seized piston?

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#1
I recently did a top end (new piston and rings) and 607 reeds. I rode the bike very easy for around an hour to break it in. After that I did a plug chop and the plug looked a tad rich. I did not rejet.
We rode another hour and it was running fine till it bogged and quit running. Is this the symptom of a seized piston or could it be something not so bad?
I changed the plug and it was carboned up but a new plug did not help. It will not start. Yes I had gas in the tank.
'93kdx200 stock pipe 150 main, 48 pilot, stock needle in the middle position. Maxum super 40:1
4000 ft. altitude 85 degrees. :ugg:
 

CaptainObvious

Formally known as RV6Junkie
Damn Yankees
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#2
If the piston was seized you wouldn't be able to kick the bike through. If the plug was wet that means you are getting fuel. How is the spark?
 
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#3
Thats good to hear! I will check into the spark. The plug was not wet just lots of carbon on it. I will also look into fuel flow.
thanks,
tom
 
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#4
Fuel seems to be flowing and there was gas in the bowl.
I am uncertain how to tell if there is a spark or not. I have a multi meter but I have never used it. I found a wire that was disconnected but connecting it did not help.
thanks again,
tom
 
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#5
Take out the spark plug, put the plug wire back on and touch the threaded part to the head. Kick the bike over and you should see the spark.

You might want to hold the spark plug with some rubber gripped pliers so you don't get zapped.

Good luck.
 
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#6
easy enough to check spark. remove spark plug , gound plug to engine , kick over engine and look at end of plug. should be nice blue spark. if not try different plug first. if that doesnt work check ign lead/boot for breaks or excessive resistance. what wire was disconnected? is your kill swich on ? to check for resistance set your meter to ohms connect between what you want to take a reading of and read on meter. power must be off to measure resistance. if still no luck check connections at coil and black box under tank. if all hooked up you could check resistaces for these items if good you might have magneto problem need to pull off mag housing and look /check the ign windings underneath.
 

beefking

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#7
I lean seized my KDX a few months back. Same scenerio, just rebuilt + in process of breaking in. On a straight I gave it a little gas and it bogged out and died on me. The intake boot ripped, letting in all kinds of air, and so it lean siezed. The bike could still be kicked over, although it was very easy.

The piston partially fused to the (freshly plated!) cylinder wall, and the aluminum fused right over the rings. Good news is, I didn't need to re-plate or even get a new piston or rings. Just cleaned it all up with some 300 grit sandpaper and a de-burring blade and it was good to go. I've got about 30 hours on it since then, and even with a small chip in the plating it runs super strong, better than new.

Maybe you lost a circlip? If you used a Wiseco I wouldn't doubt it, those things are a PITA to get seated completely.

I'd also clean the carb out really good, making sure the float isn't hung up on anything and all the jets/passage ways aren't clogged.

Best of luck, I hope it's something small. :thumb:


PS Just re-read your post. Did you go through heat-cool cycles with the engine while breaking it in? You are supposed to ride it easy for a few minutes (until warm) then let it cool completely. A few times through this and it's good to go.
 
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#9
Ok I do not have a spark so I will try these other methods you have mentioned. A yellow wire was disconnected but still nothing.
wish me luck and thanks
tom


easy enough to check spark. remove spark plug , gound plug to engine , kick over engine and look at end of plug. should be nice blue spark. if not try different plug first. if that doesnt work check ign lead/boot for breaks or excessive resistance. what wire was disconnected? is your kill swich on ? to check for resistance set your meter to ohms connect between what you want to take a reading of and read on meter. power must be off to measure resistance. if still no luck check connections at coil and black box under tank. if all hooked up you could check resistaces for these items if good you might have magneto problem need to pull off mag housing and look /check the ign windings underneath. [/QUOTE]
 
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#10
I have to take that back about the spark. I could see a small blue spark when I shaded the sun away. I pulled the reeds out to look at the piston and did not see anything that looked bad such as pieces of metal or rings. There seemed to be alot of fuel in the reed area though.
I'm at a loss here. I really don't want to pull the cylinder off again if I don'thave to.
tom
 
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#11
was the plug wet or anything from you kicking it over before checking the spark? try a new plug, never in the bike.
 
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#12
The plug was not wet but that makes sense that alot of fuel would be in the reed area from me kicking it over. I just put it all back together and it would not start. The kick starter kicked back after trying a few more times. Was that due to built up compression?
tom
 
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#13
I put the old reeds back in to try and get the bike back like it was, retracing my steps so to speak. It actually fired but then died after a second or two. It kind of makes an ugly sound when I kick it over. This bothers me so I may have to open it back up.
Darn!
any thoughts are more than welcome.
thanks
tom