Hi I've got a 2001 xvs650 dragster it starts and runs fine but once your driving it seems to accelerate fine up through the gears but as soon as you make it work and it gets up to about 70mph it starts miss firing and the engine management light comes on. When you stop bike the engine light flashes 4 times then a pause followed by another 4 flashes and just continues until you switch the ignition off any ideas?

 

try this

BTW, where is gizmo?!

I've tested the throttle position sensor and all seems well with it and the associated wiring.

I'll maybe need to try the battery disconnect trick see what happens! 

 

Could be rectifier but I think more likely the CDI which seems to be a common -and expensive- issue.  Second hand replacements are all over eBay at about £200 / $250 and upwards.  There are some aftermarket 'racing' versions of unverified compatibility for £500 / $480 and I have seen at least one for $25 but with 4+2 pin connection rather than 6+4.  I would want to spend no more than £200/ $180 to get this sorted out with a reliable component.  At present I am getting the system tested to see if analysis tells me anything other than I am anticipating.