carb tuning.

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rickie h

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Aug 6, 2009
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can someone tell me in detail as i know very little of engines how to tune my stock carb for max power output?
 

Bikeguy Joe

Godfather of Motorized Bicycles
Jan 8, 2008
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Fairly simple.
Look at your plug. What color is it? Oily and black? That's too rich. Move the small C clip up one notch on the needle that is in the middle of your slide.

If your plug is light gray, or white you will want to move the clip down a notch.

Check your plug after each adjustment.
That's about all there is.
 

freewheeling frank

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Mar 10, 2009
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ridgway colorado
io have found that the jets on these are huge and they run rich i am at 7000+ feet i mean my house is 7g i soldered my jets snd drilled with the smallest bit i could come up with i think it was a 120 were talking the size of a old mans hair and my plug still runs on the dark side but it did make an incredible difference, as i am about 30% of origonal jet size, i run my fuel at 32/1 as with it running lean i want plenty of oil as it gets colder i will try leaning the oil up some and watch it as spring gets here
 

Venice Motor Bikes

Custom Builder / Dealer/Los Angeles
Mar 20, 2008
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Before you try to tune or re-jet the carb, you should finish breaking in the engine by running about 4 gallons of gas though it, & if you plan to make any changes like a smaller sprocket & expansion chamber pipe, do them all first!! Otherwise, you'll have to re-tune it again!!
 

rickie h

New Member
Aug 6, 2009
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usa
Fairly simple.
Look at your plug. What color is it? Oily and black? That's too rich. Move the small C clip up one notch on the needle that is in the middle of your slide.

If your plug is light gray, or white you will want to move the clip down a notch.

Check your plug after each adjustment.
That's about all there is.
yay!but whats a slide and where is it

.bf.
 

BarelyAWake

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Jul 21, 2009
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and when reassembling make sure the slot on the side of the slide lines up w/the lil pin on the inside of the carb else it'll jam;

 

rickie h

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Aug 6, 2009
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ok so i moved my c clip up one and my bike now starts harder,dies if clutch is initiated and let go of, and runs for a short while before dying,is this normal and will it subside or did i mess something up?
 

BarelyAWake

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Jul 21, 2009
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The spark plug has a story to tell, you should listen to it before any of us ;)

Fairly simple.
Look at your plug. What color is it? Oily and black? That's too rich. Move the small C clip up one notch on the needle that is in the middle of your slide.

If your plug is light gray, or white you will want to move the clip down a notch.

Check your plug after each adjustment.
That's about all there is.
It could be that yer bike was just cold, as you made the mix leaner - you'd need the choke (which makes it richer) to start it and keep it runnin' till the engine warms up... and/or yer idle is just set too low...
 

rickie h

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Aug 6, 2009
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does the little c clip go above or below the big c shaped washer thing? i have managed to get it started a few times but it dies instantly when throttle is given
 

Bikeguy Joe

Godfather of Motorized Bicycles
Jan 8, 2008
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up north now
O.K. The clip goes UNDER the big pac man washer.
Put the clip back to the original position where it was before you started, and run the bike.

Read my signature...
 

Bikeguy Joe

Godfather of Motorized Bicycles
Jan 8, 2008
11,837
252
63
up north now
You said you changed it and then it wouldn't run right. If you change it back, then it will run right.

Start at the second down from the upper most groove or notch.
 

rickie h

New Member
Aug 6, 2009
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usa
oh you mean the position on the needle i thought you ment which way it was facing or something ok i see now.
 

hartungej

New Member
May 31, 2011
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Madison, WI
Hello-I realize this thread is old, but hoping someone will respond.

It looks like my adjustment needle is missing! I guess mine cannot be tuned? Is there a way to get just a needle?
 

s_mullee

New Member
Aug 8, 2011
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Madison
This thread seems to be close to the issue I am having. My throttle does not function. I just installed my Jet 66cc/ 80cc kit. It works but the throttle does not. I am able to use the thumb gear shifter to increase the speed then shift down to slow down. The throttle spins but has no impact on the idle.

The kit I got had this part already assembled. There is a small kink in the line that could be the problem but I am not sure how to check it. I guess I would like to know exactly how the throttle should be working with the carburetor. I disassemble that part and make sure it is working properly. If that is assembled properly then I can examine the kink to determine if it is the cause.
All advice is appreciated.