low cranking

[SFC]

i have rewired my bike and used m-unit , got spark and oil in the middle .everything works  but i am getting very slow cranking and will not start , i have tried 3 battery's one new lithium and all now dead , 2 starter relays and had starter motor off and tested , all seems fine . today i even hooked upto car to jump it and still the same ?  anyone got any idea before i put it away and leave till next winter

[wraith]

I'd say ever a bad earth wire, or there is something wrong with your engine?

How dose it turn over with the plugs out? Any fast?

Dose it turn over by hand ok?

[SFC]

will try in the morn , good running engine when left in september , nothing changed with it ,,,earth off engine ? starter motor spins great with engine earth and live from battery , also have earth the frame and a few in loom ? .........thinking on , i did join engine earth together as didnt have a long enough one but as said spins on battery , would that make a difference ?

much appreciated for your help

[Blubber]

 

Maybe a sticking starter clutch sprag?

Just thing out loud,  dunno what engine we are talking about. 

 

Cleaning the inside of the starter motor can help to, new grease, clean collector,  correctly spaced / shimmed stator...al those things help to het  a aged starter back to life under load. 

 

[Gixer1460]

Quote

i have rewired my bike and used m-unit 

? ? ?  - wot dat? More info pls.

[SFC]

42 minutes ago, Gixer1460 said:

? ? ?  - wot dat? More info pls.

m unit blue with dyna 2000 ignition , got spark , bandit 12 motor/750 head/cams....all lights/horn and indys plus motogadet mini speedo work. i have had it run with choke badly ,  once i turned off choke it cut out , battery flat next day , was told i wired it wrong so done as advised , lithium battery heated up and now leaking, old battery charged plus jump leads still cranking very slow...will check earth's again in the morn

 

[SFC]

if i put starter motor straight to battery it spins and cranks good , same if i arc the terminals on starter relay , must be losing power through m unit ?

[Captain Chaos]

7 hours ago, SFC said:

cranks good , same if i arc the terminals on starter relay

I would think you have a bad starter relay (high internal resistance)

[SFC]

2 minutes ago, Captain Chaos said:

I would think you have a bad starter relay (high internal resistance)

brand new , i have two of them , will have a look in a bit , thank you all for suggestions

[Gixer1460]

10 hours ago, SFC said:

if i put starter motor straight to battery it spins and cranks good , same if i arc the terminals on starter relay , must be losing power through m unit ?

There shouldn't be 'massive' power flowing through that unit to be lost. It does seem a another level of complication for what should be a simple circuit ....... Ign. switch to start button to start soli  - all small wires then other side is Battery to soli to starter - all in heavy cable. This unit does seem to be the cause of your issues ! The Dyna could be a cause if it had overly advanced timing but that's really difficult to achieve.

[SFC]

12 minutes ago, Gixer1460 said:

There shouldn't be 'massive' power flowing through that unit to be lost. It does seem a another level of complication for what should be a simple circuit ....... Ign. switch to start button to start soli  - all small wires then other side is Battery to soli to starter - all in heavy cable. This unit does seem to be the cause of your issues ! The Dyna could be a cause if it had overly advanced timing but that's really difficult to achieve.

yes i am at a loss at the moment ,  going to check crank trigger aint fouling crank , whip out plugs and hand turn engine ,  check some earths , i like to do most things myself but tried everything i know....i know the battery's are not too clever but jumping from car should be good power ?

[Dezza]

Is the battery of the correct size? If so, try a remote cable running from one of the starter motor mounting bolts directly to earth (e.g. one of the engine mounts). I had a similar slow cranking problem after frame powder coating and this cured it. It was caused by poor connection between the engine and frame, and this can also be down to corrosion between the engine mounts and frame.

[SFC]

 

[SFC]

tried most suggestions but still the same , jump leads from running car...wires are starting to look a mess as going through all of them slowly....baffled

 

[Dezza]

I would try first to eliminate the obvious by making sure the starter motor is good and will turn the engine over as intended. This can be achieved by disconnecting your battery and disconnecting the lead from the battery to the starter motor. Connect a jump lead from the battery positive to the post where the battery lead connects to the starter motor. Then connect the other jump lead to the battery negative. Now connect the negative jump lead to a good earth on the frame. Do this quickly and positively. When you hit earth the motor should crank the engine as normal. If it does, the problem is in your starter wiring; if it doesn't, go to earth directly on the engine. If it now cranks, you have a problem with the connection between the engine and frame and need to install a bypass lead to earth the starter motor. If it doesn't crank when you are directly connecting a battery, then you have  a fault with the starter motor. If so, they split and sometimes just cleaning out all the carbon dust is all that is needed.

[wraith]

If it was not for the readings in your video I'd say your battery is fucked, the starter solenoid clicking means the solenoid is fucked or flat battery, I have known it, that you need to give the car some revs to get the power to give it a good jump start, but you say the solenoid is new.

Have you tryed not putting your battery on and just putting the jump cables onto your HT leads and turning over?

Or you could just have more than one problem this and what @Dezzasays.

[nlovien]

Dezza has nailed the fault find - if its the starter - think about new brush's - seen ones that look ok - plenty life in them yet fitting new cured a sluggish motor

a wee safety note: when yir jumping big current draw - sparks can fly - i've exploded a wet battery doing this-  be mindful of where the battery vent is

[Dezza]

1 hour ago, nlovien said:

Dezza has nailed the fault find - if its the starter - think about new brush's - seen ones that look ok - plenty life in them yet fitting new cured a sluggish motor

a wee safety note: when yir jumping big current draw - sparks can fly - i've exploded a wet battery doing this-  be mindful of where the battery vent is

Yep, he is right. Be very astute and positive when connecting a battery directly to the starter motor as this will minimise the sparks. If you show any kind of reluctance and fear, it will produce mucho sparks.

[wraith]

9 minutes ago, Dezza said:

 If you show any kind of reluctance and fear, it will produce mucho sparks.

And most probably bite you 

[SFC]

done all that you said lads and starter motor was good after a clean , new starter relay was duff and they exchanged no problem then i bought a new lithium battery and all's good , will tidy back up wires and move onto next problem , thanking you all for help