never heard of this happening before...

[SIR REAL ED]

Talking to a friend last night, he mentioned having a bike with an electric starter that would not start.  The bike had gas, spark, etc.  Everything he checked was fine.  Finally, in frustration he dropped it off with a friend who has rebuilt many motorcycle engines.

After diagnosis, replacing the starter motor allowed the bike to start!

The problem was determined to be an electric starter motor that would not disengage with the flywheel.  The starter was simultaneously acting as a motor to rotate the crankshaft and also as a brake to prevent the crankshaft from spinning faster than the starter motor would allow.

First time I have ever heard of such a thing.  Not sure my thought processes would have figured that one out.

[guzzisteve]

I had one couple years ago on a Stelvio, starter stuck out. The owner opted for another Valeo not cheap Chinese.
He thought the motor was trashed too, I knew better cause I did all the maint on it.

[jamesfjamesf]

I've seen this a few times, mostly it was the worn/rusty ignition switch that didn't release so kept the solenoid engaged. But I could see a faulty solenoid or even sticky goop on the starter gear shaft causing the gear not to retract while under load.

jim

[normzone]

Thanks for sharing this, added to my bank of "other peoples problems to remember in case it happens to me". 

[SIR REAL ED]

I can understand the idea of the gear not disengaging from the flywheel, but it blows my mind that the starter motor would have enough braking power to prevent the motor from running faster than starter speed.

I would have thought that the engine would simply over power the starter.

What are the odds?  The motor actually is running, but at the same exact rpm as the starter, so essentially it seems like the motor is not running!!

It would have been fascinating to put a volt meter and ammeter on the battery and if the starter was drawing almost no current since the engine was actually running.

What a cool experiment.  Drive for miles and miles as long as your thumb is on the starter button......

Unintentional hybrid motorcycle!!

[blackcat]

Not exactly the same but the original Bosch starter on my CX would never crank consistently so I replaced it with a Valeo but the Bosch starter worked perfectly fine on my 1000S so it sat on the shelf until I acquired the Lemans and it works fine on that bike. I assume it must be the ring gear but it’s never been an issue with the Valeo.

[guzzisteve]

I wonder if anyone has converted the Briggs starter/generator to run on a Guzzi flywheel. I would imagine it's the rpm.

[faffi]

I can understand the idea of the gear not disengaging from the flywheel, but it blows my mind that the starter motor would have enough braking power to prevent the motor from running faster than starter speed.

I would have thought that the engine would simply over power the starter.

What are the odds?  The motor actually is running, but at the same exact rpm as the starter, so essentially it seems like the motor is not running!!

It would have been fascinating to put a volt meter and ammeter on the battery and if the starter was drawing almost no current since the engine was actually running.

What a cool experiment.  Drive for miles and miles as long as your thumb is on the starter button......

Unintentional hybrid motorcycle!!

I totally agree! If I should try a guess, the starter in question pulled enough juice to prevent sparking under compression, meaning the engine would turn over, but not fire.

[SIR REAL ED]

I totally agree! If I should try a guess, the starter in question pulled enough juice to prevent sparking under compression, meaning the engine would turn over, but not fire.

After my last post I started thinking that exact same thing!!

Seems too weird to be true that the engine could actually run at the starter rpm and the starter would act as a brake.

The starter gear not retracting is not unusual, but not a big factor.

Would have been educational to measure current and voltage while cranking.

Bummer!  The world's first accidental hybrid motorcycle is still out there somewhere waiting to be discovered......

Yo! Elon!  Get yer butt over here!

[SIR REAL ED]

Not exactly the same but the original Bosch starter on my CX would never crank consistently so I replaced it with a Valeo but the Bosch starter worked perfectly fine on my 1000S so it sat on the shelf until I acquired the Lemans and it works fine on that bike. I assume it must be the ring gear but it’s never been an issue with the Valeo.

I wonder if there was a significant difference in the starter cables.  There is a company out there, Hi-Cap IIRC, that makes 4 gage starter cables.  They used to have a video of a Ducati with a built motor cranking over.  Supposedly, just changing the starter cables added what sounded like approximately 200 rpm to the cranking speed.

[faffi]

I know many fit thicker cables for the starters on Viragos to assist one of the worst starter systems in motorcycling. Seems to make a difference also.