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need help with 2 cycle motor Answered

so i am having some severe issues with a motorbike i am building. i have an old 2 cycle mccholluch pro-scaper weed eater. i took it apart, cleaned it, put it back together with a brand new plug and it ran nicely. Now, a few days later, it wont even start, not even a putter. i have tried everything, even a hefty shot of ether in the carb, but still nothing. i know i am getting volts to the plug b/c i checked with my meter, but im not sure if im getting spark. it is a brand new plug. any help would be greatly appreciated. thanks.

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NachoMahma
NachoMahma

9 years ago

.  My first guess is that the plug is fouled and you aren't getting a good spark. Since the voltage will be at least a couple of kV (and a fairly short pulse), the average VOM in a DIYer's toolbox won't handle it.
.  Remove the plug, re-attach the high tension wire, ground the threads on the plug to the engine block (will probably require something to hold it in place), and yank the cord.
.  If you have a good spark, I'd next check the carburetion system.

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the mechanical engineer
the mechanical engineer

Reply 9 years ago

ok i am pretty sure its not the plug. i bought a new one and it now has about 5 min of run time on it from when it worked. i thought that may be the case, so i bought a new plug and still nothing. so i know it prolly isn't a plug problem. I have also spark checked it and did not see a spark, however when i grounded it with my hand, nothing happend till about the 3rd pull, when it zapped me pretty good. i am pretty sure its gotta be something with the ignition system i just don't know what.

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NachoMahma
NachoMahma

Reply 9 years ago

.  Just because you got zapped pretty good doesn't mean you are getting a good spark - anything over 60 V or so can bite. Make sure you have a good, hot spark at the plug gap.
.  If nothing happened on the first two pulls, it would appear that your magneto (most lawnmower/weed-eater motors have magnetos) is not working properly. It should have bit you quite hard on each revolution.

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the mechanical engineer
the mechanical engineer

Reply 9 years ago

thanks. i have another motor that is almost exactly the same and might try taking the magneto off of it. mccoulluch went out of buis so i cant get new parts. thanks though ill let you know if the new mag. works.

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skunkbait
skunkbait

Reply 9 years ago

Remove the plug, re-attach the high tension wire, ground the threads on the plug to the engine block (will probably require something to hold it in place), and yank the cord. Probably require something to hold it? That's what children are for!

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NachoMahma
NachoMahma

Reply 9 years ago

. LOL

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lemonie
lemonie

9 years ago


Fuel problem probably. If taking it apart and cleaning it once worked -try it again on just the fuel system. You might have knocked the float system out a bit for example.

L

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the mechanical engineer
the mechanical engineer

Reply 9 years ago

what do you mean float system? i know im getting fuel into the cylinder b/c i can smell it, and when i prime it i see fuel going through the lines.

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lemonie
lemonie

Reply 9 years ago


Flooded perhaps?
OK, take the plug out, hold the threaded bit on the block and turn-over - spark or electric-shock to yourself?

L