SOHC.co.uk Forums > CB500/550

500 Start Up Issues

(1/5) > >>

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

McCabe-Thiele (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

McCabe-Thiele (Ted):

--- Quote from: philward on March 16, 2021, 01:32:06 PM ---Doesn't want to start on the kick Ted (slight cough) - still need to cure this major issue as a priority

--- End quote ---

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.

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

Navigation

[0] Message Index

[#] Next page