---------------------------------------------------------- RotaxEngines-List Digest Archive --- Total Messages Posted Wed 12/15/10: 15 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 04:59 AM - Re: Re: Rough Running 912 (Ken Ryan) 2. 05:24 AM - Re: Re: Rough Running 912 (Ken Ryan) 3. 05:44 AM - Re: Re: Rough Running 912 (bjones@dmv.com) 4. 06:24 AM - Re: Rough Running 912 (lucien) 5. 06:45 AM - Re: Re: Rough Running 912 (Ken Ryan) 6. 08:24 AM - Re: Rough Running 912 (Roger Lee) 7. 09:49 AM - Re: Rough Running 912 (moosepileit) 8. 11:54 AM - Re: Rough Running 912 (lucien) 9. 12:33 PM - Re: Rough Running 912 (moosepileit) 10. 01:18 PM - Re: Rough Running 912 (Roger Lee) 11. 02:04 PM - Re: Re: Rough Running 912 (Hugh McKay) 12. 02:59 PM - Re: Rough Running 912 (lucien) 13. 03:48 PM - Re: Rough Running 912 (Roger Lee) 14. 04:44 PM - Re: Re: Rough Running 912 (Richard Girard) 15. 06:23 PM - Re: Rough Running 912 (lucien) ________________________________ Message 1 _____________________________________ Time: 04:59:45 AM PST US Subject: Re: RotaxEngines-List: Re: Rough Running 912 From: Ken Ryan I could easily be taking off at sea level and then flying to over 14000. Ken Ryan Anchorage, Alaska On Tue, Dec 14, 2010 at 6:11 PM, lucien wrote: > lstavenhagen@hotmail.com> > > > kenryan wrote: > > So all of this talk of changing needle positions based on altitude has me > wondering. What if you want to fly from sea-level to high altitude? What > then??? > > > > Ken Ryan > > Anchorage, Alaska > > > > > You shouldn't have to change anything. I live at 7000' MSL (northern NM) > and fly usually up to 9999' MSL, even on local messing-around flights. My > carbs still have the factory jetting and they compensate fairly well. Mine > run a bit rich at low power settings (i.e. between 2000 and 3000 or so on > the ground or during approaches) and it's going to idle rich also (if you > use the factory 1.5 turns on the idle needle). But at full power it still > leans out fairly well, giving EGT's in the 1250 to 1350F range. > > So shouldn't be a problem... > > LS > > -------- > LS > Titan II SS > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=323383#323383 > > ________________________________ Message 2 _____________________________________ Time: 05:24:46 AM PST US Subject: Re: RotaxEngines-List: Re: Rough Running 912 From: Ken Ryan That example was for flying from a base of 7000 to 9000. I'm talking more about flying from sea level to about 14,000. Same answer? On Tue, Dec 14, 2010 at 8:27 PM, Roger Lee wrote: > > I'm with Lucien. leave it alone. You will be a little rich for that flight, > but so what it will fly just fine. Making a permanent needle adjustment > should mean you are more or less permanently at altitude. > > -------- > 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=323400#323400 > > ________________________________ Message 3 _____________________________________ Time: 05:44:30 AM PST US Subject: Re: RotaxEngines-List: Re: Rough Running 912 From: bjones@dmv.com My home bases are at sea level in Florida Keys and adjacent to Chesapeake Bay but have flown over Grand Canyon, and around the South West Rockies up to about 10,000 plus a trip Md to Fl at about 10,000 and have not noticed any engine roughness in an early s/n 912. Can't remember going to 14,000 feet though. BJ KF IV N154K > That example was for flying from a base of 7000 to 9000. I'm talking more > about flying from sea level to about 14,000. Same answer? > > > On Tue, Dec 14, 2010 at 8:27 PM, Roger Lee wrote: > >> >> >> I'm with Lucien. leave it alone. You will be a little rich for that >> flight, >> but so what it will fly just fine. Making a permanent needle adjustment >> should mean you are more or less permanently at altitude. >> >> -------- >> 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=323400#323400 >> >> >> >> >> >> >> >> >> >> >> > ________________________________ Message 4 _____________________________________ Time: 06:24:01 AM PST US Subject: RotaxEngines-List: Re: Rough Running 912 From: "lucien" kenryan wrote: > I could easily be taking off at sea level and then flying to over 14000. > > Ken Ryan > Anchorage, Alaska > > I still think you'll be ok. By the time you get up there, you're going to be mostly wide open all the time anyway so the carbs should compensate pretty well. I've flown mine at density altitudes approaching 12,000' MSL without any visible running problems. I would make sure that you have the carb vent lines installed correctly first (i.e. going into the aircleaners or airbox). The carbs really do go rich at higher altitudes if the vent lines are just hanging out in the breeze and that could cause problems that high up. LS -------- LS Titan II SS Read this topic online here: http://forums.matronics.com/viewtopic.php?p=323419#323419 ________________________________ Message 5 _____________________________________ Time: 06:45:23 AM PST US Subject: Re: RotaxEngines-List: Re: Rough Running 912 From: Ken Ryan Thanks for the inputs! On Wed, Dec 15, 2010 at 8:21 AM, lucien wrote: > lstavenhagen@hotmail.com> > > > kenryan wrote: > > I could easily be taking off at sea level and then flying to over 14000. > > > > Ken Ryan > > Anchorage, Alaska > > > > > > > I still think you'll be ok. By the time you get up there, you're going to > be mostly wide open all the time anyway so the carbs should compensate > pretty well. I've flown mine at density altitudes approaching 12,000' MSL > without any visible running problems. > > I would make sure that you have the carb vent lines installed correctly > first (i.e. going into the aircleaners or airbox). The carbs really do go > rich at higher altitudes if the vent lines are just hanging out in the > breeze and that could cause problems that high up. > > LS > > -------- > LS > Titan II SS > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=323419#323419 > > ________________________________ Message 6 _____________________________________ Time: 08:24:18 AM PST US Subject: RotaxEngines-List: Re: Rough Running 912 From: "Roger Lee" Ok, I didn't want to post this, but for the sake of no one messing with their engine here goes. I have friends that have been to 18'K + with their 912ULS and the clip at number 3. Leave your clips alone and your engine will take you any where you want to go. -------- 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=323436#323436 ________________________________ Message 7 _____________________________________ Time: 09:49:17 AM PST US Subject: RotaxEngines-List: Re: Rough Running 912 From: "moosepileit" Roger, For the case of sea level to 14k'- I agree, CLIP #3, the standard for the 80HP Rotax UL. My experience moving from 5k' to sea level proved that out. You might want to look at the HACMAN for the case of going up high, less than $200 for the install, assuming you didn't need to send out the carbs for the tapping setup. Now, My carb vents are just tucked in the bales from the float bowl. I have the K&N filters, both pancakes, one per side, oriented properly. Should I tap into the back plastic and run the carb vents back to the air filters? Does anyone have a picture of this? It would look just like running the vents to the air inlet manifold on the ROTAX 912s that use a plenum/manifold connected to both carbs. Read this topic online here: http://forums.matronics.com/viewtopic.php?p=323446#323446 ________________________________ Message 8 _____________________________________ Time: 11:54:48 AM PST US Subject: RotaxEngines-List: Re: Rough Running 912 From: "lucien" moosepileit wrote: > > Now, My carb vents are just tucked in the bales from the float bowl. I have the K&N filters, both pancakes, one per side, oriented properly. Should I tap into the back plastic and run the carb vents back to the air filters? Does anyone have a picture of this? It would look just like running the vents to the air inlet manifold on the ROTAX 912s that use a plenum/manifold connected to both carbs. I'd definitely fix this before flying at high altitudes. Soon as I can get out to the hangar with my camera, I'll take some pictures of how I did mine. Basically, you can get a brass double-barbed fitting at Lowes or somewhere (1/8" IIRC), the fitting with barbs on each end and a disc in the center. I.e. looks like then, drill a hole in the back panel of the air filter (remove for this and clean out the scrap rubber completely). Push the barb in till it bottoms out at the disk. Push the carb vent line over the other end of the barb and you're done.... I have the big flat Rotax K&N's which makes this easy. But I'll try to get some pics of what I have... LS -------- LS Titan II SS Read this topic online here: http://forums.matronics.com/viewtopic.php?p=323459#323459 ________________________________ Message 9 _____________________________________ Time: 12:33:44 PM PST US Subject: RotaxEngines-List: Re: Rough Running 912 From: "moosepileit" Lucien, thanks! I was fine cruising at 9500' msl w/ OAT about 32F/freezing. Your description is great, thanks. I don't think she'll be getting above a couple thousand feet for a while, EGT is 1400 WOT down low now and takeoff. It makes sense to have the carbs as equal as possible, which does not include 2 vent hoses randomly in the airflow, even just tucked against the carb bowl holders/bails. So, with this setup, is there any use for carb drip trays? I don't need them for heat isolation and the carbs can't drip onto my exhaust in my kitfox... Read this topic online here: http://forums.matronics.com/viewtopic.php?p=323465#323465 ________________________________ Message 10 ____________________________________ Time: 01:18:47 PM PST US Subject: RotaxEngines-List: Re: Rough Running 912 From: "Roger Lee" Howdy Moose, The vent lines need to be in the same general area so they pick up the same pressure to balance the carbs and if the engine were to shake hard for any reason sometimes you can get some fuel down them and that's why you don't want the vent lines on top of an exhaust and having a drip tray under them can help. The drip trays aren't there for the vent lines usually, but for things like a leaking float bowl gasket which can be common. I always keep a couple of float bowl gaskets lying around. Easy to replace. The drip trays provide a barrier between any fuel that comes out of a carb which is usually right above the exhaust. I would leave them alone. If you're flying you won't know the carbs are leaking until after you're on the ground and for many of us you won't know unless you pull the cowl. -------- 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=323469#323469 ________________________________ Message 11 ____________________________________ Time: 02:04:18 PM PST US From: "Hugh McKay" Subject: Re: RotaxEngines-List: Re: Rough Running 912 Roger, What is your take on Lucien's idea of running the carb vent lines back into the air filters on a 912 UL? Hugh McKay -----Original Message----- From: Roger Lee Sent: Wednesday, December 15, 2010 4:15 PM Subject: RotaxEngines-List: Re: Rough Running 912 Howdy Moose, The vent lines need to be in the same general area so they pick up the same pressure to balance the carbs and if the engine were to shake hard for any reason sometimes you can get some fuel down them and that's why you don't want the vent lines on top of an exhaust and having a drip tray under them can help. The drip trays aren't there for the vent lines usually, but for things like a leaking float bowl gasket which can be common. I always keep a couple of float bowl gaskets lying around. Easy to replace. The drip trays provide a barrier between any fuel that comes out of a carb which is usually right above the exhaust. I would leave them alone. If you're flying you won't know the carbs are leaking until after you're on the ground and for many of us you won't know unless you pull the cowl. -------- 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=323469#323469 ________________________________ Message 12 ____________________________________ Time: 02:59:30 PM PST US Subject: RotaxEngines-List: Re: Rough Running 912 From: "lucien" hgmckay wrote: > Roger, > > What is your take on Lucien's idea of running the carb vent lines back into > the air filters on a 912 UL? > > Hugh McKay > > -- For what it's worth, I didn't make this up. This requirement on the vent lines is in the installation manual for the 912 series. There's a diagram in there showing the lines being routed to nipples on the airbox for illustration purposes, but without the box you kind of have to invent your method. Like I said, at my altitude my carbs definitely ran too rich before the fix (EGTs in the 1100's !) so I'm convinced! ;) LS -------- LS Titan II SS Read this topic online here: http://forums.matronics.com/viewtopic.php?p=323481#323481 ________________________________ Message 13 ____________________________________ Time: 03:48:15 PM PST US Subject: RotaxEngines-List: Re: Rough Running 912 From: "Roger Lee" Rotax likes them run into a common area like an airbox with the same pressure gradient going to each carb. If you had let's say one large filter then the lines running in there would be better than into two separate filters. While his is certainly better than many and by no means bad the best would be to put them out of all air streams and setup to a common point. There could be a possible air pressure difference between two carbs, probably small, that could change things slightly. It might be from maybe someone over oiling one filter compared to the other with a K&N or the way the engine is set up under a cowl. Nothing wrong with his setup and there are worse things done to vent lines out there, but if you wanted to tweak it a little better a common airbox is better. -------- 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=323488#323488 ________________________________ Message 14 ____________________________________ Time: 04:44:47 PM PST US Subject: Re: RotaxEngines-List: Re: Rough Running 912 From: Richard Girard Lucien, I wasn't in on the discussion on the Kolb forum, but I took the time to read Section 15 and 16 of the installation manual and what it says is that the carb vents must be routed to a vacuum and ram air free zone. The air box supplies this, the air filter does not. Letting them just hang, secured by the float bowl bale is a perfectly acceptable option. Rick Girard On Wed, Dec 15, 2010 at 4:57 PM, lucien wrote: > lstavenhagen@hotmail.com> > > > hgmckay wrote: > > Roger, > > > > What is your take on Lucien's idea of running the carb vent lines back > into > > the air filters on a 912 UL? > > > > Hugh McKay > > > > -- > > > For what it's worth, I didn't make this up. This requirement on the vent > lines is in the installation manual for the 912 series. > > There's a diagram in there showing the lines being routed to nipples on the > airbox for illustration purposes, but without the box you kind of have to > invent your method. > > Like I said, at my altitude my carbs definitely ran too rich before the fix > (EGTs in the 1100's !) so I'm convinced! ;) > > LS > > -------- > LS > Titan II SS > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=323481#323481 > > -- Zulu Delta Kolb Mk IIIC 582 Gray head 4.00 C gearbox 3 blade WD Thanks, Homer GBYM It is not bigotry to be certain we are right; but it is bigotry to be unable to imagine how we might possibly have gone wrong. - G.K. Chesterton ________________________________ Message 15 ____________________________________ Time: 06:23:50 PM PST US Subject: RotaxEngines-List: Re: Rough Running 912 From: "lucien" rickofudall wrote: > Lucien, I wasn't in on the discussion on the Kolb forum, but I took the time to read Section 15 and 16 of the installation manual and what it says is that the carb vents must be routed to a vacuum and ram air free zone. The air box supplies this, the air filter does not. Letting them just hang, secured by the float bowl bale is a perfectly acceptable option. > > Rick Girard > Not at my altitudes it isn't. Fortunately 15.1 does clarify the issue a bit - it also says: "Pressure differences between intake pressure and pressure in the carburetor chambers may lead to engine malfunction due to incorrect fuel supply." That effectively means the vent lines should be at the same atmospheric pressure (or in the same atmosphere) as the venturis. There is a pressure difference, tho pretty small, between the outside of the airfilter and the inside. So, if you have the choice, the lines really need to be routed to the inside. If you have the airbox, the requirement is very clear, with the diagram, etc. Now, the interesting thing is it doesn't really show up at sea level. My plane was originally in Nebraska; the mixture was fine down there with EGT's up to about 1400 with the lines run down the sides into the bales in the usual way. I guess the effect isn't that significant there. So it's normally not a problem and the carbs still compensate pretty well. But when I got it up here after the ferry mission there was a BIG difference - my EGT's were barely out of the 1100's. And the plugs were starting to get fuel fouled after about the first 20 hours or so after getting it here. I later learned about the correct placement of the lines and after the mod that put the mixture back to practically normal. My EGT's run about 1250 to 1350, a lot closer to where they should be. Still slightly rich but definitely about the expected temps for my altitudes and no more fouled plugs. So in my view, it really is something you want to comply with if you fly at high altitudes. At sea level, yeah, it's probably not that big of a deal.... LS -------- LS Titan II SS Read this topic online here: http://forums.matronics.com/viewtopic.php?p=323500#323500 ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message rotaxengines-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/RotaxEngines-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/rotaxengines-list Browse Digests http://www.matronics.com/digest/rotaxengines-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.