Spark plug fouling

L

Louis069

New member
Hi there hope you are all doing well.
I have a 2008 EC300 and been battling the jetting on this bike since i have owned it but think i have finally got it worked out. I have gone from:
-N1EF clip 1, 35 pilot, 175 main
To
-N3EG clip 1, 38 pilot, 175 main
so it is running much, much better and leaner, and im having a blast on it very powerful and tourqey.
I obviously had issues with the spark plug fouling at the start with the richer jetting

However i still havent been able to negate the problem fully, even with the new jetting. For example after spending anthing more than 15 minutes in woods singletrack and then exiting the woods onto a fire road and go to open the taps it will stutter/choke up before its gets to the powerband so i come off the throttle then on again and i will do this about 3-4 times before it clears itself out and will rev cleanly again.
Then this afternoon when i started it up, it went for about 5 seconds and before i could get the choke off it cut out. This is a photo of the plug after i took it out. Ended up putting a new one in and went 1st kick

I dont think it is running rich as the jetting seems to be on the leaner side. So all i can think of is reeds? spark plug cap? ignition coil?
I am running a BR7ES at the moment, as recomended by a former dealer in the area(linton at das, christchurch), he runs the hotter plug as he says that it is better suited for low rpm conditions. Not only that, thats what beta and ktm all use. He also says the BRP7ES with the projected tip can work better in some situations your thoughts? Im probably going to give it a go to see anyway.

Im running castrol power 1 2t at 50:1
Also forgot to mention it has had a new piston and rings about 10-15 hours ago.
Oh and i can still only get about 70km to a tank which is still double from what i used to get but not as good as some of you are getting.

Thanks very much for any advice you may have:)
 

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My personal opinion is that running a hotter plug is not the correct way to get rid of the plug fouling problem. Install the correct plug and change your jetting.

I am not discussing the N1EF as I think it is crap.

However, your clip position as well as pilot jet size indicate you try to solve a low down richness. Or why are you trying to lean out the mixture down low so much?

The N3EG is almost as rich down low (smallest throttle openings from zero to ⅛) as the N1EF. I also would not go lower than 40 on the pilot jet and choose a needle that is leaner down low (thicker starting diameter, like a NECW/NEDW). Maybe a JD kit would make sense...
 
Install new needle - look for threads here or send message to jakobi for his setting as a starting point.

When you install the needle, be sure to reset your idle screw - it will need to be backed out for the low speed (pilot) circuit in the carb to become effective. With the n1ef needle, one will typically have the idle cranked in to the point of being "coil bound" and it still won't idle...

In this carb, you can go up to 2 1/2 turns out on air screw to get things dialed off the bottom.

With the jetting issue resolved you should see easier starting, better transition off bottom into mid/top and improved fuel efficiency.

Getting the head machined to dial in squish and compression can also yield high gains in both efficiency, ride-ability and power output.

jeff
 
webmaster said:
Install new needle - look for threads here or send message to jakobi for his setting as a starting point.

When you install the needle, be sure to reset your idle screw - it will need to be backed out for the low speed (pilot) circuit in the carb to become effective. With the n1ef needle, one will typically have the idle cranked in to the point of being "coil bound" and it still won't idle...

In this carb, you can go up to 2 1/2 turns out on air screw to get things dialed off the bottom.

With the jetting issue resolved you should see easier starting, better transition off bottom into mid/top and improved fuel efficiency.

Getting the head machined to dial in squish and compression can also yield high gains in both efficiency, ride-ability and power output.

jeff
Click to expand...
Sorry didn't mean to cause confusion but I am running a N3EG needle now. I brought the bike with the bad n1ef.

However according to doc it sounds like this needle is still to rich off the bottom am I correct in saying that a N3EW or N3EJ would be leaner off the bottom as the last letter determines diameter, or did I make that up:rolleyes:

Trouble is at the moment that needles are taking like 3 months to arrive. As ktm are getting them from Austria and Yamaha are shipping them by boat from Japan.

So at this stage I will have a look for some suitable needles and order another one or two to try out. Thanks for both your help
 
Hi Louis,I have a JD Jetting 2010 model kit.It has the red & blue needle ,some main & pilot jets.If you get stuck I can send them down to try.
 
Louis069 said:
Sorry didn't mean to cause confusion but I am running a N3EG needle now. I brought the bike with the bad n1ef.

However according to doc it sounds like this needle is still to rich off the bottom am I correct in saying that a N3EW or N3EJ would be leaner off the bottom as the last letter determines diameter, or did I make that up:rolleyes:

Trouble is at the moment that needles are taking like 3 months to arrive. As ktm are getting them from Austria and Yamaha are shipping them by boat from Japan.

So at this stage I will have a look for some suitable needles and order another one or two to try out. Thanks for both your help
Click to expand...

I am not so familiar with the N3xx needles, I prefer the Suzuki needles with NExx codes as they are super easy to understand. However, I could send you some needles for testing but I fear they'll take forever to get to you. I am in Vienna (Austria, Europe).

There are several ways to get rid of the bottom richness the N1Ex needles produce. Smaller pilot jet, yes, but not too small. I would not go lower than 40, maybe 38 on rare occasions. Dropping the needle to the top clip will have a positive effect down low but it has negative effects between about ? and ?.

So my approach is to use a needle with a longer and thicker starting diameter and put it in clip 3 and see how it performs in the first quarter of the throttle range. The air screw will help to fine tune. Once I have done this I test ride and see how the engine responds, always having the air screw position in mind. It should be between 1.5 and 2.5 turns out. My bike runs best between 2 and 2.25 turns out with a 40 pilot jet.

Maybe it makes sense to think about the offer from gg3. He is obviously in New Zealand too and you'll have the JD kit in a few days.

You are using a 38 carb, not a 36, right?
 
If your bike has lots of hours maybe the needle jet has worn. They wear oval and nothing can fix that jetting wise
.
Take a viewing glass and strong light to inspect it. A Stix insert would fix that or a newer carb.

If it is ok then try another needle.

My 07 300 I have never ever fouled a plug. It just gets a bit soggy every year or two and I go, yeah? Wonder what the plug is like? Oh yeah. Rooted. New one. Sweet
But never ever fouls.
 
Hi Louis,I have a JD Jetting 2010 model kit.It has the red & blue needle ,some main & pilot jets.If you get stuck I can send them down to try.
Click to expand...
Thank you very much for the offer gg3. I have ordered a NEDW yesterday from a suzuki dealership and they said it should be get here today so i will see how that goes first, but if it still doesnt work out then i might take you up on that thanks.

Go talk to Linton at D A S !!!!!!
Click to expand...
Yes tonyraft i did talk to linton and he was the one who reccomended the 38 pilot and hotter plug among a lot of other advice. He really can talk i ended up there for an hour lol

I am not so familiar with the N3xx needles, I prefer the Suzuki needles with NExx codes as they are super easy to understand. However, I could send you some needles for testing but I fear they'll take forever to get to you. I am in Vienna (Austria, Europe).

There are several ways to get rid of the bottom richness the N1Ex needles produce. Smaller pilot jet, yes, but not too small. I would not go lower than 40, maybe 38 on rare occasions. Dropping the needle to the top clip will have a positive effect down low but it has negative effects between about ? and ?.

So my approach is to use a needle with a longer and thicker starting diameter and put it in clip 3 and see how it performs in the first quarter of the throttle range. The air screw will help to fine tune. Once I have done this I test ride and see how the engine responds, always having the air screw position in mind. It should be between 1.5 and 2.5 turns out. My bike runs best between 2 and 2.25 turns out with a 40 pilot jet.

Maybe it makes sense to think about the offer from gg3. He is obviously in New Zealand too and you'll have the JD kit in a few days.

You are using a 38 carb, not a 36, right?
Click to expand...

Thanks for the offer doc but you would probably be right about them not getting here, not in a hurry anyway. I actually threw the N1EF Needle out:D as the N3EG was way better. I ordered a NEDW yesterday which should get here today so ill se how that goes. Sorry forgot to mention im running a 38mm as1 carb

If your bike has lots of hours maybe the needle jet has worn. They wear oval and nothing can fix that jetting wise
.
Take a viewing glass and strong light to inspect it. A Stix insert would fix that or a newer carb.

If it is ok then try another needle.

My 07 300 I have never ever fouled a plug. It just gets a bit soggy every year or two and I go, yeah? Wonder what the plug is like? Oh yeah. Rooted. New one. Sweet
But never ever fouls.
Click to expand...

Unfortunately i have no idea of the hours the bike has on it i know there were at least 2 owners before me. If i dont see any improvement from the new NEDW needle then I will take a look and see if its worn.

Thank you all for your replys very helpful
 
Linton is the man if you want suspension done. Forks are pretty harsh for our conditions and deflect off tree roots. He has been evolving revalve for these.
 
(F5) said:
Linton is the man if you want suspension done. Forks are pretty harsh for our conditions and deflect off tree roots. He has been evolving revalve for these.
Click to expand...

I haven't worked out what forks I have, I haven't been able to find anything like them on here. They do have dirt action services sticker on them though so my guess is that one of the previous owners had them done by him.
 
Hi Louis, yes NEDW will work WAY better than the N1EF. Start in clip 3 and let the main and pilot as they are. It will require tweaking the air screw though.

If you don't use a lot of WOT you can change to a 170 or 172 main jet, but that is fine tuning, we are chasing plug fouling here :-) And don't forget that if it runs leaner at WOT plus the hotter spark plug can be dangerous.

When you feel it is still too rich down low you can go as far as 2,75 turns out on the air screw. GasGas says that is the border line to gor for the next bigger pilot jet. But it would be strange if you need the AS that far out with the smaller 38 pj.
Remember that dropping the needle will also lean it out down low but it will have ab effect on the mid range. If you have time it would be worth to try the 40 pj with the needle in #3.

If nothing helps check the needle jet for wear. If that is still good you can try to use different gas and oil. It sounds weird but I had a fouling problem caused by a specific oil.

Good Luck ;-)
 
I would go fatter on the pilot and turn down the idle. This will better separate the circuits in the carb. Going this way - the airscrew will have more effect and it will be easier to "dial in".

If you go too lean on pilot - then you crank up idle to supply more fuel -which also supplies more air - moving flow away from the pilot circuit. This is referred to as "pulling over". Now the needle/slide position (idle screw setting) are determining your mixture right off the bottom instead of the pilot/airscrew.

This is the problem with the n1ef or n3ef needle - you end up going leaner on pilot - turning up idle to supply more fuel - still looking for even leaner pilot to fix issue that is elsewhere. When they don't make a pilot jet any smaller - you know you got a problem. ;-)

I would look at what jetting comes oem in the suzuki and use that as a baseline for choice of pilot jet. e.g. in my old 2001 I used a 42 and rode very tight woods and it was "clean". This was with a LTR jetting kit which used a leaner needle.


jeff
 
I installed the NEDW needle on clip 2 a couple weeks ago and have had a couple rides on it and it still is running rich, choking/loading up on a br7es plug and hasn't improved on fuel efficiency noticeably. After reading a thread on here about worn needle jets they describe the same symptoms as im having. eg. poor milage, exessive smoking, fouling plugs. Seems like you were right F5

The issue is that the stic metering block is $398USD including shipping which when converted to nzd is $600. If anyone knows if there is a cheaper solution to this problem like maybe a new carburettor? Not sure where would be best to source of these though. Thanks
 
Um, yes you could but geez thats expensive.
And I don't know if will entirely sure all meter blocks are the same.

PM me and ill send you my spare carb as experiment. I put a KX carb metering block in it.
 
Do we know that it's not sucking transmission fluid through the right side crank seal? You can do a pressure leak test pretty easy if you plug the exhaust and intake, and make a small fixture with a schraeder valve to pressurize the system.

if it were my bike, i'd start there.
 
blitz11 said:
Do we know that it's not sucking transmission fluid through the right side crank seal? You can do a pressure leak test pretty easy if you plug the exhaust and intake, and make a small fixture with a schraeder valve to pressurize the system.

if it were my bike, i'd start there.
Click to expand...

I thought about that but I ruled it out because in the 10 monthes I have owned it it hasn't burned any transmission oil. When my brothers seal went on his ktm it was drinking about 50ml to 100ml every ride and it came on very suddenly. But it is another thing to consider
 
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