Funny noise in higher power range - trying to dial motor in once and for all.

Pancho86

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Ok this is a 100cc motor with an HT carb, it's new and I'd say at least 80 or 90 miles into it's lifespan. I've been very easy on it during all this time trying to break it in correctly.

At first it ran surprisingly well, and then I noticed that it started acting weird in the lower and mid range so I wanted to check the plug and see if it was fouled and that's when I noticed I even had oily residue coming out of the exhaust. So I knew the plug would be fouled, and it was, so I replaced it with an ngk and went with the 7, and adjusted the clip on the carb from the second highest to the highest to lean it out.

After burning all the cobwebs out the plug is now nice and dry and light brown, so all's well on that end, maybe. I noticed that as I get towards the high end it makes a wired buzzing / zinging noise that will fluctuate in pitch and just won't give any more power, even though I know there's more to give. Let me explain:

I use this bike to go back and forth to work on, it's only a little over a mile there. Where I work is a huge complex that asks everyone to drive 20mph and has these little speed signs everywhere that tell you how fast your going, so those have proven valuable during all my trials and tinkering. Right now it's about 23 mph before it starts the noise and 24 is the max. At one point I had 27.

It's got the standard gears that came with it, what is it like a 10/40 or 9/40? I have a 36 rear put up, but I'm not doing anything until I can get this figured out.

There's sometimes where the sound of the engine will be a nice steady growl as you get higher and higher , and there's been a couple times where I can tell it's going faster than the normal 23 or 24, and then the buzzing will start and that's that. My thought is I think I'd like to try a smaller main jet. Does anyone else have any ideas or input. Greatful for all and any.
 
To me it sounds like you could have a slipping clutch. I bought these clutch pads https://www.amazon.com/KQTshangmao-...2lkZ2V0TmFtZT1zcF9waG9uZV9zZWFyY2hfbXRm&psc=1 . They are much better than the red or green ones.

Also follow this to adjust your clutch.
 
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I run a #65 jet for my YD 100's and also drill 3 1/4" holes in the exhaust tip for better performance.
 
Chinese hand grenades make a buzzing/zinging sound before they blow up :LOL:

CG 2t engine are aluminum and engine noises are amplified
Put a dap of grease on the bevel gear and see if that helps
 
Yeah I checked those out and bought a set, couldn't pass it up on the price for 6.99. It's worth a shot, it's just I know these things are capable of so much more than where I'm at, and I'm talking stock. I don't use high speeds very often but I live in a nice size city and there's times where a reliable 27 to 30 would be helpful. I've even seen some 80s do around 30 on all stock parts. As for mony0_3, yeah I was wanting to get into some exhaust mods but I'm not trying to go crazy like I've seen some. BUT before I do anything like that I want to get this power issue straightened out.
I was even looking at that plug color chat and it says im a little on the lean side now. So my only option is the main jet adjustment. Then put my 36t on , then exhaust. To be honest I like that little ht carb it pretty much fires up on no choke every time but usually I have to go about a quarter to a third for about a minute during some of these cold mornings we've had.
 
I admit this is the first time I've ever put one of these things on a bicycle, but I know enough about engines in general that if it sounds funny it probably is funny, so every time that crazy buzzing starts I fall back, because I've thought on several occasions what wrench said about buzzing grenades.
 
I admit this is the first time I've ever put one of these things on a bicycle, but I know enough about engines in general that if it sounds funny it probably is funny, so every time that crazy buzzing starts I fall back, because I've thought on several occasions what wrench said about buzzing grenades.
Well, it seems like you've done some research
 
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