Richard Thorpe Posted April 2, 2014 Share Posted April 2, 2014 Hello chaps, I've been having some troubles with my OS46LA recently. What happens is when im flying just cruising (its a seagull swift trainer) mid throttle and i drop the throttle back to idle when making practice approaches it sometimes cuts out, which is a touch frightening. I cant have the idle set higher otherwise the plane will run off when on the field/come in too fast for landings. Also after a few flights and as the day progresses i find that the engine will stall as im walking it out to the strip. Could this be down to slight atmospheric changes during the day. I know the carb lacks a low speed needle, and has an air bleed instead. Where should i start with regards to its tuning? Could i fit a twin needle carb off another engine? (i have more experience with these from my nitro RC cars. and one last thing the engine has had 3/4 of a gallon of Model Technics Duraglow 10 through it. Thanks in advance for any help. Quote Link to comment Share on other sites More sharing options...
Comper Posted April 2, 2014 Share Posted April 2, 2014 Hi I've been flying a wot4 with a os 46 la for some time now and have had no problems , in fact I have to pull the trim back to full shut to get the engine to stop! My fuel is optifuel Optimix 12 cracking engines Hope this helps Mike Quote Link to comment Share on other sites More sharing options...
J D 8 Posted April 2, 2014 Share Posted April 2, 2014 Check the O ring on the needle,air may be getting in. Quote Link to comment Share on other sites More sharing options...
David Gilder Posted April 2, 2014 Share Posted April 2, 2014 I had a 40la that suffered the same issue once! Turned out to be a pinprick hole in the fuel tube between the rear mounted needle and the carb! Might be worth renewing this tube and check again. The hole was only visible when the tube was stretched and not when in normal relaxed position so you wont notice it on the model! hope this helps. Dave Quote Link to comment Share on other sites More sharing options...
john stones 1 - Moderator Posted April 2, 2014 Share Posted April 2, 2014 Hello Richard Os 46 LA is a good honest engine, it should not be giving you trouble, 3/4 gallon, should be running like a good un. check everything mate before you get a deadstick in bad place. make sure all bolts screws are tight, check plumming may be a tiny hole in fuel tube, make sure clunks not stuck, take needle out and flush fuel through incase there is a bit of dirt in. check cap on tank is tight. get it sorted before it costs you, and try another plug as well. cant think of owt else but that should keep you busy for now. Quote Link to comment Share on other sites More sharing options...
Richard Thorpe Posted April 2, 2014 Author Share Posted April 2, 2014 Thanks for all the input so far, Ill try everything you've suggested so far and report back Quote Link to comment Share on other sites More sharing options...
Alan Gorham_ Posted April 2, 2014 Share Posted April 2, 2014 Your engine has had probably just enough time running on it's 3/4 gallon of fuel to need a new glow plug. They don't last forever you know! So, it may be worth trying a new one and with it's greater efficiency it might just keep things turning at the lower throttle settings you are having problems with. Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted April 2, 2014 Share Posted April 2, 2014 Will it idle on the ground OK? It should tick over indefinitely....if it stops then how does it stop? Does it just "fade away" & die or does it splutter a bit first? If the former its probably a bit lean....you need to screw the airbleed screw in a bit...if it splutters a bit then its probaly a bit rich....unscrew the airbleed a tad. The airbleed screw usually sits around halfway in.....don't try & adjust it with the engine running...you will hurt yourself. All the suggestions above are good 'uns & worth trying too....also when in the flight does it happen? Anytime or after a few mins? If after a few mins then there might be an pinhole in the clunk tube inside the tank. This can be very hard to spot as the engine will run fine until the fuel level drops & uncovers the 'ole. Another thing to try...are all the engine bolts tight? loose backplate/head/carb screws can admit air & mess up the mixture. The OS46LA is a gem of an engine though....not very powerful but a lovely engine to handle. Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted April 2, 2014 Share Posted April 2, 2014 The backplate screws are prone to loosening on the LA engines so Steve's advice to check them is very sound... Quote Link to comment Share on other sites More sharing options...
will -0 Posted April 2, 2014 Share Posted April 2, 2014 IF it idles OK with the glow clip on, but cuts or drops revs when you take it off, change the plug. Did this to my 25la just this week as it wouldn't idle either. And all that other stuff people are saying. With LA engines you can of course see if air is getting into the fuel line as there is clear tube between the needle vavle and the carb. Not so easy to spot in the air, mind you. Loose backplate is usually given away by more than usual oil round the crank case. You can also spot the fuel bubbling out of it (again easier to see on the ground..............) Quote Link to comment Share on other sites More sharing options...
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