rshutchinson
XS400 Addict
Before I realized it was a tci bike I was wondering about the automatic timing unit. But your bike doesn't have one.
Anything on TCI bikes that changes behavior at different RPMs other than the TCI?
The changing behavior with the strobe light might imply that something is amiss with the low voltage side of the coils. Or it might be nothing.
Double-check all the connectors? Especially the ground connection all the way from the TCI to battery.
If you take the head off you could check that the valve springs are the appropriate length.
Not sure if it's a good idea but is it possible to check spark through the full RPM range?
The TCI does it all.
I'm going to take the side cover off and see if the timing is way off with the strobe light.
I just have a hard time seeing it being weak valve springs due to the double spring and having also never heard of an xs with that being a problem.
I did measure the springs before install and they were within specs.
I can double check the ground on the harness going to the TCI but I would think it would rear it's head all the time, not specifically at 5000 rpm.