Spark plug fouling

Got questions? We got answers....
User avatar
rbates9
Supporting Member II
Supporting Member II
Posts: 3164
Joined: 06:07 pm Apr 27 2010
Country:
Location: UPSTATE New York

Spark plug fouling

Post by rbates9 »

Do your self a favor and actually go thru the jetting steps and don't just jump around with different sizes hoping for the best. all that will do is frustrate you and lead to poor results.
Rjcapt
Supporting Member
Posts: 94
Joined: 07:11 pm Sep 25 2011
Country:

Re: Spark plug fouling

Post by Rjcapt »

Don't run a 50:1 ratio. The manual specifies a 32:1 and there's a reason for this.

Do you know why you put oil in the gas on 2 strokes?

The oil mixture is the ONLY lubrication the crank bearing gets. If you lean this out too much, you will ruin the crank bearing. Yes, the bike will run "cleaner", with less "spooge" or oil residue in the pipe, but you are doing this at the expense of bottom end lubrication. Not a good trade off in my opinion...

Jetting a bike is a little daunting at first, so take the time to really understand what your carb does, why it does it and how it does it. It's amazingly simple once you understand it and it will make a huge difference in how your bike runs. It's not black magic. Really. Once you get the hang of it all your buddies will want you to "fix" their bikes. It's a skill well worth learning.

Pete
User avatar
scheckaet
KDXRider.net
KDXRider.net
Posts: 3740
Joined: 12:09 am Nov 10 2005
Country:
Location: edmond oklahoma

Re: Spark plug fouling

Post by scheckaet »

Rjcapt wrote:Don't run a 50:1 ratio. The manual specifies a 32:1 and there's a reason for this.

The oil mixture is the ONLY lubrication the crank bearing gets. If you lean this out too much, you will ruin the crank bearing. Yes, the bike will run "cleaner", with less "spooge" or oil residue in the pipe, but you are doing this at the expense of bottom end lubrication.
you ought to re read the jetting section cuz some of your fact are not quite right...
Rjcapt
Supporting Member
Posts: 94
Joined: 07:11 pm Sep 25 2011
Country:

Re: Spark plug fouling

Post by Rjcapt »

scheckaet wrote:
Rjcapt wrote:Don't run a 50:1 ratio. The manual specifies a 32:1 and there's a reason for this.

The oil mixture is the ONLY lubrication the crank bearing gets. If you lean this out too much, you will ruin the crank bearing. Yes, the bike will run "cleaner", with less "spooge" or oil residue in the pipe, but you are doing this at the expense of bottom end lubrication.
you ought to re read the jetting section cuz some of your fact are not quite right...
Ok, just reread it. What am I missing here?

Thanks

Pete
User avatar
scheckaet
KDXRider.net
KDXRider.net
Posts: 3740
Joined: 12:09 am Nov 10 2005
Country:
Location: edmond oklahoma

Re: Spark plug fouling

Post by scheckaet »

Don't run a 50:1 ratio.
some run this with no problem when it's jetted for that specific ratio.

The manual specifies a 32:1 and there's a reason for this.
yes, it's to cover their @$$ from potential lawsuit.

The oil mixture is the ONLY lubrication the crank bearing gets.
Absolutely.

If you lean this out too much, you will ruin the crank bearing.

I assume you are talking about going from 1:40 to 1:50, in this case, you are richening your fuel mixture that's what i wanted you to understand.

RICH VS LEAN

This does NOT relate to the amount of oil in your mix. (at least not directly).
It relates to the ratio GAS / AIR
So, too rich does NOT mean too much oil, it means too much gas for the amount of air it's getting.
If you have more gas than air, then not all the gas is going to burn (think of a candle light, what happens when you close the top? the flame dies out (lack of air) and it makes a black soot, carbon deposit because it cannot do a complete burn)

Yes, the bike will run "cleaner", with less "spooge" or oil residue in the pipe, but you are doing this at the expense of bottom end lubrication.

wrong.
by increasing the ratio from 1:40 to 1:50 you are increasing your fuel ...you will get MORE spooge, not less
SPOOGE / DRIPS:

There's usually a lot of misconception about spooge, what it is, what causes it...

First, a little is somewhat normal. keeps the kips lubed up...
(please someone correct me if I'm wrong)

Second, no, it's not too much oil in your pre mix or "un burnt" oil...
This is in fact unburnt FUEL mix (not just the oil part of the premix ) caused by a too rich condition in one (or more) of your circuits.

Jet your bike properly and DO NOT jet your bike by looking at the tail end of your pipe!
Follow the guideline: viewtopic.php?f=105&t=1156
The silencer can hold LOTS of spooge, so you could be way too lean on your bike and still see spooge dropping out...

Remember the candle light example from earlier, well this is the same on your bike, not enough air (or too much gas) = partial burn = lots of black carbon + unburnt fuel = spooge

Make sense?
Rjcapt
Supporting Member
Posts: 94
Joined: 07:11 pm Sep 25 2011
Country:

Spark plug fouling

Post by Rjcapt »

There may be a little terminology confusion here, so let me define a few things. For the sake of this discussion:

Fuel--Gasoline mixed with the premix of your choice

Mixture--The actual air/fuel ratio as determined by either the pilot jet, main jet or needle position

Fuel Ratio--The ratio of gasoline to premix

Spooge--The black residue found in the exhaust

Onto the entertainment portion of this event......

A manufacturer will define a fuel ratio and specify it for their products. Modify this ratio at your own discretion, but remember that the ONLY oil your lower end gets is from this point. 32:1 works well for me and gives me a little wiggle room for mixing errors on the trail. 50:1 works for you, great, but thats outside my personal comfort level. Anybody asks me for my advice here, and I give them them the factories spec. Period. YMMV

I guess we will agree to disagree with where spooge comes from. If I read your post correctly, it's unburnt fuel. While I have never sent any spooge to my oil analysis guy, I may the next time I send a sample from my drag car. IMHO, it is infact the residue from running premix in your gas.

I run 4 strokes uber rich all the time with no spooge at all. My drag car will not idle without a stupid rich mixture and it likes to run just on this side of fouling plugs instantly. I get a bunch of carbon residue (dry), but no spooge. Try adding premix to your DRZ and see what happens. I'll bet a case of your favorite beverage that you spooge up the works in short order.....

Mixture. We are in complete agreement on this one. There are 3 distinct tuneable circuits and they must all be tunes properly for the bike to run at its peak. And yes with a perfectly tuned mixture, you will still have spooge....

Pete
User avatar
scheckaet
KDXRider.net
KDXRider.net
Posts: 3740
Joined: 12:09 am Nov 10 2005
Country:
Location: edmond oklahoma

Spark plug fouling

Post by scheckaet »

not trying to start another internet war here we all know how those turn out.

However, I have a hard time believing spooge is just "unburnt" oil. Sorry but that doesn't make any sense. Why would the gas burn and not the oil? that's the issue i have with the statement: "spooge is oil"

If spooge is indeed "unburnt oil", that would mean that the engine temp is not high enough to burn it in the combustion chamber. :hmm:
Anyone knows what is the typical combustion chamber temp?
I'd also be curious to know at what temp gas and oil burn...

If you really do have a guy that can analyse spooge, then by any mean go ahead, I'd be curious to see what it really is. (really)
Prove me right, prove me wrong, it's all good to me, that would be beneficial for everyone and we could put this spooge issue to rest once and for all.
User avatar
rbates9
Supporting Member II
Supporting Member II
Posts: 3164
Joined: 06:07 pm Apr 27 2010
Country:
Location: UPSTATE New York

Spark plug fouling

Post by rbates9 »

Mixed fuel (gas +oil) is still fuel. The fuel still burns. Even with oil in it. The oil mixed into two stroke fuel burns. To say that a mix of 50:1 is richer then 40:1 is just due to the simpletons trying to over think things.

Running lean will burn things up. Right?
Then if the mix of 32:1 is leaner then 50:1 a mix of 32:1 would be more likely to seize as you put it. BS...

When the gas is mixed with oil the complete mix will burn. The oil does not separate from the gas during combustion. It all burns. It might not burn completely but it still burns. Gas is a derivative of oil so they are made of the same thing. How is your spark plug smart enough to tell the difference between gas and oil? Which to burn and not to burn. If anything the higher the oil ratio the higher the octane would be.

Put some straight gas in a cup and some two stroke gas in a cup and light them both. tell me how much oil is left in the cup with the two stroke in it after they both burn out.

The way people make an issue out of this topic is completely stupid. Stop dragging this worn out debate out.
Rjcapt
Supporting Member
Posts: 94
Joined: 07:11 pm Sep 25 2011
Country:

Spark plug fouling

Post by Rjcapt »

scheckaet wrote:not trying to start another internet war here we all know how those turn out.

However, I have a hard time believing spooge is just "unburnt" oil. Sorry but that doesn't make any sense. Why would the gas burn and not the oil? that's the issue i have with the statement: "spooge is oil"

If spooge is indeed "unburnt oil", that would mean that the engine temp is not high enough to burn it in the combustion chamber. :hmm:
Anyone knows what is the typical combustion chamber temp?
I'd also be curious to know at what temp gas and oil burn...

If you really do have a guy that can analyse spooge, then by any mean go ahead, I'd be curious to see what it really is. (really)
Prove me right, prove me wrong, it's all good to me, that would be beneficial for everyone and we could put this spooge issue to rest once and for all.

No "Internet wars" starting here. In the end analysis, the molecular structure of the stuff dripping out of the exhaust is irrelevant so long as you are happy with your mix ratio and you're jetted properly.

Personally however, I like to know specifically the whys and the hows of the engines I work on. To me at least a comprehensive understanding of the machine is better than a simple superficial understanding, so I research, evaluate and question things. I appreciate your (and everyone else's) input here. Thank you for sharing your thoughts and experiences.

I don't consider the spooge to be simply unburnt oil, but more of a residue left by the oil after the combustion process is complete. I'll contact the lab I work with and see if they can look at it for me, if for nothing less than my own edification. If they can great, if not it will just be something for me to wonder about.....

And to answer the other question, I'm not sure what the actual combustion temp is but I would imagine the EGT (exhaust gas temperature) to be in the 1000* range. It's pretty damn hot.

Pete
Rjcapt
Supporting Member
Posts: 94
Joined: 07:11 pm Sep 25 2011
Country:

Spark plug fouling

Post by Rjcapt »

rbates9 wrote:Mixed fuel (gas +oil) is still fuel. The fuel still burns. Even with oil in it. The oil mixed into two stroke fuel burns. To say that a mix of 50:1 is richer then 40:1 is just due to the simpletons trying to over think things.

Running lean will burn things up. Right?
Then if the mix of 32:1 is leaner then 50:1 a mix of 32:1 would be more likely to seize as you put it. BS...

When the gas is mixed with oil the complete mix will burn. The oil does not separate from the gas during combustion. It all burns. It might not burn completely but it still burns. Gas is a derivative of oil so they are made of the same thing. How is your spark plug smart enough to tell the difference between gas and oil? Which to burn and not to burn. If anything the higher the oil ratio the higher the octane would be.

Put some straight gas in a cup and some two stroke gas in a cup and light them both. tell me how much oil is left in the cup with the two stroke in it after they both burn out.

The way people make an issue out of this topic is completely stupid. Stop dragging this worn out debate out.
Sorry, I didn't realize that discussing this issue was either "stupid" or "dragging out a worn out debate".

I do have a few comments however.

All "fuels" are not created equal, nor do they possess the same inherent characteristics. Try running kerosene if you're interested in an example. Just because you mix something that's flammable with something else that's flammable doesn't make it an acceptable flammable mixture

The molecular makeup of the various fuels (in this case gasoline and pre mix) will burn differently (yes they will seperate at the molecular level), and produce different byproducts. If you mix leaded fuel with your unleaded fuel, you will still destroy a catalytic converter and O2 sensor.

In our case, the gasoline will leave its own byproducts and the oil will leave its own. The spooge (perhaps) being the byproduct of the oil.

As far as your BS comment. Reread my post. I wasn't implying that a lean air/fuel ratio would ruin the bottom end (it will however do nasty things to the top end....), but that too lean of a gas/fuel ratio will. I have no idea at what point this occurs, nor am I willing to experiment on my engine to find out. That is why I err on the side of what I consider to be caution with a 32:1 mix. My bike, my opinion. Please don't think I'm telling anyone what they should do unless they ask.

Pete
KarlP
Supporting Member III
Supporting Member III
Posts: 1484
Joined: 02:26 pm Jun 29 2005
Country:
Location: Alabama

Re: Spark plug fouling

Post by KarlP »

Ho-hum

You still with us Redraider? Did you just go down one size on pilot and main and are now motoring happily around?
'08 KTM200xc
'99 CR/KDX Hybrid with that RB stuff done to it
KX100 for the boy
User avatar
rbates9
Supporting Member II
Supporting Member II
Posts: 3164
Joined: 06:07 pm Apr 27 2010
Country:
Location: UPSTATE New York

Spark plug fouling

Post by rbates9 »

I apologize for hijacking a thread for a debate. Redraider had a post up (that is gone now) that made comment to the turning of this post and he was right. It had nothing useful to his issue. If the rich vs lean debate needs to happen there should be a separate thread for it.

Again, back on topic.
User avatar
scheckaet
KDXRider.net
KDXRider.net
Posts: 3740
Joined: 12:09 am Nov 10 2005
Country:
Location: edmond oklahoma

Spark plug fouling

Post by scheckaet »

My apologies to the OP, i'm the one that started this again, I was just trying to correct misconceptions and wrong statement...
Threads get a life of their own after awhile...
I'll start another tread about spooge.
Post Reply