S4R hard starting

[vwboomer]

This has been an ongoing issue and is getting a little worse. It turns over very slow.  I've checked/cleaned the ground wire from the battery to the rear of the engine. I've pulled the solenoid and starter wires to clean/grease them. There was virtually no corrosion on anything.

Voltage reading at the solenoid is 13.7. With the starter wire removed the voltage on the other post is about 12.5 when cranking. I'm guessing this should be more than enough to turn the engine over at a reasonable speed for a quick start.

What's next? A starter rebuild kit so I can put new brushes in? Theres only 16k miles so it seems a bit premature.
If it's cool outside I take the VFR for fear that the Duc wouldn't start after work. That Honda cranks over at a million miles an hour regardless of temp

[Howie]

You kinda made up your own test.  This does not mean it isn't a valid test though.  The problem is, without knowing how many amps the solenoid winding normally draws or past experience there is nothing to compare it to.  I would start by first having the battery load tested.  Voltage indicates the state of charge, but does not mean the battery is still good.  If your battery fails the load test replace it.  If the bike still cranks slow you need to find where the excessive voltage drop is.  If you don't know how to test for voltage drop here is a tutorial  http://www.aa1car.com/library/voltage_drop_testing.htm
Or to eliminate the solenoid as the culprit, just bypass the solenoid*.  If the cranking speed is now good, replace the solenoid. 

*Make sure the bike is in neutral.  You are bypassing all safeties.

[vwboomer]

I did also bypass the solenoid and it didn't seem to start any better.
Guy at work said the starter should have the amp draw tested.


I am certain the battery is good. I replaced the stock last year with a PC310. That didnt' solve the problem so they sent me another new battery adn it was the same result. connecting that battery to another bike produces a good start.

Interesting page on voltage drop, I'll give that a shot next week.

[Howie]

Starter amperage draw test is a good way to go, only problem is Ducati does not publish a spec.  Of course, one could do the test on a known good S4R and publish the results.  Your PC310 is 2 amp hours short of the rating of the OEM Yuasa.  I doubt this is a problem except when the temperature gets real cold though.