Topic: What's that noise? / Stator rust

[TheHulk]

Fired up my 77 CB550f yesterday, and it was making some odd sounds while idling during warmup. Rode around the block to see if the noise would diminish after a little ride time. Seems like every time I came to a stop and the bike would Idle I would hear this same sound. Happened while the bike was in neutral or with the clutch disengaged, always in the low rpm range. Oil level was full, and the oil light never came on.

It SEEMS like the sound was coming from the stator, or at least the left side of the engine. Decided to pop off the stator cover and look inside.

I did finish a top end rebuild of this engine but never made any modifications to the stator. As you can see in the video below, everything seemed to be covered with a thin red dust. Probably rust? Charging system seems to work fine as my voltmeter will read 14-14.5 while riding in higher rpm's.

Check out the videos below to help identify the noise, and see if it could be coming from the stator or if I should be looking elsewhere. Thanks!

[TheHulk]

Also, I was thinking about trying to let the engine run without the stator and cover on, to see if that would help trouble shoot the source of the sound. Is it possible to run the engine with the cover off? I was going to support the cover so no wires will break.

[newday777]

Also, I was thinking about trying to let the engine run without the stator and cover on, to see if that would help trouble shoot the source of the sound. Is it possible to run the engine with the cover off? I was going to support the cover so no wires will break.

Put a drip pan under the stator area ans you should be fine.

[scottly]

Also, I was thinking about trying to let the engine run without the stator and cover on, to see if that would help trouble shoot the source of the sound. Is it possible to run the engine with the cover off? I was going to support the cover so no wires will break.

There is a plug in an oil galley on the 550 that is held in place by the stator cover, which can be pushed out by oil pressure if the motor is started. It looks there are wear marks where parts are rubbing? Are the stator and field coils properly seated, and their screws tight? Are both dowels in the stator cover?

[754]

It will be pushed out..messy..
 I suspect  that a carwash had something to do with it...

[TheHulk]

Also, I was thinking about trying to let the engine run without the stator and cover on, to see if that would help trouble shoot the source of the sound. Is it possible to run the engine with the cover off? I was going to support the cover so no wires will break.

There is a plug in an oil galley on the 550 that is held in place by the stator cover, which can be pushed out by oil pressure if the motor is started. It looks there are wear marks where parts are rubbing? Are the stator and field coils properly seated, and their screws tight? Are both dowels in the stator cover?

Both dowels were in. I'll have to do some investigating to see if/where any rubbing was occurring, but I did see wear marks as well. If the plug is pushed out, will it go back in relatively easily?

[robvangulik]

If the plug is pushed out, will it go back in relatively easily?

If you can find it again, with pressure behind it, it can shoot out 6 feet, just like the oil following it....

[754]

If there is rub marks you won't need to run it,  then you know something is wrong.

[TheHulk]

If the plug is pushed out, will it go back in relatively easily?

If you can find it again, with pressure behind it, it can shoot out 6 feet, just like the oil following it....

Update: The front three facing screws in the cover holding the inside ring were loose. I think it was just rattling and rubbing a bit. After cleaning out the rust and tightening everything up, problem was an easy fix.

Sure enough though, started it up and the plug shot about halfway across the garage! That was fun. Thanks for the tips everybody.

[robvangulik]

You can't say you weren't warned