ec 300 setting correct pilot jetting, idle low end


New member
06 EC 300, rides well, idle a bit iffy. Set up on idle adjuster to sensible tickover then 30secs later drops down to really low idle and usually stops. To make it useable have idle set quite high so it races a bit when shutting off initially then settles down. Also lacks a bit of crisp response when opened up from low revs. Read up on here and seems like I should alter jetting and needle. Currently #7 slide, N1EF needle, 180 main, 40 pilot.
Ordered CCK needle, 38 & 42 pilots to try and 178 main.
I'm no expert, never bothered messing with jetting on any previous bikes. Doing more trail riding these days so noticing lower end and idle issue more. Any advice from anyone appreciated. Especially theory of pilot, is this whats causing idle to be slow dropping down? Rich or lean? Have checked for air leaks and ok.
Away working now but hope to get some advice so I can get into it when i get home in a week or so.
cheers Simon
Had the same problem with mine, setting the float level cleaned up a lot of the idle problems that I had similar to yours. Once I set the float hieght the Carb was more responsive to changes in the air/fuel screw

40 pilot
CEK middle clip
175 main.
Air screw 1.5 out
Few things needed to get the idle circuit correct.
1. Correct float level (slightly lower than stock)
2. Manually set the idle screw into position so that the slide is only just a few mm open. You can either do this visually through the carb throat, or audibly by listening for when the slide bottoms out and then turning the idle screw in until the sound just changes.
3. Set the air screw at 1.5 turns
4. Change pilot jets until you find the one that allows the bike to idle once up to temp with all as above. If the bike idles well but still runs too rich at 1/8th throttle, and leaning the air screw doesn't help/deteriorates the idle and starting, change the needle diameter to one richer and start over. (or vice versa if lean).
Jake can you remind us what the proceedure is for getting correct pilot jet, something to do with if you getting revs peaking above 2,5 turns of AS you need to go down (?) a jet size??
The theory is that the air screw will increase/decrease the revs and they'll peak when you reach the optimum setting on the air screw. If the revs peak between 1 and 2.5 turns you have the right pilot. If its less than 1 turn out you need a richer pilot. Further than 2.5 out and you need a leaner pilot. If you change the pilot you are meant to set the air screw at 1.5 and repeat.

To be honest I find this circuit really sensitive on the gasser where it will only really start easily and idle well when you have the right pilot jet in it, which is why my personal method is to set the AS at 1.5, the slide a few mm open only, and then change pilots until it starts and idles. Then you can set the idle and air screw all within a half a turn in either direction.

Remember increasing the idle by raising the slide will also allow more air to pull through so may need more fuel to sustain the idle as well. Thats why the stock needle always ends up with everyone screwing the idle in deep. To lean things out.
Many thanks to you knowledgable guys. Just what i needed, simple steps to work through and info as what I should be looking for. No complicated theories just enough to help me understand whats going on when changing things. Got to be the most useful posts on this subject I've read, well for me being a jetting virgin anyway. Cheers
Be a couple of weeks now before I get home from offshore rig and then get stuck in. Will post findings