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Slow Cranking and Starter Performance


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Yesterday I looked on this excellent forum for any ideas that may explain poor cranking and starter performance that rather suddenly appeared when I tried starting in the morning after a fairly cold night (around 6deg.C 43F) a few weeks ago.  I first assumed that, after 5 seasons my LiPO battery was starting to age and with the cold and higher oil viscosity that this was the problem so I bought a new battery.  The effect seemed to be temperature related; always being a problem when cold starting.  The new battery didn't cure the problem; hence my looking at the forum.  There didn't seem to be a dedicated topic focused on exactly this problem, hence this new specific topic, but by various searches i did find a few ideas, even one that reported a similar problem because they had put in 20W-40 oil rather than the recommended 5W-40 oil and this became a problem on a cold day.

In fact I made a list of all the possible options and there are lots, (battery, starter, starter contactor, connections etc. including the possibility of the magnets becoming demagnetised (on a Ferrari forum), but obviously the most likely was a poor connection so I stripped down all the connections between battery and starter, including the heavy duty earth cable that fixes to the gearbox casing, cleaned them, added corrosion protective grease and reattached but really didn't see anything that gave me the slightest concern.

However, on dismantling I did take off the insulated spade terminal that supplies the voltage to the starter contactor and it didn't feel a tight push-on.  I used pliers to compress the jaws of the female insulated terminal, cleaned up the spade that emerges from the starter contactor next to the large +ve starter terminal and reattached.  Problem solved!  Obviously high resistance to the contactor coil can cause the contactor to pull in rather weakly, leading to high resistance in the main starter contacts and a weak start.  I am putting this experience out just in case anyone has a similar problem.  It might be useful for others to add their own experiences associated with solving the problem of the starter motor working but having difficulty in cranking the engine as quickly as normal.  

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Thanks, PeterT!

It always fascinates how commonly issues turn out to be something as simple as a weak connection. :thumbsup:

But nothing's really free and I expect the forum members will gang up on you for some pictures of your Trofeo . . . :food:

Welcome, Sir, and thanks again for the excellent technical post! :luigi:

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12 hours ago, PeterT said:

... I did take off the insulated spade terminal that supplies the voltage to the starter contactor and it didn't feel a tight push-on.  I used pliers to compress the jaws of the female insulated terminal, cleaned up the spade that emerges from the starter contactor next to the large +ve starter terminal and reattached....  

It sounds like you did a thorough job of troubleshooting and fixing the electrics. And you are right about this forum being excellent.

I just finished fitting a later model gearbox shifter plate with the banana link, and doing the Lucky Phil fettling of the shift hook, and finally installing the Scud/Chuck spring. I had already fitted the Phil/Chuck extended shifter lever. Shifting is a charm now. I owe so much to the wisdom of the forum members.

Now what was I saying?  Oh yes, as I took the starter off, I noticed the same loose spade connector on my bike, and I fixed it the same way you did. Clean, squeeze, grease, and go. I did the same to the starter faces that touch the bell housing, as that is the starter earth return. You may want to check the earth circuits for the regulator and coils too.

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9 hours ago, PeterT said:

Yesterday I looked on this excellent forum for any ideas that may explain poor cranking and starter performance that rather suddenly appeared when I tried starting in the morning after a fairly cold night (around 6deg.C 43F) a few weeks ago.  I first assumed that, after 5 seasons my LiPO battery was starting to age and with the cold and higher oil viscosity that this was the problem so I bought a new battery.  The effect seemed to be temperature related; always being a problem when cold starting.  The new battery didn't cure the problem; hence my looking at the forum.  There didn't seem to be a dedicated topic focused on exactly this problem, hence this new specific topic, but by various searches i did find a few ideas, even one that reported a similar problem because they had put in 20W-40 oil rather than the recommended 5W-40 oil and this became a problem on a cold day.

In fact I made a list of all the possible options and there are lots, (battery, starter, starter contactor, connections etc. including the possibility of the magnets becoming demagnetised (on a Ferrari forum), but obviously the most likely was a poor connection so I stripped down all the connections between battery and starter, including the heavy duty earth cable that fixes to the gearbox casing, cleaned them, added corrosion protective grease and reattached but really didn't see anything that gave me the slightest concern.

However, on dismantling I did take off the insulated spade terminal that supplies the voltage to the starter contactor and it didn't feel a tight push-on.  I used pliers to compress the jaws of the female insulated terminal, cleaned up the spade that emerges from the starter contactor next to the large +ve starter terminal and reattached.  Problem solved!  Obviously high resistance to the contactor coil can cause the contactor to pull in rather weakly, leading to high resistance in the main starter contacts and a weak start.  I am putting this experience out just in case anyone has a similar problem.  It might be useful for others to add their own experiences associated with solving the problem of the starter motor working but having difficulty in cranking the engine as quickly as normal.  

Do you warm the battery before you try to start your bike in cold conditions? With a LiPo battery when the ambient temps drop you must turn the headlight on for 30 seconds or so before attempting to start to warm the battery.

Ciao   

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3 hours ago, Lucky Phil said:

Do you warm the battery before you try to start your bike in cold conditions? With a LiPo battery when the ambient temps drop you must turn the headlight on for 30 seconds or so before attempting to start to warm the battery.

Ciao   

I've never had slow cranking on my bike, mainly because I am too soft to go out in the cold. But I checked what Shorai had to say about cold starting. 

They say: "If starting at 5C, headlights on for 30 seconds will help wake the battery and increase cranking performance. If at -17C, leave the lights on for 4~5 minutes before cranking. The result will be a better first crank, and longer battery life.  If the engine fails to start on first crank, that first crank has warmed the battery, and the second attempt will be much stronger."

So Phil makes a good point.

 

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One cause of slow cranking is a bad ground connection. If the ground is not making good contact the return current from the starter finds its way back to the battery via the small ground wire from the Voltage regulator. Too much of this and the wire becomes red hot melting through and shorting to other wires in the loom. Make sure the main ground is connected to a gearbox bolt and not just the seat release lock.

The battery terminals should be cleaned and protected with Vaseline.

Measure the Voltage across the starter terminals while cranking (should be at least 10V)

Battery Positive to Starter Positive (the battery terminal not the wire lug) (<1V)

Battery Negative to chassis (as above) (<0.5V)

Battery Positive to Negative while cranking (should be at least 10V)

Of course the LiPo batteries are known for weak output when cold.

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Another easy method , use a test light and test with it .

put the test light from the neg battery bolt to ground at the starter housing . Try starting the bike . IF the test light glows , you have a poor circuit / start looking .

 same goes for the positive circuit . Go from the positive battery bolt to the positive terminal (stud) at the starter . If it glows , start looking .

 A good test light is as good as ALL my Fluke meters and a lot cheaper to replace !

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