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2004 rm 125 i soaked cleaned and jetted the carburetor and still not running smoothly at bottom end if i close the fuel tap idling picks up and smooths out nicely set the floats perfect gone to smallest pilot jet still flooding bottom end mid to top range perfect just the bottom end and flooding on idle... air screw set to the book idle screw on slide turned in almost all the way.. when starting up idles very high as it warms idling drops all the way down.. anybody that can help

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When adjusting the float i check the needle working or not by putting low presure air in at fuel suply pipe it seals good

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Been thru the carb changed replaced cleaned everything but still the same problem.. if i set the float slightly less then i run out of fuel

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2004 rm 125 fine tunning help pls if anyone can. Carb is flooding when idling its cleaned properly floats set everything if i close the fuel tap it smooths out mid to top range perfect gone to smallest possible pilot jet

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2004 rm 125 fine tunning help pls if anyone can. Carb is flooding when idling its cleaned properly floats set everything if i close the fuel tap it smooths out mid to top range perfect gone to smallest possible pilot jet bottom and idling not so good air screw out to 1and half but idling screw on the slide all the way in

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2004 rm 125 fine tunning help pls if anyone can. Carb is flooding when idling its cleaned properly floats set everything if i close the fuel tap it smooths out mid to top range perfect gone to smallest possible pilot jet bottom and idling not so good air screw out to 1and half but idling screw on the slide all the way in

 

 

If you have gone down that many pilot sizes, then you are compensating for something else that is wrong.  125's usually like a richer pilot..

 

Assuming the bike is mechanically sound, with no air, seal, or exhaust  leaks, reeds in good condition, good compression, properly serviced air filter, etc.......in my experience with older 125's, when you have to lean the pilot this much in an attempt to fix the off idle to 1/2 throttle richness, then it could be an indication of a worn needle jet passage.  Go back to the proper pilot and try a needle with a leaner starting diameter.  See how the bike responds.   This will be a troubleshooting measure and what you are essentially doing is compensating for the worn, larger needle jet, with a thicker needle.  If the bike responds better (which it actually shouldn't) then it's a potential indicator of a worn needle jet.  If that's the case you may get lucky and find an off-spec needle that will suffice.  You may also have to find a needle with a larger (leaner) end taper as well.  Of course I am assuming you have already verified you are running the appropriate needle for your conditions, and have tried it in leaner clip positions?  If you find that even the leaner needles do not actually lean out the bike, then it's time to replace the carb...

 

Many riders think jetting and they focus in on the pilot and/or main jet, but I have found it's generally the needle that can make or break it :thumbsup:

 

Jetting by the way is the LAST item that is addressed in the tuning spectrum.  If even one thing that I mentioned above is amiss, then you can chase your tail forever and will never get the bike properly jetted.

Edited by Fattonz

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2004 rm 125 fine tunning help pls if anyone can. Carb is flooding when idling its cleaned properly floats set everything if i close the fuel tap it smooths out mid to top range perfect gone to smallest possible pilot jet bottom and idling not so good air screw out to 1and half but idling screw on the slide all the way in

 

 

Also...you said when you close the fuel petcock the bike smooths out.  Now, does this happen immediately when you close the valve?  Or does it happen once the bike starts to run out of fuel?  This is another troubleshooting indicator....because if it happens when the bike starts to run out of fuel, then obviously it wants to be leaner.   But even a well tuned bike might have a little performance spike when leaning out as it runs out of fuel....so not a great indicator...

 

However, if the bike immediately runs better upon closing the valve, then in my opinion it's a sign of a worn float needle/seat.  Here's why......think about what's happening when you close that valve.  The fuel is gravity fed into the carb through the float needle valve.  A column of liquid has what's called "head pressure".  In other words the weight of the fuel above the carburetor effects the "pressure" of the fuel in the line at the float needle valve.  So the more fuel that's in the tank, the higher the column of liquid, the greater the fuel supply pressure...you with me so far?  So when you suddenly close that valve you instantly sever the column of liquid and thereby reduce the pressure in the fuel supply line.  In other words the weight of the fuel in the tank is no longer pushing down on the fuel in the line.  The result is less pressure at the float needle valve.  If at this point the bike's performance suddenly improves it tells me that either your float is set too high or the seat/needle is worn...

 

Do you see the correlation?  With the fuel petcock open there is more head pressure (via the taller column of liquid) to push the fuel through the float needle valve thus making the bike suddenly rich.  Does the bike run better on an almost empty tank?

 

So do some additional checks to ensure your float is not too high, or that the needle valve is not passing.  As a trouble shooting measure you could set the float intentionally low and see how the bike responds.  Note the bike's reaction to each change to help isolate problems. 

Edited by Fattonz

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The main jet needle is droped to its leanest position float needle and seat seals good tested it.. if i close the fuel tap its a few seconds then idling picks up and i can screw out the idle screw on the slide to bring idling down.. when cold the bike starts easy but idling very high without any choke used as it warms up idling comes all the way down

For a while just not very smooth

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The main jet needle is droped to its leanest position float needle and seat seals good tested it.. if i close the fuel tap its a few seconds then idling picks up and i can screw out the idle screw on the slide to bring idling down.. when cold the bike starts easy but idling very high without any choke used as it warms up idling comes all the way down

For a while just not very smooth

 

 

As I have stated a very well tuned motorcycle will idle up when running out of fuel, but I recommend you try a lower float setting just to eliminate that problem before moving on......sometimes certain bikes like a lower than stock float setting...

 

Once you have tried that, if there's no change, then see my first post above...

Edited by Fattonz

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No fuel leaking out the carb at over flow at all and if i set the floats any lower i run out on fuel or fuel starvation could it be choke leaks or possibly the needle that's wrong size? I realy apreciate everyones advice thanx everyone localy there's no help at all.. and i realy need the bottom end sorted as the powerband from midrange to top is perfect but scares my son as he's still just starting out and i dont want to scare him away from riding its father and son time so realy need the bottom end smoother

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gone to smallest possible pilot jet bottom and idling not so good air screw out to 1and half but idling screw on the slide all the way in

If its the smallest pilot, that would make it what size? I ask to be sure that its not just the leanest you know of or what someone trying to help you knows of. You need to be specific.

What method are you using to tune the air screw? Is that 1 1/2 turns out just an initial setting?

Edited by Trailryder42

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No fuel leaking out the carb at over flow at all and if i set the floats any lower i run out on fuel or fuel starvation could it be choke leaks or possibly the needle that's wrong size? I realy apreciate everyones advice thanx everyone localy there's no help at all.. and i realy need the bottom end sorted as the powerband from midrange to top is perfect but scares my son as he's still just starting out and i dont want to scare him away from riding its father and son time so realy need the bottom end smoother

 

 

Then if you are ONE HUNDRED % sure that none of the conditions exist such as the ones I stated in my first post, then proceed as I have suggested in my first post to troubleshoot/isolate the issue.  Needles are cheap.  Grab a few from a dealer (doesn't have to be Suzuki) and try them out.  At this point I suspect a worn needle jet.  It is part of the carb body and the entire carb must be replaced to rectify it...  Unless as I have stated, you find a suitable leaner needle to compensate.

 

Pull the existing needle, there is a number stamped on the needle just below the clip notches.  Reference a parts diagram for your model.  Verify if the needle is stock.  Generally bikes are jetted for sea level from the factory.......  so start by installing the appropriate needle.

 

The most important question that I should have asked already.  Did this rich condition start suddenly?  Has it existed since you have owned the bike?  Cause if it ran good before, then it's something other than jetting that is wrong.....so look at the items I have listed in my first post ;)

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Been thru the carb changed replaced cleaned everything but still the same problem.. if i set the float slightly less then i run out of fuel

Again, you need to be specific. What is the book spec for float level? How much difference from that are you setting it. Or are you just eyeballing it.

1/2 millimeter can make a big difference.

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40 pilot jet it was a 42.5 pilot and air screw all the way in and then turn it out 1 and 3/4

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