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Discussion Starter · #1 ·
How do I tune this carburetor to the area that I am currently in which is Toronto, Canada?

The bike used to run fine but I could tell it could use some tuning. Now when I am riding it, It will shut off alot like every 100 meters or so and will be a pain to start back up. I need it tuned back so this doesnt happen and that it runs at top speed

Also, what settings does the throttle cable needle be at if the tip of the needle is the "top"?


 

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How do I tune this carburetor to the area that I am currently in which is Toronto, Canada?

The bike used to run fine but I could tell it could use some tuning. Now when I am riding it, It will shut off alot like every 100 meters or so and will be a pain to start back up. I need it tuned back so this doesnt happen and that it runs at top speed

Also, what settings does the throttle cable needle be at if the tip of the needle is the "top"?




Theres a restrictor tab in that carb in the bottom of the bowl that needs to be removed with a dremel...The tab holds the float too high so the fuel just dribbles past the needle causing a fuel starvation problem when coming off the throttle after a highspeed run.......



after you remove the restrictor tab set the c-clip on the needle to the 4th notch,,float at 10 degrees and the a/f mix screw to 2 1/2 turns out.....
 

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I would drop the float bowl and check your inlet needle, float height, and clean your pilot and main jet.
 

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Discussion Starter · #4 ·
I cleaned everything so far, i dont have a dremel or anything to grind away the tab but I know what you are talking about.

-The needle being 4TH from the top, is the top the needle tip or the other side?

-The air/fuel mixture screw, is that the screw on the angle or the one that sticks straight out?

-How do I set the idle screw?
 

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I cleaned everything so far, i dont have a dremel or anything to grind away the tab but I know what you are talking about.

-The needle being 4TH from the top, is the top the needle tip or the other side?

-The air/fuel mixture screw, is that the screw on the angle or the one that sticks straight out?

-How do I set the idle screw?
From the blunt end of the needle is considered the top,,,The sharp end is the tip and the bottom...the slots go from 1-5,,bluntend to sharp tip,,,1 is leanest setting and 5 richest setting........seeings its getting cooler out you want the 4th notch....[second from richest setting]

The a/f screw is to the left of the idle screw and is slotted...the phillips screw with the spring to the right is the idle screw

the idle screw should be set to 1500 rpms and can be set by ear.........

the a/f factory setting is 2 full turns out,,seeings its getting cooler out youll most likely tune-in at 2 1/2..............
 

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Discussion Starter · #8 · (Edited)
I also have another potential issue, before I used to cold start the bike with the level for choke in the OFF position and when I wanted to ride, I twisted it up to ON. Now the bike bogs out when I try riding with the chock ON and rides barely without shutting off in the OFF position.

And when I tune the carb, should I have the choke in the ON or OFF position (based on what I said above)?
 

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Youre supposed to be riding and tuning with the choke knob down[off]..choke on is only for cold start ups..............
 

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Float could be set too lean or the pilot jet partially dirty also......
Even with the float restrictor, it will run fine for a few seconds before it starts acting lean. And he already said that he cleaned the carb.

Sorry, I should have said:

If it only runs well with the choke on, then there is not enough fuel entering the engine. This is usually caused by to small of a jet, but can also be caused by partially clogged jets, or incorrect float level.

Jets can be found here: http://www.scooterparts4less.com/web_gas/4Stroke_Jet_pack.htm
$13.50 for a set of 6 main jets to tune with.

You can get small drill bits and try to drill the jet(s) you have, but you will usually end up breaking the bit(s), and it is more of a pain than it is worth...
 

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My new 125cc ATV, the pilot jet clogged right away, I changed from a 20mm China carb w/ no air idle screw to a Japan carb, drilled the pilot jet and main jet one size bigger, two weeks later had to pull the bowl and the pilot jet was dirty already. In California the run 10 percent alcohol in the gas in the summer, and that don't help the cheap China rubber,lol.
 

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My new 125cc ATV, the pilot jet clogged right away, I changed from a 20mm China carb w/ no air idle screw to a Japan carb, drilled the pilot jet and main jet one size bigger, two weeks later had to pull the bowl and the pilot jet was dirty already. In California the run 10 percent alcohol in the gas in the summer, and that don't help the cheap China rubber,lol.
They lie and say 10% ethanol...Its up to 22 percent blend now around here....Their goal is to fudge up carbs and the older fuel injection systems to get rid of them vehicles...good thing my 91 F250 has an MSD ignition that will burn anything cleanly and an ethanol resistant fuel regulator.........
 

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Even with the float restrictor, it will run fine for a few seconds before it starts acting lean. And he already said that he cleaned the carb.

Sorry, I should have said:

If it only runs well with the choke on, then there is not enough fuel entering the engine. This is usually caused by to small of a jet, but can also be caused by partially clogged jets, or incorrect float level.

Jets can be found here: http://www.scooterparts4less.com/web_gas/4Stroke_Jet_pack.htm
$13.50 for a set of 6 main jets to tune with.

You can get small drill bits and try to drill the jet(s) you have, but you will usually end up breaking the bit(s), and it is more of a pain than it is worth...
Indeed...I use a small safety pin to enlarge my jets....The brass is so soft it reshapes quite easily but having the jetkit is optimal because once you drill or pin the jets you cant go back...........
 

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Discussion Starter · #16 ·
im gonna tinker around with it tomorrow when I get home. if there is no upgrades on this bike except for a air filter, why would it need bigger jets then what it comes with?
 

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im gonna tinker around with it tomorrow when I get home. if there is no upgrades on this bike except for a air filter, why would it need bigger jets then what it comes with?
Because the bike was jetted in China and not jetted for the current temps or altitude..When I lost my airbox and added a hp foam airfilter NGK sparkplug I had to up the jet from the stock 73 to 75....After the hp sparkwire,,race CDI and head breather mod I had to up the mainjet to 78...Youll be surprised how much restriction the stock snorkle box has...........

Even brand new Japan dirtbikes and such dont run right straight out of the crate...thats why you pay a preperation fee........They put it together,,change out the shipping oil and get it jetted right and running smoothly................
 

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Discussion Starter · #18 ·
i dont have the bike tuned yet so would that affect the jets? my X7 has the choke on the handlebar on this tab throttle like thing where i use my tub to push it up or down. Do I tune the bike with the choke to the OFF position or the ON position?
 

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i dont have the bike tuned yet so would that affect the jets?
Getting your jetting correct is part of the tuning process. Even if the bike was still bone stock, with the stock filter setup, If the air density changes enough, you need to change the jetting to remain at optimal performance. Jetting is not a 'set it and forget it' thing.

And, as was said before, You tune with the choke OFF.
 
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