Fouling plugs

cladoo

cladoo

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My 2010 300 Nambotin has been fouling plugs quite often for the last couple of years. I thought I had it fixed when I found my crankcase gasket was causing my engine to suck in tranny oil.i fixed that but this week for the first ride of the season it has fouled two plugs already. I've been using the same oil and buy the same gas from the same station. Could I have a bad jug of premix oil? I use Amsoil Saber 80:1 and Shell V Power gas. The bike will run all day with now problems it's just that first start up for the day that it fouls!
 
New plugs gapped correctly? Using a BR8ES/G? I don't rate the irridiums.

Drop the crank case bolt and see if you have excess fuel/oil pooled up in there before the 1st start maybe.
 
Swap out the coil and cap from another bike for giggles.

Maybe float jet too. What's your mileage like?
Plugs fail due to bad spark or rich mixture. Oil is but a minor inconvenience. We all run 40:1 & cant think last time anyone actually fouled a plug. Usually just get a bit gurgly in top end and you realise that the plug is a year old..
 
Stupid question but you're not leaving it on the choke too long are you? 10 seconds max then just give it revs to warm it up.
 
New plug, new cap and high tension lead. New stator as my lighting coil burned out. Not runing rich when it starts. I can ride all day without issues, just on cold start up. Mileage is good. New top end last year and I didn't ride much as we had a OHV fire ban and I hurt myself too! Not leaving the choke on more than 10 secs. There are a few local guys that have had issues with Shell V Power gas doing the same thing on cold starts. So I'm going to try some different gas. If that doesn't work then I will try some other oil.
 
What's your needle man? We're all loving the RM250 erm, NEDW I think. Or is it J? Written down somewhere. Well actually about 10foot below where I sit at the breakfast bar. Although it isn't Breakfast. Confusing. . .

On a piece of paper clothespegged to my test power supply. Why didn't I write it in the log book I keep for all my bikes?

It's an Enigma wrapped in a Mystery.
Tied up in a Puzzle.

You know I'm going to try a 170 next weekend. Seem to be needing leaner settings than the others.
Might be the head mods.

So I'm drinking APA. . .
 
I've been using a DDK needle for years. I dont see it causing a cold start fouling. My guess is the gas.
 
If others have had the same issues on the same fuel, then that's what I'd be looking into.

I know with my car I had some rough idling on cold starts a while back... Only ever first start of the day. I wasn't the only one. Interestingly a few people had the same issues and all found it would resolve by moving from BP Ultimate 98 RON to a 95 RON fuel for a couple tanks. It must have been part of the additive package causing some issues. It was soon after they released their adverts regarding "cleaning the engine" etc... detergents.
 
That's exactly the combination I used for years in my KTM's- Amsoil 80:1 and shell V-Power and I never had an issue.

Then I bought my first GasGas in 2018 a EC 300GP. And it fouled plugs from day one. Was a a really hard time.

Parts I changed:
Ignition coil, cable and cap (twice once from a GG once from a KTM 300)
ECU

Luckily my mate had bought the same bike and let me use all of his parts. Finally I swapped the carbs but it did not help either. I tried hotter plugs but they fouled too.

I was really gutted and had no clue what to do. 8 rides, 8 plugs. It always fouled the plugs when idling.
Then in my desparation I called James Dean and described him that the problem happens even if I jet the carb extremely lean (for testing) or extremely rich. James asked what oil and fuel are you running and how the bike runs when it is correctly jetted. I told him that the bike really runs almost perfect as I am a jetting nerd. He suggested to empty the tank and carb, fill fresh ethanol free fuel and use a different oil.

So I bought a bottle of Putoline Mx9 oil mixed it 60:1 (only Amsoil I used 80:1) and went for a ride.

All was good. Next ride I used Motul 710 and after that Motul 800 (80:1) and Fuch Silkolene Titanium (80:1,60:1).
The Gasser never ever fouled a single plug!

I contacted Amsoil and had quite a nice conversation with them. The said that they can't stress enough that Amsoil Saber is not to be used in two stroke motorcycles even though it fulfils the required specs and I should stop using it and go for AMsoil Interceptor.

Lesson learned!

I sold the Gasser finally (just to buy a 2019) and the new owner is happy and it never fouled a plug again.

Please try that and let me know what you found.

Cheers Doc

edit: no I did not make the crosscheck. I still do not know was it the Saber oil or the Shell gas or even both. I just use 98 ethanol free fuel of any brand and oil designed specifically for 2 stroke bikes...
 
That was my first thought, that the Saber oil was bad. But I've been using it for at over 7 years and only now it's giving me grief?
 
Mikeyx said:
How about the obvious solution: using a hotter plug that burns soot and oil away?
Click to expand...
Because using a hotter plug is usually a band-aid solution to another problem. It can even cause other undesirable issues like holed pistons etc. I'd be changing oils and fuels like Doc said. Cheap and easy test. Oil companies can change manufacturing techniques/ingredients/facilities and not tell you a thing either. I haven't found a 2T that needs to run 98RON+ in all my years as a mechanic either. They just aren't high comp like most 4T's are. 95RON is as high as I run and that is just to steer away from ethanol based fuel.
If after changing fuel/oil doesn't solve the issue check the choke jet in the carb is nice and tight. It should be pressed in to the body but if it is loose it may allow extra fuel to bypass.
 
1. Many ideas pointing blame at the fuel, oil, mixture, float height, choke, etc... But what about an electrical issue causing a weak spark?

If you fit a new spark plug into the cap, do you get a nice juicy spark?

Using a multimeter check for good continuity on zero volt/earth side, good connection between the engine to frame to zero/earth of ignition coil.

2. What oil are you using to oil your air filter? Make sure you're not putting too much oil on the air filter. I've never had any problems fouling a spark plug... until I recently over did it with the air filter oil!

Best of luck, Dave.
 
Well I drained the gas and put in fresh gas from the same station and mixed it with Amsoil Dominator at 50:1. Put a fresh plug BR8EIX in. It started right away but that was expected. Going for a ride tonight and we'll see how it starts up tomorrow morning on a cold start.
 
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