Topic: Hot start 550/4

[Blind Bob]

Guys

Got a strange issue with my 78 550/4 F2. Battery is kept on charge on Optimate battery conditioner all the time and starts from cold first time on the starter no matter what the temp. Following a ride of 30 or so miles then stopping the bike wont fire on the starter, giving all the signs of a flat battery, except that all lights are bright, horn works etc. Bike starts with a kick start and runs perfectly.

Leaving the bike for half an hour or so it will fire up perfectly on the starter, with no problem.

Is the issue with the starter, or some heat related electric problem? Battery is six months old.

Views welcome

Bob

[Gordon]

When the problem occurs, do you hear the solenoid clicking?  Does the starter try to turn the motor?

[Blind Bob]

No the sarter turns over slowly and then dies just like a flat battery but recovers after about half and hour.

Bob

[TwoTired]

I think it is important to know the battery voltage when the bike turns the starter over slowly.

Do you do much operation below 2500 RPM?

Cheers,

[mark]

I think it is important to know the battery voltage when the bike turns the starter over slowly.

I think it wouldn't hurt to know the battery voltage period. like before leaving on that 30 mile ride. just sitting there running. rev it a bit - say 2500+ .

Optimate charges the battery just fine.... How about the alternator?

[Blind Bob]

Will check voltage at weekend. Could this be the same problem as the CB650 hot start thread? Earths,  starter issues etc Sounds very similar symptoms.

bob

[TwoTired]

Will check voltage at weekend. Could this be the same problem as the CB650 hot start thread? Earths,  starter issues etc Sounds very similar symptoms.

bob

I still feel it is quite likely that engine heat has nothing to do with either issue.  More likely it is a run time issue, and it just so happens that the engine gets hotter with time.  That's why the voltage test request.  First suspect battery low voltage.  This information is the top of the decision tree for diagnosis.  There are many branches to take where one can get to the root of the problem.  And, there is no point is describing all the branches of the tree.
Further, the 650 charging system is rather different from the 550 in many ways.

Cheers,

[Spanner 1]

So... as the motor cools down the battery mysteriously re-charges and then will spin the starter no problem!!, seriously, gentlemen !!  Brushes and bushings in the starter are the culprit, I say.

[TwoTired]

So... as the motor cools down the battery mysteriously re-charges and then will spin the starter no problem!!, seriously, gentlemen !!  Brushes and bushings in the starter are the culprit, I say.

It's no mystery.
Wet cell batteries do exhibit a self recovery phenomena.  It's a chemical process in there.  As the chemicals move around in there, fresh(er) acid gets to the plates.  Certainly isn't a full recharge.  But, it's gets better than previously flat.

It could also be brushes and bearings, I suppose.  But, when mine went bad, it actually started better when warm, as there was less motor turning required (armature shorting to frame).  Eventually, it didn't matter what temp it was.

Cheers,

Edit: In any case knowing the battery voltage is non-invasive and a logical first step to troubleshooting.   Otherwise, just keep replacing parts till it works again.

[motorhead55]

Guys

Got a strange issue with my 78 550/4 F2. Battery is kept on charge on Optimate battery conditioner all the time and starts from cold first time on the starter no matter what the temp. Following a ride of 30 or so miles then stopping the bike wont fire on the starter, giving all the signs of a flat battery, except that all lights are bright, horn works etc. Bike starts with a kick start and runs perfectly.

Leaving the bike for half an hour or so it will fire up perfectly on the starter, with no problem.

Is the issue with the starter, or some heat related electric problem? Battery is six months old.

Views welcome


Bob

Bob, I had a simular issue with my '76-550F. It had to do with the starter solenoid. It drew more current and the contact trough the starter button wasn't cutting it. I worked on DOZENS of old Volkswagens that had this same problem and we came up with a hard start solenoid set-up.
I would recommend, to make sure it isn't the starter motor, is to jump directly the two high amperage terminals on the starter solenoid. Use a heavy wire or tool to carry the amperage. YES....It will make sparks and I don't recommend trying this time after time.
Another way is to disconnect the yellow with red stripe wire from the solenoid. Take a wire from the hot side of the battery and momentarily touch it to the short yellow with red stripe wire coming from the solenoid. This closes the starter solenoid and should work the starter at full speed. If this works when the bike is at operating temp then you need to make up the hard start relay.

[Spanner 1]

+1 with motorhead on the solenoid test...but Bob said his lights don't dim as the starter tries to turn, which would suggest to me that the starter is not drawing enough current due to worn, dirty brushes and their lack of connection to a dirty commutator when affected by heat.