Engine Trouble Engine wont start? TROUBLESHOOTING GUIDE

aaron....

It's probly an air intake leak... or a compression leak.

I'll leave it to you to figure out how to check for leaks. :geek:
 
aaron....

It's probly an air intake leak... or a compression leak.

I'll leave it to you to figure out how to check for leaks. :geek:

You know, a couple times i saw grey smoke come out in a burst with a pop sound when i was looking down and riding. it looked like it came out of the engine from somewhere but not simuetaneously within a few seconds/ minutes randomly it was acting popey and poping more then usual and when it poped the bike would jump a bit and i saw smoke maybe 3 times randomly. but it also happened because of/at the same time as when my spark plug connector fell off from me going so fast. as its loose as i said. and im not exactly sure how to check for leaks actualy XD
 
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Get a couple big alligator clips (battery clips, look like jumper cable ends but smaller). You can put a piece of wire between them, and use that as a spark plug tester. (clip one on the motor fin or ground on bike, clip the other on the threads of the spark plug, and ride it. You should see plenty of sparking if its working (magneto good and plug good).

Be careful not to ignite fumes or spilled fuel.

For the wire connections, I cut off all the cheap bullet connectors and used good crimp connectors with the yellow plastic covers. You might even use "waterproof" slide connectors if you are really fancy, or put shrink wraps loosely on the wires, solder , and move down the shinks and heat them to cover the connections. Electrical tape is not a long term solution, esp if any gasoline touches it.

These are great! re-useable barrel connectors, usually available at auto stores or home improvement stores.
TOS-ZWD-608-125.jpg
http://images.opentip.com/full/TOS/TOS-ZWD-608-125.jpg
$5-10 a pack, maybe 5-12 in a package, different colors and sizes
 
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i figured out somehow the magneto died. i replaced it and it works again. the carb is on sideways and squished in tho and i was riding and gas started pouring out of the carb for a minute and the bike choked out. i think its cuz its crooked it was weird but it still works fine
 
new right out of the box china girl. assembly went well with a few mounting mods and hub mount sprocket asembly. it's run for a few blocks and die and idle was terrible. plenty of spark, no air leaks and what i thought was plenty of fuel. taking the carb apart i did find fuel in the bowl and a burr that wouldn't let the float rest evenly on the bottom. still no luck. fule flow from the petcock was minimal. i took it apart and the holes that allow fuel to flow had burrs restricting them. cleaned those out. still no luck. last thing i checked was the fuel cap. low and behold, the rubber gasket was on upside down with the conical shape facing up. i inverted it and varooooom!!!!, problem solved.
 
Hey I need some help with my 66cc engine. It was running fine before i did electrical work on it. I gave it a new CDI and magneto loop with all new wires, plug wire, plug cap and plug. It is getting plenty of spark but not even puttering. The most ive gotten lately was a few small backfires.

I think its a fuel problem but i don't know... it could be electrical.. I have tried adjusting the needle height, the idle and choke on and off with no luck. I pull the spark plug out everytime to see that some times it is wet and sometimes dry. So maybe it is sparking at the wrong time.

Is there any way i could have the magneto loop on upside down causing it to spark with the piston at the bottom of the bore and not the top? If i recall correctly the loop had 3 wires. Blue, black and white.

I did the white to a plug cap and of course blue to blue and black to black. But on the loop is the blue wire supposed to be on the top or bottom?

I would really appreciate the help.

Thanks!
--Lil-Smokey--
 
Magneto

I'm not sure what you're trying to say. There's only one way the magneto and coil will set in the case. After that you have three wires. Blue, Black and white. It's just blue to blue, black to black and cut off or cap the white wire and never use it for anything. After that all you should have left are the kill switch wires. Just to check, disconnect your kill switch completely, leaving only the black and blue wires connected. BE CAREFULL, this will leave you with no kill switch but should bypass any other problem you may have. Get back to me and let me know how it goes.
Big Red.
 
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I'm not sure what you're trying to say. There's only one way the magneto and coil will set in the case. After that you have three wires. Blue, Black and white. It's just blue to blue, black to black and cut off or cap the white wire and never use it for anything. After that all you should have left are the kill switch wires. Just to check, disconnect your kill switch completely, leaving only the black and blue wires connected. BE CAREFULL, this will leave you with no kill switch but should bypass any other problem you may have. Get back to me and let me know how it goes.
Big Red.

Yeah i know how the wiring goes. and i havent had the kill button connected since the rebuild. It is getting a spark but i dont understand why its not firing.

Im nowhere near new to the whole engine scene. I have been riding dirtbikes since i was 6 (Im 15 now) both 2 and 4 strokes. Ive rebuild many car and motorcycle engines but im not used to engines this small.
 
Wont start

Yeah i know how the wiring goes. and i havent had the kill button connected since the rebuild. It is getting a spark but i dont understand why its not firing.

Im nowhere near new to the whole engine scene. I have been riding dirtbikes since i was 6 (Im 15 now) both 2 and 4 strokes. Ive rebuild many car and motorcycle engines but im not used to engines this small.

I dunno then bro, try the loop the other way. If that don't work go back to the stock setup you had when it ran. Get it running, Then change only one thing at a time on your upgrades. when it wont run you've found your problem.
Big Red.
 
There are, from my experience, and it is limited, three things you need; fuel, spark, and compression. Have you checked your head gasket for leaks? I was riding hard one day with my Grubee and new style carb; just burning up a hill faster than my bike had ever gone, when pow!!! The high revving and vibrations and finally finding out that someone other than me had used a head gasket instead of the larger and different lower end gasket. Not sure if it was that or weak casting, but it blew a peice of the lower case apart. A small hole, but no compression, no firing. It was maddening trying new parts to fix it before I noticed the hole. The new style carb casing broke also, so it was an almost complete loss, except for the spare parts I ended up with. I am realizing that I need to take it a little easier on these little motors or get a better one.

Hope you find your problem.

Gary
 
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