Jesse_E

Member
Apr 30, 2010
22
0
im new to dirt bikes and just bought my kdx 2 weeks ago.

bike ran decent when i bought it, just needed some jetting to fix some bogging in 1st and 2nd. I had be riding the bike around in the field/hill behind my house and the bike lost power while I was on the throttle the one time and then didnt happen for a bit. Then a cpl days later it wouldn't run longer than a minute or 2 without cutting out while on the throttle and then wouldnt start for a while.

i've switched carbs with my friends '98 kdx 220 and makes no difference with the power loss. Before the power loss issue we had traded carbs to see that indeed the bogging in first was a jetting issue and his carb on my bike ran awesome. gas is mixed 50:1.

plug has spark. i took the stator cover off and there was a dime size little puddle of oil in the stator cover. Is that acceptable or crank seals shot? I was maybe thing it was a coil issue from reading different threads on here.

any ideas or imput on how to rule some stuff out?

sorry for the long read, any help is appreciated
 

julien_d

Member
Oct 28, 2008
1,788
0
Oil in the stator cover means the LH crank seal is shot. Quite likely the RH is shot too. This means your sucking in air, sucking in tranny oil, and loosing some compression. Time to split the cases....
 

Jesse_E

Member
Apr 30, 2010
22
0
julien_d said:
Oil in the stator cover means the LH crank seal is shot. Quite likely the RH is shot too. This means your sucking in air, sucking in tranny oil, and loosing some compression. Time to split the cases....

even with that tiny amount of oil? its like a teaspoon of oil
 

Jesse_E

Member
Apr 30, 2010
22
0
here is a pic
 

Attachments

  • kdx stator cover.jpg
    kdx stator cover.jpg
    84.2 KB · Views: 744

julien_d

Member
Oct 28, 2008
1,788
0
Any fuel mix at all behind the stator cover means the seal is leaking. If you pull up and down or side to side on the flywheel is there any play in that bearing? Has the bike been smoking more? How does the cylinder look? What jetting changes did you make to get rid of the bog?
 

sr5bidder

Member
Oct 27, 2008
1,463
0
bebore you split the cases I would advise a compression check you may have been lean too long and have excessive wear in your cylinder.

it is common with 2t engines to start up and only run untill slightly warm then die when compression is low.
 

julien_d

Member
Oct 28, 2008
1,788
0
Going point Bill. That's why I was asking about the condition of the cylinder. A compression test would be good. A leak down test would be good to test the condition of the crank seals as well.
 

Jesse_E

Member
Apr 30, 2010
22
0
julien_d said:
Any fuel mix at all behind the stator cover means the seal is leaking. If you pull up and down or side to side on the flywheel is there any play in that bearing? Has the bike been smoking more? How does the cylinder look? What jetting changes did you make to get rid of the bog?


there is no play in the bearing. the bike did seem like it was smoking some more after having the power loss the first time. my friend and I had initially thought it was running rich but then i started getting the bike revving up like it was running lean. i havent done the jetting yet. I had just swapped carbs with my friends kdx to rule out that it had been a jetting problem with my bike. After we had switched carbs back and I had mine then started the power loss and hard to kick. I havent looked at the cylinder.
 

reepicheep

Member
Apr 3, 2009
670
2
And keep in mind that this is a two stroke, so it's easier to pull the cylinder and check the piston on a KDX then it is to change the oil on many street bikes.

I'd pull it for sure on a bike I bought used... I did, and sure enough, it had a cracked piston skirt. It makes a nice paper weight here on my desk...
 

reepicheep

Member
Apr 3, 2009
670
2
That's good news, it rules out the "hole blown in piston" scenarios. For the record, you probably still should visually inspect the piston on a used KDX, but it's your bike so you can roll the dice and take your chances. If it goes badly, I call dibs on the front wheel and radiator shrouds when you part it out. ;)

Now back to running problems... it does sound electrical. And oil in the coil is bad. Can you do the stator check as per the manual? I don't have it in front of me, but I'm guessing the resistance between the two stator wires (disconnected) should be like .2 ohms, and the resistance from each wire to ground (again, disconnected) should be infinity.

And now that I think about it, I believe the KDX has two stator coils. One for the ignition, one for the lighting. My lighting coil was beyond shot when I got the bike, but it ran fine. The lighting coil had to be replaced. Ricky Stator had much cheaper options then the factory for my sons KX-60, I am guessing he has something for the KDX, even if it isn't listed on the website. Cooler stickers also. :nener:

Next I'd check the coil. Interestingly, I have a coil that tested bad but works fine. I'm guessing it arcs through a gap in the coil wire just like it arcs across the sparkplug.... I replaced it anyway for safety, but the old coil is in the "oh crap" box that stays with the truck on every ride...
 

Jesse_E

Member
Apr 30, 2010
22
0
i have a meter but need to get a repair manual and flywheel puller. i think i might order a coil from rickystator.com

where is the best place to get a repair manual? is cyclepedia.com online maual pretty good?
 

julien_d

Member
Oct 28, 2008
1,788
0
You probably need to check the condition of those crank seals and bearings before you spend too much money on electronics and repairs that might not be needed. Was that compression reading done hot, or cold? 130lbs is a bit on the low side regardless, but not terrible.

You can be sure that there's no way for gas/oil mix to get behind that stator cover without the seal leaking.

The cyclepedia manual is awesome. Great color pictures, and very detailed descriptions. I prefer it to the factory service manual for sure.
 

Jesse_E

Member
Apr 30, 2010
22
0
the compression test was done cold. does oil ever "evaporate" like water. thinking maybe that little bit has accumulated over the years?
 

julien_d

Member
Oct 28, 2008
1,788
0
the gas evaporates and leaves the oil behind. If it's been accumulating over the years, then it's been leaking for years. One way or another, that seal has leaked, is leaking, and will continue to leak. In my experience the main cause for the seal leaking is the bearing wearing and causing play in the crankshaft on the flywheel side. You can determine this if you try to move the flywheel like I suggested in one of the earlier posts.

If the problem your experiencing is happening when the bike is hot, how does it figure to test the compression when the bike is cold? That doesn't make sense. Warm the bike up to the point where it starts acting up again, and THEN test the compression.

The symptoms you describe could possibly be caused by the stator, but I can't see spending the money to replace the stator with the possibility of crank seals leaking, and unknown condition of cylinder and piston.
 

Jesse_E

Member
Apr 30, 2010
22
0
yeah true. i'll havta give it a try tomorrow and see what the reading is after it acts up.

the flywheel had no play. what other things would u recommend to replace the same time the cases are split? if im gonna fix it i'd like to take care of other possible problems that could arise.
 

reepicheep

Member
Apr 3, 2009
670
2
Just do all the seals and bearings... you will make 3 or 4 trips to your local bearing shop, and end up ordering two or three bits from your dealer. Or maybe one of the kits from the big online places.

It's not that bad, it just takes some time and care.
 

Jesse_E

Member
Apr 30, 2010
22
0
im contemplating on trying to do it myself but a little weary about it looking at the steps on cyclepedia. how much could you expect a shop to charge for doing the work if i removed the head and just gave them the bottom end?
 

julien_d

Member
Oct 28, 2008
1,788
0
Too much. You can do it! We're here to help if you need it. Heat and cold are your friends on reassembly. You WILL need a flywheel puller and a case splitter though. You can fashion your own case splitter from a steering wheel puller or similar tool from your local parts store.

If you're sure there's no play in that bearing, a leak down test can tell you if the crank seals are leaking or not. It could be that you're right, and that oil is from some years past and just never got cleaned out. Probably unlikely, but stranger things have happened! How was the engine when it was running? Any knocking noises?
 

Jesse_E

Member
Apr 30, 2010
22
0
got it started up this morning after a bunch of kicking. and only able to keep it running for about a minute if that before it shut off on me. took a compression test right away and was right about the same as before @ 130 lbs. Engine seemed great from when I was running my friends carb on it, no knocking noises.
 

reepicheep

Member
Apr 3, 2009
670
2
If I was in a shop with lots of tools, and had the right parts at hand, and started with the engine on the bench in front of me, and had done the job several times before... it seems like I ought to be able to do the whole job in under 8 hours. So at an $80 per hour shop rate, that's already $650. If they will only do the job with factory Kawasaki parts, you will pay a fortune for those as well, probably another $300. So yeah, its expensive... but if you like the bike and want it done right, it's just money. Shop mechanics kids gotta eat too, it will be utterly painless for you, and you will get $1000 worth of fun out of a KDX in a season no problem. For that matter, if I was going to go that route, I would just wheel the bike in there and tell them to call me back when it's fixed.

I can't afford to live that way, but I have friends that do, and at the end of the day its not as crazy as I would think. I spend a ton less money, but they have nice stuff that just works, and they don't spend days buried in the garage and in tools and in running hither and yon hunting odd seals and bearings.

But back on topic... so did the bike run fine with the other carb? I thought it made no difference? That's an important detail, as your symptoms could just be some combination of a fouled up carb, bad gas, spark plug, or petcock, which is a pretty easy fix. If the problem stayed when the carbs were switched, that leans more towards an electrical situation, which could be caused by an oil dissolved stator, which could be caused by a leaking crank seal.
 

Jesse_E

Member
Apr 30, 2010
22
0
reepicheep said:
If I was in a shop with lots of tools, and had the right parts at hand, and started with the engine on the bench in front of me, and had done the job several times before... it seems like I ought to be able to do the whole job in under 8 hours. So at an $80 per hour shop rate, that's already $650. If they will only do the job with factory Kawasaki parts, you will pay a fortune for those as well, probably another $300. So yeah, its expensive... but if you like the bike and want it done right, it's just money. Shop mechanics kids gotta eat too, it will be utterly painless for you, and you will get $1000 worth of fun out of a KDX in a season no problem. For that matter, if I was going to go that route, I would just wheel the bike in there and tell them to call me back when it's fixed.

I can't afford to live that way, but I have friends that do, and at the end of the day its not as crazy as I would think. I spend a ton less money, but they have nice stuff that just works, and they don't spend days buried in the garage and in tools and in running hither and yon hunting odd seals and bearings.

But back on topic... so did the bike run fine with the other carb? I thought it made no difference? That's an important detail, as your symptoms could just be some combination of a fouled up carb, bad gas, spark plug, or petcock, which is a pretty easy fix. If the problem stayed when the carbs were switched, that leans more towards an electrical situation, which could be caused by an oil dissolved stator, which could be caused by a leaking crank seal.

it ran fine with my friends carb. then after riding it around more with my carb the bike started having the power loss problems. We then put my friends carb back on my bike and still had the power loss problem. So the carb isn't the problem. Fuel was mixed 50:1. I had aleady ran 3/4 of a tank through the bike. I've tried it with fresh plugs still cuts out.
 

reepicheep

Member
Apr 3, 2009
670
2
If it were me, I would do the following in the following order (not because I think they are in priority of what is wrong, but because they are in priority of easy checks, and in the order of taking things apart to get at other things). Of course, stop if you find a problem at any step and fix it and see if things are better.

0) Make sure the exhaust isn't plugged with a washing plug, or a small dead animal.
1) Pop the fuel line off and make sure fuel flows freely from petcock.
2) Pop the air filter cover off and make sure the bike runs badly with the air filter off.
3) Make sure you have a bright blue spark with the plug out of the engine.
4) Pop in a fresh spark plug and fresh gas (new tank, not more of the old stuff in there) and make sure the bike still runs badly.
5) Check the stator resistance, and coil resistance, as per the book. Maybe try to read he stator output if you have a good enough AC meter and can read and kick at the same time...
6) Pop off the reed block and inspect.
7) Pop off the head and cylinder as a unit and inspect piston and jug.

That would all be an easy evenings work... and should pin down the problem for you.
 
Top Bottom