Foxy70 Posted June 29, 2014 Share Posted June 29, 2014 Took my mcd out today running well then it started to rev up went to try stop the engine by the third ch still would not stop hit the red stop switch on the engine still no joy fuel bubble on carb empty pulled the ht lead off still running pinched the fuel line engine stoped ...... Sh.... My self looked at the engine carb is loose head gasket blown would this of caused the none stoppable engine """"""""""""" Quote Link to comment Share on other sites More sharing options...
Tamiyacowboy Posted June 29, 2014 Share Posted June 29, 2014 (edited) test failsafe. you say you hit the big red button and engine kept on running ? this is an electrical fault somehwere and i would say somehwere in the killswitch system/wire loom to-from rx - KS - engine cdi. i know you have loose parts but all the same check the electrics. loose carb blown head gasket. head gasket would leak compression so engine would be tempremental under heat , start stopping etc etc. loose carb would show signs of splutter, lack of fuel flow, unusual starting-none starting. to much air to make a bang. again it comes back to the cdi ht was removed and still engine ran. this is highly unsual for a twostroker they need the spark to run. maybe worth stripping engine out and giving it a full service. Edited June 29, 2014 by Tamiyacowboy Quote Link to comment Share on other sites More sharing options...
Foxy70 Posted June 29, 2014 Author Share Posted June 29, 2014 It was still running when I pulled off the ht lead !!! Quote Link to comment Share on other sites More sharing options...
Tamiyacowboy Posted June 29, 2014 Share Posted June 29, 2014 you have a problem then.. that lump needs benching, ( bench mount ) stripping - rebuild checking all electrical areas on engine re-newing that gasket, re-newing the carb gasket fixing carb back with a little threadlock Quote Link to comment Share on other sites More sharing options...
goldman Posted June 29, 2014 Share Posted June 29, 2014 Hope you had some bog roll with you!!!!!!!. Goldman Quote Link to comment Share on other sites More sharing options...
Foxy70 Posted June 29, 2014 Author Share Posted June 29, 2014 No bog roll just rag Quote Link to comment Share on other sites More sharing options...
Foxy70 Posted June 29, 2014 Author Share Posted June 29, 2014 Just striped it down going put new ring new gaskets & clutch as it's down to metal lol Quote Link to comment Share on other sites More sharing options...
Nitroholic Posted June 29, 2014 Share Posted June 29, 2014 You got a combination of problems... The loose carb and/or blown gasket would have caused lean running...which means things would have got hotter than they ought. You probably also got a bit of carbon build up....which would get hot as well. Get it hot enough, and the fuel will ignite from that. You killswitch ( both ) assuming they were in full working order ( no reason to think they weren't ) works by killing the spark. If you pull off the plug cap...you stopped the spark for sure... but it kept running. Basically I suspect your plug had turned into a glowplug, and was hot enough to ignite the mix. Can happen on a 2 stroke engine, but I have only seen it once in 30+ years on an old GP100. That was fun...but at least I could kill it by banging it into gear with the brakes on. It blew up shortly afterwards, spitting lumps of piston out the exhaust, and jamming a lump of crown in the disc valve. So definitely strip and overhaul the motor! Quote Link to comment Share on other sites More sharing options...
Foxy70 Posted June 29, 2014 Author Share Posted June 29, 2014 Thanx nitroholic going fit new gaskets & ring piston is good no markes see how it goes then Quote Link to comment Share on other sites More sharing options...
Tamiyacowboy Posted July 3, 2014 Share Posted July 3, 2014 i would even before replacing the piston and ring set, SPLIT that engine case, get it apart, flush those bearing houses and bearings flush the whole inner two cases, and check the oil for any metalics. just because you see now scour on the barrel dont mean those ring parts etc etc aint sitting in the bottom end waiting to be churned up thrown back into the mix of things. i had heard of sparkies fusing to a glowplug like status but never ever seen or had it happen. had them get hot the tips had somewhat molten state but never fused hot. so yeah strip down flush out and re-build should be all well. treat it as a new engine and go easy to re-bed the rings and piston and lube up the fresh casing , maybe even add an extra 1/8th - 1/16th of a cap of mixing oil to your usual mix run it a bit richer in the lubrication and re-running in Quote Link to comment Share on other sites More sharing options...
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