Fun Flyer Posted March 22, 2012 Share Posted March 22, 2012 What are the reccomendations about running a small 4 Stroke inverted. Will it run reliably? Thanks in advance. Quote Link to comment Share on other sites More sharing options...
Alan Cantwell Posted March 22, 2012 Share Posted March 22, 2012 i run mine inverted, i watch the tank postion so it will not flood, but Peter Miller on here came up with a great idea for that, an inverted U bend--works too!!! i do use an on board glow though, helps keep the fire lit, i even start it on the on board, Quote Link to comment Share on other sites More sharing options...
Frank Skilbeck Posted March 22, 2012 Share Posted March 22, 2012 No different to a 2 stroke, and because the valves are in the head you can drain any hydraulic locks out via the exhaust. Quote Link to comment Share on other sites More sharing options...
Biggles' Elder Brother - Moderator Posted March 22, 2012 Share Posted March 22, 2012 I think all my 4-strokes are inverted. No major problems - just the usual common sense stuff. BEB Quote Link to comment Share on other sites More sharing options...
Paul Marsh Posted March 22, 2012 Share Posted March 22, 2012 I find that 4 strokes prefer to run inverted. Even priming is easier, but the the fuel going into the carb, rather than out the cowl. Also on 4 stokes, the plug is canted off the top of the cylinder head, so when inverted, as long as not flooded will easily start with a reverse flick. Most of my single cylinder 4S's don't have on-board glow, and have no need, as for example an inverted 52 ASP 4s in my WM Mustang never stopped in 10 years it was in the model. Only use on-board just for easy remote starting, without glow-sitck which looks cool. Quote Link to comment Share on other sites More sharing options...
Bob Cotsford Posted March 22, 2012 Share Posted March 22, 2012 Posted by Paul Marsh on 22/03/2012 20:49:29: as for example an inverted 52 ASP 4s in my WM Mustang never stopped in 10 years it was in the model. How big was the tank in that then Paul? Quote Link to comment Share on other sites More sharing options...
Fun Flyer Posted March 29, 2012 Author Share Posted March 29, 2012 Thanks for all that and apologies for not responding but I've been taking advantage of the beautiful weather. The reason I asked was that I've installed an OS 26 inverted and in an attempt to make things easier I've built a cradle to hold the model inverted while starting. The engine is still difficult to prime and start but then dies after a few seconds when turned the right way up. Quote Link to comment Share on other sites More sharing options...
Bob Cotsford Posted March 29, 2012 Share Posted March 29, 2012 I would start with the really daft things first - the carb is connected to the feed line from the tank and not the vent isn't it? Not that I would ever have done such a thing Next. is the clunk moving freely and able to reach from the top of the tank (when starting) to the bottom(when you right the model after starting)? It's easy to get the clunk wrapped around the vent pipes, or with small tanks have too stiff a silicon inside the tank so the clunk won't flex down to the fuel. Is the tank level right or within 1/2" or so of lined up with the carb? Quote Link to comment Share on other sites More sharing options...
Myron Beaumont Posted March 29, 2012 Share Posted March 29, 2012 Bob Pauls tank to provide fuel for ten years works out to contain 3,194,320 ozs .Hmm! MyronYO13 useless information dept Quote Link to comment Share on other sites More sharing options...
Bob Cotsford Posted March 29, 2012 Share Posted March 29, 2012 can we have that in gallons please Myron? Quote Link to comment Share on other sites More sharing options...
Fun Flyer Posted March 29, 2012 Author Share Posted March 29, 2012 So Bob, you've connected the carb to a vent tube too!! I wonder if there are more than just the two of us but no one else willl admit it. Not the problem in this case though and I have checked again. The clunk is also waving around quite freely. I'm using a 4oz tank, the blue one, and the feed nipple more of less is in line with the carb. Quote Link to comment Share on other sites More sharing options...
Myron Beaumont Posted March 29, 2012 Share Posted March 29, 2012 Bob Just under 20,000 gallons Quote Link to comment Share on other sites More sharing options...
Olly P Posted March 29, 2012 Share Posted March 29, 2012 And what size rx and tx batteries! obviously a relay of pilots.... Quote Link to comment Share on other sites More sharing options...
Peter Miller Posted March 29, 2012 Share Posted March 29, 2012 Back to the original thread. Just started my OS FS 48 Surpass in my new model. It is inverted and started just as easily as any other position. The beauty of inverted four strokes is that they will not flood as the excess fuel is ejected through the valves. Quote Link to comment Share on other sites More sharing options...
fly boy3 Posted March 29, 2012 Share Posted March 29, 2012 Hi Fun Flyer, No ,most of us have mixed up tubes sometime or other, especialy after an engine in and out job. Cheers Quote Link to comment Share on other sites More sharing options...
Tim Reeves Posted May 10, 2013 Share Posted May 10, 2013 I have put an inverted TT fs91 into a phoenix tucano airframe. I have had the engine running and tuned nicley. The Problem is, it takes alot of messing about with the high needle to restart it after been running for a while. I have changed all the plumbing and glow plug. The prop is a 14 x 6. Apart from putting it on ebay, I've run out of ideas! Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted May 10, 2013 Share Posted May 10, 2013 Once set Tim you shouldn't need to touch the needle.....I have 4 stroke needles with rust on them!!! You mean the engine won't start UNLESS you adjust the needle? Sounds odd.....I wonder if you are tuning just slightly too lean (easy to do on a 4 stroke) so that the mixture is too weak to fire when the engine is cold.....? When tuning a 4 stroke the main thing is to let it warm up thoroughly first.....several minutes at about 1/2 throttle should do it.....then tune for max revs. Once its at max power open the needle a couple of clicks to slightly richen the mixture.....thats it!! You shouldn't need to touch it again unless you change something. Quote Link to comment Share on other sites More sharing options...
Tim Reeves Posted May 10, 2013 Share Posted May 10, 2013 I have neverhad this problem with my other fs being inverted. As you say, I never touch them once set up. With this engine, once warm and to start it again, the high end needle has to be turned right in to about 1 1/2 turned then turned out to rev up! It might be worth changing the carb? Have changed the seals on it. The one thing I have just noticed is there is a small ringed grove at the top of the needle, tapered end! Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted May 10, 2013 Share Posted May 10, 2013 H'mmmm odd indeed....so you have to wind the NVA right in to get it to start...effectively a much leaner mixture.....the only thing I can think is that the fuel is syphoning into the carb but this IS a long shot I agree. Will it start OK if you turn the model upside down? If so that would point the finger at the tank installation for my money. The groove on the needle obviously isn't ideal but I can't think its the cause of the problem....especially if it runs OK once started....compression & valve clearances are OK I take it?? Edited By Steve Hargreaves - Moderator on 10/05/2013 13:56:44 Quote Link to comment Share on other sites More sharing options...
Tim Reeves Posted May 10, 2013 Share Posted May 10, 2013 Haven't tried turning the model upside down yet. Have had a look on another site and the recommend having the choke venturi on. Will give these both a try and see what happens. Will give an update wih the results.Valve clearance are okay. Edited By Tim Reeves on 10/05/2013 14:11:15 Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted May 10, 2013 Share Posted May 10, 2013 Choke venturi being a kind of bellmouth yes? Might be worth a try but I'd be surprised if it made any difference...... Inverting the model totally re-arranges the relationship between the tank & the carb & can sometimes point the way forward.... Good luck.... Quote Link to comment Share on other sites More sharing options...
Tim Reeves Posted May 10, 2013 Share Posted May 10, 2013 The frustrating thing is, my mate who sold me the plane had an OS 91 fs in it and had no problems. Thanks for your help. Quote Link to comment Share on other sites More sharing options...
Tim Reeves Posted May 12, 2013 Share Posted May 12, 2013 Have tried starting the engine with the model inverted, and the fuel came out of the exhaust like water out of a hose. Needless to say it didn't start. I then put the engine in a test stand and to get it near max reves, the high end needle was taken out 5 turns. At least it started up again! Quote Link to comment Share on other sites More sharing options...
Steve Dorling Posted May 26, 2013 Share Posted May 26, 2013 engine doesn't care which way up it is - tank position is important though Quote Link to comment Share on other sites More sharing options...
.. Posted April 15, 2014 Share Posted April 15, 2014 I have an SC 70 fs fitted into my ME 109. The fuel tank is high , about 30/35mm above the carb. I have an on board glow but the tank is syphoning fuel resulting in the engine cutting out at tickover. Turn the plane over and it runs a treat. I'm not going to fit a perry pump as I don't want to throw anymore money at this one but has anyone had any luck with the U bend trick mentioned above? How big a bend would I need? Thanks J. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.