Question about 2003 Suzuki RM 125

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What size is the main jet in an 03 RM125 - 2003 Suzuki RM 125

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The stock plug is an NGK R6918B8. At only $22 each.
what size is the main jet in an 03 RM125 - 44ef13e.png

Posted on Jul 30, 2009

  • tombones Aug 14, 2009

    Man, did I mess up an answer or what. I am extremely sorry for my blunder. I gave you an answer to a question someone else had just asked. I am surprised you ranked he answer as "somewhat helpful". A better rank would have beed "not helpful". Let me try again.

    The RM125 has many choices for main jets. There are six models of the RM125 and a couple of "sub" models as well. The jet needle has just as many choices.

    Models K1 and K2 get a 460 stock jet. Optional jets range from 400 through 600

    Model K3 gets a 460 stock jet on the E3 and a 560 on the E28 Optional jets range from 400 through 600

    Model K4 gets a 390 stock jet on the E3 and a 460 on the E28 Optional jets range from 300 through 500

    Model K5 gets a 370 stock jet on the E3 and a 390 on the E28 Optional jets range from 300 through 500

    Model K6 gets a 370 stock jet. Optional jets range from 300 through 500


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Posted on Nov 08, 2009


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1 Answer

Main jet size

Bigger jet is not the problem. More fuel would be put in and you said that it runs well at the top end. So it is not a fuel shortage issue.

May 28, 2015 | 2005 Yamaha DT 125 RE

1 Answer

I have a 1980 rm125 and I have a 140 main jet on it is that the right jet or if not please tell me the right stock jetting.

You should really have the workshop manual if you are working on the carb. Not only will this tell you the correct main jet size, you will also get the pilot jet size, mixture screw, and jet needle positions. All of these should be checked if you're taking apart the carb yea?

Mar 10, 2015 | Motorcycles

1 Answer

Factory Jet Sizes

Front cylinder carburetor:

112.5 Main Jet

17.5 Pilot Jet

(1) 0.020" thick shim washer under the needle

PMS setting apparently varies from bike to bike... but it should be 2.5 turns

Rear cylinder carburetor:

110 Main Jet

17.5 Pilot Jet

(1) 0.020" thick shim washer under the needle

PMS setting apparently varies from bike to bike... but it should be 2.5 turns

May 23, 2013 | 2000 Yamaha V Star 1100 Classic

1 Answer

Fuel line routing



Fine tune your motorcycle before rejetting your carburetor. If it's still running too lean, you can replace the pilot jet as a first step

Remove the bowl at the base of the carburetor by unscrewing the screws holding it in place. Unscrew the pilot jet inside, but be careful not to strip it. The jet size will be on top.

5 Year/ unlimited mile warranty No up front core charge

Use a screwdriver to remove the main jet from the brass jet needle holder, which is also called the emulsion tube.

Put in a pilot jet that is one size larger. Replacing it with a jet two sizes larger will make your mixture too rich.

Tune the slow/idle settings before replacing the main jet. Replace the main jet with one size larger. The sizes are in increments of 5.

Put the bowl back on, and align the accelerator pump shaft and rubber boot.

Reinstall the carburetor on the motorcycle and retune it to finish the rejet procedure.

Jan 11, 2013 | 1998 Honda VT 600 C Shadow

1 Answer

Mileage problem

Hi Patrick, you can start by going to smaller main jets untill you notice poor performance then go up one size, and the usual suspects are:
1. Excessive use of enrichner system.
2. Enrichner valve not seated or leaking
3. Dirty air cleaner element.
4. Restricted fuel tank vent system.
5. High speed riding style.
6. Idle speed improperly adjusted.
7. Loose jets.
8. Float level too high.
9. Plugged or restricted bowl vent.
10. Worn or damaged needle or needle jet.
11. Vacuum piston assembly malfunction.
12. Plugged air jets or passages.
13. Excessive accelerator pump output.
Good luck and have nice day.

May 12, 2012 | Harley Davidson Motorcycles

1 Answer

1996 Honda CA 125 Rebel carburetor tuning

Hi, Johngraves if you have changed your engine size, 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" you're not getting enough fuel.
1. Close 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. A 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, the 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 for viewing or printing please click on the blue links below. Good luck and have a wonderful day.
Honda Rebel 250 Carburetor Re Jet Needle Shim
Honda rebel 250 Service Manual
Honda CA125 Rebel Owner Manual

Jul 26, 2011 | 1996 Honda CA 125 Rebel

1 Answer

What is the size of main jet of YZ125?

  • Main Jet: 410
  • Main Air Jet: 2.5
  • Jet Needle: 6BFY43-74
  • Needle Jet: S-1
  • Pilot Air Jet 1: #40
  • Pilot Outlet: 0.7
  • Pilot Jet: 40

Jun 05, 2011 | 2003 Yamaha YZ 125

1 Answer

Engine revs up while idling

Check the Exhaust Valve actuating rod is firmly in it's bush and the actuating arm is screwed to the valve actuator...the diagram on this link below refers.

Have you looked closely for air leaks between carby and engine, airbox obstructions or wrong sized pilot jet? Choke plunger thread not loose allowing extra fuel to surge through? Try turning air mixture screw IN half turn. The site below has the complete bike in exploded diagrams. Hope this all helps, good luck.

May 10, 2010 | 2003 Suzuki RM 125

1 Answer

My rm125 spews oil out of the exhaust

Are you running 32/1?
You should be, and then jet to match that.
If you pilot, or idle jet is too big, you will have a black plug at idle.
If your main jet is too big, you will have a black plug from 3/4 throttle to full. You want the plug color like chocolate brown. (White is too lean)
The needle jet clip cover between the pilot and main jet.

Mar 19, 2010 | 2003 Suzuki RM 125

1 Answer

Main jet sizes

The sizes are stamped on the Jet it self. For the Honda Shadow it is a 185. Not sure for the steed.

Jan 12, 2009 | 1990 Honda VT 600 C Shadow

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