So close...Jetting my 2003 EC250

TavisB

TavisB

Bronze Level Site Supporter
I needed to rejet my 2003 EC250 after I cleaned out my clogged up pipe and silencer. I'd been running a 38 pilot and 172 main most of the time, but with my newly better flowing exhaust that combo is too lean. I kept bumping both the pilot and main up until I settled at a 42 pilot and 178 main (I stopped here because I don't have any richer jets on hand). I haven't messed with the slide or needle. AFAIK the slide is the original #7 and the needle is on the middle clip (but I haven't verified).

I currently have the air screw at 1.25 turns out. With the 40 pilot I had to have it at 0.75 turns or I got a hanging idle. With the 42 at 1.25 I get no hanging idle, and no bog when I blip the throttle. However, I like the jetting crisp enough that I can blip the throttle in 2nd gear and easily loft the front wheel. With the way I have it set now it is a bit sluggish and doesn't get enough power to lift the wheel until I am guessing I'm off the pilot circuit and onto the needle. If I open the air screw to 1.5 turns + the idle hangs a bit at times and I get a bog if I snap open the throttle at low rpms.

Can anybody give me a hint to get it where I want it...not so lean I'm going to seize anything but with good throttle response right off the bat?

The temp is dropping fast around here so I'll probably wait until this weekend before I mess with it again.
 
What needle is in it?

Stick with the 42 pilot. Open the air scre to 1.5 turns. Then drop the slide down (idle adjuster out) a touch to clean up the hanging idle.
 
Jakobi said:
What needle is in it?

Stick with the 42 pilot. Open the air scre to 1.5 turns. Then drop the slide down (idle adjuster out) a touch to clean up the hanging idle.
Click to expand...

Not 100% sure but the PO told me it was the original needle. I'll give it a ride like you suggest this weekend and see how it does.
 
TavisB said:
Can anybody give me a hint to get it where I want it...not so lean I'm going to seize anything but with good throttle response right off the bat? .
Click to expand...

If you want an easy starting bike that rips off the bottom has some torque and can pull a higher gear you need to be on the richer side of things.
 
The needle is where the magic is. If its the stock needle you may be wound in too far on the idle screw already, and if the bike isn't settling down after say sustained half throttle that could be where you are lean (ie clip pos too high).

Lowering the slide will richen the idle and off idle a bit (less air flow).

As sweeper said, going too lean/clean off the bottom will give up a lot of torque.
 
Jakobi said:
The needle is where the magic is. If its the stock needle you may be wound in too far on the idle screw already, and if the bike isn't settling down after say sustained half throttle that could be where you are lean (ie clip pos too high).

Lowering the slide will richen the idle and off idle a bit (less air flow).

As sweeper said, going too lean/clean off the bottom will give up a lot of torque.
Click to expand...

Good point. I've been thinking of trying a different needle. In the meantime, I'll mess with the clip position and see what happens. Everything else needed richened up, I suppose the needle may need the same.
 
I played around with the needle some this afternoon. First, the needle is marked N1EF. It was at clip #2. I moved it to position #3 and it felt improved once warmed up. I also tried clip #4 but that resulted in sputtering and poor performance. So I left it in the third clip. It runs pretty well like that, but I don't get an indefinite idle (I know I probably shouldn't expect that). It will usually idle about 30 sec or so and then drop RPMs and want to die. Air screw seems best right at 1.5 turns out.
 
Your airscrew should be "further out" with the cck needle. Make sure you have your idle screw backed out with the cck needle installed. You need to get the slide and needle "down" to better separate the carb circuits (low and mid).

42-45 pilot with airscrew 2 1/4 to 2 1/2 turns out. Idle screw should not be turned in so far that it is "coil bound".

Bike should start easily and idle... Should be a good transition from bottom up to mid without a burble or "lurch" (as it cleans out).

Bike can run well with n1ef needle on a particular day - but will be too sensitive to changes in atmospheric conditions. e.g. one day you will think yo have it dialed and on another day it has some issue...

jeff
 
webmaster said:
Your airscrew should be "further out" with the cck needle. Make sure you have your idle screw backed out with the cck needle installed. You need to get the slide and needle "down" to better separate the carb circuits (low and mid).

42-45 pilot with airscrew 2 1/4 to 2 1/2 turns out. Idle screw should not be turned in so far that it is "coil bound".

Bike should start easily and idle... Should be a good transition from bottom up to mid without a burble or "lurch" (as it cleans out).

Bike can run well with n1ef needle on a particular day - but will be too sensitive to changes in atmospheric conditions. e.g. one day you will think yo have it dialed and on another day it has some issue...

jeff
Click to expand...

Hmmm...to get it to idle consistently I had to have the idle screw in pretty far, which was not what I expected. Yesterday I started out with the air screw at 1.5. Next weekend I'll turn the air screw out more along with the idle screw and see what happens.
 
My idle screw is 4.5 turns out from fully in. Does that sound too far in? Should I pull the carb and check the slide gap? I'm thinking I should try a 45 pilot next. Am I on the right track???
 
Today I tried turning the idle screw out and put the AS at 2.5 then to 2. This only resulted in a hanging idle. Just for S&G I also tried the CCK needle at clip 4 and it was too rich so 3 is definitely the right spot for the needle. I really like how it runs right now, with the exception that now that the temp has dropped to 35F I had to put the AS at under 1 turn out. I'm pretty sure the 45 pilot will do the trick. I had one ordered that should have been here yesterday but the shipment was delayed :(.

If that doesn't work I think I'm going to order a Lectron :D.
 
The saga continues...

I pulled the carb today and checked the slide height and float height. Floats were good. Here's where the slide was for my ride last weekend.

https://www.youtube.com/watch?v=zMld0jFuEN8

It ran really well, but I had to have the air screw at 1 turn out or less.




So I thought going up a size to a 45 pilot would get me just right. However, with the 45 pilot it's really behaving strangely. I have to keep the air screw at about 1/2 a turn in now or it wants to hang or even start to take off and rev up on it's own. It's almost like I have an air leak...but I can't find one.

Should I try a 48 pilot? Should I pitch this carb? For now, I'll take it apart and clean it again.
 
Jakobi said:
Try a 'new' 45 pilot.. or clean it really well. Double check air leaks.
Click to expand...

It was a brand new jet :/. I sprayed around the rubber boots to see if there was any evidence of a leak and couldn't hear anything. I'm done for today. I'll pull it apart and take another look when I can.
 
If it ran fine with 42 pilot at 1/2-1 turn out on air screw, why not just leave well enough alone? I've had very good results with that a/s setting.
 
I pulled it apart again :). Made sure they sold me the right size pilot (they did) and that it was clean (it was). Put it all back together again and runs the same. Anything above 1/2 turn on the AS and it's too lean. I think it just needs more gas. I'll get a 48 pilot.

I think I may have been bypassing the idle circuit when I was running the 42 pilot.

Hey, at least I'll have learned a lot about jetting by the time I get this right.
 
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