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230F jetting issues-- how is this happening?

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Phew! So-- I have my stock '07 230F set up with an '05 carb, stock needle clip in the 4th position, 50/120 jetting, air screw 1.5 turns out (optimal settings according to Mike Coe). So my bike ran beautifully, and everything was perfectly smooth in life. So yesterday it was hot, and it was about to rain. My bike ran fine all night then all of a sudden it started sputtering, and wouldn't run on top?? WTF?? Can humidity affect jetting on an engine that isn't really a performance oriented type of engine? What would be the fix for this problem?? Definitely not happy!!!!  --L*64

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6 minutes ago, luckystar64 said:

Phew! So-- I have my stock '07 230F set up with an '05 carb, stock needle clip in the 4th position, 50/120 jetting, air screw 1.5 turns out (optimal settings according to Mike Coe). So my bike ran beautifully, and everything was perfectly smooth in life. So yesterday it was hot, and it was about to rain. My bike ran fine all night then all of a sudden it started sputtering, and wouldn't run on top?? WTF?? Can humidity affect jetting on an engine that isn't really a performance oriented type of engine? What would be the fix for this problem?? Definitely not happy!!!!  --L*64

First of all there is no "best setting" or "recommended setting" for the idle mixture screw.  It will change as the environment changes.

As humidity increases the density of air decreases because some of the volume is displaced by water but major differences occur only near 100% humidity.  For most all riding conditions the impact upon our bikes is minimal at best.

If your engine was sputtering I'd be looking for a too-high float level due to debris in the needle or perhaps a loose jet.  This is assuming no tight valves, bad CDI, etc.

 

Edited by VortecCPI
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1 minute ago, 1gr8bldr said:

Main jet may have come out. I have had it happen.

You can see if it falls out when removing the big head hex nut/access on the bottom of the bowl

Edited by 1gr8bldr

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3 hours ago, luckystar64 said:

Phew! So-- I have my stock '07 230F set up with an '05 carb, stock needle clip in the 4th position, 50/120 jetting, air screw 1.5 turns out (optimal settings according to Mike Coe). So my bike ran beautifully, and everything was perfectly smooth in life. So yesterday it was hot, and it was about to rain. My bike ran fine all night then all of a sudden it started sputtering, and wouldn't run on top?? WTF?? Can humidity affect jetting on an engine that isn't really a performance oriented type of engine? What would be the fix for this problem?? Definitely not happy!!!!  --L*64

If humidity or minor changes effect the bike from running well then you were on the far right or left of the jetting parameter for this bike. If you get it tuned correctly, in the middle of the parameter, then it will run fine during temp, humidity or elevation changes. Your extremely rich on the idle jet. Which is not your current issue, however, you should be smelling gas. There is no optimal majic number of turns out. It is only a goal to prove tuning being in the middle of the parameter. Reason is that idle jets come 40,42,45,48,50, etc. Your perfect tune according to temp, humidity,elevation may be 43.5, which they don't make, thus the air/fuel screw allows it to be adjusted perfectly. It's basically a micro adjust of the idle jet. If the bike runs best at 2.5 turns out then your to small on the idle jet.... I think that's right, if it runs best at 1/2 out then you need a larger idle jet. It really helps to dial it in to able to run best at 1.5 to 1.7 turns out so that you are in the middle of the parameter, however, middle now since it is hot, is not the true average year tune. But you can redo it come fall. I may have told you opposite on the size up or down. Sorry if so, I am recalling with several carbs on the brain. I know this is so with the PWK, can't recall if this carb is the same

Edited by 1gr8bldr

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Looks like the guys have you covered here but if it doesn't work contact Mike's brother Sam, he's a better mechanic, but Mike does now how to ride... Good luck, don't have to deal with those extremes as much on the west coast. :lol::ride:  But seriously listen to the guys, go back to the basics they are covering above. 

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I guess I have no idea where to go from here? If it ran worse when it's hotter-- would I turn the air screw out a half turn? --L*64

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These bikes run good at a wiiiiiiiiiide selection of jets. I ran a 118 through 138 and all performed equally well, me not able to tell the difference except with a stop watch on timed runs. The better jet was only a split second faster. 

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If it was "all of a sudden", it's not jetting. An extremely dirty air filter does this on our ATV. The main jet vibrating out does it. Among other things, but my bet is on the jet being out of it's hole..... if fuel is not coming out the overflow

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Nothing wrong with the carb at all. I'm thinking that it ran out of air on top because of the humidity? I went a half turn out on the air screw, so I'm at two turns out with a 120 main now. If that fixes it, then I guess I'd go back in the fall when it's cooler? We'll see how the small adjustment works out when I ride it this week.  --L*64

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Quote

I'm thinking that it ran out of air on top because of the humidity? I went a half turn out on the air screw, so I'm at two turns out with a 120 main now.

From my Carb Notes web page:

Although I, and many others, call this part a fuel screw, Honda calls it a pilot screw. We use the term fuel screw to distinguish between this part for four strokes and the 2-stroke version, called an air screw. This is done so we can be ever mindful that screwing the "fuel" screw in and out adjusts the amount of "fuel" we are adding to the mix; 'in' is leaner (less fuel), and 'out' is richer (more fuel).

http://rickramsey.net/CRF230Fcarb.htm#extfuelscrew

So you've richened the mixture by screwing the fuel screw out.

:ride:

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Sounds like to me you have been running rich this whole time right on the edge of fouling the spark plug and now you have.

You need less fuel when it is hotter, more fuel when it is cooler.  Do you have to use choke when cold starting the engine?  If not then that 50 pilot and your mixture screw are too rich.  I like the way a 45 pilot and Kouba pilot screw work together here at +/-800ft.  I tried a 48 first but it worked weird.

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4 hours ago, MetricMuscle said:

Sounds like to me you have been running rich this whole time right on the edge of fouling the spark plug and now you have.

You need less fuel when it is hotter, more fuel when it is cooler.  Do you have to use choke when cold starting the engine?  If not then that 50 pilot and your mixture screw are too rich.  I like the way a 45 pilot and Kouba pilot screw work together here at +/-800ft.  I tried a 48 first but it worked weird.

+1   I am also using a 45 pilot and kouba fuels screw (2 turns out) and I need full choke until it starts and then I move it immediately to half choke for maybe 30 seconds then ride off and it runs great. I'm at right around 300ft.

 

Also you can try turning your fuel screw all the way in while the bike is warmed up and idling.  If the engine doesn't stumble and/or die than you are too rich on the pilot jet.  I used the guide written by Rick Ramsey to re-jet my bike and get it running it's best, good to print out and have it laying on the workbench.   Thanks Rick!

Edited by jjmaine
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I had the pilot size wrong. I'm only at a 45 pilot. I had it confused with a different bike. So the screw on the bottom front of the carb isn't an "air" screw? I was thinking the half turn out would allow more air into the mix? So I was thinking that I leaned out the mixture by keeping the same 120 main and adding some air into it? Is that wrong?  --L*64

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It is the fuel screw.  I do believe 2 strokes use an air screw and 4 strokes, a fuel screw.  That half turn out added more fuel not air into the mix.

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8 hours ago, luckystar64 said:

I had the pilot size wrong. I'm only at a 45 pilot. I had it confused with a different bike. So the screw on the bottom front of the carb isn't an "air" screw? I was thinking the half turn out would allow more air into the mix? So I was thinking that I leaned out the mixture by keeping the same 120 main and adding some air into it? Is that wrong?  --L*64

Do you have to use choke to start the engine when it is cold?

How is the idle?

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See the new "LOOK! Any 150/230F pilots have THIS problem?" thread. I think I see what's going on in this carb. --L*64

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