Ongoing charging hassles

still havn’t solved my charging problems of my 1994 750 Strada and was wondering if anybody could assist please.

My question is -
Are there any club members out there with a Saprisa-Equiped bike who would be good enough to (or already know) check the AC voltage across the two yellow wires coming from the Alternator when the engine is running. Although my alternator seems to be o.k. when checked statically (i.e. the resistance to earth is infinate and across the coils is around 1.5 Ohms) it does not seem to produce enough volts when running (between 10vac and 18vac dependant on revs).

So before I shell out £170 for a new alternator it would be great if I could get some comparison with another similarly equiped member’s bike.

Many thanks in advance,

that ac voltage isnt half enough if i remember correctly. should be over 30 v ac

What’s the correct procedure for measuring? Multimeter may be telling fibs, unfortunately AC measurements with a meter are only accurate IF the signal is a pure sine wave, otherwise the reading is nonsense. The AC output from an alternator tends to be more like a square wave, with very flat tops to the peaks. Also there’s often a frequency limit for a meter’s AC measurments too, often just a few hundred Hertz. If the freq. is very high again reading tends to be too low. All depends on quality of meter. Still, 10V is not a lot.

Hi, might not be the same but figures for the Quota 1000 alternator (Magnetic rotor that spins inside a set of coils)are;
Disconnect two yellow cables and check Continuity 0.2-0.3 Ohms.
AC volts, connect AC voltmeter to the yellow cables and start engine, output should be around these values.
AC voltage 15v @ 1000 rpm, 40v @ 3000 rpm 80v @ 6000 rpm.
These figures are from the Quota workshop manual.
Just a thought, has the rotor lost some of its magnetism? (rotor should be stored inside the coils if taken off for any length of time)

Thanks for responding, a colleague mentioned the meter innacuracy thing but I wasnt sure whether the innacuracy was in the order of 10% or 100%, so I have tried 3 different multimeters and they all give a reading which is broadly the same (one of them was a relatively expensive Fluke). About the magnetism thing, not sure how to measure Gauss levels but a screwdriver sticks to the magnets seemingly with some force - not exactly scientific I know! The bike was stored without turning the engine over for 9 years, not sure whether the coils could have become ‘magnetised’ in any way? Cheers,Mick

Not looking good then.

That does make sense if not connected to a load.

Many thanks for the info,
looks like a new alternator is on the cards.