1) I changed the electrical system so the bike does NOT run off of a battery, it runs off whats called a "CDI" which is what all new bikes use....
As CDI and other electronic ignition systems (as not all EI systems are CDI) have been commonly fitted to motorcycles as standard or aftermarket units now for over thirty years you may be surprised to learn that even some of us old fossils over the age of 25 have heard of them.
The problem is, after about 5 minutes of use when the engine is nice and hot, it starts to MADLY back fire, I mean it sounds like repeated gun fire, bam, bam bam bammmm, bam bam!
Unfortunately you haven't given any details of which particular system it is that is fitted, so makes any kind of diagnosis rather difficult?
Another thing is I currently use a VESPA spark plug (I dont know what else to use)....
What make and type is this
"Vespa spark plug"Why not use a C12 plug?
Is the bike too powerful to use a CDI?
I think that would be highly unlikely!
Could this simply just be the wrong type of "spark plug" I am using (spacing etc)?
Sorry I don't know what you mean by
"spacing". Do you mean spark plug gap?
Or is this a bigger problem?
Unfortunately you haven't given much technical detail so makes it difficult to say what the actual problem could be, but using the correct grade of plug would be a good starting point. The plug cap, HT (spark) lead or coil could be faulty? Or the CDI unit may not be compatible with the output from the C12 generator?
The problem may also be nothing to do with the ignition system as it could be carb or engine problem?
Have the valve clearances been set correctly?
Is the carb flooding at all?
