cymaz Posted May 12, 2019 Share Posted May 12, 2019 i have an RCGF 30cc petrol engine. The engine is inverted. Starts well, idles well.....until you put the nose down whilst holding it. It slows and dies! However, invert the plane ( so the engine is upright) and do a nose down it’s a smooth steady idle. The plug is tan brown and shows no oily residue. The mix is 32:1 with fresh fuel and good quality Castrol oil. There are no carb leaks, metering needle is set correctly. There is a small leak in the crankcase around the casing halves. It’s a 3 line plumbed tank. Its got me ! Anyone know the cause ( apart from the usual joke , the wrong letters are on the crankcase ) Quote Link to comment Share on other sites More sharing options...
J D 8 Posted May 12, 2019 Share Posted May 12, 2019 Any leaking on a crankcase of a two stroke can lead to problems. Quote Link to comment Share on other sites More sharing options...
cymaz Posted May 12, 2019 Author Share Posted May 12, 2019 That’s what’s puzzling me. Up right it will run strong and steady in any position. If it was stopping upright or playing up then I would reseal all the mating surfaces. As it’s only in one tiny spot. I’m afraid I might introduce more leaks reassembling it. I’ve got some high temp gasket sealer when I took it apart 6-8 months ago...it been reliable up to now. Quote Link to comment Share on other sites More sharing options...
alan p Posted May 12, 2019 Share Posted May 12, 2019 Leaks in the fuel supply chain, has the tubing developed pin hole leak in the tank , tipping nose down could be exposing it to pulling in air? Quote Link to comment Share on other sites More sharing options...
Paul Marsh Posted May 12, 2019 Share Posted May 12, 2019 What aircraft is it in. I have a RCGF 30cc in a Yak 54 and had to modify the carb to get it to run right - by adding a pressure equalization pipe. Quote Link to comment Share on other sites More sharing options...
cymaz Posted May 12, 2019 Author Share Posted May 12, 2019 I’ve got one on Paul but it doesn’t go all the way into the fus. The engine is being run in the fuselage in the back garden at the n moment. It still shows almost the signs of fuel starvation or the plug getting swamped with fuel, can’t make up my mind! Very worrying. i need it done soon, I hope to take it to Wings and Wheels Edited By cymaz on 12/05/2019 17:34:26 Quote Link to comment Share on other sites More sharing options...
cymaz Posted May 12, 2019 Author Share Posted May 12, 2019 The two halves of the crank case have no gasket and I can’t seem to find one in the parts pictures. Therefore gasket paper ordered. Quote Link to comment Share on other sites More sharing options...
Paul Marsh Posted May 12, 2019 Share Posted May 12, 2019 That was the symptoms i was getting, no fuel, then a full load swamping it and making it wet. Cured by the above mods. Extend the pipe via fuel tube into the fuselage. Quote Link to comment Share on other sites More sharing options...
cymaz Posted May 12, 2019 Author Share Posted May 12, 2019 Great ! Will do. And the newly made gasket, I will report back. Thanks Quote Link to comment Share on other sites More sharing options...
cymaz Posted May 17, 2019 Author Share Posted May 17, 2019 Purchased a sheet of 0.4mm gasket paper. Cut out a gasket for the mating halves of the crankcase. The surfaces where quite fine like machined bit obviously not good enough for a tight seal as some fuel leaking was seen on engine run. The diaphragm air bleed modification I did has now been extended into the fuselage. Now all is needed is an engine run Quote Link to comment Share on other sites More sharing options...
Dwain Dibley. Posted May 17, 2019 Share Posted May 17, 2019 Fingers crossed here, Cymaz................. D.D. Quote Link to comment Share on other sites More sharing options...
onetenor Posted May 17, 2019 Share Posted May 17, 2019 IDEALLY BOTH ENDS OF THE BALANCE PIPE EMERGE TOGETHER imho IN THE SAME SPACE This irons out the ripples hopefully.. Quote Link to comment Share on other sites More sharing options...
cymaz Posted May 17, 2019 Author Share Posted May 17, 2019 Came in from running the engine. No leaks anywhere on the crankcase or carb. Nose down there is no sudden cut. It will idle for at least a minute. It’s very sensitive on needle adjustments. Will fly it at the field Saturday. Quote Link to comment Share on other sites More sharing options...
cymaz Posted May 18, 2019 Author Share Posted May 18, 2019 Well it had a couple of runs. Fine tuned the needles and all was well......until........ it started to idle roughly, hard to start and poorly. After some research it seems the Hall effect sensor could be playing up. Changed the sensor, now waiting to run it up again. Quote Link to comment Share on other sites More sharing options...
Denis Watkins Posted May 19, 2019 Share Posted May 19, 2019 You have climbed a mountain and back again Cymaz, with this one The sensitive needle is usually an indicator of Plumbing ! ! ! So somewhere from the fuel to the cylinder Is a leak or blockage Is there any chance, on the bench, of running another supply in tandem, directly to your carb nipple Removing your present fuel installation from the equation. I have done this by banding on another tank and pipes on the fuz side bypassing the model installation entirely for the test Quote Link to comment Share on other sites More sharing options...
bert baker Posted May 19, 2019 Share Posted May 19, 2019 It may be worth checking that all the battery leads are a good fit and do make a good contact across the connector rather than a tight plastic connection,,,, and the battery is there a possibility one of the welded terminals has or is failing under vibration and loads, I had similar problems and that was what cured mine Quote Link to comment Share on other sites More sharing options...
cymaz Posted May 19, 2019 Author Share Posted May 19, 2019 Cheers Bert, will look into that. There’s not much that’s been checked and double checked. Now it’s a process of elimination all over again. By the way, are you on for Wings and Wheels this year again? Quote Link to comment Share on other sites More sharing options...
cymaz Posted May 19, 2019 Author Share Posted May 19, 2019 Caught the problem on video today.... HERE Quote Link to comment Share on other sites More sharing options...
Tony Richardson Posted May 19, 2019 Share Posted May 19, 2019 Cymaz, are you sure its not the throttle servo, I had a mini digital - spektrum 5030 - on an NGH38 and the vibration caused it to keep trying to find neutral and it would "hunt" eventually stalling the engine, just a thought. Quote Link to comment Share on other sites More sharing options...
cymaz Posted May 19, 2019 Author Share Posted May 19, 2019 I've changed the servo to a Hitec, that's what I thought the problem was originally. Off to order a new carb rebuild set and carb gaskets Edited By cymaz on 19/05/2019 21:36:46 Quote Link to comment Share on other sites More sharing options...
Tony Richardson Posted May 19, 2019 Share Posted May 19, 2019 Do you have a spare CDI unit you can try? Quote Link to comment Share on other sites More sharing options...
cymaz Posted May 19, 2019 Author Share Posted May 19, 2019 I changed the CDI box about 9 months ago..... I will have a look but I doubt it. Quote Link to comment Share on other sites More sharing options...
Tony Richardson Posted May 21, 2019 Share Posted May 21, 2019 Cymaz do you have a switch -opto coupled - that you can turn on/off from your transmitter, if so is it in conjunction with a manual switch? you may want to check all the wiring and connections, I have a clubmate who had similar issues and traced it to a failing opto switch, the switch was fine on startup bur after running for a while tended to heat up a little and made for erratic running. I"m clutching at straws here and am inclined to think it is a fuel feed problem but you have checked all that and it appears to be fine. When you find the answer - as you certainly will - please let us know what it was and the solution I hate unsolved mysteries.. Quote Link to comment Share on other sites More sharing options...
Martin McIntosh Posted May 22, 2019 Share Posted May 22, 2019 I have an RCG (not RCGF) 30 which is fine, also a similar RCG 50. The 50 started to quit after 2.5 mins in the air or on the ground. Someone spotted a tiny piece of black crap in the fuel line just by the carb. It could not be sucked out due to the diaphragm being closed but I got it out in the end. Could be a similar problem with yours. Hope you sort it before W&W. Quote Link to comment Share on other sites More sharing options...
cymaz Posted May 23, 2019 Author Share Posted May 23, 2019 Carb rebuilt kit has arrived, the gasket set is in the post. I’ve also ordered all the fuel tube, bung, brass pipe and barbs to completely rebuild the fuel system. Quote Link to comment Share on other sites More sharing options...
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