KDX Engine Problems

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#1
I'm new here, and thumpertalk guys couldn't help. My 220 will not start. It ran great at one time, slowly got worse, and now will not even start. What is my problem. The running great to no go, is about a 3 month period where I ran it maybe 15 hours total. The spark plug is getting gas, and the electrical is testing out in ohms ok. I believe that its a spark problem since the plug is wet with gas when I pull it out. The stator is new the newest electrical item. I'm about to the point of taking it to the dealer and asking if they can find the problem for me.
 

dirt bike dave

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#2
Have you tried replacing the plug, or are you just drying off/cleaning the fouled one?

Worn reeds can make a two stroke very hard (or impossible) to start when cold, and it's a problem that tends to gradually get worse. Worn out rings or piston can also make it hard to start.
 
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#3
run a compression check on it. if thats good put another plug in it. if you have been kicking the crap out of it it could be very flooded
 
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#4
cochran03 said:
I'm new here, and thumpertalk guys couldn't help. My 220 will not start. It ran great at one time, slowly got worse, and now will not even start. What is my problem. The running great to no go, is about a 3 month period where I ran it maybe 15 hours total. The spark plug is getting gas, and the electrical is testing out in ohms ok. I believe that its a spark problem since the plug is wet with gas when I pull it out. The stator is new the newest electrical item. I'm about to the point of taking it to the dealer and asking if they can find the problem for me.
What plug do you have in BRES 7, 8 or 9 ? put in a new plug, see how it runs.
 
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#5
Tried 3 new plugs and I've just put new boyson reeds on. The guy before me used BR9ES plugs, I personally think those are better, but I've got a 10 pack of BR8ES. The only thing I havn't done or checked is the compression. I don't know where I can find a checker at??? I've checked with my thumb in the hole and it seems to be sufficiant enough to run?? The stealer wants $82/hr to diagnose it for me. That is looking a little better everytime I touch this thing. :bang:
 
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#6
I agree with the others. Sometimes the plug will get fouled but still look OK. Remove the old plug, take the new plug and install the spark plug wire on it, but don't thread it into the head yet. Rest it against the cylinder head, kick the engine over and see if you're getting a spark . If the spark is OK, move on to the next step. Turn off your gas . Now kick over your engine untill your leg gets tired, maybe 100 times. This will clear out most of the old gas that might be trapped in your engine. Then install the new plug and try to start it, as you normally would. After 5 kicks take out the plug and see if its wet again. If it's soaked, try the 100 kick routine again. There could be alot of gas down in the bottom end. With this method you should be able to at least get the bike running. Then you can determine if there are other problems that need to be fixed. Hope this helps. Hockeyboy
 

_JOE_

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#7
Sounds like compression may be an issue. Take the seat and tank off and haul it to a repair shop. They should be able to run a comp check in a quick minute for little cost. Like hockeyboy said check your spark first.
How long have you had the bike? How old is the top end?
 
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#8
I've had it for 2 years and my bro had it for 3. He didn't ride it at all. So with his 20 hours, and my 80 hours, it doesn't add up to much. I don't know what the previous owner did though, and I am planning a new top end soon, just don't have the $$$ for it now. It probably does need a new top end, but shouldn't it still at least start/run a little? It doesn't even sputter.

Tonight I will change the spark plug AGAIN, and try to clean out all the gas in the engine by kicking it 100+ times. I'll report back my results when I get them in.
 
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#9
If your running rich and riding in tech terrain where the revs don't get too high, the 9 is too cold of a plug
 
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#10
I finally got it......kinda. I took the plug off and watched for spark and nothing, not even with a new plug. I got to investigating and found my flywheel was spinning freely?? :yell: The cotter key snapped in half. So I made a run to Ace and picked up a new one. Put it in and what do you know it sparked its tail off. Put the plug in and it fired on the first kick, but died soon after. I'm now going to work on my original problem which is the jetting. I'm putting a turbine core II on and need to get that straightened out. 145 main, 2nd clip from top, stock 42 pilot, and air screw 1.5 turns out should do it. Its stock was 125 main but I cut the air box, have a gnarley woods pipe, boysen reeds already on and adding the turbine core II.

I understand I'm not out of the clear yet, but I am a lot better than I was. SHE FIRES.
 
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#12
cochran03 said:
I finally got it......kinda. I took the plug off and watched for spark and nothing, not even with a new plug. I got to investigating and found my flywheel was spinning freely?? :yell: The cotter key snapped in half. So I made a run to Ace and picked up a new one. Put it in and what do you know it sparked its tail off. Put the plug in and it fired on the first kick, but died soon after. I'm now going to work on my original problem which is the jetting. I'm putting a turbine core II on and need to get that straightened out. 145 main, 2nd clip from top, stock 42 pilot, and air screw 1.5 turns out should do it. Its stock was 125 main but I cut the air box, have a gnarley woods pipe, boysen reeds already on and adding the turbine core II.

I understand I'm not out of the clear yet, but I am a lot better than I was. SHE FIRES.
Stock main is a 145, not 125.

If your flywheel has been spinning around a while it may be galled up from the crank. You might have to use some emery cloth to clean things up or else it will never seat properly and you'll keep shearing keys.
 
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#13
76GMC1500 said:
100 hours on a top end? There's your problem.
Depends how it was riden. A KDX220 is a very low revving 2 stroke that is in a very mild state of tune. Under the right conditions they can go a LONG time with the same top end. With mine I changed rings every 40-50 hours and piston every 80-100, it was all preventative as it was never out of spec. And this was on a heavily breathed on engine that got worked hard and would spin almost 2000 rpm higher than a stocker.

That being said, it was still just a 36-37 hp 220 that wouldn't rev much past 9K. Much milder than an MX bike, therefor longer part life.
 
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#14
Well that was the setup when I got it was the 125 main. Nice to know the truth I guess, but all I know is it ran perfect with that setup and never fouled a plug. I'm not an MX'er by any means. I'm a mild trails rider. I don't push the bike hard at all. All this stuff went wrong and made it stop running good when I put the turbine core II on. Now I took it off and returned it to its before state to see if it would run and nope. I'm now just trying to get it to run smooth with the stock silencer again. Then I'll slap on the FMF. Yes I agree. I should put a new top end on. But I don't have the $$$ and I'm pretty confident its got plenty of compression. If you would like me to demonstrate I'll buy a compression checker and prove myself. 150 psi or more.
 
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#15
My 2000 is still on the original top end and runs fine. I'll put a new piston in later this year for prevention.