Rubbing Ceramic Sound

Molotov256

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Nov 6, 2008
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St. Louis, MO
I know it's hard to diagnose sounds through textual description, but when my Happy Time motor is running, I hear a sound that sounds like a rough ceramic disc rubbing on something... it sounds like something is slowly turning in a circle and gently scraping against something else. It's not too loud, but I can hear it when the engine is at idle.

Any ideas? Should I be concerned or just ignore it?
 
I bet it is the 3 clutch studs grinding into the inside of the clutch cover.
Quite common actually.
One poor guy had the thing actually cut all the way through the cover. He ended up with a perfectly round hole in his cover, good for keeping things cool with air flow, bad for keeping dirt and junk out of the gears.
 
Thx for the responses...

Gearnut: sounds possible... I will remove the plate and check for circular wear on the interior tomorrow. I'm not too familiar with clutch adjustments and whatnot... if it is the screws rubbing against the inside of the cover, how would I go about adjusting that? Perhaps I could just let it wear a path until it's settled in? heheh... Your acquaintance's air intake on the clutch sounds unique :eek:

Aussie: I think the noise is happening all the time, regardless of clutch engagement. Still, it's hard to tell, because it's a lot easier to pick out the noise with the engine at idle than with it revving.

Follow Up: Gearnut: Hey, I took a look at the inside of my clutch plate and there's no visible signs of scoring or friction. Does that eliminate the clutch studs?
 
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Yes, the three studs and/ or the flower nut screw are not merrily grinding away in your engine.
Now I wonder what the noise could be. I know that as the transmission gears mesh they do make a heck of a racket compared to, lets say, a motorcycle. (Harleys excluded)
It is best described as a whirring noise, the frequency of it increasing and decreasing in step with the engine speed. There are threads in here where folks have glued computer mouse pads, rubber sheets, ect to the outside of the cover to act as a damper.
I have read that one vendor cuts out a piece of the box that the engine kits are shipped in to fit precisely inside the cover. He then bolts the cover back on with the cardboard inside it and he claims that it helps deaden the noise alot. I haven't tried this myself...... yet, but it does seem plausible. And cardboard bits that get shredded up will not really hurt any of the parts that are inside the transmission. These engines are not a precision NASA satellite component. LOL!
 
There are threads in here where folks have glued computer mouse pads, rubber sheets, ect to the outside of the cover to act as a damper. I have read that one vendor cuts out a piece of the box that the engine kits are shipped in to fit precisely inside the cover. He then bolts the cover back on with the cardboard inside it and he claims that it helps deaden the noise alot. I haven't tried this myself...... yet, but it does seem plausible. And cardboard bits that get shredded up will not really hurt any of the parts that are inside the transmission. These engines are not a precision NASA satellite component. LOL!

If the noise is just part of the motor's standard operating procedure, I'm not going to sweat it. Granted, the noise is a little bothersome and makes the bike sound like the hackjob it really is, but if there's no serious problem then I'm going to be reluctant to cut up my nice ASUS leather mousepad. It just seemed odd that this motor makes the whirring and scraping noise and the other one doesn't.
 
The reason that I asked if it was only doing when the clutch is disengaged is because then, the clutch driven gear is very badly supported and flops around a lot as it spins, making a lot of noise.
If nothing's touching the inside of the case, then as Gearnut says, the cardboard method works well to quieten the noise. I did it to mine with good results.

For a bit more overall noise reduction, it's hard to beat pieces of rubber between the engine fins.

More here: HT Engine Noise Reduction

Sorry, Molotov256, I was typing while you were posting.
 
Upon further investigation, I think it is only making the noise when the clutch is disengaged. Do you think it's okay to ignore it?
 
How often to you apply fresh grease to the transmission gears?
Have you greased the ball bearing that fits behind the bucking bar recently?
How much wobble does your clutch gear have on the clutch hub?
 
How often to you apply fresh grease to the transmission gears?
Have you greased the ball bearing that fits behind the bucking bar recently?
How much wobble does your clutch gear have on the clutch hub?

1. Grease Transmission Gears: I've never done that. Is this something MB owners need to do on a regular basis? Also, would regular axle grease be appropriate or is there a better lubricant to use in this scenario?

2. Grease ball bearing behind bucking bar: I think I know what you're talking about, and if we're talking about the same thing, then yes, I did that recently. I mounted the motor onto a new bike a week or so ago, and when running the chain, the clutch pin fell out so I cleaned and re-greased it. I'd assume that grease was enough to satisfy the needs of the ball bearing behind it as well.

3. Wobble of the clutch gear on the clutch hub: My terminology is lacking, so I'm not sure what you're referring to here. Which gear is the clutch gear, and what's the clutch hub? (please, forgive me for being a n00b).
 
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