GrumpyGnome Posted December 17, 2020 Share Posted December 17, 2020 Morning all I am still having issues with my RCGF 15cc petrol engine. Switched ignition on, closed choke, spun it with starter..... just one single 'pop'. I tried for around 15 mins with no joy. I know fuel is getting through because I could see it in the cylinder when I later removed the exhaust. So, I suspect the spark plug or the CDI unit. How do I test these ? TIA. GG Quote Link to comment Share on other sites More sharing options...
Brian Dorricott 1 Posted December 17, 2020 Share Posted December 17, 2020 Hi If you get no joy try an OS G5 glow plug instead , it replaces ignition and fires up like a glow . I can't see any difference between it and the CDI to be honest its how OS supply there 10cc petrol 2 stroke . Quote Link to comment Share on other sites More sharing options...
brokenenglish Posted December 17, 2020 Share Posted December 17, 2020 Exactly. Put simply, that means go back to glow, but using an OS G5 will allow you to still consider that you're flying petrol! Quote Link to comment Share on other sites More sharing options...
Jon H Posted December 17, 2020 Share Posted December 17, 2020 You have flooded it i suspect. Take the plug out of the engine and put it back in the cap. Turn the engine over and see if it sparks, If so its likely fine unless the timing is off. I would then suggest you give the engine a blast with the starter and no plug to clear it, put it back together and try starting it without choke and see how you go. Generally you dont want to electric start a petrol engine with the choke on, especially a small one. Unlike glow they dont want to be dripping wet. If you get nothing trying to electric start it with no choke put the choke on and hand flick it until it fires. Choke off, keep flicking until it fires up. Quote Link to comment Share on other sites More sharing options...
Ace Posted December 17, 2020 Share Posted December 17, 2020 Others may know for sure but with a CDI unit I was lead to believe you shouldn't discharge the CDI ie. turn the engine over with the ignition on, without the plug being grounded (could be out resting on a fin) otherwise it damages the electronics? Quote Link to comment Share on other sites More sharing options...
Andy J Posted December 17, 2020 Share Posted December 17, 2020 GG suggest you simply remove the sparkplug connect up the cdi and visually check for a spark as you turn over the engine. Plug does need to be earthed via the engine. You can also buy buzzers that check the Hall sensor output which when used with a protractor can validate the engine timing. Quote Link to comment Share on other sites More sharing options...
Jon H Posted December 17, 2020 Share Posted December 17, 2020 Posted by Andy Joyce on 17/12/2020 09:59:57: GG suggest you simply remove the sparkplug connect up the cdi and visually check for a spark as you turn over the engine. Plug does need to be earthed via the engine. You can also buy buzzers that check the Hall sensor output which when used with a protractor can validate the engine timing. rcexl cdi units models use have the ground in the cap so you can test it very easily and dont need to ground through the engine. You will damage the unit if you fire it with no plug but as long as a plug is installed its fine. Edited By Jon - Laser Engines on 17/12/2020 10:38:48 Quote Link to comment Share on other sites More sharing options...
Engine Doctor Posted December 17, 2020 Share Posted December 17, 2020 Hi if you can see fuel in the cylinder then your engine is flooded and will not fire. Try closing off the fuel supply , remove the plug and open the throttle fully. MAKE SURE ignition is OFF. Now spin with starter for a minute or so to clear the fuel from the engine . Don't do this indoors as this vapour is explosive. Close the throttle and reconnect the fuel supply and refit spark plug. Don't apply choke just yet.Switch on ignition and starting. Engine should fire now and will probably due . Now apply choke and try again. Engine will / should pop a couple of times. Stop spinning and turn off choke then restart . Provided you haven't messed with the timing or the carb mixture screws it should run but will probably need fine tuning . Whatever you do DONT spin engine with ignition on and no spark plug fitted to the cap. Doing this can and probably will damage the windings in the CDI unit. With a plug fitted you should hear or see a spark across the plug. It doesn't need to be a big fat spark. Engine will need to be spun quite quickly to generate the spark on some systems ,others can generate a spark with a slow spin. Le us know how you get on . Don't bother with the petrol glow plug just yet but get it running and the mixture set then try the glow plug if you need to. Ps John beat me to it about damaging the CDI unit etc. Edited By Engine Doctor on 17/12/2020 11:10:37 Quote Link to comment Share on other sites More sharing options...
bert baker Posted December 17, 2020 Share Posted December 17, 2020 I’ve had exactly the same problem with one of my CDI units. I have the test gear to check the sensor and the tool to set up the timing settings. All looked ok with the CDI and sensor setting. tried another CDI and it fired up straight away. like the others don’t power the CDI Up without a plug in the cap securely. Edited By bert baker on 17/12/2020 12:48:07 Quote Link to comment Share on other sites More sharing options...
Rich Griff Posted December 17, 2020 Share Posted December 17, 2020 In the car and bike world you can check HT delivery and relative strength with a red neon plug cap which flashes as HT passed thru, with the plug in, but sizes of plug and access may prevent Thier use on model engines? Is this a self contained system with "crank Genny coils" or is it a battery dependant system? Crank sensor "keyed" to crank? Bike/lawn mower etc., Has fuel and spark but does not run? Suspect sheared flywheel Woodruff key... Quote Link to comment Share on other sites More sharing options...
GrumpyGnome Posted December 17, 2020 Author Share Posted December 17, 2020 Thanks all - will try tomorrow. Hi Rich It's battery dependent - will need to check that out too. GG Quote Link to comment Share on other sites More sharing options...
Engine Doctor Posted December 17, 2020 Share Posted December 17, 2020 Hi CDI units do take a bit of current. Make sure the battery is up to the job and a the cells are good under load. Quote Link to comment Share on other sites More sharing options...
cymaz Posted December 21, 2020 Share Posted December 21, 2020 If you check the timing, it should be 28’ before top dead centre. With an ignition tester, the buzzer comes on at 28’. Quote Link to comment Share on other sites More sharing options...
Ronaldo Posted December 21, 2020 Share Posted December 21, 2020 Check that you are getting a spark. You may not believe this, but it is true. My club mate bought a petrol RCGF 30cc twin, we couldn't get it to start, there was fuel getting in as the plug was wet with petrol. We checked for spark, but there was none. We then discovered that the prop hub wasn't drilled out and did not have the small magnet inserted that activated the spark pick up sensor. A call and a photo of the hub sent to the supplier. After a few embarrassed apologies, a new prop hub with the magnet fitted was sent out for us to fit (this was much quicker than returning the engine) and the engine has run great ever since, as have all the other RCGF engines we have Edited By Ronaldo on 21/12/2020 21:55:34 Quote Link to comment Share on other sites More sharing options...
GrumpyGnome Posted December 22, 2020 Author Share Posted December 22, 2020 I really must check this - I have been side-tracked....... GG Quote Link to comment Share on other sites More sharing options...
cymaz Posted December 22, 2020 Share Posted December 22, 2020 I’ve had one of these for years, very useful. I didn’t use the pointer, only the degree wheel. I made my own pointer that could be attached more firmly to the engine. This gives a more accurate measurement. It does sound like it’s flooded. Turn off the ignition take out the plug and dry it. Then turn over the engine to remove all the fuel. Check the voltage specs on the ignition and get a battery with plenty of capacity and that will handle current draw, I use sub C types on some older ignitions. Double check the spark gap 25/1000 is a about right Reset both needles to 1 1/2 turns out from fully closed then adjust from there Edited By cymaz on 22/12/2020 06:21:00 Quote Link to comment Share on other sites More sharing options...
GrumpyGnome Posted February 14, 2021 Author Share Posted February 14, 2021 I haven't forgotten this ........... I have cleaned the plug and simplified the install so it's 'back to basics' with a shiny new battery for the ignition, which seems to be generating a spark. When BoJo lets me out, I'll go to the field and try it - not sure my neighbours would appreciate my trying it in the garden ? In case I can't make it work, I have bough a practically unused Saito FA82 from a clubmate. If I can make the RCGF work, I'll need to get a home for the Saito ? GG Quote Link to comment Share on other sites More sharing options...
Petrol Pete Posted February 18, 2021 Share Posted February 18, 2021 Hi I would suggest you adjust the pick up hall sensor to be as close to the magnet, (about the thickness of a sheet of paper), i have seen this give all sorts of trouble if the gap is too large. i set the plug gap to the thickness of a stanley blade never fails, good luck. Quote Link to comment Share on other sites More sharing options...
Engine Doctor Posted February 19, 2021 Share Posted February 19, 2021 As Petrol Pete says plus make sure the magnet in the prop driver hasn't picked up any metal fillings . If it has clean bothe the hall sensor and the magnet with a piece of masking tape or electrical tape . The sticky side removes any metal particles quickly and easily. Quote Link to comment Share on other sites More sharing options...
GrumpyGnome Posted February 19, 2021 Author Share Posted February 19, 2021 Will do these before I try again Cheers GG Quote Link to comment Share on other sites More sharing options...
GrumpyGnome Posted May 16, 2021 Author Share Posted May 16, 2021 Finalising this thread now. Ultrastick now has a lovely shiny Saito and is a joy to fly with it's multiple flight modes using coupled/uncoupled flaps - ta OpenTx. RCGF is in a Yak54 which it powers nicely. And economically. Shiny new 20cc petrol (another RCGF) sitting in box while I finish building my P47. Cheers all GG Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted May 16, 2021 Share Posted May 16, 2021 All’s well that ends well then. Did you establish why it wasn’t starting? Quote Link to comment Share on other sites More sharing options...
john stones 1 - Moderator Posted May 16, 2021 Share Posted May 16, 2021 2 hours ago, Martin Harris - Moderator said: All’s well that ends well then. Did you establish why it wasn’t starting? New Plug sorted it. Quote Link to comment Share on other sites More sharing options...
GrumpyGnome Posted May 16, 2021 Author Share Posted May 16, 2021 Yes, new plug. A bit frustrated with myself as if it were a glow engine, I would have changed the glow plug at a very early stage, irrespective of seeing a spark..... GG Quote Link to comment Share on other sites More sharing options...
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