Question about 2003 Hyosung RX 125

3 Answers

Accelerator stuck open

Hyosung rx 125. after storage for one year the engine starts but races like the throttle is fully open. I've cleaned out the carb and checked the cables but the problem is still there.

Posted by on

3 Answers

  • Level 1:

    An expert who has achieved level 1.


    An expert whose answer got voted for 20 times.


    An expert that has over 10 points.


    An expert whose answer got voted for 2 times.

  • Contributor
  • 18 Answers

This has happened to me before, and i know just what the problem is. Under the fuel tank, the throttle cable goes into a plastic cable housing, and sometimes the cable guard gets stuck out of the housing, causing the throttle to be constantly open. Just take off the tank, follow your throttle cable to find where it's stuck and release it.

Posted on Jun 15, 2009

  • Level 3:

    An expert who has achieved level 3 by getting 1000 points


    An expert that got 20 achievements.


    An expert that got 10 achievements.


    An expert that got 5 achievements.

  • Master
  • 3,567 Answers

An air leak will cause this type of problem. I assume the carb slide is moving up and down freely. Try tightening the carb manifold bolts and the carb mounting bolts. The carb and manifold gaskets may need to be replaced. Spark plug tight? Cylinder head tight? > any oil stain on the cooling fins where the head meets the cylinder = bad head gasket or the head isn't tight. Valves set with correct clearance? Find the air leak and fix it. :)

Please rate this solution when the problem is fixed. Thanks!

Posted on May 21, 2009

  • Level 2:

    An expert who has achieved level 2 by getting 100 points


    An expert that got 5 achievements.


    An expert whose answer got voted for 20 times.


    An expert who has answered 20 questions.

  • Expert
  • 36 Answers

Chances are the piston that is inside your carb is sticking. This happens when vehicles sit and dirt, grime, whatever gets built up. This piston has to be able to move completely unrestricted. I would recommend removing the carb and completely disassembling it, cleaning it which would include lightly rubbing the cylinder wall that the piston moves up and down in to remove anything that may cause the piston to hang up. I hope this helps and please do not forget to rate me.

Posted on May 21, 2009

1 Suggested Answer

  • 2 Answers

SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

a 6ya expert can help you resolve that issue over the phone in a minute or two.
best thing about this new service is that you are never placed on hold and get to talk to real repairmen in the US.
the service is completely free and covers almost anything you can think of (from cars to computers, handyman, and even drones).
click here to download the app (for users in the US for now) and get all the help you need.

Posted on Jan 02, 2017

Add Your Answer

Uploading: 0%


Complete. Click "Add" to insert your video. Add



Related Questions:

1 Answer

Took the airbox out my hyosung rx 125 and fitted a pollini air filter starts and drives but when I hit 35-45mph it starts sort of sputtering tried adjusting rev screw but nothing still does the same??

Hi, Ricky if you have changed your fuel delivery system, air filter size or flow rate, mufflers or exhaust system or a significant change in altitude your carburetors need re-tuning and if your fuel system (gas tank, filters, fuel valve and carburetor) is contaminated with ethanol sludge, varnish, rust, dirt, water etc. or your bike has been sitting for months or years without running these components must be "PROPERLY" cleaned and reassembled "CORRECTLY" before any adjustments can be made. Tuning your carburetor is fairly simple once you understand the basic principals. You engine is a simple airbox sucking air in and blowing it out, it is finely tuned at the factory for maximum performance once you upset that delicate balance by changing air filters, camshafts or exhaust systems your performance may go down the and the engine may run poorly, you need to compensate the air-fuel mixture in the carburetor in order for the engine to run smoothly and at peak performance. If you are running multi carburetors you need to sync them first and make sure your air cleaner element is clean and dry for paper elements or lightly oiled for foam and meshed elements and properly installed. Here is how and where you compensate trouble: "TIP" if your engine "BOGS" your not getting enough fuel.
1. Closed to 1/8 throttle is managed by the air screw and pilot/slow jet.
2. 1/8 to 1/4 throttle is managed by the air-screw, pilot/slow jet, and throttle slide.
3. 1/4 to 1/2 throttle is managed by the throttle slide and jet needle.
4. 1/2 to 3/4 throttle is managed by the jet needle, needle jet, main jet, and air jet.
5. 3/4 to wide open throttle is managed by the main jet and air jet.
6. Wide open throttle is managed by the main jet.
If you are running lean, spark plug electrode color is white, engine runs hot and feels like it is starving for fuel you need to go up on the jet size or move the c-clip down one notch. If you are running rich, spark plug color is black or dark gray, engine runs cool, and bogs down when accelerating you need to go down on jet size or move the c-clip up one notch. When your carburetor is properly tuned for maximum performance your spark plug electrode will be a light tan color like coffee with cream. If you prefer fuel economy over performance you can go down on main jet sizes until a satisfactory level of lower performance is acceptable versus MPH, your spark plug color will be whiter and your engine will run warmer. These tuning adjustments will only make improvements if your intake and exhaust system have no air leaks or sealing issues and the entire electrical system is in proper working order and you have no mechanical issues. For more information about your issue and valuable "FREE" downloads that you will need please click on the websites below. Good luck and have nice a day.
How to remove welch plug air fuel screw cap from any motorcycle or small...
Carburator Theory and Tuning
Life On 2 Wheels
HYOSUNG RX 125 Service Manual
HYOSUNG RX 125 Parts Catalog

Apr 12, 2017 | 2002 Hyosung RX 125

1 Answer

My grandson got a hyosung rx 125 bike. Want to know if the gearoil and engine oil go together or not

Hi, Barney the engine oil also lubricates the transmission for this scenario you will need your service/owners manual if you can't find the first and best tool you ever bought for your Yamaha, despair not, for a mere $0 you can download another one. For more information about your issue and valuable "FREE" downloads that you will need please click on the links below. Good luck and have a nice day.
HYOSUNG RX 125 Service Manual
HYOSUNG RX 125 Parts Catalog
2007 HYOSUNG XRX125 XRX 125 SM pdf
Hyosung XRX 125

May 21, 2016 | Hyosung Motorcycles

1 Answer

Honda 125 nsr 1990 wont idle and engine races

sounds like your throttle cable might be frayed or broken, when you pull the throttle and let go does it go back on its own? and can you here a clicking sound when you close the throttle? If you could send me pictures of the carb how every thing goes in and take it apart and take pictures, that would be helpful.

Jun 12, 2010 | 2001 Honda NSR 125 R

3 Answers

2002 Hyosung GV250 running problems

Time for carb cleaning , blow the jets with compressed air,check the float level.
Check the spark plug and replace if neccessary.
Check the air filter too, and if you don't have an 'inline' filter for your fuel line,install one.
Basically yr bike's engine needs a tune up...check the valve clearance too!
Hope this helps!

Oct 30, 2009 | 2002 Hyosung GV 250 Aquila

1 Answer

Is there anywhere in the U.S. to get Hyosung RX 125 parts?

Google " hyosung RX125 dealers USA " There seems to be a bunch of them. Please rate this answer.

Aug 03, 2009 | 2003 Hyosung RX 125

1 Answer

My xrx 125 starts up but when riding it theeres

Tube is probably OK. It may be a drain.
Perform a compression check.

Jun 14, 2009 | 2002 Hyosung RX 125

2 Answers

Strange thigs about YAMAHA TW 125

I have been working on my carb today,the pipe from the bottom of the carb should just run down by the bottom of the swinging arm,there should be another pipe from the pipe on the left side of the carb just above the fuel intake which also runs down to the swinging arm and connect to nothing.

May 30, 2009 | 2001 Yamaha TW 125

2 Answers


open the carburetor air flap then press down on the accelerator lever like you are twisting the throttle do you see a stream of gas in the bowl? if not check your fuel filter and, or, float assembly

May 21, 2009 | 2002 Hyosung RX 125

Not finding what you are looking for?
2003 Hyosung RX 125 Logo

416 people viewed this question

Ask a Question

Usually answered in minutes!

Top Hyosung Experts

Arnie Burke
Arnie Burke

Level 3 Expert

4514 Answers


Level 3 Expert

75005 Answers

Colin Stickland
Colin Stickland

Level 3 Expert

22095 Answers

Are you a Hyosung Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides