500 Start Up Issues

[philward]

Another issue for your assistance! Having sorted oil pressure priming issue, plugs in and attempt to start (or not) - this is the issue:-
- Post getting oil pessure and having previously timed, etc, without plugs in, motor spins freely and spark at plugs
- Plugs in and motor does not turn but solenoid makes noise - thinks solenoid duff (new Motobatt fitted but not used since bought about 6 weeks ago) - changed solenoid for the one from my 750k2 - same (put back on 750 and tried starter as double check and works fine).
- Checked battery voltage and about 11.8 volts - charged overnight and 13.2 volts
- Fitted and pressed button and solenoid engaged and all lights went out - checked fuse and NOT blown - - - checked voltage on battery and ZERO - on to charger and no response at all (shows not connected on Optimiser) - battery shorted and blown?.
- Put jump leads from old car battery on bike battery leads and when pressing starter button, major sparks from live jump lead joint to bike leads
- took solinoid off and run + and - to input leads and switches with continuity
My initial thought was when battery at full charge, it was strong enough to engage solenoid and put a ground direct to battery due to permanent ground on starter cable (to solenoid) - but if this was the case, why didn't this issue happen when spinning motor without plugs in (solenoid engaged with lower battery voltage due to lower starter motor current draw) as motor ground lead still providing same poarity source.
I have continuity from ground on engine to starter lead - is this normal? (if not, why did motor work when solenoid engaged with motor spun with plugs out?)
- Trying to recover Motobatt via tandem battery method
Also got carbs dumping fuel but got my thoughts on that.
I'm taking a step back today as naffed off that it didn't start first time! (my previous projects started up straight away!) and before I strip the starter motor out and check (although it worked with plugs out!) would appreciate your views
Thanks in anticipation
Phil

[Macabethiele (Ted)]

Does it have a kick start - if it does will it start up manually so as to speak?

[philward]

Doesn't want to start on the kick Ted (slight cough) - still need to cure this major issue as a priority

[Macabethiele (Ted)]

Doesn't want to start on the kick Ted (slight cough) - still need to cure this major issue as a priority

If with no spark plugs fitted the starter motor spins the engine well but adding the plugs hence much more load ends up a fail I would at first suspect the battery. The clever chargers will usually identify an issue with the battery but a  modern digital drop tester is much better you input the battery specification and the little device does its magic - certainly my CTEK does indicate battery issues. In many ways what you are describing indicates that at lower current draw all is okay but at compression load it fails to turn to me that sounds like a duff battery - naturally you might suspect the starter motor especially if its of unknown condition or you have had it appart.

FWIW I would rule out the battery first. Next I would look at earth connections - engine to frame, battery to frame etc.

[Oddjob]

Not saying this is the case but I had a similar thing on one of my 500s. The starter motor end cap (the one with the bolt holes) has a brass bush inside it, for some reason this went oval shape and the armature was grounding on the casing when the motor was trying to spin.

Is chain casing fitted? check you haven't trapped the cable when fitting if it is.

If you need a starter motor I may have some spare. Does 750 one fit? just to see if it will spin with that in place.

[Nurse Julie]

Having had a very similar experience on Millie, my 550 Mongrel, I would say a bad earth somewhere.
http://www.sohc.co.uk/index.php/topic,15937.msg133703.html#msg133703

[philward]

It was the battery slightly low (hence not working with high current draw - plugs in and higher compression/load on the solenoid/battery.) The issue is the direct short when the solenoid switches - which points to what Ken suggests - but the baffling things is why this didn't happen when the motor spun without plugs in? (a short is a short?)

[Oddjob]

Saying that Julie, Phil have you cleaned the earthing points on the engine and on the frame? frame just above coils. Engine, upper back hanger bolt.

Easy to miss when you've had powder coating etc done.

Short isn't always a short, no plugs no real load on starter as it spins so much faster so may avoid dropping into the oval, plugs in and compression, totally different story.

[Oddjob]

Is starter getting hot when attempting to spin?

[philward]

Julie, I have made new positive cable (crimp and solder) - I used the original earth strap but put new frame end terminal on but didn't change battery end as couldn't get a connector that would go through the right angle - will make a new complete cable up
Think I've done a continuity check on that coil area earth Ken (cleaned paint off) but will re-check
Should I have that permaent earth on the starter cable? (as to non electrician, the starter solenoid switching a live onto an earth doesn't make sense - unless it 'shunts' earth polarity to the one side of motor)
And why would above issues 'short' the battery to show zero?
No battery at mo as trying to recover - don't want to risk using my 750's Motobatt incase I nacker that one - so can't check motor temp - but zero's battery before motor able to spin (motor never spun under load)

[K2-K6]

"Should I have that permaent earth on the starter cable? (as to non electrician, the starter solenoid switching a live onto an earth doesn't make sense - unless it 'shunts' earth polarity to the one side of motor)"

That doesn't seem right at all. With no battery at all connected you shouldn't be able to meter continuity via main starter lead positive to any earth.

[K2-K6]

Forgot to add, as Ken suggested it looks like the starter motor is failing in some way. I'd look at that firstly, the car battery would probably have enough grunt and size to melt something if there's failure, that's in comparison to the bike battery.

[K2-K6]

You could use the 750 as reference.

Meter for continuity down the positive starter lead across  to earth to give yourself reality check on numbers. 

[philward]

Forgot to add, as Ken suggested it looks like the starter motor is failing in some way. I'd look at that firstly, the car battery would probably have enough grunt and size to melt something if there's failure, that's in comparison to the bike battery.

My thoughts too - when I fitted sprocket cover, the starter lead was inserted in the case grommet but from memory, on some of the Honda starter motors, the cable entry point can be suspect (short on the starter casing?). Got to take the better half for her covid jab this afternoon, so maybe tomorrow before I get the starter motor out

[philward]

You could use the 750 as reference.

Meter for continuity down the positive starter lead across  to earth to give yourself reality check on numbers.

Why didn't I think of that! Just checked and I get same - ie, continuity - the live switching must 'shunt' the earth to the other side of the load (starter motor). This complicates it as why is the battery shorting itself out when I press starter button - solenoid engagement - bearing in mind that I've tried another solenoid? (its been on tandem charge - method to recover completely nacked battery - for 3 hours and still zero!)
Do I risk another shorted battery if I use the 750's battery!