Bike won't idle

9679 Views 21 Replies 4 Participants Last post by X7 Brap, Sep 28, 2012

patthehat033

Discussion Starter · Sep 23, 2012

Hi,

I haven't started up my X7 Pocket bike, in months. So I took it a part and cleaned out all the jets and the rest of the carb and got it so it will start up. I also replaced the spark plug.

I cannot seem to get it to idle. I have tried the fuel mixture screw on the carb in about a million different positions. I have also tried the idle screw a million different ways. I also adjusted the float to where it was set before, which is just slightly lean.

I can only get the bike to idle when the choke is fully on. I had this problem about a year ago, and I thought it was because the bike was running too lean but apparently it was running to rich.

Do you think it is possible I need to adjust the throttle needle to a different position?

Any help is needed! Thanks!

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CAM2

· #2 · Sep 23, 2012

Sounds like you need to richen the float setting...sounds like its too lesn now........What are you using for fuellines and have you taken the time to wassh out the tank? ethanol is evil stuff and once it goes bad and gumms up the carb chances are the tank,,filter and lines are too........

Id try cleaning the carb,,tank and lines again aswell as changing the sparkplug.....Good luck

patthehat033

Discussion Starter · #3 · Sep 23, 2012

Sounds like you need to richen the float setting...sounds like its too lesn now........What are you using for fuellines and have you taken the time to wassh out the tank? ethanol is evil stuff and once it goes bad and gumms up the carb chances are the tank,,filter and lines are too........

Well after I cleaned the carb I did not adjust the float setting and it was set quite rich. That is when the bike finally started up but would not idle unless the choke was on. So I adjusted the float so it was set slightly lean. It is still experiencing the same problem. So I am thinking maybe the little throttle needle needs to be either set leaner or richer.

I have 1/4" (I believe) clear fuel line. I have washed out all the old gas from the tank. The fuel line looks clean as can be.

Everything is pretty much cleaned I think it is probably an adjustment problem on my part haha.

CAM2

· #4 · Sep 23, 2012

patthehat033 said:
Sounds like you need to richen the float setting...sounds like its too lesn now........What are you using for fuellines and have you taken the time to wassh out the tank? ethanol is evil stuff and once it goes bad and gumms up the carb chances are the tank,,filter and lines are too........

Well after I cleaned the carb I did not adjust the float setting and it was set quite rich. That is when the bike finally started up but would not idle unless the choke was on. So I adjusted the float so it was set slightly lean. It is still experiencing the same problem. So I am thinking maybe the little throttle needle needs to be either set leaner or richer.

I have 1/4" (I believe) clear fuel line. I have washed out all the old gas from the tank. The fuel line looks clean as can be.

Everything is pretty much cleaned I think it is probably an adjustment problem on my part haha.

If your carbs set rich and still needs to run with the choke on then you have an airleak somewhere

patthehat033

Discussion Starter · #5 · Sep 24, 2012

CAM2 said:
If your carbs set rich and still needs to run with the choke on then you have an airleak somewhere

I was thinking that, but I didn't notice any leaks.. that I at least didn't already have in the past..

patthehat033

Discussion Starter · #6 · Sep 24, 2012 (Edited)

CAM2 said:
If your carbs set rich and still needs to run with the choke on then you have an airleak somewhere

Okay so you may be on to something. I have always had to have the fuel mixture screw almost all the way in for it to idle pretty good. Unfortunately the bike won't idle. So today I decided to back out the mixture screw a few turns and I noticed fuel started surrounding the threads. Could this be the source of my air leak? And how can I fix this?

CAM2

· #7 · Sep 24, 2012

patthehat033 said:
Okay so you may be on to something. I have always had to have the fuel mixture screw almost all the way in for it to idle pretty good. Unfortunately the bike won't idle. So today I decided to back out the mixture screw a few turns and I noticed fuel started surrounding the threads. Could this be the source of my air leak? And how can I fix this?

Thats an indication of a float set too rich....Only air should pass through that circuit til the atomizer tube........

Make sure the plastic isolator is in correctly and the o-rings are good on both the isolator and the carb aswell as make sure the isolator isnt cracked,,,,,,,,The o-ring on the isolator should face the intake flange and the o-ring on the carb facing the blank side of the isolator..

With the bike running spray carb cleaner at the intake base and the carb connections to see if you get a change in idle pitch...If so you have an airleak and an improperly set float combo...............

EPR

· #8 · Sep 24, 2012

What does your spark plug look like wet. Gas should not come out the air mixture screw, I am pretty sure. There is all kinds off stuff in gas that gums up. On my new 125cc ATV I cleaned the pilot jet and 2 weeks later it was dirty had to clean it again, If you let gas sit in your carb to long it will gum up everything. The pilot jet is very small .020" or so.

patthehat033

Discussion Starter · #9 · Sep 24, 2012

CAM2 said:
Thats an indication of a float set too rich....Only air should pass through that circuit til the atomizer tube........

Make sure the plastic isolator is in correctly and the o-rings are good on both the isolator and the carb aswell as make sure the isolator isnt cracked,,,,,,,,The o-ring on the isolator should face the intake flange and the o-ring on the carb facing the blank side of the isolator..

With the bike running spray carb cleaner at the intake base and the carb connections to see if you get a change in idle pitch...If so you have an airleak and an improperly set float combo...............

Wait I thought that was the screw to adjust the fuel not air?

Also is it safe to spray carb cleaner at the base of the intake if it is running? lol

EPR

· #10 · Sep 25, 2012

Make sure the isolater O ring is facing the intake manifold. I cracked on e of mine by over tighten the carb bolts. WD40 might work too. The air screw controls how much air mixes, I believe. If you spray for an air leak and it gets sucked into the engine it will make it run faster. Your pilot jet is for idle and the main jet for high speed, there is a permanent Choke jet too.

patthehat033

Discussion Starter · #11 · Sep 25, 2012

EPR said:
Make sure the isolater O ring is facing the intake manifold. I cracked on e of mine by over tighten the carb bolts. WD40 might work too. The air screw controls how much air mixes, I believe. If you spray for an air leak and it gets sucked into the engine it will make it run faster. Your pilot jet is for idle and the main jet for high speed, there is a permanent Choke jet too.

I don't believe mine is a air screw, it is on the intake side of the carburetor. That is why I am confused.

CAM2

· #12 · Sep 25, 2012 (Edited)

patthehat033 said:
Wait I thought that was the screw to adjust the fuel not air?

Also is it safe to spray carb cleaner at the base of the intake if it is running? lol

Fuel is picked up through the pilot and mainjet by vacuum pressure through the a/f channel and its fed by metered force up to the venturi by the 6 side holes in the pilot jet and 20 tiny holes in the atomizer tube and is metered by the a/f mix screw....Thats why its important the 6 and 20 tiny holes are clean and clear....I have a mod for the mainjet atomizer tube that adds fuel pressure to the venturi for a positive power burst........

The air comes through a small channel hole in the carb inlet mouth that goes through the a/f screw circuit to mix with the fuel at the pilot jet and mainjet atomizer tubes to get a pre-metered rate of atomized fuel to mix with the inrush of main air going through the venturi.........

If you shut off all 6 and 20 side holes in the atomizer tubes in both the carb will not get any fuel....The mainjet atomizer tube comes in a few configurations too from 20 holes down to 6 holes...the larger amount of holes is used for 4 stroke and the lesser holes for 2 stroke.........The pilot stays at 6 holes and goes to 4

Its relatively safe to spray carb cleaner around the intake and carb while the engine is running...one time I burned a hole in my gastank from an exhaust leak and the bike never ignited luckily..LOL

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patthehat033

Discussion Starter · #13 · Sep 25, 2012

CAM2 said:
Fuel is picked up through the mainjet by vacuum and its fed by metered force up to the venturi by the 20 tiny holes in the atomizer tube and is metered by the a/f mix screw....

The air comes from a small channel in the carb inlet that goes through the circuit to mix with the fuel at the atomizer tube to get a pre-metered rate of atomized fuel to mix with the inrush of main air going through the venturi.........

If you shut off all 20 side holes in the atomizer tube the carb will not get any fuel....The atomizer tube comes in a few configurations too from 20 holes down to 6 holes...the larger amount of holes is used for 4 stroke and the lesser holes for 2 stroke.........

Its relatively safe to spray carb cleaner around the intake and carb while the engine is running...one time I burned a hole in my gastank from an exhaust leak and the bike never ignited luckily..LOL

Doesn't the main jet only release fuel when the throttle needle is disengaged from the hole? I thought at idle the pilot jet was doing most of the work, and I also thought the fuel mixture screw was located in the pilot jet circuit, that gets mixed with air coming in from a small port in the front of the carburetor, which is not restricted by any mixture screws. Then the fuel mixture screw is located above the pilot jet tube, regulating fuel.

Or is that wrong? That's why it makes sense to me that the fuel mixture screw is leaking fuel from the screw threads, even though that is supposed to be fuel and air tight. Which in return would fudge up the mixture.

CAM2

· #14 · Sep 25, 2012

patthehat033 said:
Doesn't the main jet only release fuel when the throttle needle is disengaged from the hole? I thought at idle the pilot jet was doing most of the work, and I also thought the fuel mixture screw was located in the pilot jet circuit, that gets mixed with air coming in from a small port in the front of the carburetor, which is not restricted by any mixture screws. Then the fuel mixture screw is located above the pilot jet tube, regulating fuel.

Or is that wrong? That's why it makes sense to me that the fuel mixture screw is leaking fuel from the screw threads, even though that is supposed to be fuel and air tight. Which in return would fudge up the mixture.

Go back and re-read my last post...i revised it a bit.............

patthehat033

Discussion Starter · #15 · Sep 25, 2012

Ah okay I understand it now. I got all those holes in the pilot and main jet really clean, when I cleaned the carburetor before. I also did your mod about a year ago.. if you are referring to the safety pin mod.

By closing that a/f mixture screw almost all the way I am probably restricting almost all of the mixture from coming through. If I open the screw to much it will probably not do much since fuel is coming through the threads. Do you think if I threadlock those threads on the screw, that it will close up that leak and maybe make it run a little more smoothly?

Also I would like to make the carb cleaner spray a last resort as my parents will be quite mad if I light the house up in flames trying to test for an air leak on my pocket rocket..

EPR

· #16 · Sep 25, 2012

Maybe you have an internal problem inside the carb.

CAM2

· #17 · Sep 25, 2012 (Edited)

patthehat033 said:
Ah okay I understand it now. I got all those holes in the pilot and main jet really clean, when I cleaned the carburetor before. I also did your mod about a year ago.. if you are referring to the safety pin mod.

By closing that a/f mixture screw almost all the way I am probably restricting almost all of the mixture from coming through. If I open the screw to much it will probably not do much since fuel is coming through the threads. Do you think if I threadlock those threads on the screw, that it will close up that leak and maybe make it run a little more smoothly?

Also I would like to make the carb cleaner spray a last resort as my parents will be quite mad if I light the house up in flames trying to test for an air leak on my pocket rocket..

The carb cleaner is safe...you wont light the house up if you spray it outside..You dont spray a whole can,,,just a couple of 1 second bursts..Airleaks are the worst to have...You can get an airleak from the carb top if you dont have the rubber boot on the carb top at the cable nice and tight,..you can also get an airleak from shrunken o-rings thats why I RTV my o-rings into my isolator and carb

As far as the gas coming through the screw threads..only thing that comes to mind is the float setting being too rich,,,....

Tilt the bike on its sidewalls of the tires like youre turning sharply..If the carb overflows the float is set too rich

When you did the atomizer tube mod did you reshape the holes into a funnel shape or did you poke them through and enlarge the inner hole size....?

The mod wasnt to make the whole physical hole size larger...The mod is to reshape the holes funnel shaped only so it cuts down the time through the thick brass atomizer tube body wall and adds a lil velocity to get a better atomized mix up to the venturi.....if you even enlarged the inner part of the hole just a lil bit youre gonna have to take superglue and block off atleast 2-4 holes at the bottom of the atomizer to compensate....That will give you some more adjustment on the a/f screw

At one time if I remember correctly...Didnt you buy a supercoil?,,,If so i would install it to get a stronger spark to burn the heavier mix youre getting and see if it helps.................

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X7 Brap

· #18 · Sep 25, 2012

Think I need to check my tank for melts rofl

My x7 evejn has an exhaust leak and I don't have that idle problem. Only 2 adjustments I made on the brand new carb was a slight idle screw tweak or 2 and the fuel screw 1/4 - 1/2 turn out (from factory position). I might go a little richer still. The bike idles fine after ~30 seconds of warm up and after riding. I went from 36:1 to 50:1 and it seemed a little less boggy when taking off. By the way I had a half tank sitting in it for probably 5 years or more.. I dumped it after winter this year and just poured in fresh, it ran. All I did since then was replace the carb. I'm not saying it's a bad idea to clean the tank, lines, and carb if you had bad gas in it though. lol

There's a thread on cleaning the carb. I'd probably put a new plug in it and put the carb back to stock adjustments and go a little richer from there.

EPR

· #19 · Sep 26, 2012

He has a 4 stroke w/ 19mm piston carb.

X7 Brap

· #20 · Sep 26, 2012

Didn't say in the 1st post. On my klx 125 it had to be choked alot before I went up from a 17.5 to a 22.5 pilot jet to get a smooth idle. and it warmed up faster. The fuel screw and idle would only do so much for idle and would idle rough with the pilot jet too lean. Even stock it was like that, and then I had piped it and stuff.

I'm sure the china 110's come lean from the factory if the jap bikes do. It's for emissions aka the co2 that plants eat and breath. But if you pay a carbon tax to a world bank, that solves the problem.

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