forum2.trikingsportscars.co.uk

What size battery to starter cable are folks using ? I'm looking at 35mm2 rated at 240amps.
https://www.amazon.co.uk/Autowiring-Aut ... r=8-4&th=1

That cable size should be perfectly fine, I wouldn't go any smaller, no harm (only cost) in going bigger.

Car Builder Solutions do a range of cable sizes for starter motors, maybe worth a look. I also found this on the web which may be pertinent.

Moto Guzzi starter motors (Bosch/Valeo) typically draw a high initial surge, often around 50 amps for the solenoid alone, with total cranking amperage ranging from 150 to 300+ amps depending on engine size. The solenoid uses a dual-coil system, pulling ~40A initially before dropping to ~10A once engaged.

Key Findings on Guzzi Starter Current
Solenoid Draw: The solenoid is notorious for high draw, taking 40–50 Amps instantly to engage, with some models (e.g., Breva 1100) suffering from "Startus Interuptus" (click no start) due to excessive voltage drop in the circuit.
Total Cranking Current: While small motors are ~600W, the total system can pull over 200A at the moment of engagement, dropping as the engine spins.

Dave

I would only add to this, use the multistrand as in your link - don't be tempted to use 240v with 7 or 12 strands, remember you will have to bend this cable so don't go mad with the size. Use proper lugs properly compression crimped, solder if possible is good too but it is hard not to damage the insulation due to the amount of heat required.

Oh yes, also if you are using battery clamps for a round post battery, the 2 screws that go down onto the copper strands are rubbish. They miss one third of them, cut the next third and grip the remainder.
Again I would solder them into a chunk that the screws can dig into or "whip" the strands with a single wire to bind them into a single chunk. Clean sound vibration-proof connections are everything. Apply silicon grease to prevent oxidisation once you are completely satisfied the jobs a good-un.
I didn't know the starters had such a sizeable current draw but then they are turning a fair old piston over a high compression.