Need help Tuning 49cc Carb - Pocket Bike Forum - Mini Bikes
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post #1 of 45 (permalink) Old 05-02-2009 Thread Starter
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Need help Tuning 49cc Carb

I need some help on how to tune this 49cc carbs. I am talking about the carbs with the mixture screw that be on x2 and stuff. I have one of this carbs on my gas scooter but i am not sure on how to tune it. Like how many turns do i need to do to the mixture screw? What is the mixture screw for? I trying to get my scooter to run top notch but just not sure on how many times i got to turn the mixture screw.

It also bogs a little during mid-throttle going to full throttle.
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post #2 of 45 (permalink) Old 05-02-2009
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Re: Need help Tuning 49cc Carb

turn ur screw clockwise til all springs r touching each other, then counter screw it 2 1/2 - 3 turns back see if that works, the more u clockwise it, the more ur engine will shut off from WOT ( wide open throttle)
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Re: Need help Tuning 49cc Carb

Alright i will give that ashot
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post #4 of 45 (permalink) Old 05-02-2009
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Re: Need help Tuning 49cc Carb

Ok what you want to do is you need to tune it with a load on it. so you have to ride to WOT and stop and adjust.
Like DiceLimit said start at 2 1/2 turn out ride to WOT stop turn the mixture screw to the left a 1/8th turn ride to WOT stop adjust 1/8th turn. Now you will want to keep doing this until the motor sputters at WOT than turn in back in to the right 1/8th turn and it should be tuned. I hope that if that bike was stored with old gas in it that you cleaned the tank and lines before you start riding it?



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Re: Need help Tuning 49cc Carb

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Originally Posted by StrayDawg63 View Post
Ok what you want to do is you need to tune it with a load on it. so you have to ride to WOT and stop and adjust.
Like DiceLimit said start at 2 1/2 turn out ride to WOT stop turn the mixture screw to the left a 1/8th turn ride to WOT stop adjust 1/8th turn. Now you will want to keep doing this until the motor sputters at WOT than turn in back in to the right 1/8th turn and it should be tuned. I hope that if that bike was stored with old gas in it that you cleaned the tank and lines before you start riding it?
I tried that.. I got it to work sort of.. But now i am having a problem.. Like when i crank it up i have to have the choke on.. Then i ride it for alittle turn it off.. And when i re-crank it up i have to have the choke on in order for it to start up then i have to turn it off.. Witch is not rite.

Another problem i notice is when i am just about to start off going it will bog out on low end. I didnt have the air filter/cover on there when i was riding could that be a problem?

Also this is a scooter not a midbike.. Just posted it here sense it has the same kind of motor as a x1,x2 a 49cc
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post #6 of 45 (permalink) Old 05-02-2009
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Re: Need help Tuning 49cc Carb

Does that carb have 2 mixture screws or just 1? If it just has the 1 mixture scew make sure the brass colored straight head screw on top of the carb is screwed in all the way. What's the idle like?



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Re: Need help Tuning 49cc Carb

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Originally Posted by StrayDawg63 View Post
Does that carb have 2 mixture screws or just 1? If it just has the 1 mixture scew make sure the brass colored straight head screw on top of the carb is screwed in all the way. What's the idle like?
The carb has 1 mixture screw at the bottom. and a Idle screw at the top. I did screw the mixture screw all the way in and it did not start. So i had to unscrew it out alittle..

The idle seems fine at times then sometimes it wont idle good.

Do i need the airfilter/cover on there? Could that be the problem? To much air is getting inside the carb causing it to bog out?
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post #8 of 45 (permalink) Old 05-03-2009
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Re: Need help Tuning 49cc Carb

I think you misunderstood me. If you look at the idle screw and than look at the very center of the top of the carb there is a brass colored straight headed screw that looks like it has a hole in the center of it make sure it is screwed in all the way.
So where did you end up with the mixture setting like how many turns out? Yes you should have a air filter on there and not because it sucks in to much air. Because it may suck in some crap that may harm your motor. So get yourself a V-stack with a choke and air filter for it. If it is bogging at the bottom end it's to lean. Also turn the idle up some.




Last edited by StrayDawg63; 05-03-2009 at 01:27 AM.
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Re: Need help Tuning 49cc Carb

Ohh my bad.. I did unscrew that brass screw a few days ago.. But i didnt tighten it back up really tight. Do i need to have it real tight?

Alright I will put the airfilter back on. So removeing the air filter isnt my problem?

I think i let the fuel mixture screw about 2 turns out and 1/2.. I stop after that because it kept bogging at low end.. Another thing is why do i have to have my choke on in order to start the scooter up if the scooter motor is already warmed up? Because it wont start up without it on.
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Re: Need help Tuning 49cc Carb

Just screw that screw on top in all the way in it doesn't need tobe tight like a lug nut if you know what I mean. That screw on top is kinda like your needle in your carb on your cag where you adjust the clip in the notches. It can be adjust any where from all the way in to about 1 1/2 turns out.

I think you better check for a intake leak since you have to have the choke on every time you go to start it just to rule it out if anything else.



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post #11 of 45 (permalink) Old 05-03-2009 Thread Starter
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Re: Need help Tuning 49cc Carb

The intake i sealed it up with some 98H some thats fine. I believe my problem is the fuel line is too short and not getting down in the gas tank. So i am going to buy a longer fuel line.
Because i know it not getting enough gas in the primer bulb because when i pump it i dont feel the gas going in there. But when i stick the fuel lines in a gas can with gas in it and pump it i feel the gas going into the primer bulb. So i am thinking my fuel lines are to short and not getting deep enough in the gas.

Now its just hard to find this small weedeater fuel lines. I think a lawn mower shop might sell them. Witch i am going to go check out 2morrow
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Re: Need help Tuning 49cc Carb

Check out DDM if you order it today you will most likely have it by wednesday plus you will beable to pick out a colored fuel line.




Last edited by StrayDawg63; 05-03-2009 at 08:09 PM.
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Re: Need help Tuning 49cc Carb

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Originally Posted by StrayDawg63 View Post
Check out DDM if you order it today you will most likely have it by wedsday plus you will beable to pick out a colored fuel line.
Yeah i was going to order it but i rather if i can get it local.. Because i wont have to pay for shipping and handling fee's
But hmm does that sound like what i said is my problem with it not running?
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Re: Need help Tuning 49cc Carb

Yes very well could be. I don't think you will beable to find it locally not atleast see through fuel line. Most likely all you will find is some vacume line at a auto parts store or even at a lawnmower shop. Because they don't sell clear fuel line by the foot just by a part # that is precut for which ever small motor it would go to, But they will have some black stuff which will still work but no cool factor with having a colored line you know.



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post #15 of 45 (permalink) Old 05-03-2009 Thread Starter
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Re: Need help Tuning 49cc Carb

Well matter of fact all the local auto zone don't have the size. I am not sure what size fuel line it is in diameter. I seen a clear fuel line but i am not sure if its the right diameter it didn't look like it. That was at advance auto i think. But i check a few auto stores and they didn't sell nothing that small.

But the lawn mower shop should have something. Yah i know that sucks but its just a fuel line doesnt really matter..

If i order from davemotor its going to be 7 buxs to ship to me! And the item is like 1 dollar or soo. But i emailed him asking if he can ship it a cheaper way.
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Re: Need help Tuning 49cc Carb

The size is 5/32" and if you look for a vacume line you should find it at a auto parts store.



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Re: Need help Tuning 49cc Carb

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Originally Posted by StrayDawg63 View Post
The size is 5/32" and if you look for a vacume line you should find it at a auto parts store.
Hmm are you sure its that size for this kind of carb
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Re: Need help Tuning 49cc Carb

Yes I'm sure it's the size for that carb. If you have a 5/32" drill bit slip the fuel line you have on it if you don't beleive me. That's what I always use for those carbs.
Now the vacume line maybe bigger on the outside than the fuel line your using now.




Last edited by StrayDawg63; 05-03-2009 at 08:53 PM.
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post #19 of 45 (permalink) Old 05-03-2009 Thread Starter
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Re: Need help Tuning 49cc Carb

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Originally Posted by StrayDawg63 View Post
Yes I'm sure it's the size for that carb.
Alright thanks. for the help..
I will update the thread when i get a new fuel line to see if that's my problem.
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Re: Need help Tuning 49cc Carb

Just so you know the inlet is 5/32" and the return line is 1/8" but I just wrap a zip tie around the inlet and return as a clamp and it will stay put and seal and will shrink to return. I don't think it's worth getting 2 different sizes you know.



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