Strange problem with the starter of my quadrunner 250 1988

[Cheetah]

Hello,

recently I removed my starter because it was to slow so before buying a new one I thought cleaning it. So I did and it did went much better. 
 

The thing is I replaced it exactly as it was but since then the starter goes freely like there’s no dentelywheels.

Did I do something wrong ?

[Parham]

Yep, solenoid is not engaging...the starter actually has two functions built into it.  A solenoid moves the starter gear forward to engage with the engine as the starter motor is spinning.  That same solenoid retracts the starter gear when you release the switch so that the engine does not continue to spin the starter.  Take it back off and figure out what you did to make the solenoid not work...

[Mech]

No that's not right Parham..  Not for these bike starters.. They aren't the pre-engaged/solenoid-engaged sort that cars have.

If it was working for a while when you first put it back in Cheeta then it's most likely that the ratcheting mechanism inside the cases has played up. There's a ratchet called a "sprag clutch" that rides on the back of the flywheel in the side case and it allows the starter to turn the engine over but once the engine is running it just slips and doesn't turn the starter. If you take the starter out and partly strip it so you have the commutator/shaft and the end housing thatbolts to the engine, you can bolt those two parts in and test it by turning the shaft by hand. It should turn freely one way but the other way it should try to turn the engine.

[Mech]

Part #1 is the gear the starter engages with, and the sprag is the part of set #4 nearest us in the picture.

[Parham]

21 minutes ago, Mech said:

No that's not right Parham..  Not for these bike starters.. They aren't the pre-engaged/solenoid-engaged sort that cars have.

If it was working for a while when you first put it back in Cheeta then it's most likely that the ratcheting mechanism inside the cases has played up. There's a ratchet called a "sprag clutch" that rides on the back of the flywheel in the side case and it allows the starter to turn the engine over but once the engine is running it just slips and doesn't turn the starter. If you take the starter out and partly strip it so you have the commutator/shaft and the end housing thatbolts to the engine, you can bolt those two parts in and test it by turning the shaft by hand. It should turn freely one way but the other way it should try to turn the engine.

Thanks Mech!  I knew we would get at the RIGHT answer...even at the expense of my ignorance! 🙂

[Mech]

All the bike starters use a sprag clutch like that Parham..  Well everything except a harley perhaps..

[davefrombc]

Cheetah,  Did you  have the entire starter assembly out or just the starter?  On some bikes the sprag ( the part in #4 that looks like a roller bearing) can be put in wrong way round.  Those "rollers"  are actually an oval shape.  Turned in one direction the cam out and jam against the bore they run in  and turn the assembly to  start the motor.  When the motor  runs it is faster than the  starter turns allowing those "rollers"  to  drop down  and free the assembly.

If you had the whole assembly part and  put that sprag in  wrong way round  it would let the starter spin the assembly without locking up and turning the motor over. If that is the case,  testing it like Mech suggested , you'd find  turning the starter shaft forward it  would turn freely but if you turned it  back it would lock up, trying to turn the motor in reversed  rotation.

[Mech]

I don't think the sprag comes out unless you unbolt the unit from the flywheel in that particular bike Dave.. just going on the picture here.. The sprag looks to have a shoulder/flange at our end of it, which would be up against the flywheel I think..  And the flywheel would need to be off as well.

 It's possible that one of the gears could have shed two or three teeth..  but that's unlikely too.. Never seen a broken tooth. But then..  The sprags are normally very very reliable.. unless they get full of.. metal shards !!!

Edited September 23, 2023 by Mech