Originally Posted by
Mike Rainbird
When mine last did this, it was the CPS (does the rev counter jump about at the same time? If so, then deffo this, otherwise as Stu says, it's in limp mode).
Mine was doing exactly this before I stripped it to a shell for the resto. I'm guessing becasue my front crank seal was leaking, the oil was smearing the cps sensor and I was wiping all the crud off it every couple of weeks
I'm hoping it does'nt return when it's rebuilt.....