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

[Chainlube]

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.

Don't try to go over 20 for the first three tanks of fuel, after that then you can open it up some. It will get faster too.

 

[Pancho86]

Yeah I'm well over that amount. I normally don't get much over 15ish but occasionally I take it out a ways to see how it's acting at that given moment. Kinda like the ol lady

 

[fivestar45]

Does your carburetor have a slide piston throttle valve, and three fuel circuits ( main jet, needle jet, pilot jet)?

 

[Wyvern]

How old is your mixed fuel? Does it sound like this?

 

[Pancho86]

I'm sorry I somehow missed those last two posts, and I'm not sure if anyone is even watching this anymore, but I have solved some of my problems. By balancing back and forth between the fuel / oil mix, and the clip setting on the carb I'm now pulling 27mph with no prob. I was running a 35 to 1mix when I had the too rich problem, now I'm using a 38 to 1 with the clip in its second highest slot. I'm still having those weird sounds at higher range. When it makes that noise it stops gaining power then it'll smooth out gain some more pull and then do it again. I'm thinking about trying out this other CDI I have. I'm hesitant to go any hotter on the plug number tho. Just figured I'd update this since I did kind of make some progress. For what it's worth.

 

[Wyvern]

I'm sorry I somehow missed those last two posts, and I'm not sure if anyone is even watching this anymore, but I have solved some of my problems. By balancing back and forth between the fuel / oil mix, and the clip setting on the carb I'm now pulling 27mph with no prob. I was running a 35 to 1mix when I had the too rich problem, now I'm using a 38 to 1 with the clip in its second highest slot. I'm still having those weird sounds at higher range. When it makes that noise it stops gaining power then it'll smooth out gain some more pull and then do it again. I'm thinking about trying out this other CDI I have. I'm hesitant to go any hotter on the plug number tho. Just figured I'd update this since I did kind of make some progress. For what it's worth.

Does it sound anything like the video above?

Going down in oil actually leads to slightly richer running.
By the clip's highest spot, do you mean closer to needle tip or closer to the flat end? Putting the clip closer to the flat end will lean out the engine (in the low to med RPM range).

Have you investigated if you have an air leak?


Also, does it do it fully warmed up? I know my engine will "load up" when it is not up to temp, but it doesn't make strange noises ever.

 

[fivestar45]

Well, since you didn't reply to my question I will guess that your carb is some sort of imitation Mikuni. That being said you start tuning from the top down.
So to start center clip on the needle, ride it wide open and change main jets until you get it right. In your case I'd guess you are lean so go up. After that the mid range from 1/4-3/4 throttle is mostly the needle, so adjust as needed.
The pilot jet plays in up 1/4 throttle. And the curb idle is adjusted with the air corrector screw.

 

[Pancho86]

Sorry about not replying to ur question five-star, yeah I have a slide piston throttle but as far as I know the only changeable jet is the main jet. As for the clip position I meant second from the top of the flat piece, and my engine isn't sounding like the video. The only way I can describe it with words is like this: ok you know how when you make a buzzing noise with your lips if you keep your lips tight it's more of a higher pitched buzz and if you relax your lips it becomes a little deeper in tone and and the gaps between each buzz or bubble becomes more pronounce, that's what happens no more power gain during the "bigger bubbles". Sorry about the description I'm not the greatest with words and such.

 

[Nickt919]

As soon as I read buzz I thought engine vibes.

Higher rpm’s create more vibration.
Higher speed takes higher rpm’s to get there.
Buzzing and vibes go hand in hand…one and the same.
If you’re feeling the buzz increase in the grips, seat, pedals as you speed up then tune may not be the issue.

Crank balance vibrations on these engines show up more and more at higher rpm’s. It’s a very common issue.

Short of balancing the crankshaft for higher rpm’s … the 36T may help increase the speed some while keeping the the buzz down at a little higher speed.

But..it’s usually human nature for most to want more speed. So if the 36T quiets the buzz at 25 mph or so.. if you push the rpm’s up the buzz will surface at a little higher speed.

If it is vibes causing the issue it would be best to slow down and not cause it. Vibes are bad.

 

[Pancho86]

Yeah it's not vibes, it's super smooth on that note it's just , idk like I said it's hard to explain. I do have a 36t sprocket put up I've just been waiting to put it on. I almost think it's what they call 4 stroking at some points, sometimes it does it sometimes it doesn't. It just cuts power and does it for a sec then picks up. I've seen what the bike can do it can get way up there I'm sure 30 at least , I only have it officially at 27, it just won't do it all the time.