Charging System Specification

[philward]

Should be ok then Ken - Just spoke to Andy at Good Bits and he's had 5 modified covers (of his smaller race alternator covers) made now that relocates stator into the cover allowing the stater gear to be re-inserted. So ordered one and saves adding width using the standard alternator casing and cutting fairing to accomadate

[K2-K6]

Seems like a good way to go as that race type alternator cover is a big marker in replica terms,  and not having to cut the fairing.

The manual data for original states 12volt at 15amp rectifier output,  180 watts baseline as I understand it.

The bike looks fabulous by the way  Phil.

[Oddjob]

I thought the later 750s got 200w alternators.

I read the other day the 500K0 was originally supplied with a 200w alt but they stopped doing that about the same time as they changed the crankcase and went with 150w afterwards, not a great decision.

[K2-K6]

I think it's how they write it as the above quote is from early 750 manual in which the quote "at 12volt battery voltage" so looks like a baseline/minimum of 180 as most system are going to run above that notional 12volt. 

So pure technical supply is able to be supported at 12volt 15amp  but reality is most likely higher in normal use for "marketing purposes"

[K2-K6]

Realized my post wasn't clear as the manual I've got doesn't state the total wattage,  just the data above and noted it's conditional on the battery supply voltage as to the total watts. Effectively it's variable within a range rather than single figure across all operational conditions.

[Sesman]

Phil said his alternator was a 25A output unit…..300W?

[K2-K6]

That's the new compact one, the other/original from manual data is to compare the two.

[Bryanj]

The 750 auto had a higher output alternator

[Oddjob]

So if Phil fitted an Electrex alternator I wonder if they ever made one for the 500/550.

[Bryanj]

Dont think so Ken, i have seen one somewhere but it was nearly a grand

[Oddjob]

Just found one on the Electrex website Bryan, RPK1550, fits 400/500/550. 25amp output, cost around £550. Improved HP and quicker throttle response as it replaces the flywheel as well, I'd imagine less torque as a result?

[SteveD CB500K0]

Less inertia surely. Same torque.


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[Sesman]

Yes, same torque. Might improve engine response and net horsepower if the savings in gross crankshaft mass (inertia) exceed the increased alternator flux coupling forces.

[philward]

Electrex website says 3 - 5 HP increase for 750 (I have 836 standard compression piston kit as well which Hondaman says is about 5 - 8 hp increase), so useful overall gain without high tuning/revs.
The good thing about the 500 (from my limited once only rebuild knowledge of a 500) is theres no starter gear issues in fitting the Electrex alternator that I am aware of hence none of the issues I'm having. Its worth checking how it affects the fitting of the cover though as I had to source the narrower cover seperately. (Electrex don't supply with the kit). The standard Electrex alternator on the 750 uses a machined alloy plate thats about 15mm thick that fits between the narrower alternator cover and the crankcase. If the 500 version uses the same setup and you use the standard alternator cover, it would widen the engine width. I'm only assuming this is the case based on the 750 setup as havn't looked at 500 version. Worth the pre sale research considering the cost.

[K2-K6]

Bhp is only a calculation of torque at X rpm, which means that if the torque remains the same at the same rpm (it's just a function of combustion effectiveness) then the bhp can't alter.

Rotating mass affects the time to accelerate the crankshaft, making it accumulate revs faster (when not moving vehicle mass) but not change the total.

Capacity change increases torque as the combustion total energy is larger for the same rpm,  minus the increaes in heat and friction between the two in comparison.