(chinese 2-stroke) Mixture Adjustment - needle - pic

G

gone_fishin

Guest

there are 4 slots on the needle, these are used to adjust mixture

by putting the circlip in a different slot, you're changing the position of the needle (gas) in relation to the slide (air)

1st (top) = leanest setting, not used by many
2nd = common setting for shipping & initial start-up
3rd = seems to be applicable to sea-level or high-flow setups, a pretty rich mixture
4th (bottom) = not used much, but some burn it fine at sea-level
 


spad4me

Member
Joined
Jan 6, 2008
Messages
572
Question where is the needle to adjust the fuel to air ratio

I believe I left it at the factory setting when I installed the throttle slide assembly.

But I don't remember (recognizing) seeing it as an adjustable item.
A small black circlip attached to a brass needle on the slide assembly, Not the larger silver circlip that holds the throttle assembly together.
Please describe in detail where the E-clip fuel mixture adjustment is?
I have seen the pictures of the adjustment at this site using the search function.
Way too close up .
Thanks in advance.
Too windy now but riding soon.
 
E

eltatertoto

Guest
it is the brass pin that is in the throttle assembly, you have to remnove it to set up the throttle cable, it you look VERY close there are notches for the c clip..
 

Instantbacon

New Member
Joined
Feb 25, 2008
Messages
19
I am wondering if I need to readjust my needle. it was working fine, and then I cut the baffle one inch from the exhaust tip to improve performance and now im having problems with my bike. here are the symptoms. with the choke off, the bike will only go if you hold it full throttle, but when its there it cruises around 30 and it doesnt sound bad at all, but the downside is that if you left off it wont go it will just coast to a stop untill you full throttle again.

The only other things I have done is remove the engine (rather lifted it up) so that I could reduce vibration via tubing (it was actually pretty difficult to size the tubing to get the bolts to get past it while still covering the mount bracket).

One more thing, if the choke is fully on it will only go on the lower side of the throttle, and the more throttle you give it the more it bogs down, and then when you let go it revs up even if your hand is off the throttle (kinda scary).

If anyone has any advice I would appreciate it, I dont know if its the bowl, or the needle that needs adjustment.
 
M

mickey

Guest
I am wondering if I need to readjust my needle.
With the baffle cut to reduce backpressure, you could well be running lean. Have you read your spark plug?

If that's all that changed (no sudden air leak in the intake), it would be no big deal to move your carb needle up by moving the C-clip down a notch. Try it and see if it helps. If it gets better, try another notch.
 

Instantbacon

New Member
Joined
Feb 25, 2008
Messages
19
I had a feeling it had something to do with back pressure, and I also thought maybe changing the needle position would help, but I really dont know why I thought that, so I wanted to ask before I adjusted it (Its just kind of a hassle because my bicycle frame has such a small frame triangle that I have to take the carb off because it touches the top). gonna see if it helps!
 

Skyliner70cc

Active Member
Joined
Nov 17, 2007
Messages
1,347
Tip: do not adjust your mixture while on a ride. You are guaranteed for that little e-clip to pop off never to be found again.

I keep my clip on the top notch and use miniature washers to adjust my mixture. It gives me a little more flexibility and allows me to adjust on those long rides if needed. I found it often necessary to fine tune the needle height during break in.
 
M

mickey

Guest
I keep my clip on the top notch and use miniature washers to adjust my mixture.
Now thats clever. Where do you find washers small and thin enough? The would have to be as thin as gear box shims to be equal to moving notch by notch. Do you cut them yourself?
 

Skyliner70cc

Active Member
Joined
Nov 17, 2007
Messages
1,347
I don't know. I've got tons of tiny parts from tearing and repairing electronic items over the years I want to say that the tiny washers cam off of casette tape recorders/players.
 
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