93 KDX250- CANT START IT

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gregp
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Post by gregp »

Everybody here who is offering jetting suggestions should be aware that the OP has an older 250, and not a 200 or a 220. I am unfamiliar with recommended jetting specs for this bike.
It sounds like you need at least a top end rebuild (piston/rings/gaskets), and you should clean the entire power valve system while you have everything a part. This, along with proper carb set up, should alleviate your hard starting.
FYI - My KDX 200 started getting a bit more difficult to start, and it also did not want to rev out well at high engine speeds. I rebuilt the top end, chased jetting to the end of the world, and pretty much came up with nothing that would improve the condition to my satisfaction. I eventually found that the source coil (the ignition coil under the flywheel, that is responsible for generating current for all of the ignition components) was weak. The service manual called for 270-320 ohms of resistance, and I measured something like 170. A new coil from Ricky Stator read about 370 ohms, and my bike has never run so good.
So, it can be difficult to diagnose problems over the internet, but a little investigation on your part can provide enough information for us to point you in the right general direction. A service manual is immensely helpful when you get into electrical specs and measurements.
2004 Dual Sported KDX200
1999 Ninja 250 (Daughter's)
1996 DR 650 (stock, mostly street use)
romanm
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Post by romanm »

Thank you.

Yes i have purchased the manuals, both for the 220 (or 200....whatever your supposed to get) and the 250.

Im actually about to start tackling everything electrical. The manual says you have to use the Kawasaki ohm tester or else you will ruin thigns....is this true? I have one of those cheap Canadian tire....powered by a 9v tester......can I not just use that??

I haven't cleaned the power valve system....that will happen when I rebuild the motor. For now i just want to get it running again until fall is over....once the snow hits the motor is getting ripped apart.
gregp
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Post by gregp »

With my standard multimeter, I was not able to verify *any* of the values listed for the ignition module. I do not know why, but I was unable to get any kind of useful information from it only on that particular item. For reading the source coil, the lighting coil, and the ignition coil, my multimeter worked just fine.
2004 Dual Sported KDX200
1999 Ninja 250 (Daughter's)
1996 DR 650 (stock, mostly street use)
KarlP
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Post by KarlP »

Romanm-
In June you were having problems but I assume you got the bike running.
On September 26 you posted that you had gone 200 km but now the bike won't start again.

Is it possible that the bike is sitting too long between runs or that you are getting out of whack on the starting procedure, or both?

How well did it run? Your compression readings seemed reasonable. I'm just thinking there is nothing really wrong with the bike, just the OP. :lol:
A motor rebuild won't fix that!
'08 KTM200xc
'99 CR/KDX Hybrid with that RB stuff done to it
KX100 for the boy
romanm
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Post by romanm »

Karl- Yes I got the bike running. Cleaned the carb out again for good measure with brake clean after taking it all apart, and set the float height as per the manual. Tightened wires on the plug/coil, and installed a new plug. NGK br9es. Checked the reed valves right away. It fired up and ran pretty good. The only other bike I can compare it too was a 250 motorcross bike I rode a few times....full port and polish, ect. TONS of power. Mine runs nothing like that lol.

Bike would run good but constantly needed the plugs cleaned to fire up. After 2-3 rides it would need a new plug.


So before my last post, I took my bike to my cousins. We ripped around for a while. I brought it back to my gf's house and then i went to kick it over and it sputtered and woulndt start.

How I transport- Back of a 1500, strapped down with two straps in an upright position.

How I start the bike- Turn fuel on. Turn on the choke. Put in neutral, and pull the clutch in. Find the compression stroke. set the lever to the highest position and kick hard.

How I turn off the bike. 30 seconds before I shut off the bike, I shut the fuel line off. I give a few high rpm throttle blips as well to try to clean the plug up a bit. press kill switch till engine no longer rpm's.

Fuel mix- Lucas semi synthetic smokeless. 32:1 mix with 91 octane.

Plug. NGK br9es initially. the last time it worked i was running an 8 instead of 9 hoping the hotter range would keep the plug alive longer.




Now that it doesn't work, I brought the bike home. Double checked the spark plug connections and put a new plug in. I can visually see spark. tried starting a few times but didn't start. Pulled the plug. It wasn't wet or anything. So now Im kinda stumped. Im going to re-clean the carb and put a fuel filter on it just incase (rated for up to 75hp). But I also plan on checking the resistance of everything electrical. i will also double check the compression to see whats going on there. Im pretty stumped with this one.
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scheckaet
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Post by scheckaet »

what's the plug look like? wet? dark?...
Pics would be good.
Have you try to jet it according to the tutorial in jets and needle section?
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gsa102
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Post by gsa102 »

Still sounds like an electrical issue. The magnets on the flywheel can get weak over time, that is why they do a voltage test on the spark. You may have to have a mechanic test it for you.

My nephew's kx 60 did a similar thing. It would run until the plug was just slightly fouled. The spark was just too weak. He sold the bike but that is what I suspect it was.

I think you need to try a different flywheel or primary (spark) coil. If you are a little rich, that is only making it worse. Try starting without the choke and with a new plug.
This is my rifle, this is my gun, the YZ to go fast, the KDX is for fun!

96 KDX 200, 09 YZ 250
KarlP
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Post by KarlP »

The fact that your plug was not wet tells a bit about it.
You may be right in wanting a fuel filter.
One thing you can check is to remove the plug in the bottom of the carb. You don't have to take the carb off or anything, just shut the gas off, undo the plug, and see if gas runs through.
It does sound like a classic jetted too rich and fouling plugs kind of thing.
I don't know what the spec for compression ought to be. It could be that you are going to need to do the piston and rings job....
'08 KTM200xc
'99 CR/KDX Hybrid with that RB stuff done to it
KX100 for the boy
romanm
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Post by romanm »

Ok....UPDATE

Bought an ohm meter.

Coil....measured fine. weird thing with this is I removed the wire/boot and measured just the coil....it was something like 6.5 ohms. I measured with the wire/boot on and got around 11 ohms. This seams very high. Could someone please if the have the time verify if the whole system combined (coil, wire and boot) resistance should be this high? The repair manual does not list wire/boot values.

The stator was all within spec.

Now, the CDI box. I could not get any values to register. It all listed them as 1 on my meter. WTF. Would I get spark if my cdi box was shot? Because I do get spark.

Also, I tried to double check my compression, but my stupid gauge wont maintain peak pressure. It looks like it maybe would bump up to 140-150 if it help pressure, but it jumps past 120 every kick....so this thing should atleast be able to start.
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rbates9
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Post by rbates9 »

Sounds like you might need a new plug wire / boot.
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gsa102
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Post by gsa102 »

I have not had any luck in the past checking CDIs with a digital multimeter. The analog meters work much better. But CDIs are hard to test anyway.

I have a spark tester that looks like a spark plug with an alligator clip on the base. It has a wide gap, and basically if it has sufficient spark it will jump the gap. Something like that might help you out.
This is my rifle, this is my gun, the YZ to go fast, the KDX is for fun!

96 KDX 200, 09 YZ 250
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Post by TWMOODY »

>|<>QBB<
romanm wrote:Ok....UPDATE

Bought an ohm meter.

Coil....measured fine. weird thing with this is I removed the wire/boot and measured just the coil....it was something like 6.5 ohms. I measured with the wire/boot on and got around 11 ohms. This seams very high. Could someone please if the have the time verify if the whole system combined (coil, wire and boot) resistance should be this high? The repair manual does not list wire/boot values.

The stator was all within spec.

Now, the CDI box. I could not get any values to register. It all listed them as 1 on my meter. WTF. Would I get spark if my cdi box was shot? Because I do get spark.

Also, I tried to double check my compression, but my stupid gauge wont maintain peak pressure. It looks like it maybe would bump up to 140-150 if it help pressure, but it jumps past 120 every kick....so this thing should atleast be able to start.
If you measured 11 ohms resistance in the wire boot combination the resistance is VERY LOW and NOT your problem.

With your other readings are you using "auto ranging" or locking the meter in the range you are supposed to be getting.
Auto ranging can cause problems with these type of applications.
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Post by romanm »

I had it set at 20k and 2k.....I cant really recall which one exactly...but it just moved the decimal place over.

Im pretty confident in saying the stator was fine and the coil was fine. No damage to the wiring harness.

The cdi box....I tried it on the 200....2k.....20k and 200k settings. Nothin....just showed a 1. But Im getting spark though. My understanding is that if the cdi is gone...you get no spark
gregp
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Post by gregp »

From all of the findings you have posted here, I would start to suspect fueling issues. Make sure you have good fuel (mixed with good quality 2 stroke oil), that the cap vent is working well, that there are no air leaks (cracked boots), and that your reeds are in good shape. After that, with good compression, you are pretty much looking at low speed carburetor settings. A high float level can flood the engine right away, so be sure that the float level is set correctly. My 200 will dribble fuel if I tip it much past the normal lean of the kick stand.
2004 Dual Sported KDX200
1999 Ninja 250 (Daughter's)
1996 DR 650 (stock, mostly street use)
gregp
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Post by gregp »

FWIW - Your KDX250 will never run like a 250 MX bike, without a lot of work done to it. It is a mildly tuned Enduro bike.
Other things that I can think of that might cause the issues you are having are: Is the air filter clean? Have you actually cleaned it recently? If not, do so now.
32:1 is a pretty rich oil/gas mixture for most modern oils. Try going to 40:1, or even 50:1.
Drain the entire tank by removing it from the bike and turning it upside down. Pour out everything that is in there, and start with a fresh batch. Sometimes mixing different types of oils together can give you plug fouling issues.
2004 Dual Sported KDX200
1999 Ninja 250 (Daughter's)
1996 DR 650 (stock, mostly street use)
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scheckaet
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Post by scheckaet »

Sometimes mixing different types of oils together can give you plug fouling issues.
I second that. Had this happen to me.
32:1 might be rich but if it's jetted right for THAT ratio should not matter that much.
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Post by romanm »

Oh, I don't expect it to run like an MXbike. Im well aware its a de-tuned motor. I would just like it to run.

The cap vent. I dont have one. Do I need one? The hose is long gone....didnt even come with the bike. The gas tank I took apart and cleaned out 3 tanks ago.

CARB
- Set at 1mm below where the bowl separates. I purchased the manual and set it exactly like it said to.
- So you think I need to change the pilot jet eh....its 42 right now....Id rather run the bike on the rich side to air on the side of caution.....so you think I should step down to like a 40? The main jet I stepped down from 165 to 160. The clip is in the stock location. The bike does have a full fmf system on it, so I dont want to lean it out too much.

OIL MIX
I wont run 50:1....this isn't a race bike. My main concern is reliability, not overall power. I dont see how deviating from the factory recommended mix is a good idea. Id rather my bearings stay well lubed.

AIR FILTER
Its clean....but Ill clean it out again for good measure. I don't ride in dusty conditions


TONIGHT.
Ill clean out the carb and make sure the float height is still cool. Im going to call around and see who stocks jets and pick up the 40. and put it in when I get it
Ill clean and re-oil the air filter
Ill add a second fine fuel filter
New plug
Ill inspect the boots for cracks. the read valve i verified was fine earlier with a feeler gauge (no gaps)
The fuel mix I am not changing. I stored the mix in my garage. It is lucas semi-synthetic with 91 octane mixed at the proper 32:1 mix. The old oil mix has already all been used up, and that was with even better oil (full syn). There is no way anything is wrong with it.

If it wasn't for it being fall and dirt bike prices so low, Id sell this stupid thing and get something newer. No more "project" buys anymore lol.
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gsa102
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Post by gsa102 »

I have sheared off flywheel keys in the past, especially if someone had it off and didn't retighten it properly. If you shear your key, it will spark but will never start. Worth checking. You will have to buy a puller for about $20

I still think you need to do a spark voltage test. Just because you see a spark in clean air does not mean you have enough in the engine under compression.
This is my rifle, this is my gun, the YZ to go fast, the KDX is for fun!

96 KDX 200, 09 YZ 250
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Post by KarlP »

That dry plug from the post on Sept. 30 makes me think you are not getting gas.

I'd pull the seat and airfilter off. Try and start it. If the plug is still dry check fuel flow.

I would not clean and oil the air filter at this time, it'll just add another unknown.

I've also seen keyways get 1/2 sheared. Good spark at the wrong time.
'08 KTM200xc
'99 CR/KDX Hybrid with that RB stuff done to it
KX100 for the boy
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