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Discussion Starter · #1 ·
Today the mini dirt bike wouldnt switch off when i hit the kill switch. Tried turning off the key ... still running. Pulled the safety cable....still running
All wires are connected inc. 2 earths on engine/mounr, 2 ignition barrel wires, coil wire, kill switch wires etc. I didnt open the ignition barrel, just pulled off the back grammet thing which exposed the soulder points.
Any ideas?
 

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Discussion Starter · #6 ·
Just connected little wire from coil to frame - still running. Tried connecting it to engine - still running. I had to unplug the HT lead from spark plug to kill her.im thinking the coil is rooted inside where the earth is. The wire looks sweet
I might just use another wire and see. Thoughts guys n girls?
 

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Discussion Starter · #7 ·
Same crap. I used another good quality wire from coil earth to frame/ground/engine (i tried connecting it everywhere) and she still wont cutout. Doesnt even stutter! Had to d/connect the HT lead again...im real sure its coil. Ive never had this happen on any engine vehicle before. Do the chinese have any quality control whatsoever? This coil is like 1.5 mnths old!
 

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Same crap. I used another good quality wire from coil earth to frame/ground/engine (i tried connecting it everywhere) and she still wont cutout. Doesnt even stutter! Had to d/connect the HT lead again...im real sure its coil. Ive never had this happen on any engine vehicle before. Do the chinese have any quality control whatsoever? This coil is like 1.5 mnths old!
There is no ISO quality standards in China...
 

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Discussion Starter · #9 ·
When u say take the wire tab and hook it direct to the ground, do u mean the engine mount where the earth is originally or do u mean the ground beneath my feet? Lol i know it sounds dumb but i wanna be sure. Cos ive already connected it to the engine mount ground/earth nut/bolt.
Cheers cam2
 

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When u say take the wire tab and hook it direct to the ground, do u mean the engine mount where the earth is originally or do u mean the ground beneath my feet? Lol i know it sounds dumb but i wanna be sure. Cos ive already connected it to the engine mount ground/earth nut/bolt.
Cheers cam2

I meant try hooking the coil back against itself by hooking the sparkplug end to the killswitch wire and pulling the pullrope to see if shock therapy helps

You can put an a/c electrical tester on the killwire and see if the wire lights the tester when running...You could add a long tywrap to the sparkplug boot and yank it.....
 

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What about the engine is so hot or carbon on the piston is so hot it ignites the air/gas mixture even when the coil is grounded or dieseling.
 

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Discussion Starter · #12 ·
EPR, thats what i thought at first. I was riding it for about 30 - 40 mins flat out around a 'track' in an indust. estate. Lots of full throttle an backing off then throttling 1/2 way thro turns then then full again. All the mods i been doing have paid off and it reaches its top end quickly but now i have the topend reed flutter and i think the petcock mod needs to be done because the bowl cant fill fast enough after all those f/t bursts.
When i stopped i let it run for about 20 - 30 seconds before i tried to kill it then i tried everything. All kill switches didnt work. When i shut the fuel tap it started revving off its head then finally died. Thats when i thought what u mentioned EPR. probably dieseling and it happens all the time now even when cold, after 1 quick ride around the hood and it still wont activate the grounding when i hit the switch.
1 thing i did notice last night was all that track work the carb mounting bolts came loose and air was getting in cos it was running like ****. But the air leak shouldnt keep it running though, if anything it should help stall her out. Looks like ill just buy a new coil and go from there, can get them here in oz for bout $10 delivered.
Any last thoughts before i order?
Cheers guys you've been a great help and also given me ideas i couldn't think of when i was diagnosing the bike.
 

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The engine taking off with the gas off is when it gets lean. Lean is fast, but too lean and your engine burns up. I run mine pretty hard so I like a hair rich & oily. We have all had the same kind of problems at some time.
 

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Discussion Starter · #14 ·
Yes. And air leaks (like my carby being loose) decrease manifold vacuum and cause a richer condition. This explains why my plug was black and carboned up. Every other time before this incident the plug has been brown. I have the needle clip on 4th position. I want to try 5th for a lap or two to see if 1/4 - 1/2 throttle changes. At the moment it kind of is a bit rough but WOT keeps the plug brown indicating the jet is of correct size. Yesterday i tapered the needle and the low to midrange improved noticeably but i may just check the poistiob ob 5th and see how it goes.
Ive been building a street/strip car (nissan rb30 turbo motor) and its going good. But these little bikes are ADDICTIVE! Performance modding them is sooo much fun! lol
 

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The only thing left I can think of is, if the kill wire off the coil is broken inside, when you tried to stop the engine it would not, or that wire might have diconnected inside the coil. When you ground the coil it should stop.
 

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Discussion Starter · #16 ·
Yep exactly right. The tab on the coil itself feels a little loose so it has to be broken. The coil itself is still firing. New one on the cards anyway, should arrive in a couple of days, until then at least i can still ride.
Thanks for everyones help, good to know i can ask wuestions on here and not be shot down or belittled. Some forums here in oz have the biggest idiots on here doing nothing but putting people down. The odd joke is ok i guess at someones expense as long as that person has a sense of humour and it doesnt go too far. But making somebody feel stupid when they ask for help?? That i just cant understand....
 
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