Trouble shooting.

[Sam_M]

Hi,i have a 80cc motorized bike, its one of those chinese brands i bought of ebay.. it worked perfectly fine for about 50km's. then out of no wherei tried to start it and it will not start, ive tried changing the petrol, cleaning the carb, cleaned the spark plug, but it just wont start.. if anyone knows what the problem could be, your help would be amazing.

 

[crassius]

search the board here for checking for spark - if no spark, there are tests outlined to find out why

if you have spark, see if spark plug gets wet - if not, search for fuel problems here

 

[darwin]

Yea sounds like the dreaded kill switch problem.

 

[dougsr.874]

I've noticed that in the past few months several of the bikes I have built are coming back to me with bad mag-coils....never had this many problems with them till recently...??????????????

 

[bluegoatwoods]

Go ahead and prop your rear wheel up off the ground somehow.

Then take out the spark plug. Re-attach it to the wire, lay the threads of the spark plug against the engine and spin the rear wheel. If you see spark, then that's not the problem.

If you don't see spark, then have a look a this;
https://www.google.com/url?q=http:/...ds-cse&usg=AFQjCNFUCQ_Xfi8w7w3r4IjVwgTTnNmVtw

Best of luck. You should do alright.

 

[sublunacy]

high voltage wires require a relay for remote mounting so a short inline water proof sealed and soldered is the best solution for a unrelayed kill switch.
make sense?

 

[crassius]

I've noticed that in the past few months several of the bikes I have built are coming back to me with bad mag-coils....never had this many problems with them till recently...??????????????

Been rainy there recently? Getting even a small amount of water inside the mag cover will usually kill a coil - try sealing with a lot of silicone seal & perhaps some clear nail polish on the cover seam.

Another problem that happens when riding so fast as to cause a lot of vibration is that the solder joint at the top of the coil goes bad - just resolder it.

 

[HeadSmess]

high voltage wires require a relay for remote mounting so a short inline water proof sealed and soldered is the best solution for a unrelayed kill switch.
make sense?

um?

high CURRENT switches require relays. else you burn out contacts.

the 300v or so on a ht killswitch is about the same as what most switches are rated at...250v at 5 amps or so. a HT wont make 5 amps, fullstop.

3000v and they start arcing, and even relays cant stop that.

set of points on old school ignitions have to handle the same type of voltages and currents, yet are switched a few hundred times a SECOND? using a shunt cap across the switch (points) reduces arcing to a minimum.

relay on a HT killswitch? where you going to get the 12v to run the solenoid?

i swear i answered this thread already!