Buzzing/vibrations noise at top speed

[Sir Scoots-A-Lot]

I have a 2011 50cc 139qmb long case tao tao I bought well used with 6k kilometers on the clock. I think its mostly stock and hits 40mph (gps verified because my scoot speedo stops at 50kph and was reading way past that) on a slight downhill. When I hit about 39mph it starts making a buzzing noise and refuses to go faster. Im wondering is it valves? Exhaust restriction? Maybe Variator (although it seems to be coming from engine area)? Or bearings? Any ideas are very much highly appreciated!!!. I will attempt to safely take video with my phone in a few hrs and upload here or Youtube with a link. Thank you!

[Sir Scoots-A-Lot]

Couldn't capture high rpm/only happens at top speed noise due to wind noise but here is the Youtube link to my loud idle: youtu.be/9rrin9rrinypVq5

im wondering if my valves are off and that is my top speed buzzing/rattling noise and idle noise? Or if the top speed is another limiting factor such as exhaust restrictor, roller/variator loose or even cdi rev limit. Please let me know if you recognize that noise. I am considering handing out 1 prize for the first person who diagnoses it correctly if it leads to me fixing it before I can figure it out on my own. Thank you

[PirateLabs]

Jul 16, 2018 18:21:55 GMT -5 Sir Scoots-A-Lot said:

Couldn't capture high rpm/only happens at top speed noise due to wind noise but here is the Youtube link to my loud idle: youtu.be/9rrin9rrinypVq5

im wondering if my valves are off and that is my top speed buzzing/rattling noise and idle noise? Or if the top speed is another limiting factor such as exhaust restrictor, roller/variator loose or even cdi rev limit. Please let me know if you recognize that noise. I am considering handing out 1 prize for the first person who diagnoses it correctly if it leads to me fixing it before I can figure it out on my own. Thank you

Youtube link is bad.


Bill

[Sir Scoots-A-Lot]

Jul 16, 2018 18:53:28 GMT -5 PirateLabs said:

Jul 16, 2018 18:21:55 GMT -5 Sir Scoots-A-Lot said:

Couldn't capture high rpm/only happens at top speed noise due to wind noise but here is the Youtube link to my loud idle: youtu.be/9rrin9rrinypVq5

im wondering if my valves are off and that is my top speed buzzing/rattling noise and idle noise? Or if the top speed is another limiting factor such as exhaust restrictor, roller/variator loose or even cdi rev limit. Please let me know if you recognize that noise. I am considering handing out 1 prize for the first person who diagnoses it correctly if it leads to me fixing it before I can figure it out on my own. Thank you

Youtube link is bad.


Bill

Sorry Pirate Labs. That was the first YT video I ever uploaded!

youtu.be/9rrinypVq5o

I tried this one a min ago & it works now. Please tell me what ya think if ya have time

[PirateLabs]

I could not really hear anything all that bad. I think your idle is set too high, but, other than that...
It might be helpful if you could hold the camera along side the scoot on either side of the engine and, especially where you think the noise is the loudest. Like maybe down by the CVT area as well.

Bill

[Sir Scoots-A-Lot]

Thanks Bill I really appreciate you taking the time. I am taking out my scooter soon & I will attempt to post a better video tonight.

You are 100% spot on about my idle being way high. I bought a fairly low odometer reading 6,300 kilometers but well used and not set to factory specs 50cc scoot such as one of the two intake vacuum lines is blocked off although I believe tge PCV one is still connected & I was having starting and stalling issues so I had the idle set way hi to compensate, although now I believe I have it set properly.

My 4 stroke 50cc scooter has the big 12" wheels, has a Tao Tao 50cc stamp on the engine, but 2stroke Yamati Rx-8 plastic badging and a Tomos CVT cover lol...so I have no idea what components it is running. It goes about 40mph, 41.4mph gps verified top speed, on a long straight in a tailwind or slight downhill. I want to eventually buy a big bore kit but kind of wondering if they already have it set to 63cc. I guess the only way to check is measure the piston diameter by pulling the head when I pull the head cover to make sure my valve lash clearances are good.

So thanks again, if you listen to the video tonight & send me a mailing address in the USA, then I will send you a gas card to Mobil since I mentioned a prize and I appreciate your taking time to help.

[PirateLabs]

Jul 18, 2018 13:58:15 GMT -5 Sir Scoots-A-Lot said:

Thanks Bill I really appreciate you taking the time. I am taking out my scooter soon & I will attempt to post a better video tonight.

You are 100% spot on about my idle being way high. I bought a fairly low odometer reading 6,300 kilometers but well used and not set to factory specs 50cc scoot such as one of the two intake vacuum lines is blocked off although I believe tge PCV one is still connected & I was having starting and stalling issues so I had the idle set way hi to compensate, although now I believe I have it set properly.

My 4 stroke 50cc scooter has the big 12" wheels, has a Tao Tao 50cc stamp on the engine, but 2stroke Yamati Rx-8 plastic badging and a Tomos CVT cover lol...so I have no idea what components it is running. It goes about 40mph, 41.4mph gps verified top speed, on a long straight in a tailwind or slight downhill. I want to eventually buy a big bore kit but kind of wondering if they already have it set to 63cc. I guess the only way to check is measure the piston diameter by pulling the head when I pull the head cover to make sure my valve lash clearances are good.

So thanks again, if you listen to the video tonight & send me a mailing address in the USA, then I will send you a gas card to Mobil since I mentioned a prize and I appreciate your taking time to help.

Thanks anyway, no need for a prize.  We all try to help one another here if we can.  I still learn new stuff about scooters here every day.

Bill

[Sir Scoots-A-Lot]

Thanks Bill. I keep learning a lot here too. I also keep wanting to make my scooter faster on hills and give it a 50+mph top speed but since it's my primary transport until winter I think other than checking that my cvt and exhaust are derestricted I feel like I should leave my scooter like it is and maybe go for a BBK and switch the final drive gears whenever it's time for a top end rebuild. Either that or get my motorcycle endorsement and a 150cc scooter.
I lowered my idle and its still a bit loud and can hear a little chirping from my cvt from time ti time. Almost like crickets lol. Youtube link below. Wish I could capture top speed sound but wind is too loud. Maybe i can leave camera in underseat storage or have a friend record roadside. Thanks. Presto

youtu.be/lUZGHia8Rek

[PirateLabs]

Jul 18, 2018 18:38:55 GMT -5 Sir Scoots-A-Lot said:

Thanks Bill. I keep learning a lot here too. I also keep wanting to make my scooter faster on hills and give it a 50+mph top speed but since it's my primary transport until winter I think other than checking that my cvt and exhaust are derestricted I feel like I should leave my scooter like it is and maybe go for a BBK and switch the final drive gears whenever it's time for a top end rebuild. Either that or get my motorcycle endorsement and a 150cc scooter.
I lowered my idle and its still a bit loud and can hear a little chirping from my cvt from time ti time. Almost like crickets lol. Youtube link below. Wish I could capture top speed sound but wind is too loud. Maybe i can leave camera in underseat storage or have a friend record roadside. Thanks. Presto

youtu.be/lUZGHia8Rek

I heard the chirping this time...not very pronounced but, it was there a few times in this video.  Nice job moving the camera around to hear it...that helped.  This is the same noise you hear at speed?  Or is that different?  That sounds to me like metal on metal contact someplace and, since it is intermittent, it would make me suspect a bearing going bad.  Is your kick lever start pulled all the way back to the up position?  With the engine off and the scoot on the center stand,  spin the back wheel by hand the direction it would be turning if riding.  See if you hear anything bad.  I have had like 4 clutch bearings go out on my scoot and, this bearing is only in use when the clutch is not engaged...as in idling.  Could be a belt noise also...very hard to tell.  Have you opened up the cvt case and done a good inspection?  I would do that if you have not just on general principles.  you might find a belt that is ready to let go at any time, or some other issue.  If I can think of anything else, I will let you know.  Some of the other guys here might have some more ideas as well.

Bill

[pepi]

Sorry, not to hijack your thread, but I am having the same problem on a 2008 with 2200 miles on it. It was running a little sluggish and when I opened the throttle wide open, engine would make like a hollow sound and hard starting. I took carb apart to clean it up and found accelerator pump gasket torn. For a few dollars more than the new gasket, I was able to get a complete carb. I put new carb on and it fires right up. I took it for a drive and got up to about 40 mph with wide open throttle and now I get a metal buzzing sound. Almost like when you blow through a blade of grass through your thumbs.

I took belt off and put cover back on and started it up. If I go full throttle, when it maxes out on RPM I start to get the same metal vibrating buzzing sound. I have it up on the center stand and with it at max RPM's the bike does like to try and shake because the center stand is scrapping the cement.

So I have eliminated the clutch and the rear end. I can definitely hear it towards the front of the engine.

Thanks,
Karl

[GrumpyUnk]

If there are metal(muffler/heat shield) or plastic pieces (shroud) that are loose, or missing fasteners, they can make loads of noise at higher rpms. Look for loose things...
tom

[pepi]

I have tried looking but couldn't see anything. It is not coming from the exhaust at all.

[Sir Scoots-A-Lot]

Thanks again Bill and sorry for the late reply.

I have done a cursory cvt inspection just by taking my cover off but I don't have tools to take off my variator or clutch. My belt has good tread and beef left but light cracking in the teeth of I bend them during inspection.

The top speed noise I made this post about sounds like it is unrelated to the idle noise, but I am not so sure. I do suspect the idle noise to be the clutch maybe part of the clutch whatever is under the worn out clutch dampeners hitting the clutch bell? That guess is from reading a thread.

I read another thread that says the top speed noise could also be one or more of the clutch pads or clutch parts hitting the clutch bell but I'm not convinced it's my clutch 100% as my noise also seems to be coming from the front of the engine. If I had to guess by ear I would say its coming from my exhaust and it's somewhat similar to an intermittent heat shield noise I had on my 2001 Subaru forester.

All this being said guys... I think this thread might have the answer :

scooterdoc.proboards.com/thread/7781/gy6-strange-noise-top-speed

Please listen to the video at the bottom of the thread to the very end because I didn't hear the noise until one of the last times the engine/cvt revved up.

On that thread they say a clutch bell and belt replacement solved it and I hope that was all it took cuz that sounds a lot loke my top speed noise. Bill-- do you know if the clutch bearings you had go bad were in the bell? And did your clutch bearings seize completely and eventually halt the scooter from running entirely or were they jist noisy? I have heard that some noises and rattling are fairly normal but im a noob.

Thanks Bill and Tom-- I will check the clutch everything is tight-- for input-- this is how we learn and get to the bottom of scoot issues and upgrades so don't worry about hijacking Pepi. The only dumb questions are the ones you don't ask!

[PirateLabs]

My clutch bearing made a terrible grinding noise when I spun the rear wheel on the stand with the engine off. I was not too concerned about it until I tested a guy's scooter at work just to compare, and his were silent. I mean, the noise on mine did not instill confidence that I would make it to work, or back home. So, I bought a new clutch and installed it. This one sounded worse on my tests. I pulled it off and stuck my index finger in the roller bearing and spun the clutch by hand and I could feel terrible things happening inside. When I pulled my finger out, it had the grease, of course, and, a lot of tiny metal shavings! That grease was loaded with them and, I had never even fired up the engine with this "new" clutch. So, I ordered another one and that one would not even go onto the axle shaft as 2 of the pins in the I.D. were sticking out too far and blocked the shaft from passing inside. So, I tore it apart thinking I could swap the shorter pins from my other "new" clutch and would be good to go. Nope. Turns out, the reason those pins were sticking out too far is because 2 of the 3 holes for those pins where countersunk waaay too deep. The pins were all the same length but this caused them to sit too far inside the I.D. So, I bought another clutch and this one had a really bad weld where the rear pulley is attached and it was so bad, that when I spun it on the axle, the rear pulley run out was about 3/4 of an inch! So, I bought yet another clutch...keep in mind these were all from different vendors, and this one seems fine and I have about 200 miles on it thus far and all is well. I have enough clutch linings to last me 20 years on those bad clutches in my spare parts bin.

So, long story to tell you that no, I never had one fail on the road but, my work commute is 15 miles round trip and if I get stuck I have to push it home and it is 100 degrees here in KY and I just turned 60 so I would like to avoid that if at all possible, ha ha. So, if a bearing makes a bad noise, I replace it, or the component it is in.

Bill

[pepi]

Jul 20, 2018 21:17:05 GMT -5 Sir Scoots-A-Lot said:

Thanks again Bill and sorry for the late reply.

I have done a cursory cvt inspection just by taking my cover off but I don't have tools to take off my variator or clutch. My belt has good tread and beef left but light cracking in the teeth of I bend them during inspection.

The top speed noise I made this post about sounds like it is unrelated to the idle noise, but I am not so sure. I do suspect the idle noise to be the clutch maybe part of the clutch whatever is under the worn out clutch dampeners hitting the clutch bell? That guess is from reading a thread.

I read another thread that says the top speed noise could also be one or more of the clutch pads or clutch parts hitting the clutch bell but I'm not convinced it's my clutch 100% as my noise also seems to be coming from the front of the engine. If I had to guess by ear I would say its coming from my exhaust and it's somewhat similar to an intermittent heat shield noise I had on my 2001 Subaru forester.

All this being said guys... I think this thread might have the answer :

scooterdoc.proboards.com/thread/7781/gy6-strange-noise-top-speed

Please listen to the video at the bottom of the thread to the very end because I didn't hear the noise until one of the last times the engine/cvt revved up.

On that thread they say a clutch bell and belt replacement solved it and I hope that was all it took cuz that sounds a lot loke my top speed noise. Bill-- do you know if the clutch bearings you had go bad were in the bell? And did your clutch bearings seize completely and eventually halt the scooter from running entirely or were they jist noisy? I have heard that some noises and rattling are fairly normal but im a noob.

Thanks Bill and Tom-- I will check the clutch everything is tight-- for input-- this is how we learn and get to the bottom of scoot issues and upgrades so don't worry about hijacking Pepi. The only dumb questions are the ones you don't ask!

Yes, that is the noise I hear when revved all the way up. I hear it pretty quickly in the video and it sort of pulses. I do not think it is my clutch, because I took the belt off and put the cover back on and revved it up and still there.

I cannot rev mine up like that because the scooter shakes so bad, that it trying to "walk" when on the center stand. I have several nice parallel scrapes in the concrete from the center stand "walking" the bike. I do not notice the bike shaking or moving in the video.