Weird noise - valve tapping or what? (incl. recording)

[jigglypuff]

Not too long ago I've bought a second hand Kymco Agility 50 2012. The problem is that it makes this noise (link below) when riding. It happens when accelerating and it also stays at the top speed (~30mph). Sound is coming from somewhere below the seat area or the back. Also this sound is much more audible than it feels in the video, for example when I pass somebody with my scoot, they instantly ask why does it sound like that.

Figured it might be valve clearance, so I've checked that. It was as it is recommended: ~0.08mm. But does this noise even sound like valve problem? If so, which direction should I try, tighter/looser? If not valves, what else could it be? I had also opened the variator and checked the rolls, they seemed ok.

Overall performance is good, except the problem with bogging down from idle (changed carb for that, didn't help) - that may or may not be related.

Any suggestion, tips? what would be your guess where this sound could be coming from?

https://www.youtube.com/watch?v=M4uo-3i0Dt0&feature=youtu.be

[JayAre]

Hold a long screwdriver to your ear like a stethoscope, moving it to different parts, clutch cover, head... while running the bike on the center stand to locate the sound. You may need to run against the brake to load the motor but not for more the a few seconds at a time you don't want to overheat the brakes.

[CROSSBOLT]

Valve clearance for Agility 50 and most other Kymco 4-strokes is .04 mm, NOT .08 mm. Audio sounds nominal to me but then I am a really old guy! Wait a minute! I just checked the service manual for the A-50 and it said what I said. But every other Kymco is .1 mm so we better wait for Zombie or Bettin' and losin' to check in. Your valves may be tight. Tight valves don't make noise unless they hittin' the pistons! I did hear a "rum-rum" noise which sounds like the CVT belt and sounds normal.

Karl

[JayAre]

Valve clearance on my 2013 is .04mm=.002" cold/ambient temp. You're better loose than tight, loose you'll hear some ticking. Tight may hold the valve open after the motor heats up & you'd lose power/compression, or worst case like Crossbolt said slap the valve into the piston & bend or break things! I have my valves set at .002' intake & .003" exhaust (more thermal growth) with no ticking, but I'm running a 72cc BB. Some older bikes may have a clearance of .004".
Listening to your recording it sounds like a fan noise. Are you running a stock air box or aftermarket air filter/may be louder? Like I suggested try the screwdriver or a Piece of hose or even a straw from McDonalds, to listen with & locate where the sound is coming from.

[Mr. Paul]

I could not get the Youtube vid to load, prob my crappy internet connection. I have a similar problem. Do you notice a vibration in your drive train? With the scoot on the center stand, make sure the rear tire is off the ground, accelerate to normal rpm. Listen for noise in the front of your CVT belt cover. If your hear it, it is most likely a worn variator drive face. The splines on the inside of the variator face just behind your kick start pawl gear get worn and introduce slop and vibration, along with noise. You can confirm by pulling CVT cover off and creating slack in belt. Work the variator drive face plate back and forth with your hand. If you feel any looseness or "slop" it needs replacing. A common issue from what I understand. I hope this helps you. Maybe someone else could chime in.

[blue]

rollers could be going flat. But im thinking try resiting the valves.I do mine to .004 on both. the bottom valve gets hoter and will sometimes work its way back to.003