approach) Re-set it to 1600 and just keep it idling a bit faster on the ground to stop the gear teeth and clutch chattering. Finals now more controllable and stable. 1 Link to comment Share on other sites More sharing options...
pmccarthy Posted January 4, 2014 Share Posted January 4, 2014 912ULS set to 1600 with a 3 blade ground adjustable prop. But I have been warming up at 2500 rpm as per handbook and LAME advice... Link to comment Share on other sites More sharing options...
cscotthendry Posted January 4, 2014 Share Posted January 4, 2014 Mine seems happiest at about 1800 when warming up. At 2000 it feels rougher. I have to keep my hand on the throttle to keep it down to 1800 when it's warm, otherwise it sits around 2000-2200 Link to comment Share on other sites More sharing options...
metalman Posted January 4, 2014 Share Posted January 4, 2014 I have also found that props make a difference. A Tecnam P92 Echo Super that I maintain used to comfortably idle on the book figures of 1400rpm (others in this thread have already covered the problems with leaving the engine running for extended periods <2000rpm) when the original 2 blade GT propeller installed. However once this was replaced with a 3 blade ground adjustable Bolly prop the idle needed to be set higher as it would not happily idle at anything less than 1700rpm. Also a VH registered Flight Design MC aircraft, that we maintain, with a Neuform 3 blade ground adjustable prop also needs to be set at +1700rpm. Should've let you answer for me ,since you tune mine,,, Matty 1 Link to comment Share on other sites More sharing options...
alf jessup Posted January 5, 2014 Share Posted January 5, 2014 Tecnam Sierra 912ULS running a Hoffman prop, mine is set to 1800 rpm at idle, pads are cheaper than a gearbox overhaul as Maj points out. Never found any problem floating with a higher idle, just need to fly the numbers on final. They get the name rattly Rotax for the gearbox chattering at low idle settings which is not at all good for the gearbox. My 80 hp in the trike was also set at 1800, idle was very smooth at that. Alf Link to comment Share on other sites More sharing options...
DrZoos Posted January 13, 2014 Author Share Posted January 13, 2014 Thanks all. Great info and appreciated. Link to comment Share on other sites More sharing options...
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