bad miss

W

wan37

Member
I have a 48cc grubee engine with about a 1000 miles on it and it's been having a dead miss for awhile at low idle and it will kill the engine at times. I have to set the idle up for it not to kill engine. Now it seems to be worse doing it at higher idle. I have had it to go away at times. I always thought it was a bad cdi or magneto but nope it stills does it with new ones. So I tried different gaps on plugs can't say that it worked but some thing has worked at times because it goes away at time and I can't pin point it. I also tried to reinstall the magnet and see if it was timing but it didn't help either. Oh but when riding it runs smooth for now, never has had a problem there. Any a vice would be helpful. Thanks
 
you could try raising or lowering the needle to see what effect that has - might give you more info
 
Well it really seem like a spark or something hitting in the engine but when does it I can feel it makes a clicking sound and dies...I know the plug isn't hitting tho .I also took head off tho to see if the plug is hitting and checked the piston. There's no way it can hit. The plug doesn't go in the head far enough to hit the piston. I'm running now ngk b6hs plug now.
 
put the handle of a long screwdriver in your ear and hold the blade against various parts of the motor - you may be able to locate just where that click is - could be the cage of a main that is bent a bit & off and on, sticking and dragging

sound near the top could be same with the small end bearing
 
I have had my engine for 2 years riding it every day , lots of miles and it started missing , your bearings might be going bad , mine just recently fell to pieces on my way to town I now have it rebuilt , which was easy , got her to sputter a couple times need to get an answer on setting the timing
 
First thing that comes to mind is to ask if you're using the kit supplied spark plug boot. If so, replace it with a good automotive quality boot and get back to us with the results.
Your problem is almost without a doubt electrical/ignition.

Tom
 
I agree with an ignition problem. The ignition wire unscrews from the coil. Toss an ohm meter on each end of the old wire and I bet you get a lousy reading, if any. If it ohms out good, replace it anyway. May have a broken wire inside. Eliminate one piece of the puzzle (cheapest first) and move on.; what's the color of the plug?
 
New plug, then new wire, then check for signs of water inside the coil side case.
Water can cause intermittent failures like you describe...but try the plug and wire first. The factory parts are famous for being iffy at best.
 
The solder joints on the magneto coil are notorious for failing, and a little bit of moisture can make them go much more quickly. They may still look solid, but if you heat the connection and resolder it you may fix your problem.
 
It's very weird, change the idle sometimes it goes away. I have changed the plug to iridium it's better, but still there. I really think that it's one of those round engine that grubbe made and I had to turn the head around for spark plug clearance is the problem. I have try a lot of things but have not changed the head back... Thanks every body for your input...
 
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