EC300 dies slowly at idle when warm

[Mikeyx]

Well, the headline pretty much sums it up.

Pilot jet is #35, and neither of the setting screws (idle, pilot air) has an effect on idle speed. Of course, the engine dies if the air screw is wound in.

Don't know if it's relevant to the issue, but the bike is equipped with VForce3 reed valve.

Any suggestions?

 

[(F5)]

Yeah. Why do you care? As long as it idles for like 3 seconds it won't stall in normal riding circumstances.

But if you have a N1F-anything needle it will run badly at closed to low throttle and small pilots won't help the wet gas blobs being sucked past the too thin needle.

 

[Jakobi]

Yeah. Why do you care? As long as it idles for like 3 seconds it won't stall in normal riding circumstances.

But if you have a N1F-anything needle it will run badly at closed to low throttle and small pilots won't help the wet gas blobs being sucked past the too thin needle.

This entirely!

The N1EF needle has a super short straight section, and is rich as all buggery on both the diameter and 1st taper. Most people try and bump the idle up and go to a smaller pilot (35) to overcome the richness, but you're then left with a more inconsistent idle and an air screw with little effect.

Have a read in the jetting threads.

 

[Mikeyx]

Well, there is the N1EF needle in, with the clip in 3rd groove. The bike came w/ also N1EG and CHN (brass) needles.

I changed to #40 pilot jet, air screw 1 out. Now the engine has sluggish and sputtery throttle response up until the opening of the PV when the bike really takes off and has a significantly higher power output than w/ #35 jet. On a 4-stroke, sputtering would be a sure sign of a lean mix...

Another issue: There is a significant misalignment between the carb body and air filter box outlet, and I cannot make the flanges go flush - not even close. Actually, yesterday I managed to get the carb out of the airbox and used a good hour to get it back there (what a f****ing ordeal). Any pointers?

 

[(F5)]

Undo the subframe,

Throw away those needles or forever be subservient to shitty running.
Your choice.

 

[Nocams]

Undo the subframe,

Throw away those needles or forever be subservient to shitty running.
Your choice.

I always use a heatgun to lightly soften the airbox boot to aid refitment of the airbox. Also what carb size,elevation and ambient temps have you got?

 

[gassybill]

hey man just posting to say i feel you.
i have similar issues to yours.
0 to 1/8 throttle if i roll on throttle then back off it stalls. seems to be rich.
the alignment to the airbox boot is pretty poor. because im taking the carb on and off so much the fastners are getting worn out and the airbox is getting cut by the gear clamp.

one tip for you though. if you loosen the fastners on both sides of the carb then you can rotate the top towards you undo the cap remove the slide, then you can rotate the carb the other way to get at the bottom screws and bowl. this way you dont have to remove the exhaust and the subframe

anyways good luck. ill be posting a new thread with the details of my own woes

 

[Mikeyx]

I always use a heatgun to lightly soften the airbox boot to aid refitment of the airbox. Also what carb size,elevation and ambient temps have you got?

I didn't have the balls to use a heatgun - thought that the risk for fire was too great. One question: Is the rubber joint between the carb and cylinder straight or is there any shape? The problem is that the airbox outlet kinda comes inclined from the frame of the bike, and now the carb is actually in contact w/ the frame. And still not nearly flush w/ the auirbox flange.

Carb size I don't know; I believe it's OEM. Altitude is close to sea level and ambient temps have been 15...20 C (50...70 F).

Just using basic math, #40 pilot gives 30% higher fuel flow than #35. I'll acquire #38 (+18% flow), and continue my efforts.

 

[Mikeyx]

hey man just posting to say i feel you.
i have similar issues to yours.
0 to 1/8 throttle if i roll on throttle then back off it stalls. seems to be rich.
the alignment to the airbox boot is pretty poor. because im taking the carb on and off so much the fastners are getting worn out and the airbox is getting cut by the gear clamp.

one tip for you though. if you loosen the fastners on both sides of the carb then you can rotate the top towards you undo the cap remove the slide, then you can rotate the carb the other way to get at the bottom screws and bowl. this way you dont have to remove the exhaust and the subframe

anyways good luck. ill be posting a new thread with the details of my own woes

Okay - I thought that there might be an issue w/ the subframe alignment, as the compatibility is so poor, and the airbox is pretty much solid in its own location. Thanks.

 

[Nocams]

I didn't have the balls to use a heatgun - thought that the risk for fire was too great. One question: Is the rubber joint between the carb and cylinder straight or is there any shape? The problem is that the airbox outlet kinda comes inclined from the frame of the bike, and now the carb is actually in contact w/ the frame. And still not nearly flush w/ the auirbox flange.

Carb size I don't know; I believe it's OEM. Altitude is close to sea level and ambient temps have been 15...20 C (50...70 F).

Just using basic math, #40 pilot gives 30% higher fuel flow than #35. I'll acquire #38 (+18% flow), and continue my efforts.

Oem carbs have been both 38 and 36mm. do you have a screw top (as 1)or a cast slim top retained by 2 small screws(as 2)??? if you have the later,there will be a hex shape in the top with either 36 or 38 cast in.
once this is established,many here can give you their recommendation.

 

[Jakobi]

Oem carbs have been both 38 and 36mm. do you have a screw top (as 1)or a cast slim top retained by 2 small screws(as 2)??? if you have the later,there will be a hex shape in the top with either 36 or 38 cast in.
once this is established,many here can give you their recommendation.

This. Topic has been covered many times. A little searching will help.

Any pictures of the fit? Your carb shouldn't be contacting the frame anywhere. My 13 can touch the cap against the frame if it's rotated over too far, but generally has significant clearance.

 

[Mikeyx]

The carb is 38 mm.

I installed #38 pilot. Despite having read several how-to's on how to adjust the air screw, I had to eventually adjust it by riding. I could not get any coherent response at idle or while gently revving the engine.

Throttle response off-idle was still very sluggish. I am an old fart who is a newbie in dirt riding - so engine performance is always exceeding my abilities. But the sound of the engine was so heart breaking that something had to be done. So I dropped the needle down as far as it goes - and presto - throttle response improved significantly. Arm fatigue is now an issue again.I do appreciate that my jetting is most likely far from ideal, but I'm an old fart w/ limited riding skills. The only clear issue I can pinpoint is that while riding on a highway in 6th gear @8000 rpm, the engine kinda hunts - something which it did not do w/ #40 pilot jet -> a larger main jet might do the trick.

A lot has been learned by Yours Truly.

Four-strokers with CV carbs seem to be a whole different ball game, and experience w/ them gives very little help. The effect of pilot jet size goes much further on my GG, and needle setting has a much greater impact than what I'm used to w/ CV carbs on 4-strokers.

 

[(F5)]

Here we go. Last time.

The needle is too skinny. It let's gas through in big wet blobs. So the pilot adjustment can't fix this. Stop pissin around.

CV carb slides raise with more airflow.
Slide carbs raise when the cable pulls the slide open.
Think throttle position. Ignore revs.
Write this down.

My frustration and resultant rudeness is because no one listens.

 

[Jakobi]

Here we go. Last time.

The needle is too skinny. It let's gas through in big wet blobs. So the pilot adjustment can't fix this. Stop pissin around.

CV carb slides raise with more airflow.
Slide carbs raise when the cable pulls the slide open.
Think throttle position. Ignore revs.
Write this down.

My frustration and resultant rudeness is because no one listens.

Of F5. You've only said the same thing at least 4 times this week already!!

I'm just sitting back watching, nodding my head.. The topic has been covered a million plus times and a little searching/reading will give all the info needed.

Maybe we should make a sticky?

 

[barossi73]

If youre new to the forum its hard to know whos advice to follow.Lucky for you f5 and jakobi know what theyre talking about.Throw away that stock needle! Post your altitude,average humidity,and temp range and theyl get you in the ballpark,from there its finetuning to your own style/preference.