2003 kx125 problems

[turbophein]

ok here is the scoop, i bought this 03 kx125 Item number: 330031452144 Its a great bike and well worth my money.

But here is the start of my problem, this guy never mentioned any motor work being done, so i go and pick the bike up and i see the PR2 sticker you see in the auction on the motor, i thought it was just a sticker when bidding on it, but after seeing it in person, it is engraved with PR2 in the head, so i imediately ask the guy if he ran race gas, he says no! just 93 octane. he has had the bike a year and never had a problem. So i bought it and drove home.

When i get home the bike performs awesome, and runs like a raped ape!!!! it has so many extras the guy never mentioned, like the works full suspension and the front fork air cells, hinson clutch basket, radiator guards, tag oversized bar and clamp kit, tag sprockets, RADD hubs and excell wheels, and some other nice things.

ok so 2 riding days go by, a couple hours each not even a tank of gas, i foul a plug. so i go to my dealer and ask for the same plug and out of curiosity what the factory plug is and if i am using it? turns out Factory plug is a br9eix and i am running the bpr7es. so i buy both and go home. put the stock plug in and start it up, rev it a little, it seemed fine, so i let it warm up, while i got my gear on. about 2 min. jump on my bike take off 20ft late the bike dies. i fouled the stock plug already????? put the bpr7es the bike runs fine and it did for the rest of the day. a week goes by and me and my buddy decide to go riding, i let him use my 98 rm125 i just rebuilt so i could get some break in time on it. He thanks me by buying the gas and oil. so i meet him at the spot with the bikes, we fueled the bikes up and took off, about a 45 min later :ride: poof my bike locks up the rear wheel on a long straight away 6th gear wide open, almost wiped it, put it in nuetral and it still kicked over with not much compression, i didn't think much of it, maybe a plug i said, top end worst case scenario, i wanted to change out the piston anyways, so after a 1/2 mile walk back to the main riding spot, i jump on the rm125 i just built to see how it was running, so i take it out to the same straight away 4th or 5th gear half throttle poof, the motor shuts off but keeps cranking and didn't lock up, absolutely no compression. another 1/2 mile walk back to the spot and another 1/2 mile to the truck. ****ty day!! 2 bikes 5 min. i was trying to figure it out, while walking and the only thing that came to mind was the gas. sure enough no oil in the gas!!!!!

i melted the side of my piston slightly because i still had a half a tank of gas left in my bike, light damage, the rm125 melted a complete hole right in the center of the piston, didn't mess the walls up at all. Both the plugs completely melted.

ok so now the top end is rebuilt on the kx125, the cylinder has a light mark on it, i didn't hone it because kawisaki plated cylinders are thin already, and i am getting great compresion, and the bike runs great with the bpr7es, as if nothing has happened to it. rode it for a hour, ran great, took it next day for a ride about 2 hours in, i hit another straight away, the bike had 3 hours on it already, varying my rpm's constantly, so i go for it, but slightly holding off full power, POOFFFFFFFF!!!!!!!!!!!!!!!!!!! there it goes again, This happened yesterday, i haven' taken it apart but the plug is melted the same way again!!!!


My questions are doesn't a lower number on a plug mean that it will burn hotter, like a bpr7es should burn hotter compared to the br9eix? right?

If i run race gas will this avoid my problem? I really don't want to buy race gas!!!

Or is this a plug problem?

i also run engine ice as a coolant, and at the second blow up i was running bel ray gas mix. 35:1 mix. 12 oz to 3.5 gallons.

thanks ahead of time for the help, sorry for the long paragraphs.

matt

 

[kawicam250]

i had a slightly similar problem on my 00' KX125( most people will remember this). my bike continually fouled plug after plug( at most 3 plugs a day!). well we rejetted the bike to death, then we put a wiseco top end in it. most people know( we didnt at that point) that if you rejet the bike before rebuilding the top end, you have to rejet it again. sure enough, after about 6mon., we finally solved the problem by rejetting it again after replacing the top end. we also tried a couple of different plugs. well, where i ride( TNT) there isnt any place i can get in 5th or 6th gear, but still i ride pretty darn hard in 3rd. first, to answer one of your questions, the smaller the number, the hotter the plug. anyways, we, at first, ran a BR8EG/BR8ES( there's pretty much no difference between a EG and a ES). those went out pretty quick, so we tried a BR9EG/BR9ES, those lasted a good bit longer, but not long enough. we eventually tried an expensive BR9EIX( EIX means its an Iridium plug) that lasted a long time, but still not long enough. we also tried different fuel mixtures. we, at first, went 32:1, but that just loaded up the bike( i wasnt experienced enough back then, i am now, if you know what youre doing, running 32:1 will give you a little bit more power because there's more oil to burn). we switched to 40:1 and it works magic( were using Maxima SuperM oil). admidst all this turmoil, we also had a transmission oil problem. the oil just started turning milky-whitish/pink after about 20-30min. of riding. first, we drained the radiator fluid and filled it back up. after a while, we changed out the water pump seal, and it seemed to work. we used to ride on a couple of trails behind out neighborhood, but you had to cross over a 8in. deep creek first. well, once i took my bike threw it( after changing the oil), about 45min. later the oil turned that milky color again. needless to say, my dad and i were furious. Matthews Fun Machines told us the oil seal was bad and needed to be replaced. they said its got a gap/hole just big enough to allow water to get into the transmission. back to present, my bike runs extremly strong and has had no flaws at all since then( no fouled plugs, no oil problems, nothing). hope this helps. :ride: :uh:

 

[trial_07]

Decidedly, you should have stayed in your bed on this day! My manual says the spark plug should be a BR9EIX just like you, but I run with a BR9EG. I rode all summer with this plug and never did it foul or did I have any problems with the top end.

 

[Zenith]

A 7 plug is definitely a bit hot for that bike, 8 maybe but I wouldn't go to a 7. The last guy probably didn't know how to jet properly so the hotter plug was solving his fouling problem.

Are you sure the end of the plug is melted off and not just snapped off from detonation? If you could get the top end off and post some pics of it and the plug it would be useful.

 

[Imack]

Plenty of factors involved...!

Guys:

Any TC certified oil will do the same than those designer oils. Spark plugs are all the same and work right if you choose the right thermal grade. All these racing guys are being sponsored and paid well to promote certain products that do not do too much for you at all...
When changing oil mix, the carburetor need to be adjusted since the more oil in the mix the less gass, so need to go richer..and viceversa. Altitude is another factor, higher elevation less air pressure, and viceversa. Also climate will affect the animal, colder means more air..! So, you need to play around with that carburetor. Slightly rich is a safe setting since leaning will increase the heat and will burn the cylinder.
I used Castrol TC 2-stroke oil 30:1 at $3.00 the quart and plain Champion spark plugs at $2.50, adjust the carburetor well and they run forever. What out these piston rings and open the top end every 15 hrs, since when it wears misses the locating pin, starts rotating and dissaster is near.
With that setup I have ran engines for over 50 Hrs with only .010" wear in the ring.
I do not have sponsors so I use the best for the money....!

 

[kawicam250]

A 7 plug is definitely a bit hot for that bike, 8 maybe but I wouldn't go to a 7. The last guy probably didn't know how to jet properly so the hotter plug was solving his fouling problem.

Are you sure the end of the plug is melted off and not just snapped off from detonation? If you could get the top end off and post some pics of it and the plug it would be useful.

if youre referring to me, where did you see say a hotter plug solved my problem? i forgot to post that ive been running a BR9ES in my bike for a couple of months know with no fouls. we knew how to jet right, but we didnt open the top end till after we had rejetted the bike. youve got the wrong idea. :fft: :coocoo:

 

[turbophein]

so what your saying is that it fouls out the stock plugs because of the wrong jetting, so what would be the reason to little of fuel or to much?

does anyone know the stock jetting? or where i can get a repair manual?

 

[turbophein]

and how about that race gas, do i absolutely need it???

 

[MXP1MP]

The needle should be okay I doubt the guy changed that, I think it was a #400 - 420 main stock. The pilot I'm not sure like a 40 thru 50? my '04 was similar. Go look at the parts diagrams on kawasaki it's on there.

That hotter plug isn't the hot setup rejet the bike leaner if it's fouling out a #9 plug you plug should be a TAN color alittle black is okay. White is or nothing at all is bad.

You air screw should be set at close to 1.5 turns out to 2 turns out. Normally anything above 2 is to rich. The first quarter turn on your air screw from fully closed doesn't count.
The screw driver slot should be at a 12 o'clock postion then count the turns.

mikuni pilot jets starting at #30 and up numbers go by 5 at a time. higher the number the richer. go like 30 - 35 - 40 - 45
anything below 30 decreases by 2.5 you shouldn't be any leaner then like a 40 though.

Main jets are also the same so example 390 - 400 - 410 - 420

Needles are numbered different and are usually unique to the brand of bike sometimes. Just play with the clip position for now I think the stock needle was good but it was better in leaner clip pos #2. There are 5 total positons the bottom one is the richest #5 the top is the leanest #1.

Try the leaner pilots and mains first then try the needle pos.

I would say read eric gorr's website but it's down right now

Remember this also

Pilot effects only from fully closed to 1/4 opening
Needle effects 1/4 threw 3/4 opening
Main effects 3/4 threw fully opened

There is no real magic spec someone can give ya jetting is alittle bit trail n error but the pilot and main jets can be removed by loosen the carb and removed the large nut on the bottom of the carb bowl and a flat bad screw driver.

The main is in the middle the pilot is off to the side kinda up in alittle further then the main. Pilots are longer then mains so don't worry about switching them up.

If your bike needed race gas it probably would of siezed all ready with the hotter plug.

I bet it will be alot faster once you dail in the jetting better.

 

[Zenith]

kawicam250 - No, I meant the guy that turbophein bought the bike off may have been running the 7 for this reason ;).

I'd recommend Eric's jetting guide as well (from his site www.ericgorr.com) or here's one I wrote up a while back which is based on Eric's and a couple of others - http://www.mxboards.com/forums/viewtopic.php?t=4

 

[kawicam250]

kawicam250 - No, I meant the guy that turbophein bought the bike off may have been running the 7 for this reason ;).

I'd recommend Eric's jetting guide as well (from his site www.ericgorr.com) or here's one I wrote up a while back which is based on Eric's and a couple of others - http://www.mxboards.com/forums/viewtopic.php?t=4

okay. i was starting to say............... ;) :whoa:

 

[turbophein]

First off thanks guys. i appreciate all the help, i have been fixing 2 strokes for about 2 years now, and every now and then i get a tuff bike to tune and now i know why! I always messed with the air/fuel screw but never the needle position.

So here is were i am so far:

MY BIKE

450 main jet,
1st needle clip position
6137.5 pilot jet ( does this make sense?)
1 3/4 turns out
bpr7es

Factory Bike

is a 420 main,
3rd needle clip position,
a 40 pilot jet,
2 1/2 turns out.
br9eix


WOW whats going on??? Did the former owner know what he was doing or what, he didn't seem to smart.

Here is the pics of the piston and spark plug, its just like last time when the gas had very little oil.

http://i102.photobucket.com/albums/m84/turbophein/5.jpg
http://i102.photobucket.com/albums/m84/turbophein/4.jpg
http://i102.photobucket.com/albums/m84/turbophein/3.jpg
http://i102.photobucket.com/albums/m84/turbophein/2.jpg
http://i102.photobucket.com/albums/m84/turbophein/1-1.jpg

 

[turbophein]

where can i buy a jet kit for my bike?

 

[turbophein]

a little help on where to start would be great.

 

[MXP1MP]

Well I'm at work so I can't look at the pic's but from the spec's posted they sound alittle off to me. what I've near head of mikuni pilot size numbered like that are you sure?
The needle is in the leanest clip position and main seems kinda on the rich side to me. Always a good idea to kick back to stock settings and go from there. You won't find a kit that has needles just mains n pilots most common all you can find in a kit. All your needles will come from a kawasaki dealer. Just goto the dealer and pick up some pilots n mains oh yea maybe get an "E" clip for the needle they a so thin it's pretty easy to break'em or loose it they have been known to shoot across the room cause they wasn't clipped on all the way.

oh yea becareful not to scratch the slide n needle surfaces either. No get crackin on that jetting go back to the #9 plug also.

 

[turbophein]

ok this is where i am going start! i have been reading alot about jetting the last few days, and feel i can do it now.

First i am going back to the stock plug, and pilot jet. Then i will drop the needle clip position to the 2nd slot, only because the bike ran fine in the first slot but might of been to lean. I will keep my main jet and adjust the air fuel accordingly. Hope this does the trick.

What do you guys think?

 

[MXP1MP]

Your gonna have to do plug readings to be certain what's going on. you must try changing all the circuits. jetting is trail n error typically best to start off rich and then slowly lean out. what's better a fouled plugs or siezed out top end. pick up some cheap BR9EG's for now and then get the properly BR9EIX.