Battery low

The battery has had it, do not continue to use it or you could end up with a very expensive repair bill. 

You also need to unmake the cable connections, clean them and any terminals back to bare metal and remake with protective grease. The cables could do with an upgrade to a heavier gauge.

Hi Kevin, welcome to Mk3 ownership. I suggest that you search this site under starter, there is a wealth of information. First of all upgrade the battery to solenoid and battery to earth wires to something much heavier. Norvil stock replacements. With regard to the starter upgrade there are two options. Norvil sells a much better starter but not original in appearance and quite expensive. Alternatively you can convert a new four brush prestolite starter using parts from your original starter. Peter Shand can help with this. Details in earlier posts.

Finally you need the biggest battery that fits in, an increase in size is easier to achieve if your bike no longer has the original black box air filter. You can have an excellent starter with some work.

You say your charger says 'showing fully charged on charger.' Do NOT trust it. A further check of battery charge could/should be done with a decent volt meter across the battery under load conditions. 

I'm with Al, before the rods exit the cases, though I hope it does not have an old boyer fitted. Something is not correct, it should spin freely, the slower it spins as the starter labour's is not ideal for the engine, the starter or the battery.

The cost of the items above though expensive are well worth the benefit you get from them. 

Hello Kevin, Welcome to the club!!

Unless I haven't read the comments properly you haven't said what starter is fitted to your MK3? The original Prestolite starter is often politely referred to as an 'assister', which basically meant a warm engine and even better if there was a petrol mist in the combustion chambers! 

If indeed you have the original starter that in itself is possibly the reason, it just wasn't up to the job. There are lots of Forum users who have experience of your problem and I'm sure you'll find a solution. I am assuming that the bike will fire into life on the kickstart {I'm taking your bad ankle into account here} so should you be investigating how easy it is to swing the machine into life on the Kickstarter as well? The Alton Starter seems to be the one by which all others are judged, make sure you're sat down before you look at the price!

The original Mk3 starter is feeble but a car battery will crank it. For regular use, follow the tips to upgrade the motor, fit heavy leads and put a Mini solenoid on it.

You can try starting it with a fully charged car battery, just remember it's positive earth. Put the positive jump lead to an engine bolt and the negative to the terminal on the motor. Turn the ignition (and petrol) on using the bike's battery but don't press the starter button, just touch the jump leads.

If it hasn't started for a while, remember the sump's probably full of oil, which will make it hard to turn over. You can help by draining and putting back in the tank. On balance I think I'd find someone with a good right leg to get it going with the kickstarter, then play around with the starter.

See https://www.nortonownersclub.org/node/11919  for some useful background from Peter Shand.

Before using anything to jump start the bike, it must start easily on the kickstart, using the electric start to overcome problems with carburation and ignition is dodgy route to follow.  Once these have been set up correctly then look at the start system. The starter should spin freely, if it does not then your battery will not last, and if it is a decent battery I suggest looking at motor stall speeds and see what the motor does at this condition - do not go there. 

You should not need a car battery to jump start a MK3.The Yuasa YTX 14AHL is more than good enough, mine is 2.5 years old and used often and still cranking like the day I fitted it.  

The original prestolite starter has a built in fault that will manifest itself after prolonged use.  Due to the design of the drive end bearing assembly the starter rotor windings will begin to shortout, touching the end plate and causing a drop off in starter performance. Jumping the starter, if it is worn as described, could cause more damage.

I,m with Ashley with this one. Get it running using the kickstart first, even if it requires the use of a helper or starting rollers.

What else has the bike been fitted with? Has it had a belt drive fitted? If it has i strongly recommend replacing it with the original chain drive (as the  starter sprag likes lubrication)   

These bikes can be made reliable starters using the green button. Indeed Mitzi, my Mk3, doesn't have a kickstart anymore as it starts so well on the button, (and that is using a two pole prestolite starter with my bearing modification) 

Photos of the bike and  upgraded starter kit etc will help tell us what has been fitted. 

Even though I have never had a MKIII I have listened to quite a few relevant stories about them. Apparently the 4 brush conversion although looking a good idea might not be the real answer, but certainly the bearings being changed can make the starter into a 'star turn'.

All of the cables and the solenoid need to be in good order. In fact I have found that car solenoids are extremely reliable. I have never changed one on my Reliants in 300K miles.

Testing a starter motor-this can be dodgy so I will tell you what I do. Connect a heavy lead to the starter terminal. Connect the other end of the lead strongly to the battery. Then with BOTH hands hold the body of the starter to other battery terminal (car battery) The starter, if good will want to jump out of your hands! But should wizz! I didn't tell you that.

I dont recommend holding the body of the starter to the battery terminal. No doubt it will make a connection but the arc when the metal of the starter touches the battery terminal will ruin any polished/smooth finish and damage the battery terminals as well. I test rebuilt starters by bolting proper leads onto it, and using a solenoid between the starter and battery. Seen a few starters with burn marks where someone has 'tested' it with jump leads 

Hi Kevin,

Another excellent resource can be found at:-

https://www.nortonownersclub.org/html/archive/rh/elecbk/index.html

page 185 onwards.

Tony

Hello Kevin,

A lot of people have chipped in on your 1st forum post, hopefully some of the contributions have been of use to you? Could you chip in and let us know whether the problem is now resolved?

Many Thanks