Hot start problems

[Bubb]

My little R80st (1983 build) will start fine when cold…. But struggles when warm/hot.
Seems like the starter is not spinning the engine, and sometimes doesn’t spin at all.
It’s the original BMW starter….. all electric connections checked and appear to be okay.
Valves checked … and within tolerance.
New coil, new HT leads, new plugs…… fitted to solve previous problems.

Once cool, the bike starts fine again.

Time for a new starter motor? …..

 

[Gelandestrasse]

Probably of no use but if your 'original BMW' starter is the original Bosch starter, they respond well to a good dismantle/clean. If your stater is the original Valeo starter, you could be suffering from incipient magnet detachment (glue fails, esp when hot) which jams it up. But as it starts ok when cold. And I don't know when BMW introduced the Valeos, but this article is well worth bed-time reading: https://bmwmotorcycletech.info/boschvaleostarter.htm

 

[Bubb]

Thanks Tim

I think it’s a Valeo as I can see “made in Spain” on it….. think Bosch would be German.
I’m wondering if the starter motor or the starter solenoid is the problem.

Maybe it’s time for an upgrade to nippondenso starter as I believe they have more “punch”
It’s annoying as bike is running well…… but once hot it’s starting problems mean I either have to leave it to cool properly, or not stop!

 

[Gelandestrasse]

Don't rule out the starter relay, though. All this stuff could behave differently when it is subjected to heat.

 

[Nin]

I fixed an R100GS PD with exactly the same symptoms - replaced the yellow relay, problem went away.

 

[Bubb]

Thanks nin…will try that first

 

[Bubb]

New starter motor (Nissan denso) and new starter little yellow relay….. problem gone. Very good starter now, hot or cold.
Worth the time and money spent imho, as it means I can continue to enjoy the old girl without worrying about will she re start….

 

[Pukmeister]

Worth the time and money spent imho, as it means I can continue to enjoy the old girl without worrying about will she re start….

Must be reassuring, unlike me with a modern 1250GSA that can’t decide whether to start again or not once ridden. (I’d replace the OE battery but it passes a load/drop and cranking tests with flying colours.)

 

[Bubb]

Pukmeister

That was what my problem was. Sometimes once hot I could get a restart, sometimes not…
Was annoying me, and this was lowering my love for the old airhead….. I do like to ride the old girl, so thought that it was worthwhile to spend the money on her…..
It’s a never ending story with old bikes…they always need something doing, or some money spending on them.

Hope you find the solution to your problem with the 1250gsa.

Ride safe