I have a Talon 150, and I'm at 4500' elevation. I just added an MRP air filter, got rid of the stock air box, gutted the exhaust and at first tried a 125 main jet. It was running so rich the plug was wet. But others at my elevation are running as high as 130 and having no issues. So on a whim... I tried the 128 jet.. a little bigger right? So it should run even RICHER right? Wrong.
With the 125, I could barely keep it idling, it was choking and sputtering. But as soon as I got in that 128, it ran great. Took it on a WOT run, no problems except for a bit of a studder on acceleration (even after it warmed up.) Does that seem backwards to anyone else? I thought it would run WORSE with the larger jet, if the 125 was already too rich. But the plug was just a little dark grey with the 128.. still a bit rich, but way lighter then with the 125.
Next I need to adjust the valves (haven't done this since I owned it). Will that get rid of the studder on acceleration or could there be a different issue? Why would a larger jet run leaner for me and not the other way around? _________________ 05' Carter Talon GSX 150 2R
39t rear sprocket
9.5g sliders
NGK Iridium Plug
H.O. Bando Coil
Dr.P Hit clutch (backup)
1500# torque spring (soon...very soon)
125 main jet
42 pilot jet
MRP Air Filter (rednecked)
Drilled out stock exhaust
I have a Talon 150, and I'm at 4500' elevation. I just added an MRP air filter, got rid of the stock air box, gutted the exhaust and at first tried a 125 main jet. It was running so rich the plug was wet. But others at my elevation are running as high as 130 and having no issues. So on a whim... I tried the 128 jet.. a little bigger right? So it should run even RICHER right? Wrong.
With the 125, I could barely keep it idling, it was choking and sputtering. But as soon as I got in that 128, it ran great. Took it on a WOT run, no problems except for a bit of a studder on acceleration (even after it warmed up.) Does that seem backwards to anyone else? I thought it would run WORSE with the larger jet, if the 125 was already too rich. But the plug was just a little dark grey with the 128.. still a bit rich, but way lighter then with the 125.
Next I need to adjust the valves (haven't done this since I owned it). Will that get rid of the studder on acceleration or could there be a different issue? Why would a larger jet run leaner for me and not the other way around?
mikek i would definitely ajust the valves if they have never been adjusted
make sure you have run it long enough for the (choke) fuel enrichment to shut off before trying a plug read.that might have gave you the false reading with the 125 jetting.
still sounds like you are running a little lean with the 128 jet, plug should be a light tan or brown color.so you still might get that 130 jet you are looking for
also you might have to give your airfuel screw a 1/4 turn out for more gas. with the better flowing air filter you have probably lean out pilot jet,that should help the studder on take off and acceleration.you will get it though it just takes a little balancing.
pud _________________ 2006 sunl 150b
Dr. pulley 10 gram sliders, 1500 torque spring,39 tooth sprocket,2000lb winch, red neck uni filter, 125 main jet at 1,450 elevation, drilled out exhaust,ngk iridium plug,performance intake
trying a set of 10gram rollers now
Thanks pud.. turns out, the choke had a bad seal causing it to flood out, and the new HP coil I installed had a loose connection, so the problem was twofold, but nothing to do with the jets afterall.
Lucky I brought my tools in the bush with me, cuz after I got it going, it died 3 times about 5 miles down the mountain away from my house!!! BAD palce to be stranded... the grizzly bear are getting ready for winter, and I'm just another member of the food chain!!!!!
Got the choke fixed, and still kept dying and sputtering. Most of the problem is the new coil. It's too short, and isn't screwed into the bracket, so it loosens up after a few bumps in the road, starts sputtering and just dies. Got it tightened, and it ran great. Put in the 125 again, and it ran even better... but the plug is still black. Will adjusting the air/fuel screw clear up the richness a bit, or should I go down to a 122 jet? Whatya think?
I'm going to adjust those valves first though before I do any more experimenting. (and throw some bear spray in the tool box ) Thanks for the advice.
-MikeK _________________ 05' Carter Talon GSX 150 2R
39t rear sprocket
9.5g sliders
NGK Iridium Plug
H.O. Bando Coil
Dr.P Hit clutch (backup)
1500# torque spring (soon...very soon)
125 main jet
42 pilot jet
MRP Air Filter (rednecked)
Drilled out stock exhaust
I'm really big on checking compression before I do anything on the engine.I check cold then warm and see what the diff is.I would check the valves and adjust if not correct,1st then I the go from there.
Thanks funnyman...that's smart advice. Now.. uh... how do I check compression? (Adjusting valves is already pretty advanced for me, so...) _________________ 05' Carter Talon GSX 150 2R
39t rear sprocket
9.5g sliders
NGK Iridium Plug
H.O. Bando Coil
Dr.P Hit clutch (backup)
1500# torque spring (soon...very soon)
125 main jet
42 pilot jet
MRP Air Filter (rednecked)
Drilled out stock exhaust
Ok, it's not hard,but first u have to get a compression tester.They're not expensive but u have to get the right adapter I dont know off hand what size it is so take your spark plug out and bring it with u to match it up.Not all auto stores have that size.Screw in the tester (spark plug hole)ground the plug wire, put gas pedal full,and crank untill gage needle stops.That is your compression.Hope this helps.
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Took it on a WOT run, no problems except for a bit of a studder on acceleration (even after it warmed up.) Does that seem backwards to anyone else? I thought it would run WORSE with the larger jet, if the 125 was already too rich. But the plug was just a little dark grey with the 128.. still a bit rich, but way lighter then with the 125. 
) Thanks for the advice.
