Cranks over, wont start

Hello all, looking for some wisdom here. My '81 XJ550 has serious issues starting, itll crank over fine but not start. I have fresh gas and spark, and it'll jump start and run fine but not start under its own power. The only hint I have of heading towards an issue is it doesn't turn over every time I press the starter button. Sometimes I'll have to hit it a few times for it to then start cranking it over. Any clue if that could be whats causing the problem even when it does turn it over? Thanks!

 

Weak battery

 

^ +1

And rebuild the starter if you haven't done so yet.

 

^^^+2 besides a weak battery you may have a bad solenoid ...they can corrode and it could be intermittent....this happened to my Seca.

 

disassemble the right controler and clean the starter button or replace it . make sure the part of the controler that contacts bars is clean too it is your ground for starter button. you could add a ground at the controler harness connector near the coil pack to the mounting bolt for the coils. sounds like a bad battery do a voltage drop test . measure battery voltage and press starter button see what voltage drops to if it goes under 10 volts bike will not start.
the 550 will crank fast even with 9 volts at the battery. charge your battery record voltage after fully charged then do drop test.
after doing the above consider new solinoid and starter rebuild. do a voltage drop test to each side of solinoid where the battery connects and the starter connects. to tell if contacts are failing. make sure your battery terminals are clean then the motor ground wire

 

Thank you all!