GPR Camp: Replica Racers

So my bike won't start.When i bump start it the electronics are like a disco.Im 100% sure that it's either the coils or the cdi.Is there a way to know for sure which one is the ruined one?Thanks.My bike is derbi senda 50

There's no PowerCommander on the Senda 50. PowerCommanders are for re-interfacing four stroke fuel injection systems. The Derbi is a two stroke with a carburetor. The coil on the Senda doesn't interface with any of the of the lights on the bike, although can effect the tachometer signal.

With internal combustion engines that don't run it is one of three things: fuel, spark, or compression. Below I explain how to test for spark. When you pull the plug out, if you've been trying to start it then it should be wet with fuel. For compression, if when the plug is in, and the bike is in gear, when you push the bike you can tell if there's compression buy how much resistance there is to turning the rear wheel. These are just basic descriptions of basic trouble shooting techniques, but they apply to nearly all internal combustion engines.

In this case the first thing I would check would be for spark. Pull the plug, put it back in the plug cap, carefully hold the metal part of the plug on the engine (but not near the plug hole), don't touch any of the metal parts of the plug with your hand, then kick the engine over. You should see a good healthy spark on the plug. If you don't then it tells you that you have a spark issue.

If you find that you don't have spark then you can suspect anything from the stator to the plug. One of those items will be the cause of the issue. Items like, plug, plug wire, coil (which in this case is the CDI unit because they are integrated), CDI unit, stator—wires from the stator could be bad, unplugged, or in the wrong location.

Along those lines on the Senda the lowest wire in the CDI unit is the kill switch ground. It's the green with a black stripe. If that wire is grounded then the bike wont start. You can do a test by unplugging it, but in this state the key switch, and kill switch will not function. To stop the engine it would have to be stalled (hold the brake, do not give it gas, put the bike in first, and let the clutch out—be careful!).

I'm sorry my mistake,by power commander I meant the cdi unit,I'm Greek and I didn't know the exact english translation.I tested a different cdi from one of my friends (an old of his and one that barely works)and the bike starts with the first or second kick.The rev meter works,the km indicator as well,but my indicators on low revs don't hold a pattern and flash irregularly.Aside from that my senda has a really deep sound and not the regular rind ding.It sounds like a 4 stroke almost.My mechanic suspected that the pipe(not the tailpipe) of my exhaust may be blocked,is that a possibility?My tailpipe(?)(the last part of the exhaust sorry don't know the exact translation)isn't blocked because I burned all of the carbon in it and it still didn't fix anything.Carb also cleaned and spark plug recently changed

English is hard! Even for people that have spoken it all their lives.

The charging system on this bike is directly connected to the head light, and tail light. The blinkers run off of the battery—when there's enough charge. If not they have to run off of the charge being sent to the battery to charge it, which as you can tell since it's already being sent to the head light, tail light, and the battery there's not much left. Try getting a good charge on the battery. You may have to replace it too.

The four stroking sound usually comes from having the carburetor tuned too rich. Meaning too large of a main jet. I don't know if this is your issue though.

Sometimes when you take off the air box, and run with a pod filter or no filter the engine will have a deep throaty sound. You could check to see if the connector from the carburetor to the air box is properly connected.

Thank you very much,will try out your suggestions