Oil-fouled plugs

[Rupe]

I've gone through two plugs in the last two rides, and they are new ones. Basically I go for a ride come back to the car for a rest, when I get on it again and give it some gas it has died. I think the bike is set up fine, and the pre-mix is fine, I'm prob just a bit slower then the last owner as I'm learning:scooter: What I was wondering was can I clean the plugs and re-use them or do I have to go buy new ones. Also hows best to clean them?

[scott411]

you can not really clean them,

sounds like your bike is running a bit rich on the bottom if it is fouling plugs when idling, , try a smaller pilot jet,

also if you still are having trouble, nromal type plugs are less prone to fouling than platnium or irridium ones,

[Rupe]

you can not really clean them,

sounds like your bike is running a bit rich on the bottom if it is fouling plugs when idling, , try a smaller pilot jet,

also if you still are having trouble, nromal type plugs are less prone to fouling than platnium or irridium ones,

Ok, maybe I'll try a BR8ES instead of a BR8EG?

Not sure if I want to fiddle with the jetting as the last owner said he'd spent a bit of time getting it just right.

[laRIKin]

As said it is hard to clean spark plugs.
You can if you sand blast them.
I use river sand as it is not to abrasive and I can get it free, you guessed it, from the river bed.
Just make sure you get all the sand (or want ever you use) out of the plug as it will do your engine some harm.

As for the reason for fouling, I can not fix a bike I can not see.
And because you think that the jetting is right as the last owner spent a lot of time jetting it.

Now the last guy maybe riding the bike harder and has set up the jetting a little rich at the bottom, so the motor gets a bit more oil when you button off. (I use to do this)

And is normally not a problem as when you get back on the throttle it will burn off the extra oil.
It can be a problem if you have to ride slow in tricky conditions for to long.

If this is not the case, the motor may be flooding between stopping and starting again, so try turning the fuel tap off if you are not doing this already.

And for some unknown reason this seems to happen a lot when buying a new bike.
For some reason you think that you are mixing the same oil to fuel and the bike fouls plugs.
Different measuring jug's, petrol who knows, but you are not alone with this problem.
So you may have to re-jet the bike or try a hotter plug.

Hope this helps.

[Rupe]

Thanks, looks like I'll have to try re-jetting it.

Not sure what you mean with the fuel tap? Do you mean I should run the bike with the tap in the off position while riding slow tricky stuff?

Also any ideas on the plug, the manual says to use a BR8EG, but the guy I brought it off had a BR8ES in it (But I fouled that one). Scott said normal plugs foul less than irridium or platinum ones?

[scott411]

i have not used eg's for a while, we normally use br9eix irridium plugs and they are especailly bad for fouling

[chop]

I never had any luck with eix`s in my rm always used eg`s or ev`s and didnt have any greif with them try lifting the needle a clip a notch thatll lean it up a bit down low.

[laRIKin]

Not sure what you mean with the fuel tap? Do you mean I should run the bike with the tap in the off position while riding slow tricky stuff?

Also any ideas on the plug, the manual says to use a BR8EG, but the guy I brought it off had a BR8ES in it (But I fouled that one). Scott said normal plugs foul less than irridium or platinum ones?

No I did not mean turn the fuel off when riding, I just meant turn it off when not riding.
Most people do this ay the end of the day when finished riding.
But if the needle seat in the carb is leaking, it could be doing it enough to flood and foul the plug on start up if the bike has been sitting for a while.
Not that likely, but worth a try as it costs nothing.


And try a BR7EG or a BR7ES, they are one grade hotter and it could be enough to help stop the plugs fouling.
And I like to carry a hotter plug as a spare, because if you foul a plug for some reason in the bush, there is a chance that you could do it again.
So a hotter plug could stop it happening again and get you home.:scooter:
You just can not ride as hard for a long time with a hotter plug or if the mixture is lean.
Just check the plug if you are unsure and if to light a colour, ride slow or put the colder plug back in and sort out the mixture.:dodge:

[Henk]

The other thing to look at is your premix ratio. Is it the same as the previous owner? A lot of people get this backwards but running less oil actually makes the bike run richer and more prone to fouling plugs not the other way round.

[Danger]

First things first check your air screw setting. back it out a 1/4 turn from where it is now, if it idles high for longer than a few seconds when you come to a stop, turn it back in an 1/8.

[F5 Dave]

He is actually running more oil than the predecessor, 40:1 rather than 50:1 (sez in another post).

The ECs are jetted a but weird. Most bikes are rich std, mine had been played with & I tried some different jets but I bought an LTR jet kit (~$36US I saw recently) & learnt something I didn't appreciate.

I think I had a 40 pilot jet but was still a bit rich & with the LTR kit it was a 50. (don't quote me on numbers). This seemed queer, but it worked!

The needle they use stock ties to operate over a range it can't fully control. Hence it is trying to use the needle to meter fuel for the idle, but that only results in too large droplets where it would be better to try & run that range (just off idle) through the pilot jet.

Fine adjustments from idle mix for conditions was all it needed (for my 02).

Spend the small amount of money for the kit, with the stock needle you won't get anywhere. But do check that the float needle isn't leaking. If left on its stand does it overflow out the tubes? That would be an issue. Otherwise I only turn the tap off at the end of the day.

I think I run 8s & we faff around a bit trail riding so no racer. I changed the plug the other day more out of guilt than anything else. (now that I've said this I hope I won't regret it but:) I don't think I've fouled a plug on it.

[Danger]

F5 Dave has some good advice. I only just picked up that we were talking about a Gas Gas (thought you had an RMX for some reason:sick:).

A person that has a lot of experience with Gas Gas is Linton from Dirt Action Services in Christchurch. I would give him a call if I was you. He is a great guy and will chew your ear off and my bet is that he will know what jets you need and will be able to send you the right jets for the job. I have a KTM 200 which are also too rich down low and then break into a lean midrange and a straight taper needle sorts those out along with some other changes. I got mine from Linton a few years ago. If you do run straight taper needle you need to go up at least 2 x on the main jet size.

Lintons number is 03 389 0080.

Let us know how you get on.

[Danger]

i have not used eg's for a while, we normally use br9eix irridium plugs and they are especailly bad for fouling

Whats the advantage of using these plugs if they foul more easilly?

[laRIKin]

He is actually running more oil than the predecessor, 40:1 rather than 50:1 (sez in another post).

That bit of info I did not know.
And would explain a lot.

[scott411]

Whats the advantage of using these plugs if they foul more easilly?

more consitant spark in race conditions,

[Rupe]

[QUOTE=F5 Dave;1160801]He is actually running more oil than the predecessor, 40:1 rather than 50:1 (sez in another post).QUOTE]

No it was the other way round. he was running 40:1 but after I fouled a plug I changed to 45:1. After another fouled plug I went to 50:1 as 50:1 is what the manual states. But is this making it more likley to foul?????

The manual states it should have a br8eg, but it had a br8es in it (which I fouled). When I first got the bike I took it to muriwai a few times to get used to it, so I would of been opening the throttle a fair bit.

Basically when I've fouled the plugs is going round the dead wood bit up woodhill, which I'm slow round and the bike is prob idling quite a bit. Then I come up the road with the bike ticking over so I don't run any kids over, and have a break (prob without turning the fuel off, can't be sure). When I get back on the bike when I've opened it up it dies, fouled plug, new one in, runs fine.

Not too sure if the bike leaks fuel with the tap on and on the stand, but I think it could do I'll have to check. I know it leaks fuel with the tap on while being transported in the trailer as I could see fuel on the trailer deck when I stopped on the way home a couple of weeks ago.

Anyway thanks very much for the help so far.

[laRIKin]

Read this and it may help.
And read the part after the stop sign just down from jetting and you will under stand what you have done, better than I can type.

http://justkdx.dirtrider.net/printcarbtuning.html

[Danger]

Running less oil makes your bike run richer. Less oil, the fuel droplets are thinner and pass through the jets easier. I know it sounds funny, but its a fact. Its fuel, not oil that is causing your plugs to foul. A 200 should be run on 32-1 oil ratio. 250's at 40-1. Oil provides the lubrication for your crank and seals your piston rings on compression. A faster reving engine like a 125 requires more oil than a slower rever like a 300 or a 500.

[Rupe]

Ok, after having a read through a few bits of info I see it is best to change the fuel ratio to 40:1.

I also remembered that the bike was idling a bit low so I just gave the idle speed screw a twist to fix it. Maybe I should have adjusted the air mix screw too as it may be running to rich at idle to 1/8 throttle. Could something this simple also be the reason?

Thanks heaps so far for all the help

[F5 Dave]

well its a start, Did we ascertain if the airfilter was clean & oiled with air filter oil?

[Aero165]

What oil are you mixing with the fuel? I was using Yamalube on my YZ and I was fouling 2 plugs to every 1 ride sometimes(I don't ride like a nana either) I then switched to castrol tt-s and I haven't fouled a plug since.

My mechanic reckons it has something to do with the oil separating from the fuel in colder temperatures.

Thats my 2cents. Hope it helps

[cheese]

Yeah I'm in teh TTS fan club, I got sick of paying over the top prices for motul.

[vr4king]

Yeah I'm in teh TTS fan club, I got sick of paying over the top prices for motul.

Plus it smells good........Which reminds me i need some where you guys buy it from,I normaly go supercheap autos

[cheese]

Yeah wait for a big supercheap auto special and get it then. Or ask Booom, you have to get it it bulk though and you only save a wee bit.

[Rupe]

well its a start, Did we ascertain if the airfilter was clean & oiled with air filter oil?

I clean and re-oil the air filter with air filter oil after every ride.


The oil I've been using was what the guy gave me with the bike, it's fully synth, motorex oil????? Anyone heard of it/rate it.

[Rupe]

Ok went up Woodhill today to have a run, and try to sort out the plug fouling problem.

I went back to running 40:1 instead of 50:1 to see if that would help. And I adjusted the air mix screw on the carb, (as I sdjusted the idle speed and not the air mix).

This didn't help, it was fine on the trails, but it's seems to be when I gently cruise up the main road to my car this is when I'm fouling plugs. And they are wet when I pull them out. I was also thinking it might be that I'm putting to much oil on my air filter, but then again the bike is fine when you open it up.

So basically I'm no further ahead, any ideas would be great.

Another thing that I was unsure of was if I'm adjusting the air mix correctly. I'm assuming that 1 1/2 turns would be turning the screw 540%???

Also I opened and clean the carb in the week, and I was thinking today that by turning the black plastic idle screw to make it idle quicker, did I move the whole jetting needle? Should I make it slower again.

[dammad1]

The Jetting must be out, take it to some one who knows what they are doing, pay the money and sort it out once and for all so you can actually enjoy riding it like your suppose to.

[Rupe]

The Jetting must be out, take it to some one who knows what they are doing, pay the money and sort it out once and for all so you can actually enjoy riding it like your suppose to.

No thanks, I'd rather learn to sort out the minor problems myself. prob come in useful in the future and I'm enjoying fixing the little problems, and the riding thanks.

[Buddy L]

I was putting a bit to much oil on my filter at one stage, but his only ended up making the bike run more smokey then normal. Is the main jet standard size? if you just puttering around the car park with a over size main jet? maybe?
http://www.snowvalley.20m.com/bikes/jets.htm
Have a look at this might help!

[smoky]

If you want a 2 stroke then you need to ring its neck and rev the thing, if you think you'll only ever be a plodder - sell it and buy a 4 stroke.

[Rupe]

I was putting a bit to much oil on my filter at one stage, but his only ended up making the bike run more smokey then normal. Is the main jet standard size? if you just puttering around the car park with a over size main jet? maybe?
http://www.snowvalley.20m.com/bikes/jets.htm
Have a look at this might help!


Thanks had a read some good info.

I'm thinking that maybe by winding in the idle screw in to raise the idle speed, it has raised the slide and needle so while idling and at slow speed to much fuel is going through.

I'll try setting a very slow idle and setting the air screw and see what happens next ride.

Thanks for the helpful posts, I'll sort it in the end I'm sure.

[Buddy L]

OK followed a few linky links anf found this its for a 03 ec125,200.250 but im sure they woulden't have changed the bike dramaticly between the years.:yes: happy reading.
manual
and parts list.
Just for you.
"Gasoline and oil mixture(premix ratio)(50 parts gasoline to 1 part oil.
Standard Spark Plug
HGK CR8 E o DENSO U24ESR-N Gap 0.7-0.8mm

to big to upload on to KB so heres the link to down load it.
took about 5 mins on broadband to download.
http://www.gasgasmotos.es/esp/frame.htm
:shit:

[dammad1]

If you want a 2 stroke then you need to ring its neck and rev the thing, if you think you'll only ever be a plodder - sell it and buy a 4 stroke.

On a modern two stroke, if its jetted correctly you can plod along on it as much as you like I have never fouled a plug once on any of my two strokes.

My brothers old race bikes used to foul easily but they were jetted for top end and needed to be kept on the pipe, but this is no good at all for trail riding or cross country's.

[vr4king]

If you want a 2 stroke then you need to ring its neck and rev the thing, if you think you'll only ever be a plodder - sell it and buy a 4 stroke.

Well i got a 1992 cr125 with a BR9EG plug and will happily plod without fouling a plug........I think your wrong if its setup right it should run at any engine speed fine

Having said this though i normaly "blip" the throttle when plodding just to clear it and everytime i pull the plug shes as black well you know lol

[Danger]

Just call Linton. I don't think you have even told us what jetting you are running?

[F5 Dave]

Well I won't poke any more derision at the ill informed flat earth comments about 2 strokes needing their necks wrung, but I guess by association I already have. . .

Main jet largely controls the wide open throttle position so not so relevant. As I said the LTR jet kit helps enormously. Linton probably stocks them, he can get them if you don't want to order on line.

Does seem odd that it is fouling so regularly even so. Have you checked your gearbox level lately? Is it going down? How much does it smoke when warm? (always smoke like a pig when cold).

[smoky]

Well I won't poke any more derision at the ill informed flat earth comments about 2 strokes needing their necks wrung, but I guess by association I already have. . .

Cal me ill informed if want - but it's a known fact,
You’ve got to get a 2 stroke hot to burn off the oil - the best way to do that is rev the thing.
2 strokes are made to go fast, get the revs up and hit the power band - other wise what’s the point of them? If you want torque low down and to plod along then you’re not riding a bike suitable.
The thing about exhaust pulse tuning (fuel snatching) is you only have 2 strokes of the piston to charge and expel the waste in the cylinder. They rely on higher revs to maintain good volumetric efficiency.
Hot plugs, higher revs, and a hot sealed tuned exhaust system. They’re an art form.

[Rupe]

Cal me ill informed if want - but it's a known fact,
You’ve got to get a 2 stroke hot to burn off the oil - the best way to do that is rev the thing.
2 strokes are made to go fast, get the revs up and hit the power band - other wise what’s the point of them? If you want torque low down and to plod along then you’re not riding a bike suitable.
The thing about exhaust pulse tuning (fuel snatching) is you only have 2 strokes of the piston to charge and expel the waste in the cylinder. They rely on higher revs to maintain good volumetric efficiency.
Hot plugs, higher revs, and a hot sealed tuned exhaust system. They’re an art form.

It's fouling plugs on the road from my car, 300-800m depending where I got a parking space. If I ride it back to the car hitting the power band etc I would flick stones over everyones cars, run over a couple of kids, and get kicked out prob.

Anyway I spoke to Linton from Dirt Action Services who has been very, very helpful, and really knows his stuff. He has got me to make a few adjustments for this weekends ride, and fine tune from there. So It should all be sorted over the next couple of rides, as the carb didn't have a standard needle, slide etc.

Anyway thanks for everyones help, I'll put what the changes I made once it's 100% sorted so it might help someone in the future.

[Danger]

Good man! Have fun!

[CaMo]

hey people. Thought I'd post here as is sorta relevant.

Anyway, bought me a new 2008 kx125 and am having a similar problem. Basically the manual and sticker on the bike says to run it at 32:1. I do, and I use yamalube 2-r racing oil.

However, the problem begins when the bike is ridden slowly for about 30-sec (say if you are going down a wet slippery steep hill in the bush and you can't rev the damn thing). The plug fouls up very quick.:mad:. Once fouled its a no go so put new plug in.

I use NGK irridiums ( br9eix ). Shop recommendation

the jetting etc should all be standy as when it came out of the shop as am first owner.

Will running it a 40:1 fix this problem? The only concern I have is that the guy in the shop I bought it said you can't thrash it when running this mixture or it will blow up.

I can ride it fine and aint no amatuer rider. Just worried that it is going to cost me a truck load in tyres as I have to be thrashing it everywhere to keep it alive. This aint so good when riding on gravel road etc....

One last thing... I noticed someone mention that yamalube was the reason it was fouling and I am sorta thinking he maybe correct as I did notice this on my older bike a few years ago. As soon as we changed the oil it went fine?

?? Cam

[Rupe]

hey people. Thought I'd post here as is sorta relevant.

Anyway, bought me a new 2008 kx125 and am having a similar problem. Basically the manual and sticker on the bike says to run it at 32:1. I do, and I use yamalube 2-r racing oil.

However, the problem begins when the bike is ridden slowly for about 30-sec (say if you are going down a wet slippery steep hill in the bush and you can't rev the damn thing). The plug fouls up very quick.:mad:. Once fouled its a no go so put new plug in.

I use NGK irridiums ( br9eix ). Shop recommendation

the jetting etc should all be standy as when it came out of the shop as am first owner.

Will running it a 40:1 fix this problem? The only concern I have is that the guy in the shop I bought it said you can't thrash it when running this mixture or it will blow up.

I can ride it fine and aint no amatuer rider. Just worried that it is going to cost me a truck load in tyres as I have to be thrashing it everywhere to keep it alive. This aint so good when riding on gravel road etc....

One last thing... I noticed someone mention that yamalube was the reason it was fouling and I am sorta thinking he maybe correct as I did notice this on my older bike a few years ago. As soon as we changed the oil it went fine?

?? Cam

In the manual for my gasgas it states that you should run a hotter plug in the break-in period. This could be the case for your bike, but check first.

Also as pointed out to me going from 32:1 to 40:1 would make the fuel richer and more likley to foul plugs, read through this tread if that doesn't make sense.

I think my problem was the float hight, but I need to test run it againg.

[Danger]

Run the 125 at 40-1 and back the airscrew out a 1/4 turn.

[scott411]

we normally put one smaller pilot jet in the 07-08 KX125's (it is in the spares kit) it helps them stop fouling plugs,

and i agree iwth danger, run it at 40:1

also is yamalube full synthetic, i am not sure ithink it might only be semi synthtic, i wouold reccomend a ful synthetic

Scott, Mr Motorcycles

[Lion]

while were on the subject of jetting, how much will a rejet normally cost?? just done a rebuild and looking at getting the jetting sorted now.