CB400N no crank?

[Steven T]

Having an issue with my cb400n. It's only electric start. Pulled the starter motor out to see why it wasn't starting and took it apart. When I apply 12v to it out of the bike it spins freely. However when I install it, it clicks and moves a little, but doesn't turn the bike over. The bike has been sitting for a few months.

I can turn the engine over with a spanner, and I can turn the small sprocket, the one that the starter motor turns, by hand.
I have changed the wiring around drastically a little while ago and haven't had it running since - only just tried now though

I'm hoping it's something silly. Is it possible when I removed the neutral light and all that stuff I've done something? I'm trying it with a car battery so I wouldn't think so.

Thanks

[spanner spinner]

check the solenoid sounds like bad contacts in the solenoid, short the terminals on the solenoid with a screwdriver (there will be sparks) and see if the starter motor will then turn over. If it turns over new solenoid needed, if it doesn't check all the other connections in the starter system ie battery terminals connection to the starter motor etc.

[Steven T]

check the solenoid sounds like bad contacts in the solenoid, short the terminals on the solenoid with a screwdriver (there will be sparks) and see if the starter motor will then turn over. If it turns over new solenoid needed, if it doesn't check all the other connections in the starter system ie battery terminals connection to the starter motor etc.

Thanks for the reply. To clarify, I have tested the starter motor both off the bike and installed, with a car battery directly onto the starter motor. The other thing I thought was that possibly the starter motor is now too weak to even turn the bike over? Perhaps there is a way to test that?

[cs363]

Thanks for the reply. To clarify, I have tested the starter motor both off the bike and installed, with a car battery directly onto the starter motor. The other thing I thought was that possibly the starter motor is now too weak to even turn the bike over? Perhaps there is a way to test that?

The starter solenoid is separate from the starter motor, you should find it under the right hand side cover, item number 10 in the attached diagram. Use a screwdriver or similar to short the two threaded terminals together as per spanner spinner's post.

I've also attached a photo of the actual solenoid to give you a better idea what to look for.

[spanner spinner]

what condition where the starter brushes and commentator faces? (the copper faces on the end of the armature)
if the brushes are worn down or the springs have gone soft, or the commentator faces are dirty they wont pass the correct current and a weak starter motor will result. have seen these problem or quads dragged out of the back of the shed after being parked up for a while just like your 400n was maybe check the starter motor again?

[Steven T]

The starter solenoid is separate from the starter motor, you should find it under the right hand side cover, item number 10 in the attached diagram. Use a screwdriver or similar to short the two threaded terminals together as per spanner spinner's post.

I've also attached a photo of the actual solenoid to give you a better idea what to look for.

Yeah solenoid is fine, there's 12v getting to the starter motor when I use the starter motor. My issue is trying to work out why the starter motor turns uninstalled, but when it is installed it wont start the bike.

[cs363]

Yeah solenoid is fine, there's 12v getting to the starter motor when I use the starter motor. My issue is trying to work out why the starter motor turns uninstalled, but when it is installed it wont start the bike.

Ah, ok....in that case testing as per spanner spinners last post is in order. This might help with that: http://www.prestolite.com/pgs_training/training_4.php scroll down to 4.4--Diagnostic / Troubleshooting Procedures . It's for a car starter but the same principles apply.

Best of luck!

[Steven T]

what condition where the starter brushes and commentator faces? (the copper faces on the end of the armature)
if the brushes are worn down or the springs have gone soft, or the commentator faces are dirty they wont pass the correct current and a weak starter motor will result. have seen these problem or quads dragged out of the back of the shed after being parked up for a while just like your 400n was maybe check the starter motor again?

The brushes still had a bit of life left in them and the faces were a little grubby so I gave them a little clean.

[Steven T]

what condition where the starter brushes and commentator faces? (the copper faces on the end of the armature)
if the brushes are worn down or the springs have gone soft, or the commentator faces are dirty they wont pass the correct current and a weak starter motor will result. have seen these problem or quads dragged out of the back of the shed after being parked up for a while just like your 400n was maybe check the starter motor again?

I cleaned up the armature as it was dirty. Is it possible the starter clutch is to blame? Or is there anyway to test the starter motor is powerful enough?

[Steven T]

So I can hear the starter motor turn when I push the bike backwards in gear. Does that mean there's nothing seized? Still really confused why the motor won't crank and I know the starter motor works

[Steven T]

Turns out the alternator has corrosion on the inside, meaning it turns over when I use a ratchet on the flywheel, and when I try to roll start it, but it doesn't turn with the starter motor alone. I took the plugs out and the starter motor turns it fractionally. So off with the alternator to clean it up

[sully1987]

Hey, in having the same issue with my CB400N, how did you remove the alternator cover? And has this fixed the issue?


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