Simon Lumsdon 2 Posted November 6, 2022 Share Posted November 6, 2022 Spent an hour this afternoon trying to get an SC61 engine to start on the test bench. Its ABC but my geared starter (which is a good un) doesn't have the guts to get it started. Can't say I'm that keen to hand flicking it but guess Im going to have to try. Its bloody tight at the top end with lots of compression which is making it difficult to get going. It really needs to be run in and loosened up. I have a 12x6 prop which should be fine but just need to get the damn thing started. I don't have a spinner on it so struggling to get good grip on the nut but this should still be enough? All tips on starting a tight new engine appreciated please Quote Link to comment Share on other sites More sharing options...
Frank Skilbeck Posted November 6, 2022 Share Posted November 6, 2022 Not sure if it helps, but I start my OS AX55 using a cut off broom handle with a finger guard on the end using the reverse flick method. Basically prime the engine, turn it over a few times with the glow driver off, with the throttle about 15% open, give it a few reverse flick with the stick. 1 Quote Link to comment Share on other sites More sharing options...
john stones 1 - Moderator Posted November 6, 2022 Share Posted November 6, 2022 It'll be tight, I would fit an old spinner myself or an ali one that won't get marked up. Quote Link to comment Share on other sites More sharing options...
Braddock, VC Posted November 6, 2022 Share Posted November 6, 2022 Slacken the glowplug a turn-ish then try again, soon as it gets going tighten the plug back up. Quote Link to comment Share on other sites More sharing options...
Jon H Posted November 6, 2022 Share Posted November 6, 2022 Grab a heat gun a nuke the head. Get it up to 80c or so. This will expand the liner and allow a smoother ride. A little turn on the plug might help too. Once its running get it up to high rpm and running temperature as quickly as you can with say 90% peak tune. If you leave it cold and lumping over compression it will kill the rod in short order. I wouldnt recommend more than 30 seconds before getting it at least half way tuned to get the temperature up. 1 Quote Link to comment Share on other sites More sharing options...
Simon Lumsdon 2 Posted November 6, 2022 Author Share Posted November 6, 2022 Thanks everyone, some great tips here, never tried loosening the plug before and the heat gun is a good one, suspect that will help a lot, will try all these tmrw Quote Link to comment Share on other sites More sharing options...
Paul De Tourtoulon Posted November 7, 2022 Share Posted November 7, 2022 I soak the engine with fuel then carb fully open and take the plug out and give it a spin, for it's first start two washers under the plug fast idle and back flip, be careful with the starter con rods aren't made of steel,,, 1 Quote Link to comment Share on other sites More sharing options...
Denis Watkins Posted November 7, 2022 Share Posted November 7, 2022 Good strong bright glow on the glow plug, Worth fitting a new plug to be sure Quote Link to comment Share on other sites More sharing options...
Jon H Posted November 7, 2022 Share Posted November 7, 2022 2 hours ago, Paul De Tourtoulon said: I soak the engine with fuel then carb fully open and take the plug out and give it a spin, for it's first start two washers under the plug fast idle and back flip, be careful with the starter con rods aren't made of steel,,, I wouldnt really recommend this as the engine will be cold and the liner will not expand to its correct size as it heats up. raw fuel is also a dreadful lubricant and you do risk damaging the engine. When the engine is running the fuel and oil separate to give the lubrication needed but this will not happen if you just fill the engine with fuel and whizz it on the starter. Quote Link to comment Share on other sites More sharing options...
Engine Doctor Posted November 7, 2022 Share Posted November 7, 2022 Some of the above posts and then run up to temp at near full throttle for a min or so then stop and allow to cool down . Repeat until it starts to ease at tdc. Then fit I plane and fly it . Do t scream it or run slowly as this will / can cause damage Have just finished working on a V Tech 61 f9r a mate that is exactly the same. It's near new but had been run a short time and put away wet. Bearings rusted and have been replaced. What was interesting was the amount of swarf and debris fron ball bearings and alloy that came out after a Ultrasonic Bath ! Personally think they were made too tight as QC seemed to fall off when the last engines were made before they closed down. Quote Link to comment Share on other sites More sharing options...
Keith Berriman Posted November 7, 2022 Share Posted November 7, 2022 I could suggest two glow plug washers to easy the compression problem Quote Link to comment Share on other sites More sharing options...
Robin Colbourne Posted November 7, 2022 Share Posted November 7, 2022 I agree with Jon. Talk about compression when the engine is cold is a red herring here. It is the interference fit of the piston in the tapered bore that is the issue. The tapered bore is intended to expand to be parallel, or at least less tapered when the engine is warm, so the engine still has good compression when at running temperature. Using heat gun, or even a hair drier to warm the head is the way to go with this. Even if you loosen the plug, you are still forcing a big piston into a small bore when the engine is cold. This diagram is from Adriansmodelengines.com here: Breaking in an ABC Model Engine - By Adrian Duncan 3 Quote Link to comment Share on other sites More sharing options...
Simon Lumsdon 2 Posted November 8, 2022 Author Share Posted November 8, 2022 Well, tried again today, new F type plug, hair drier on the head to heat it up and still too much for the starter. Loosened the plug half a turn and bingo! Quickly had a slightly rich WOT and it working nicely. Ran a tank through it and all good. Even adjusted the low speed needle so it idles nicely. Many thanks for the help and tips, so useful Quote Link to comment Share on other sites More sharing options...
Jon H Posted November 8, 2022 Share Posted November 8, 2022 Nice one Simon Just be careful with F or long reach plugs in 2 strokes as some do not have clearance and you will punch a hole through the piston. OS No8 plugs would be my preference for a 2 stroke. Quote Link to comment Share on other sites More sharing options...
Simon Lumsdon 2 Posted November 8, 2022 Author Share Posted November 8, 2022 👍 Quote Link to comment Share on other sites More sharing options...
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