Topic: Cb400f whining noise

[123mclaren]

My 400f has developed a whining sound. Haven't ridden it since, but it's there when the bikes in neutral and when I accelerate it gets louder and faster. Is it possible the starter clutch is stuck ( any way to check that). Could it be anything to do with the kick starter or clutch plates

[scottly]

I'm not real familiar with 400s, but I think they may have a primary drive gear, instead of a drive chain like the larger SOHC4s, which does contribute to a whining noise? Did the noise suddenly increase, or has it been there all along, and you just noticed it?

[Bodi]

There's a primary chain (single HyVo on the 400) and straight cut gear drive from the primary shaft to the clutch basket. I think all the fours have this chain plus gear primary drive. The electric start turns the primary shaft, kick starter turns the transmission input shaft.
The 400F engine does have a characteristic primary gear whine sound.
If the starter clutch jammed the noise would be very very loud indeed, the engine would be very slow to rev, and the starter motor would disintegrate at higher engine RPM. You can check the clutch by trying to turn the engine over backwards with the alternator nut. The effort difference between turning forward and backwards will be obvious if the clutch is working. It is basically foolproof though, it fails by not grabbing rather than not releasing.
A dragging main clutch might whine but it would probably drag and make shifting difficult as well.
Kick starter pawl can fail to disengage - the sound is more like a spinning ratchet than a whir. Rare problem. Try moving the kickstart lever down with the engine running and you will hear it loud and clear.

[123mclaren]

The noise suddenly came on. It's quite loud and as you rev it up it gets louder. Some say bearing noise but there no play in the primary shaft??? Ill look into what Bodi mentioned when I have some time and get back to you guys. Thanks alot

[123mclaren]

Also I had the oil pan off last night and tried turning the starter gear would only turn one way. Jammed?  Cud I just pull the starter motor and plug it. Wud I be okay running it like that till I can pull the starter clutch. Think you have to split them cases to get it out.

[Bodi]

It will normally only turn one way, one way you're trying to turn the starter motor over through the planetary gears - not easy. There's a 3-roller sprag clutch between the starter gear and the primary shaft. One way it grabs, the other way it's free. At running rpm the centrifugal force on the primary shaft rollers pushes them away from the stub on the starter gear so there's no contact or friction then.
Test it by removing the alternator cover and turning the engine both ways with the rotor bolt. Counterclockwise is normal rotation and only the crank should turn. Clockwise should also turn the starter motor which should be difficult and the motor turning should be audible.
Clutch problems can make oddball noises. A broken plate or bad bearing may be the cause. If the clutch ramp is misadjusted the throwout bearing could be turning with clutch fully engaged, that might wear it out pretty quickly.
Changing oil type can cause significant changes in the primary gear whine.
The cam chain will make some really weird noises. Too loose is more a rattling noise, too tight is more a whine. If one of the blades has failed you might get an odd noise.

[123mclaren]

So tried turning the alternator. Only heard starter when u turned clockwise. When turned counter clockwise just felt compression. So starter not stuck? Will check clutch tomoorow

[123mclaren]

So put everything back and put some oil in her. The noise has quieted a little but is stil there on revs. Haven't tried riding it yet but will do lager

[Bodi]

Don't do too many lagers before riding.