speedfight 2 100cc running prob?

i doubt its the card freezing up mate the other pssibility is that the primary coils are fooked,these have this symptom too and they do go on these speedfight 100's basically the coils that generate the intial power for the igntion system fail and they partially seperate when they get to a certain temperature,you need to see if it has a good healthy blue spark just after it has died or a yellow weak one or none at all.That would also give a good reason for the backfiring mate as a weak spark cannot burn the fuel under pressure.

adam bike doctor(of milton keynes motorcycle centre)
December 2010

ha adam i have looked at the piston and all is ok the kick start and electrick start are fine i just dont get how i changed all that stuff and it run fine for that few days ..... could it be the carb frezzing as the weather hear has been very cold i have herd this happen have you heard of this

chaz
December 2010

it sounds like its seizing up to me mate,the chuffing type of noise you can hear from the exhaust is the unburnt gases firing in the exhaust pipe,you need to see if its smoking well or not it should be burning a good amount of oil and you should be able to see the exhasut fumes as a blue haze if its not then the oil pump isnt working or it needs bleeding,i take it there is plenty of oil in the oil tank ?i would say that its likeley that you will end up taking the head and barrel off to see the extent of the damage that has been caused by the seizures and you may well have to get an oversized piston and get the barrel rebored.does it get a bit tight/hard to kick over once it has stopped ?its very common for the 100cc speedfights to suffer from seizing for some reason i have rebuilt loads of them.

adam bike doctor(of milton keynes motorcycle centre)
December 2010