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Richard Hyatt View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Richard Hyatt Quote  Post ReplyReply Direct Link To This Post Posted: 11 Nov 2020 at 13:05
A volt drop test is designed to indicate where the volts are disappearing!
So, yes , the 2 big terminals on the solenoid (1 from the battery and the other big bolt going into the motor)
Put your meter on volts and clip onto those 2 terminals.
Should show 0 volts at this point
Try starting it , press the button to spin the starter and ideally you should still show 0 volts, might get tiny tiny voltage , but ideally 0
This shows that 100% of the battery is crossing the solenoid internal connections
See what you get
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Brian UK View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Brian UK Quote  Post ReplyReply Direct Link To This Post Posted: 11 Nov 2020 at 13:35
To be honest, that only checks any drop through the solenoid contacts.

You do need to check the drop in the complete circuit from the battery positive terminal to the lower terminal on the solenoid.
Three voltage checks, this is the simplest way.
1. Check battery voltage across the terminals off load.
2. Try to start the bike and check battery voltage again across the battery terminals.
3. Then put the voltmeter onto the lower terminal on the solenoid and earth and check the voltage seen there while trying to start.

In 1. you should see a minimum of 12.6 volts. Anything lower and the battery is well down.
In 2. you should see more than 10 volts.
But the important one is 3, which should be the same as 2. If it's lower by more than half a volt you have a propblem in that circuit.

But always also check the earth strap from battery negative to the frame, all clean and tight.
Brian.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Punchy England Quote  Post ReplyReply Direct Link To This Post Posted: 11 Nov 2020 at 14:20
Thanks for the help

I must have a problem because I have 12 volts across the two solenoid terminals without the ignition on.
I also have 12 volts across the same terminals with the ignition on.
When cranking the motor I have less than one volt.

I clearly need some helpful advice on your post before I look at the second more comprehensive voltage test.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Punchy England Quote  Post ReplyReply Direct Link To This Post Posted: 11 Nov 2020 at 14:21
Sorry that should read 12.6 volts across the terminals
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Richard Hyatt View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Richard Hyatt Quote  Post ReplyReply Direct Link To This Post Posted: 11 Nov 2020 at 15:27
That 12.6 is actually correct
Whats happening is your red meter lead is on positive and you're seeing the earth of the bike coming up from the frame to engine to stater windings, through them to the 2nd big bolt.

When you try to start it see what happens then ?

This test will check only the quality of the solenoid internal contacts, their ability to pass 100% of the power to the starter.

You may be losing power "up towards" the battery of course but start here.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Brian UK Quote  Post ReplyReply Direct Link To This Post Posted: 11 Nov 2020 at 16:20
He said he was seeing "less than 1 volt" between the solenoid terminals when trying to start. That means the contacts are "losing" less than 1 volt surely. Now exactly what "less than 1" is really I don't know, but it should be almost zero.

Check across the battery terminals when cranking.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Punchy England Quote  Post ReplyReply Direct Link To This Post Posted: 11 Nov 2020 at 16:40
Thanks I am going to charge the battery again now.
The starter motor was getting hot somewhere because I could smell burning paint.

During cranking the voltage across the battery was showing about 8 volts but I needed to recheck that with a fully charged battery. I have hooked up an old car battery showing 12.5 volts, to the bike battery (whilst still connected to the bike) and that makes a marginal difference to the speed or cranking.

Engine turns over without the spark plugs in (earthed). 

Tested across the two solenoid terminals whilst cranking showed the less than one vault which was all over the place from 0.2 to 0.6/7 as I cranked the engine.

I had a jump lead directly from the battery earth terminal to the engine block to ensure that I had a good earth.

Still very slow cranking.

I have stripped the starter motor put it back together cleaned commutator.

Barry
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Richard Hyatt Quote  Post ReplyReply Direct Link To This Post Posted: 11 Nov 2020 at 18:49
The .2 to .6 your showing is quite high loss
Ideally you should have 0

The fact you were showing 8 volts whilst cranking is worrying about the state of your battery under load.
As you say , charge it and try again.

You've proved the quality of your earth with a jump lead which is good.

Brian's already suggested to clip 1 meter lead on the battery pos terminal and the other clip attach to the solenoid bolt terminal.
This will show what if anything is disappearing between those 2 points
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Brian UK Quote  Post ReplyReply Direct Link To This Post Posted: 11 Nov 2020 at 19:02
Certainly 8 volts will cause the starter to turn very slowly.

Jump leads, in my experience, are not always that good at making good connections either. Plus the cheap ones are just not thick enough.

Charge the battery, charge the car battery too if you can, then try again, with both connected.

Bear in mind, if you connect a reasonably charged car battery to a fairly discharged bike battery, the car battery will immediately discharge into the bike battery until both show the same voltage.
Brian.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Punchy England Quote  Post ReplyReply Direct Link To This Post Posted: 16 Nov 2020 at 16:47
Thanks for the advice folks.

I have bought a new battery and it starts with that. The new battery was showing 13v after a CTEK charge. Even so it still has to work hard to get the motor turning ( I was going to put spinning but I guess Hondas spin and Guzzis just turn).

Considering a reconditioned starter motor to finish the job off.

Barry
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Post Options Post Options   Thanks (0) Thanks(0)   Quote c13pep Quote  Post ReplyReply Direct Link To This Post Posted: 16 Nov 2020 at 19:11
You may want to consider the new cheapo (£70 ish) starter motors on Ebay which virtually makes them a throw away item

CHRIS
you can`t have any fun in a straight line

Monza
Honda CB77 project

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Post Options Post Options   Thanks (0) Thanks(0)   Quote danmiluk Quote  Post ReplyReply Direct Link To This Post Posted: 30 Nov 2020 at 23:24
Strip and clean you starter motor, that will do the trick.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Punchy England Quote  Post ReplyReply Direct Link To This Post Posted: 09 Dec 2020 at 13:09
Update

New battery, it started a little better.

Cleaned and rebuilt starter motor again but no better.

New/Reconditioned starter motor, it starts brilliantly.

Thanks for your help


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Richard Hyatt View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Richard Hyatt Quote  Post ReplyReply Direct Link To This Post Posted: 09 Dec 2020 at 14:16
Got there in the end, but possibly the greatest result is all the knowledge that you've learnt along the way.
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