Plug problems.

DirtyJoe · Mar 11, 2007

Im having an issue with my plugs. They foul or burn out fast.

My oil mix is good, factory specs.

The motor is running at a good temp. Not too hot or cold.

Bike runs GREAT when the plug is new, but over an hour time or so, it starts to spudder in the higher RPMS then will finally just shut down.

I have a feeling that I may have a bad seal in the motor. It seems to be loosing the trans fluid. Maybe its just me but I swear its going down. Maybe getting sucked into the motor end?

BTW, the bike is a 1996 KX 125 with a weisco piston (sleeved cylinder), very mild port job, and FMF fatty and silencer. Dont think that stuff will make a diffence but just incase, I posted it.

earl pittz · Mar 11, 2007

If your bike was burning transmission oil you would see big puffs of smoke coming out of your exhaust. Is your spark plug in the right hot/cold range, is it the specified plug for the bike?

DirtyJoe · Mar 11, 2007

earl pittz said:
If your bike was burning transmission oil you would see big puffs of smoke coming out of your exhaust. Is your spark plug in the right hot/cold range, is it the specified plug for the bike?

I have something like B9es plugs. I know its not the EXACT same as Kaw says they should be but its never ever been an issue bfore this.

kawicam250 · Mar 11, 2007

try a BR9EG or BR9ES, there's very little difference between the two, if any. they are the enhanced version of the B9ES, which is kinda outdated. factory specs have always proven to be rich, so you need to lean out the jetting and the oil mixture, try 40:1 as far as oil. mess around with the air screw, and lean out the pilot or main jet, whichever you feel like. i doubt you are burning the plug since you are running it rich on both ends, just try what i said and let us know how it turns out.

killerkx · Mar 12, 2007

i forget the name right now... but i had to spend like $14 for the plug in my kx 125, but it starts on the first kick everytime now, and ive had that plug for about 6 months and havnt fouled it.

earl pittz · Mar 12, 2007

If I were you I would get the corect plug, I think that will solve your problem.

TimberPig · Mar 12, 2007

Are the plugs really oily, and thick with carbon? That could be a sign of burning tranny oil. If you suspect a leaking right side crank seal, you have a couple options. Burn out a few more plugs while keeping close track of the tranny oil level, or simply pulling the clutch and changing the seal. You could also pressure/vacuum test the crankcase (with the oil fill plug off, so that it will show if the crank seal is leaking). Given the behaviour and the fact you are fairly sure it has been losing tranny oil, I'd be ordering a seal and changing it out myself.

earl pittz · Mar 12, 2007

How do you do a crankcase pressure test without special attachments? I had to have one tested once and it was pretty spendy.

TimberPig · Mar 12, 2007

earl pittz said:
How do you do a crankcase pressure test without special attachments? I had to have one tested once and it was pretty spendy.

Here's a thread to build your own. $17 Leakdown Tester

To test pressure, you need a pressure gauge, and a source to provide compressed air (hand pump style). For vacuum, you need a vacuum gauge and a source of vacuum (Mity vac style brake bleeder/vacuum pump).

rmc_olderthandirt · Mar 12, 2007

kawicam250 said:
try a BR9EG or BR9ES, there's very little difference between the two, if any. they are the enhanced version of the B9ES, which is kinda outdated.

That information might be very misleading.....

Sparkplug manufactures don't assign model numbers on a random basis, every letter & number means something. For NGK, the break down of a BR9EG is as follows

B = 14 mm thread with a 13/16" hex
R = Resistor Type
9 = heat rating (higher number is colder)
E = 19 mm reach
G = Fine Wire Nickel Alloy Electrode

A BR9ES would be the same plug with a Standard center electrode.

A B9ES is the standard tipped plug without the resistor.

The thread you can't mess around with, the wrong thread simply won't fit.

The reach you really don't want to mess around with. Too long of a reach and it will extend too far into the cylinder and hit the piston. Too short of a reach and it won't put the spark in the cylinder and it may not run at all.

The choice of tip is not that critical for a two stroke bike. The "G" tip will last longer, which can be a great thing in the family car but on a two stroke you will usually foul them out and replace them long before the tips have eroded away.

Dirtyjoe:

My recommendation would be to run a hotter plug. I run BR6ES plugs in my YZ-125 and my son's YZ-250 (factory specification for both). A BR9ES (or B9ES) would be three heat ranges colder. If the plug doesn't run hot enough to burn off the oil deposits is will foul.

Rod

earl pittz · Mar 12, 2007

How do you do a pressure test anyway. I have a pressure guage and a floor pump. What I mean is how do you attatch to the engine, through the oil fill hole?

TimberPig · Mar 12, 2007

earl pittz said:
How do you do a pressure test anyway. I have a pressure guage and a floor pump. What I mean is how do you attatch to the engine, through the oil fill hole?

You block off the intake and exhaust with plugs. The pressure/vacuum source and gauge assembly is attached either through the spark plug hole, or through a fitting in one of the intake/exhaust plugs. Pressure to a safe, known value (<15psi pressure) is applied, and the engine is left and reckecned for pressure loss. A good engine will leak very little, while one with leaks will lose a significant amount. Same procedure for vacuum testing. Soapy water or similar will often help find pressure/vacuum leaks, if they are unable to be heard or seen otherwise. It may or may not be necessary to strip the engine down to test, as it is primarily the crank seals which need disassembly for inspection.

earl pittz · Mar 12, 2007

Ok, that makes sense. How to you attatch the floor pump to the plugs?

TimberPig · Mar 12, 2007

earl pittz said:
Ok, that makes sense. How to you attatch the floor pump to the plugs?

You have to drill/tap and seal it to take a hose barb, onto which a line can be connected, and you hook the pump to that hose.

DirtyJoe · Mar 12, 2007

Thanks to everyone with info on the subject. Im goingo t try to answer or respond to everyones comments or suggestions...

Im going to try a few things one by one.

Correct my order if you think something else should take priority to the other.

#1, Try a different plug. Im thinking of a 7 or 8 to start.

#2, Change my oil mix and oil brand (running normal 2 cycle oil)

3# I beleive I have the wrong fluid in my trans. I was told by a few people to run a heavy oil, instead of the 10-30 or 40 that Kaw says to run.

Im almost certain Im losing trans oil to the motor (no leaks on the outside.)

I have to ask, why cant I vaccum or pressure test the trans side instead of going thru the spark plug side. Is there an issue with doing it this way instead of the way you all suggested? It seems to me to be easer and I dont have to block the intake and exaust side.

Just to give more info on my plug issue aswell......My plugs are comming out near black near on the center of the ceramic and "tong". It doesnt look wet or anything like that. Just like real heavy carbon deposits possably.

As far as the re-jetting or whatnot. Im VERY new to 2 stroke motors, and Im alittle leary on playing with the jets on/in the carb. So if it comes to that, I will take it in to the STEALERship to have that played with.

Once again, thank you all for your help, please if you feel Im missing something, or have other ideas, let me know. Im willing to try anything to get the bike alittle more reliable.

DirtyJoe · Mar 28, 2007

OK, well, after changing a few things, taken the motor apart a few times (yes, a FEW) I think the problem my be fix with an exception...let me explain...

I made sure all gaskets were in good shape (for the oil loss) and they were, BUT, I found a bad (going bad) crank bearing that made the oil seal on the crank not seal properly...

I changed the plugs to an #8 plug...Hasnt fouled yet. But under an hour of "easy" riding. Problem may still exist. ..

I used a full synthetic oil for the trans (noticed a power increase beleive it or not) It pulls the front wheel fairly easy in first when it never did before without "popping" the clutch....Highly recommend trying it if you arnt already.

I still am mixing the oil alittle "strong" to be on the safe side. Kaw says go 40-1 but I would say Im going about mid 40s to 1.

whenfoxforks-ruled · Mar 29, 2007

BEFORE you go aimlessly throwing plugs in there to compensate for mechanical or jetting problems look at the porcelain for proper heat range. Your bike requires a resistor plug in the 9 range.The thrifty es plugs are great for lazy or bewildered by the jetting,or the ones that are trying to drag every last foot before they blow.Your bike was sucking trans fluid,the es may have worked,3 ranges hotter may have melted!The es plugs have a large electrode and throws a big spark on bottom,but are no good in that old race bike on the top end,and on a 125 guess where the power is?Jetting once done correctly is no big deal,geez! http://dirtrider.net/forums3/showthread.php?t=92818&page=1&pp=20 rmc_olderthandirt,may have been a typo but the heat range for your bikes is 8or9,not6,do not know why you would need that hot a plug???http://www.ngk.com/

Red Ryder · Mar 29, 2007

What IS an iridium spark plug? What other plugs are there? Is iridium the best kind?

rmc_olderthandirt · Mar 29, 2007

Red Ryder said:
What IS an iridium spark plug? What other plugs are there? Is iridium the best kind?

iridium is a precious metal. Noted for being able to withstand extremly high temperatures. Very dense, very hard but brittle.

When used in a spark plug it will be the electrode part. Being so dense, hard and able to withstand temperature it will last MUCH longer than a standard plug. This is a very good thing when used in a car that requires the removal of the engine to change the plugs!

Why you would want that on a dirt bike I have no idea.

Rod

Red Ryder · Mar 29, 2007

That's cool. Is the electrode on a standard plug just steel or something?

ds66 · Apr 6, 2007

rmc_olderthandirt said:
That information might be very misleading.....

Sparkplug manufactures don't assign model numbers on a random basis, every letter & number means something. For NGK, the break down of a BR9EG is as follows

B = 14 mm thread with a 13/16" hex
R = Resistor Type
9 = heat rating (higher number is colder)
E = 19 mm reach
G = Fine Wire Nickel Alloy Electrode

A BR9ES would be the same plug with a Standard center electrode.

A B9ES is the standard tipped plug without the resistor.

The thread you can't mess around with, the wrong thread simply won't fit.

The reach you really don't want to mess around with. Too long of a reach and it will extend too far into the cylinder and hit the piston. Too short of a reach and it won't put the spark in the cylinder and it may not run at all.

The choice of tip is not that critical for a two stroke bike. The "G" tip will last longer, which can be a great thing in the family car but on a two stroke you will usually foul them out and replace them long before the tips have eroded away.

Dirtyjoe:

My recommendation would be to run a hotter plug. I run BR6ES plugs in my YZ-125 and my son's YZ-250 (factory specification for both). A BR9ES (or B9ES) would be three heat ranges colder. If the plug doesn't run hot enough to burn off the oil deposits is will foul.

Rod

Thank 'Oldderthandirt' :cool: you very much, I was running a BR7es plug in my kdx250 91' model and the plug lasted a bout an hour before fouling up badly... Do you think it will be ok to run a BR6ES plug in my old bike??? Motor is fresh...

jason33 · Apr 6, 2007

well im telling you you need a new crank case oil seal!!!-
change it and your problem is solved - you shouldn't need a hotter plug- your just going to burn a hole in your piston ,and make things worse
i had the same problem with my kx -
also oil can get in the cyl from the center case if theres not a paper gasket -i make 1 for my kx's its better than the liquid crap
im not sure but you might need to split the cases to change the oil seal - i had to on my kx - good luck - let us know

snb73 · Apr 6, 2007

JET, JET, JET, JET!!!!!!!!!!!!!!!!

List your current jetting!!!

Do not chase a jetting problem by changing plug heat range or changing fuel/oil ratio.

Choose a ratio 32:1 or 40:1 mixed with super unleaded and stick to it.

Use a BR9EG or BR9ES (BR9EIX is the stock plug, but very expensive)

10W40 is pretty standard for an MX transmission, your manual will tell you for sure.

Don't fear jetting, if you are meticulous and methodical, it can be very straight forward. I have used the same plug in my bike all year. I only changed it because I did a top end and felt guilty not replacing the $5 plug.

Here are a few links for reading;

http://www.all-offroad.com/DirtBikes/Beginners/BGNov98.html

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

http://www.keihin-us.com/tune.htm

http://www.keihin-us.com/am/_media/pdf/slide_valve.pdf

http://www.maximausa.com/technical/lubenews/springsummer2001.pdf

http://www.powroll.com/tech_specs_jetting101.htm

http://www.duncanracing.com/techfaq/Tech_keihin-carburetion-jetting.phtml

http://www.keihin-us.com/am/tuning/

Plug Reading;

http://www.dansmc.com/spark_plugs/spark_plugs_catalog.html

http://www.strappe.com/plugs.html

http://www.ngksparkplugs.com/techinfo/spark_plugs/techtips.asp?nav=31000&country=US

Good luck, Steve.

mopower440 · Apr 15, 2007

I have a 1998 rm125 and have been running the BR9EG plug in it, the center electrode is so small im afraid that it will break off and fall into the engine. Is it ok to run the BR9ES instead?

mox69 · Apr 16, 2007

Just something to note here.

I went to mills fleet farm and picked up a BR9EIX plug for $6.29 yesterday.

Being pissed off at the price (and wanting more spare plugs) I stopped at the powersports dealer by my house and asked for some NGK plugs for my bike. He came back with the BR9EG. I figured they would be $2-3 bucks so I didn't ask about the price. When I looked at the receipt they were $5.50.

Moral of the story: Don't buy your plugs at the dealer :)

Plug problems.

DirtyJoe

earl pittz

Uhhh...

DirtyJoe

kawicam250

I bleed green!

killerkx

earl pittz

Uhhh...

TimberPig

earl pittz

Uhhh...

TimberPig

rmc_olderthandirt

earl pittz

Uhhh...

TimberPig

earl pittz

Uhhh...

TimberPig

DirtyJoe

DirtyJoe

whenfoxforks-ruled

Old MX Racer

Red Ryder

rmc_olderthandirt

Red Ryder

ds66

jason33

snb73

mopower440

mox69

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Plug problems.

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I bleed green!

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