How to know if the bike is running lean?

[Munch]

Hello GG riders!

I purchased a gas gas ec 250 2006 a few days ago from a family member with a spluttering problem.

Basically it would start first kick every time but the bike would splutter very bad at anything more than 10-20% throttle, I solved this by running a hotter plug (br9) and changing the mixture from 40:1 to 50:1.

Now I am afraid the bike is running lean, I put a fresh plug in and took it for a test ride for approx 5 minutes and the plug was a very light colour, yellow/white colour which I believe means it is lean?

Is there some sort of trick to finding if it is lean? If it is lean how do I go about making it richer?

My settings:
Pilot: 42
Main: 172
Needle: #3
Needle type is "N1EF"

 

[Munch]

Also something else is that when I first got the bike I tried to set the float however I think I've messed it up somewhere because when the bike is on it's stand leaning to the side the fuel will leak out of the overflow pipe which I'm sure isn't meant to happen?

 

[Brian VT]

Air leak at rubber carb. connection?

 

[GGRider01]

Also something else is that when I first got the bike I tried to set the float however I think I've messed it up somewhere because when the bike is on it's stand leaning to the side the fuel will leak out of the overflow pipe which I'm sure isn't meant to happen?

Your float height is either improperly set, or the viton tipped needle is worn out/hardened.

It's hard to even guestimate whether those jetting settings are lean without elevation, humidity and temperature data. However, if you're below 4000ft, I'm going to say you're lean. However, sputtering is indicative of rich which I'm going to attribute solely to that needle. Drop it (put the clip higher on the needle to lower the needle) one clip at a time without changing jets. This will lean the bike out. If it is bogging however, start raising the needle. Bogging sounds kind of how it is spoken.. "BAAWWWWG.."

If you get to the bottom clip position, you need a richer main jet. If you get to the top of the needle, you need a leaner main jet. (Fixed) More information on this: Clip positions are numbered from top to bottom 1 being leanest, 5 being richest. 3 is, obviously, right in the middle.


Changing from 40:1 to 50:1 increased your FUEL to AIR ratio. The 2 cycle oil in the gasoline is neither fuel nor air. Point here is, you made it run richer by using less oil. The downside is.. you're using less oil...

Finally, your last misconception is that the BR9 is hotter than a BR8. It is opposite. The lower the number on an NGK spark plug, the hotter the plug is. The number indicates the plugs ability to dissipate heat. The higher the number, the longer the insulator is, and the more heat the plug is able to "absorb." You say that by putting a colder plug in, you solved your sputtering problem, but I believe your previous plug was merely fouled. Moving forward, I sincerely suggest you stick to one oil ratio and one spark plug. The BR8 is a perfectly sound plug, and hotter than the one you're currently running. All in all, the changes you've made are minuscule and inconsequential.

Poof. Also, good luck.

EDIT: I just saw another post of yours. You're in England, so I'm going to assume you're fairly close to sea level. Get a 178 or 180 main jet in that bike and your woes may soon disappear. You'll be in the ball park at the very least. Take a look at the jetting database stickied here. There are several members in the UK whose jetting you could copy and modify to your own needs.

 

[barossi73]

If your heat range is correct the j shaped outer electrode should show a color change in the mid section (between 1/4 and 3/4 of the electrode length)

 

[Capz85]

I'm in the uk munch, as GGrider said try some richer jets or even a better needle, I used to run a 45pj and 180 main with one of the N3 series needles on my 300 worked pretty well.

Also worth checking your not pulling air in from somewhere, which might be causing it to be lean

 

[Jakobi]

Hello GG riders!

I purchased a gas gas ec 250 2006 a few days ago from a family member with a spluttering problem.

Basically it would start first kick every time but the bike would splutter very bad at anything more than 10-20% throttle, I solved this by running a hotter plug (br9) and changing the mixture from 40:1 to 50:1.

Now I am afraid the bike is running lean, I put a fresh plug in and took it for a test ride for approx 5 minutes and the plug was a very light colour, yellow/white colour which I believe means it is lean?

Is there some sort of trick to finding if it is lean? If it is lean how do I go about making it richer?

My settings:
Pilot: 42
Main: 172
Needle: #3
Needle type is "N1EF"

With todays fuel blends (detergents etc), synthetic oils, and not to mention 5 minutes ride time.. I'm not surprised you have very little colour on the plug. It started out white. If you fear you are lean get a well used plug that's nicely coloured and do a run on it. If you're lean you'll turn whatever colour/carbon is on it white and ashy.

Lean symptoms are as follows
- Hard starting when cold. Needs choke, and needs choke for a long while before continuing to run.
- Once hot you could see weak flat power, hesitation and cold stalling when cracking the throttle open (BOOOWAAAH sound) that drops rev and sounds like its gasping for fuel. Backing the throttle off the engine will want to surge or run on for bit before the revs drop. Pulling the clutch the revs won't drop immediately. At idle the engine will surge, race, and resist settling into a steady idle.
- The engine will run very hot. Pipe may discolour. Coolant may be expelled.
- The throttle response will sound sharp and crisp. If too lean you'll note that it appears the bike makes more noise but doesn't go any harder or faster.

Rich symptoms are smoke, spooge, blubbering wet sound (similar to what you feel when you forget to take the choke off, or ride around too slow and load the engine up with fuel).

A lean setup will typically run like a cut snake for a short period of time and then the power will flatten right out as the engine gets too hot and the symptoms will show.

A rich setup will run poorly in general. Depending on where it is rich it won't take throttle well.. but if transitioning into a leaner area of the jetting it can work through and run ok at certain throttle positions.

After all that, you can be rich in one throttle position, and lean in another. You could be rich across the board, or lean as well. Work methodically and adjust each circuit to seek improvement. If you go lean and pick up symptoms move back the other direction.

 

[Munch]

Wow I got a ton more information/replies than I expected, thanks all!

Because of all the info I will explain below exactly what I have done and then hopefully I can be given advice on what step to take next.

A family member bought the bike for super cheap from a friend, it was stood for approx 3 years without any use, old fuel still in the bike. He doesn't know much about bikes and only rides so I was doing all the work for him.

• Emptied tank
• Put straight fuel in and washed it out making sure tank is clear
• Cleaned the carb with carb cleaning, including jets ect
• Fresh plug (BR9)
• Fresh mixture, 40:1 putoline oil

After all of the above it still spluttered so I did a lot of researching and did the below:

• Another fresh plug
• Checked reeds
• Leak down test on the inlet with carb cleaner
• Checked for any obvious sign of damage to electrics
• Tried a different muffler

I also purchased a few jets both bigger and smaller pilot and main ready to try.

The splutter was extremely bad, right through the range too and the bike smoked a lot (blue smoke though)

I was reading the manual and noticed it recommends 50:1 so I tried that with a different type of plug (br8) and it seemed to do the trick, the bike is hitting powerband in every gear, zno spluttering at all.

I don't get to ride the bike until Sunday but my plan is to run it and see how it rides, check the plug after some more riding. If the plug is lean what steps should I take to make it more rich?

 

[95jersey]

I have learned not to bother with the plug. It is too vague to read 1/2 the time.

I go by sound and feel. Lean has a high revving pinging sound. Also, the throttle will hang. It will also be down on power but may hit hard on the top out of no where.

Richen it until it gets blubbery then go one step back.

 

[Munch]

I have learned not to bother with the plug. It is too vague to read 1/2 the time.

I go by sound and feel. Lean has a high revving pinging sound. Also, the throttle will hang. It will also be down on power but may hit hard on the top out of no where.

Richen it until it gets blubbery then go one step back.

Yeah it sounds very snappy and loud right now, almost like my kx 125, I'm sure they are meant to sound a lot more tamed because of the longer muffler right? I also noticed inside the muffler only around 30% of the length of it was packed, the rest empty.

How do I go about richening it?

 

[Capz85]

Isn't the n1ef needle the one everybody says to throw away?

You said you had some other jets, why don't you see how it runs at the weekend, either richen it up on the needle or go up on the jet sizes and see how it feels, try a 45 and 178

 

[GGRider01]

How do I go about richening it?

Pay attention to how the bike is responding to throttle. You have the pilot, needle, and main jet to play with. The main is the easiest of all because all you have to do is dump the throttle wide open. The others take some persistence to sort out.

Bigger numbers = richer jets. Always go in one step increments. 170-172-175-178-180 for main jets.

Your bike is a 250 if I recall, so you're even leaner than I first though. The smaller lung can't pull fuel through the jets as readily as a 300, and it's even worse on the 125s.. I'd start at a 180 main, 45 pilot, and fine tune from there.

Get the bike nice and hot before deeming your jetting good or bad.

Eventually you should get rid of that N1EF. Junk needle only good at sub freezing temperatures.

 

[Munch]

Ok I will get rid of the needle, what one should I replace it with? Maybe I can get one locally.

I am checking out the jetting database on the forum and I have a few examples of people who are at similar temperature and elevation to me:
http://www.gasgasrider.org/forum/showpost.php?p=134152&postcount=209
http://www.gasgasrider.org/forum/showpost.php?p=121345&postcount=188
http://www.gasgasrider.org/forum/showthread.php?p=13712&highlight=EC250#post13712

Looking at the above maybe I should consider changing my main to a 178 and leave the pilot at the 42?
Unfortunately I didn't get a 178, I have 170, 172, 175, 180, 185. Suggestions?

I am super nervous about seizing the bike because it's too lean, with my previous bike it came working and I have put over 150hrs on it (2 pistons) and no problems so I don't have any experience with jetting at all.

Also something that was pointed out to me while I was getting advice was how thick of a reed spacer(?) I have on the bike, the pic below is around the thickness, mine may even be a little thicker. Would this effect the jetting and explain the low main jet?
https://www.economycycle.com/wp-content/uploads/2014/12/spacers.JPG

 

[Capz85]

You can order needles from jim aim motorcycles online they arrive pretty quick

 

[GGRider01]

Just throw the 180 in. If you deem it too rich then get the 178. A lot of people are content with the n1ef so it's hardly an urgent change. It's a very rich needle anyway, so it's safe to leave it.

I know when I got my first 2 stroke I spent days reading forum posts I'd pulled up with Google and my head felt like it was going to rot and fall off. Point is don't over think it.

That reed spacer isn't going to have a measurable change.

 

[Munch]

Ok cool so I am going to ride it on Sunday, get it warm and see how it's running. Once I confirm all is good and no problems I will switch over to the 180 main and see how it's going and report back.

If I put the 180 in and it makes it a worse ride, would it be ok to revert back to the 172 do you think? Or am I likely to cause damage?

I am coming from a kx 125 so I won't be riding the bike hard.

 

[Jakobi]

Ok cool so I am going to ride it on Sunday, get it warm and see how it's running. Once I confirm all is good and no problems I will switch over to the 180 main and see how it's going and report back.

If I put the 180 in and it makes it a worse ride, would it be ok to revert back to the 172 do you think? Or am I likely to cause damage?

I am coming from a kx 125 so I won't be riding the bike hard.

I am in hot humid tropical environment at some elevation.. a 172 main is lean on my 250's and they use the newer model carb that has better efficiency. Old one, without knowing your conditions. I'd be looking at starting at 180 easily.

 

[barossi73]

The plug has some use,but the key is its relative to how the bike was ridden last/rider style.a lot of puttering will darken,look rich/a wot run right before pulling plug will show a greyer/hot/drier leaner looking plug.
Pay attention to where the problem areas are-pilot=0-1/8 with a small affect to 1/4.main=3/4 to wot.needle type/clip=everything in between.
With that needle the best youl likely get is ok 0-1/8,blubber 1/8-1/4,then whack,clean mid hit to wot.
The blubber just before the hit makes it difficult in tight technical stuff.if you ride wot/fast the mid to top hit is fine,but when you roll on/off it may burble then hit.changing needle type will help get a smoother transition

 

[Munch]

Can you guys recommend some needles I can try?

 

[Munch]

I am in hot humid tropical environment at some elevation.. a 172 main is lean on my 250's and they use the newer model carb that has better efficiency. Old one, without knowing your conditions. I'd be looking at starting at 180 easily.

I'm really sorry but I am finding it hard to get some clear instructions from the posts in this thread.

I am currently running 172 which seems to work fine, power is there through the gears, powerband hits. However running 172 is likely to be far to lean so I should switch to the 180 main. What should I do if I switch to the 180 and it has some running problems like bogging/spluttering?

Edit: Also in regards to the needle I am searching places like ebay for "LTR" but not coming up with any results, from the jetting database I noticed a few people were running the LTR needle.