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MkIII charging/ battery/ starting

Submitted by felix_hall on Sun, 28/02/2016
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Commando

Hello. First post (on a well worn subject) as a new member and a new owner of my first Norton - a 77 MkIII.

I bought the bike from my uncle. He used to own and race a 750 in the late 60s, and bought this as a project 7 years ago. He finally lost the plot with it at the end of last year as it never ran....so here I am. The bike has been refurbished/ restored from ground up, but hasn't run bar the 60/70 miles I've put on it in the last few weeks.

Bear with me. I've always had old cars and new bikes until now. But bottom line is I have no idea what I'm doing. Hoping someone here can help steer me....

I have the bike running, but have two issues. I'm going to start another thread on the oil......this one's fundamentally about starting (but I mention the other in case it's relevant).

As far as I can tell the set up is: Boyer ignition (MkIV, it tells me). A non standard starter motor (which from an ancient, 2008 receipt looks to be from Norvil, part 064791B0). A powerbox that is also Boyer. A new generator (no idea of brand - fitted 4 weeks ago). A Yuasa YB14-A2 battery (new at the same time).

After an initial problem with mis-wired ignition (hence new generator and battery) swiftly followed by dry joints (so lots of misfiring/ backfiring then nothing) I thought the only problem I had was the badly smoking (and spark plug fouling) left cylinder.

It has never started freely on the button. However, using a battery booster it has turned over to start. And once running for a while, once stopped it then did turn freely on the button and start. So my only problem was at home.

The next development was it not starting even with the battery booster. However I was able to kick it (not something I'm keen on....25 years ago it wasn't a problem, but with a plate in one ankle, a sewn together achilles on the other a non existed knee ligaments - I used to enjoy my XR650 super motard more than I should).

Then on Friday I found that it would do nothing on the button at all. Even after 1 1/2 hours cruising, no lights (lowish speed and revs admittedly as I'm trying to shake a rebuild engine down), whenever it stalled or I stopped the button wouldn't turn it and I had to kick.

This is not my plan.

Now I need to chase down the problem turn by turn. But can anyone, based on the above, help me know where to start? What I have done so far is check there's 12v back to the battery when its running. There is. Next step is to take the battery out, charge it and test it (only reason I haven't done that yet is a small accident involving the rear wheel of my citroen DS and my multimeter).

My immediate thoughts are 1. How hard do I need to ride it to charge the battery given demands of ignition (surely not that hard with no lights?). 2. Would a different/ new battery help me?

Last thing to mention: When trying to start it from cold unsuccessfully with the booster one of the rubber spade covers on the bottom of the solenoid burned off. The connection looks sound and its worked since. So I'm guessing that's fine?

Really long post. Apologies. But I really hope someone can help me.

Felix

Submitted by martin_freeman on Mon, 29/02/2016

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Felix,

I have had similar issues with mine.

First buy or borrow a multimeter; you need to be able totrack down how much the voltage drops and where.

Assuming your battery is charged and you can start the engine check the battery voltage which now should be 12.5 -13 volts.

if not check AC output from alternator with it connected to a car headlight bulb, if bright and 13v AC then fault is wiring or voltage regulator/rectifier.

Now onto starting issues

measure battery voltage while cranking engine - less than 11v and Boyer is unlikely to work ( I returned to points to get round this one.) Now is solenoid hot by any chance? or cables to starter? Originals have issues - as a classic car man get that Morris 1000 solenoid (later square one) and leads off the shelf and fit them in place of originals.

If that does not help you need a better battery; I fitted an Odessey 680 which just fitted after ditching MK 111 airbox and fitting earlier version.

If you wish to remain with electronic ignition there are many versions available that can cope with voltage drops unlike early boyer ones which have a nasty habbit of kicking back if battery is low.

good luck

Martin

Submitted by lance_crossley on Mon, 29/02/2016

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Hi, Felix.

In case it helps I had a problem a little while back with my 650SS not charging properly. It was charging but not enough. Turned out to be simply that one of the alternator leads had become disconnected at the bullet connector behind the engine.

Hope your problem is as simple!

Submitted by david_evans on Mon, 29/02/2016

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To elaborate on the quick method of testing the output of the alternator. Obtain a car headlight bulb and rig it to light both filaments at the same time. In turn connect this across two of the three wires from the alternator and run the engine at about 2000rpm max. the bulb should light reasonably brightly. Swap the wires around in turn to test all three circuits in the alternator.

My Boyer power box puts out about 13.5 Volts at 2000 rpm and up to 14.5 at 3000rpm

Submitted by felix_hall on Tue, 01/03/2016

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I really appreciate all this help.

I have a new multi-meter arriving today. In answer to specific questions:

- The alternator is putting out 12v+ (from memory it was about 12.8, but will have to check with new meter)

- The solenoid got so hot it burned the spade covers. Sounds like that might indicate a problem, Martin? I'll do as you suggest in replacing it

- Yes the bike starts when battery is fully charged (or car battery attached). So the starting issue is likely the battery not having enough charge to support 12v to the ignition when the button is prerssed. I'll check drop with the new meter.

- assuming that is the case I need to work out whether 1. Charge to battery is fine but battery is knackered 2. current to battery isn't enough to charge it given load of ignition (unlikely given what charles says, unless as lance says, it's dropping somewhere) 3. Something's draining the battery that shouldn't be

In terms of immediate purchases, sounds like step 1 is a new solenoid and step 2 is a new battery, before I get into replacing ignition system?

thank you again

Felix

Submitted by tony_ripley on Tue, 01/03/2016

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If you are measuring the actual alternator output before the rectifier then you cannot get an accurate reading using a digital multimeter. This is trying to measure the RMS voltage of the ideal sine wave. This is not what the alternator puts out. If you are using a good old fashioned moving coil meter (An Avo or similar) then it will be more accurate. As mentioned earlier. Stick a headlamp bulb directly on the alternator and at tickover it should be fairly bright and then bring the revs up a little. Not too much otherwise you will blow the bulb.

The solenoid getting hot could simply be a loose connection as this will cause localised heating which will then loosen it more and just get worse.

Regards

Tony

Submitted by felix_hall on Wed, 02/03/2016

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I was indeed using a digital multimeter.

I will do as you suggest. If there is 12v+ DC on the other side of the rectifier would that suggest the alternator is fine?

Submitted by tony_ripley on Wed, 02/03/2016

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Previously Felix Hall wrote:

I was indeed using a digital multimeter.

I will do as you suggest. If there is 12v+ DC on the other side of the rectifier would that suggest the alternator is fine?

Hi Felix,

If it is only 12V then you have a problem. You need about 13.8V to charge the battery. With ignition only on I would expect to get this with about 1000 to 1500RPM

With headlights on I would expect at least 3000RPM would be required.

Regards

Tony

Submitted by felix_hall on Fri, 04/03/2016

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So where I am is this (and thank you all again for your help).

i've replaced the solenoid. Is suspect it was fine with a loose connection on the starter motor side which had caused the connection to corrode and the terminal cover to burn off. So no bad thing replacing it.

the alternator was new quite recently, and testing the voltage back to the battery through the two little holes at the terminal on the right of the bike (from the Boyer power box) I get 13.5v at 2000k revs (I think. I stupidly broke the Rev counter cable. Or pulled it out at the engine end. This may be the subject of another thread once it's cool enough to open up without burning any more of my knuckles on the pipes!).

The Boyer boxes (ignition and power) have been checked out by them and are fine.

Battery seemed fine (ran a 100w bulb off it for over an hour) BUT having charged it over night, read full 12.5v on bike but when starter button pressed went down to 5v and wouldn't turn starter motor. But with battery booster span starter and fired up no problem

so I'm thinking new battery.

Yes?

Submitted by felix_hall on Fri, 11/03/2016

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Well this is all a bit depressing.

Having fitted a brand new (and therefore fully charged) Motobatt battery, I am no further forward.

on the button the starter motor succeeded in turning the engine about once. The voltage drops across the battery as before. It then doesn't have the strength to spin it.

possibly useful or irrelevant:

- I can still kick start it, despite the fact it's cold and been standing for a week (so far it hasn't tried to break my ankle alough I'm nervous every time....I read too much)

- sometimes there's a nasty noise from down the bottom somewhere. Sounds like something not engaging properly or grinding (this has happened before with things working fine subsequently)

- I didn't have time to try starting it with a battery booster attached also. Previously this has allowed the engine to spin on the starter

- it still won't start on the button when the bikes been running for 10 mins before switching off. It tries but no strength. Previously once it was started once it would work subsequently

any thoughts would be very welcome indeed.......

Submitted by martin_freeman on Fri, 11/03/2016

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Dear Felix,

Forget the battery booster as it may well develop a higher voltage than a battery; get some good old fashoned jump leads from a car battery. If that starts it, you need a more powerful ( not necessarily bigger ) battery.

I again reccomend Odessey 680, this may be motorcycle size but will start small cars too. Do a search for it's dimensions and see if it would fit.

Yes they are not cheap - you get what you pay for!

Martin

Submitted by barry_carson on Fri, 11/03/2016

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not a commando owner . is there a good hefty earth from the battery to the main frame then from main frame to the engine .with everything being rubber mounted i assume there would be a braided earth wire to the engine from the frame . Baz

Submitted by martin_freeman on Sat, 12/03/2016

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felix,

You need to know if it will start using a 12 v battery/jump leads.

not with a battery booster or with a car having it's engine running as both of these may well deliver 14v.

barry made a good point - have you a good thick earth lead from battery to frame and another from Z plate to one of the lower engine to cradle bolts?

Your battery spec seems up to the job

Don't suppose you are near Doncaster you could bring it over and compare with mine.

Submitted by felix_hall on Sat, 12/03/2016

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Thanks, Martin. That's a really kind offer, but I'm down in London.

Interesting about the car battery. It wouldn't jump off the car last time without the engine running. At the time I thought the battery in the bike was completely flat so put it down to that, but I now suspect that battery was also fine.

I will do the same again later if I get the chance. See if it is still the case.

Re the solid earth leads: they LOOK fine, and no obvious poor connection I have been wondering whether it would be worth changing them to eliminate that possibility, though

I've also wondered whether there's a way of testing the starter motor through eg applying voltage directly to isolate it from the rest of the system and either isolate that as a problem or eliminate it? (It's one of the US ones from Norvil no idea how old)

The last thing I've been wondering is who might be good people to take this too as I'm running out of road in terms of my own ability to sort this!

thank you for all your help and input it's much appreciated in a time of frustration! The oily leftcyclinder I can cope with if I can trust the bike to get me home again...

Submitted by martin_freeman on Sat, 12/03/2016

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Now we are getting somewhere, go for the sparks get one jump lead on engine cradle/ top gearbox mount and press other on output lead from solenoid if that does not spin it you will have to remove starter and bench test it.

Submitted by felix_hall on Sat, 12/03/2016

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Ok. Been looking at the two things above.

First, no it won't start off a car battery, which is big. Starts/ runs an old Citroen DS with no problems. Same thing is true. The voltage reads 12.5+ before the button is pressed. Falls to 3-4v while trying to turn engine.

second. And this is either possible important, or me being stupid. Which is very probable. I can find a big positive braided wire which runs straight from the battery to a stud in the engine. But I cannot find any thick braided wire from the engine to the frame. Should there be? Now the stupid bit is I might just not be looking in the same place.

But....(only applying ignorant logic again)....There are heavy negative wires from battery to solenoid and from solenoid to starter motor. As the starter motor earths to the engine, which is as I say earthed back to the battery with a heavy duty wire, shouldn't that complete the circuit?

Submitted by felix_hall on Sun, 13/03/2016

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That didn't go as I expected.

Today I used a different car battery and different jump leads (not deliberately...).

The starter motor span and started first time when the car battery was connected to the engine bolt and the solenoid. I then tried on the engine bolt and the battery. Then on a frame bolt and the battery. Span every time.

Not with the (new) bike battery though.

I'm not sure where that leaves me.

 


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