Rubbing Ceramic Sound

Discussion in '2-Stroke Engines' started by Molotov256, Jun 19, 2010.

  1. Molotov256

    Molotov256 Member

    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?

  2. GearNut

    GearNut Active Member

    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.
  3. AussieSteve

    AussieSteve Active Member

    Molotov, do you hear the sound all of the time, or only when the clutch is disengaged, (pulled in)?
  4. Molotov256

    Molotov256 Member

    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?
    Last edited: Jun 20, 2010
  5. GearNut

    GearNut Active Member

    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!
  6. Molotov256

    Molotov256 Member

    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.
  7. AussieSteve

    AussieSteve Active Member

    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.
  8. Molotov256

    Molotov256 Member

    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?
  9. GearNut

    GearNut Active Member

    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?
  10. Molotov256

    Molotov256 Member

    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).
  11. GearNut

    GearNut Active Member

    1. You need to put a peas sized blob of grease right where the two gears contact each other at least every 300 miles or every other fuel tank refill. Don't over do it or you will only be making a bigger mess inside there and risk contaminating the clutch friction pads with grease. If you do not grease the gears regularly, the gears run dry of lubricant. You can figure out the outcome of that.
    It is a good idea to wipe out the excess grease that flings off of the gears from inside the gearcase too. You don't want it turning into a grease packed mess. Do not re-use the grease unless you have no better alternative. A q-tip helps you get into in some areas in there.

    2. Yes, that is what I am talking about only you need to remove both the bucking bar and ball bearing. (a pencil style magnetic pick up tool helps sometimes) Clean the ball bearing and bucking bar. Pack a blob of grease inside the hole, place the ball bearing back in the hole, put a little more grease in the hole, then put the bucking bar in the hole. Wipe any excess grease off that got squished out. Leave a little grease on the tip of the bucking bar to lubricate where the clutch release cam pushes in on the bucking bar.

    3. The clutch gear is the larger of the two gears on the transmission. It is mounted on the clutch hub. There are a whole frigging bunch of teeny loose ball bearings that fit between the clutch ring gear and clutch hub. Don't ever try to separate the ring gear from the hub or all those bearings will go every which way.
    Those tiny ball bearings need to be lubricated at the same interval as the transmission gears. Most folks have the best luck with white lithium grease in an aerosol can. You can squish the end of the red straw that comes with the can of grease to a flat tip and work a little grease between the hub and ring gear. It does not take much grease to do it, and if you get too much in there the lithium grease will fling out and contaminate the clutch friction pads.

    If you feel especially adventuresome, you can remove the clutch from the shaft, flip the clutch over and there will be a small hole, factory drilled, in the back of it to let you squirt grease directly into the bearing race.
    FurryOnTheInside likes this.
  12. ariel

    ariel New Member

    I have a similar issue. I hear a rubbing noise, like metal rubbing the flywheel or something. This happens when I'm riding the bike without the engine on. Is this normal? Is there anything that can be done to eliminate that resistance? I think this is happening within the clutch assembly. Any suggestions?
  13. AussieSteve

    AussieSteve Active Member

    ariel, that's fairly normal.
    I'd suggest that you follow the lubrication steps suggested by GearNut, then if it's still too noisy, take a look at this:- HT Engine Noise Reduction

    (Very thin cardboard inside the clutch cover helps a lot, if the noise bothers you as it did me.)
  14. 1max

    1max Member

    I did not build my motor I bought this bike second hand is there anyway I could find instructions on how to lubricate these items