Weird vibration.

[Finfan]

I've been getting a strange sound from my bike that I can't quite isolate the cause of. It is like a rythmic buzz that get's really loud when I squeeze the clutch handle and dies out when I apply the coaster brake even a little. I'm thinking it must have something to do with the drive chain tension or alignment but I have tweaked it time and again and it doesn't go away. Any ideas out there? Thanks!

 

[Motormac]

These chinese motors make all kinds of weird noises, its almost normal for them to do that! if you are really concerned you can start up the bike on a kickstand and have a freind hold in the clutch and open it too, and hold the throttle for you while you pinpoint the sound. I use a mechanics stethoscope (like what a doctor uses to listen to your chest)or you can use a cardboard tube from a roll of paper towel hold it your ear and place it at different points on the running engine, you should find the source of the noise that way.Be careful of the running chain or you will have no fingers left!

 

[Venice Motor Bikes]

Check the chain tensioner... The plastic rollers are always moving out of alignment on the bearings!

 

[Bikeguy Joe]

Sounds like the chain/tensioner/sprocket "music" to me.

 

[MikeBike]

it could be a rear weel bearing problem.

 

[Finfan]

That would make sense Joe since I just had it apart and put it back together. I have also noticed irregular "popping" sounds like the chain is clicking against something. Do I need to reposition or replace the tensioner? I don't want anything to sieze at 20 mph!

 

[Norman]

I've found that the rear engine mount bracket can be rubbed by the chain it will make a sort of poping sound a little work on the bracket with a dremel will cure it.
Norman

 

[Bikeguy Joe]

How tight is the chain? 3/4" play.

Get up to speed, pull the clutch and kill the engine. A few times of that will root out the exact cause of the noise.

 

[Scotty]

I heard a wierd buzzing noise while riding once, turned out to be the downtube cracked right through, just above the engine mount. Scared the crap out of me.

Can you hang the bike and test the noise location with a screwdriver against your ear, or with a piece of hose?

 

[hiker472]

I would think hanging the bike would work--sounds like something I would do. Just becareful. When that engine is running, that bike could be wanting to swing all over the place.

The screwdriver trick works good also. The longer the better, just becareful of those moving parts though.

Mine was making noises too and it was coming from the chain tensioner. Mine was moving all the time so what I did was I put a screw through it into the frame. This fix for the chain tensioner (if that's the problem) isn't recommended because it could eventually make my frame crack. I only mention it to tell you what I did to fix this problem.

 

[Dave31]

Finfan, you need a little more slake in your chain

 

[Finfan]

Well, I'm bumping this thread because I have a little more information now. Today I broke a chain and got to pedal home with the engine out of play. The "popping" sound was still present so it is from the bicycle not the engine or drive chain. Since it also happens when I'm under power and not pedaling I have to believe at this point it is coming from the rear hub. So I guess I will be tearing the hub down. :/

 

[Finfan]

I have now taken apart the coaster hub, inspected all parts, packed bearings with grease, reassembled, and readjusted. I am still getting that clicking sound from the hub. I have it adjusted so that the wheel turns freely but there is no play in the axle. When I push it either forward or backward the pedals do not turn. Have I missed something in the adjustment or do I just have a bad hub? It is a cheap chinese made Huffy so poor quality is a distinct possibility. Any insights would be appreciated! Thanks!

Edit: In case it matters the clicking sound is intermittant, not every rotation.

 

[Bikeguy Joe]

Flat spot on a ball bearing?