Starting problems Yamaha XJ550

[Shiny side up]

My old XJ is getting hard to start.
If it starts first time all is good.
If it has been started in the last 24 hours usally all good
If it has been left for the weekend it will catch once when first wound over, fail to start and not start off the button no matter what.
Once the bike has failed to start putting the jumpers from the biggest 12v truck battery I can find does not start it.
Putting the tank on to prime (or leaving it on prime) makes no difference to the starting problem.
Once the bike has failed to start on the button it will usally start on the second go at bump starting. (me pusing it on my own on flat ground)
Once started the bike runs very well and will restart easily on the button.

The TCI has been suggested but big jumping battery made no difference.

Any thoughts?

[Mom]

My old XJ is getting hard to start.
If it starts first time all is good.
If it has been started in the last 24 hours usally all good
If it has been left for the weekend it will catch once when first wound over, fail to start and not start off the button no matter what.
Any thoughts?

Ride her everyday?

Failing that, replace the battery or look at the brushes in the starter.

[FROSTY:Me]

Im thinking dodgy starter motor
That said--Try running the power from said big battery as directly to the starter motor as possible.Ie commect the positive leadof jumper leads directly tothe bolt the starter getsits power from.-basicly bipass all the potential power drains If it fires up you have issues in your High amperage leads fromthe battery to starter solenoid or solenoid to starter motor