Firstly Welcome, there are some different solution, I currently am running the battery out of my unused Honda St 1100 sitting in the air-box and connected in pos to pos and neg to neg so it still maintains 12 volt with 60 amp cable, it works for me, there is also the heavier pos to starter and heavier neg to engine earth cables, and there are Li Po batteries available that are the same physical size as the Std battery but have up to 600 CCA but at a price, as funds allow I will be switching to a Li Po and the heavier cables
Lithium Powerbloc 18aH from Germany.
Maximum pulse discharge - 1,000 A
181x78x174 mm
The major reason why batteries do not discharge as fast when cold is CHEMISTRY. A reaction has to take place - and it's thermo sensitive.
One reason why (for example) a Softail will fire up is because the battery is surrounded by an oil filled radiator. It's also why Softails can boil batteries in summer.
The R3 battery is as about as isolated from heat as it can be.
Obviously - dirty contacts, high resistance cables (through cross section or resistivity) will augment the energy required to adequately spin the starter.
But let's not get silly here - a 1.2kw motor needs 100amps at 12V (on paper. In reality add 50% for mechanical and other losses) 150amps.
A 1.6kw needs more amps - but produces 1.2Kw with less internal resistive losses - the internal windings are normally thicker wire.
A good 400Amp cable is more than enough - Use welding cables. They're flexible and have many more strands - so suffer less resistive increase if individual strands break (and they will).
If you really want to go the whole hog - use silver core cables.
Battery construction matters too. Close spaced plates - high quality components.
There is an additional problem with MODERN ENGINES. As the battery turns the engine - it obviously drains.
Lead Acid batteries will tend to supply amps whilst the voltage drops - if the voltage drops too low - many ECU's simply will not send "fire" signals
I don't know what the threshold is on an R3 - but I've seen cutoff values of as high as 12.2V.
LiFePO4 will tend to maintain VOLTS as they drain. But Amps seem to drop off.
ime - a mix of the two maintains volts and amps.
Add to this they fuel vaporisation at low air temps IS a factor - and the more open the inlet flow is to ambient temps - the more likely it is that fuel will NOT vaporise correctly.
An advantage to the serpentine R3 inlet tubing is that it maintains an insulated air volume.
I think what I'm saying here is that there can be many causes and fixes.
