starter slow

[David]

I have a fully charged battery (12.7v) and on pressing the start button the starter barely turns the motor. The same on a fully charged car battery. Tomorrow I am going to attempt it with spark plugs out in order to see how the starter performs.
Is there more to a battery than its charge or is my starter in need of some TLC? I assume that since the starter does turn the motor (albeit slowly) the problem may not be there.
Thank you

[fastbysuzuki]

Yes there is more to a battery than voltage it can read 12+ volts but when it's put under load can fail.
if you are confident that the the battery's you have tried are good.
Try bridging the contacts on the starter solenoid with a decent screwdriver ( make sure it's not in gear) if the starter operates ok then the fault lies between solenoid its self or the starter motor.
if bridging the solenoid does not work, first make sure it has a good earth then try again also check the lead that goes from the battery to the solenoid has good contacts.

[Brendan W]

.... and one way to check the earth is to look at the voltage drop between the crankcase and the negative pole of the battery when cranking. Ideally less than a Volt. Alternatively, disconnect the bike battery completely and then jump directly to the supply pole on the motor and return to your good battery from the crankcase. If it's still slow it may be the brushes and or commutator are worn,stuck, dirty etc. If so a clean up and or repair kit could sort it out. There are two and four brush types. If something more serious like delaminated magnets or evidence that the armature has been rubbing then it's likely replacement motor time.
If you remove the motor you may need to think about replacing the o-ring at the sharp end of the motor or oil will leak out from the generator space. This is the 850 part, generally easily available from engineering suppliers.

https://www.cmsnl.com/suzuki-gs850g-1981-x-e01-e02-e04-e17-e18-e21-e22-e24-e25-e26-e34-e39_model13500/o-ringd2-id245_0928024001/

Is a hot restart faster spinning than a cold start?

[Redman]

A way to determine if problem of slow cranking is the battery or the starter motor is to measure the battery voltage while cranking. If the battery voltage drops to 9 or 8 volts while cranking, then I would suspect the battery. COuld also look to see if headlight dims to dim. Make sure the battery is well charged first.
If the voltage doesnt drop that much, then I would suspect the starter motor or a bad connection. Check out Stocker Starters web site for rebuild kits or rebuilt starters.

>> Oh, Australia. Might want to find a local supplier.