Engine Trouble New motor behaves weird

[moghog]

Hi guys!

My all new motorized bicycle have some issues. It has only gone about 20-25km and it is a cheap motor of Ebay. On my last ride (about 7km) it began to act weird in the end. It seemed to lose a little bit of power but not much but it also started to go bad. It sounded like it died for a second here and a second there. At the moment i didn't really care so I put it in the garage over night. The next morning it was impossible to start (almost). I tired and tried and tried. After a while I used a "starter gas" to see if that would work. And it actually worked, I got the motor running and I drove full speed for maybe 1 minute, then I had to slow down to make a U-turn, but as fast as it didn't have full gas it died. So I tried to start it again and again, sometimes with and sometimes without the starting gas. I managed to get i running one more time but had the same problem once again, it died as fast as i didn't drive full speed. I tried a couple of more times, but it still didn't work so I removed the exhaust pipe and the air filter. It started on the third try and i could drive it for about 2-3 minutes before it died. No I can't get it to start...

One thing to notice is that once it started it went super bad. It liked chopped and didn't go even at all. It also seemed to be very week.

Does anyone know what the problem is? It is really frustrating since it is almost unused.

 

[crassius]

my first thought is a leaking head gasket - look for oil stains around head & retorque if you see any

 

[moghog]

my first thought is a leaking head gasket - look for oil stains around head & retorque if you see any

No i don't think so. The bolts on the head are really tight and i can't find any leaks around the head. But if it would be so, how could this prevent the motor from starting? I tried to start it like 30 times and it started 3, but died all of them...

 

[Deleted member 12676]

it don't matter if the head bolts are tight if the head is warped, which most of them are. Use sandpaper on glass to plane the head and cylinder top.
Also check to see if the crank seals are leaking.
Also check the screw head contacts on the stator coil frame since that is the ground return path for the current.
also clean out the main jet in the carburetor.
also replace the spark plug.

 

[HeadSmess]

id be firstly ensuring its got a "new" twin wire magneto, and if its got any white wires, remove them...

check the wiring is well connected.

remove the killswitch.

clean the carb.

check fuel line for flow.


ponder on why i bought a cheap one on ebay again

 

[moghog]

I removed the spark plug and it was all black, so i just cleaned it. I also disassembled the carb but everything seemed to be fine in there, so I just put every thing together again and tried to start it and i worked. Actually it was very easy to start. So I filled it with gas and drove about 20 km.

One problem that occurred was that the carb came loose, when it was about to fall off the motor span extremely fast and I could't stop it. Once the entire carb fell off, what can I do about this?

 

[crassius]

first look to see if there are any burrs or rough spots on the intake that might prevent a good fit - if any, file them a bit till smooth then refit carb all the way till it hits the metal stops, and tighten gently till it wont rotate easily

 

[HeadSmess]

I removed the spark plug and it was all black, so i just cleaned it.

the carb came loose, when it was about to fall off the motor span extremely fast and I could't stop it.

this is "leaning out" and to a certain degree, its what you want... except the carb falling off bit? thats a nuisance...

if nothings broken, just make sure its pushed on HARD and the clamp is well tightened... replace the cruddy little screw they use with something BEEFIER

two things here telling me that you should investigate into getting slightly smaller jets. tuning, that sorta stuff

and possibly you had your choke on previously and it flooded?