TOPIC:

So i recently came into some extra money and have been working hard on getting my motorcycle road worthy. I am very close but i have a question I am hoping one of the many smarter than me people around here can help me with. I built a battery pack for this bike - lithium iron phosphate cells - I am shopping up a bms but it dawned on me that i dont really know what kind of amperage these starters pull. If someone can throw that number at me so I can size my bms properly that would be awesome.

I checked my KZ440 starter last week with a Fluke 376fc clamp meter. 77 amps...battery voltage probably around 11.7v. Stock wires
Your starter is a different part number, but at least you'll have a point of reference.

Starters are hard to measure. The faster they spin the lower the amperage.
Good wiring and a fully charged battery means you won't pull as much current.
Back EMF...I'm reading more on it now..gotta keep learning!

Thank you for that. I'll probably get a 150 amp bms for a little overkill and be safe.

I do not know the answer to your question as to the 750 twin starter. But for the 650 the starter was .5 kw and the 750 four was .7 kw. Some simple math (volts x amps = watts) would mean they pull somewhere between 40 and 60 amps. Keep in mind that the starter does not care how it gets what it is looking for, it will pull more amps if the voltage is not enough or pull more voltage if the amps are not enough.

Keep us up to date on the battery install. I'm intrigued on your build.