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KX85 died

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Previous thread: http://www.thumpertalk.com/topic/1083477-kx85-bogging/#!IuQZl

 

Summary: I purchased a 2005 kx85, bogged from the start, it had a bogging problem that I mostly solved by simply learning how to ride a 2 stroke bike properly as I had only had a 4 stroke pitbike previously, the bogging was still there slightly but this was my first ever "real" ride after my uncle teaching me how to ride, I had plans to re-jett the bike after this ride.

 

I started the bike first kick, let it warm up for a couple of minutes and off it went (uncle was riding) he was riding for around 5 minutes, staying in 3rd gear (I could keep up on a crappy 110 pitbike, he wasn't going quick). After riding for around 5 minutes we stopped to change bikes, I got on and was in 2nd for about 2 minutes, went into 3rd and hit a hill and was half way up when the bike got really boggy and then just "conked out" sort of thing, sounded like way too much fuel went in and it just shut itself off. 

 

We tried for around 20 kicks to start it, nothing. We tried 2 new spark plugs, checked the spark, checked kill switch and a few other small things. Left it for 24 hrs, tried again and nothing. 

 

I then checked the piston and my friend said it is completely ruined and I should do a top end rebuild but then my neighbour who is a car mechanic says the piston is OK and shouldn't be the reason it isn't starting. Pic of piston: 

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You can clear see it is chipped or something, what do you think? 

 

I am going to purchase a compression checker tomorrow and see what that comes back with, does it look like I need a top end rebuild? If I do how much is it going to cost me to buy the parts and am I able to fit it myself? This is my first real bike (previously had a pitbike but I never touched anything except basic maintenance like cleaning, ect)

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My honest opinion would to do a top end rebuild. I can see some damage to the crown and the rings seem worn. Well put it all back together, and kick it over, you should feel some compression if the top end is ok. If the top end is as bad as it seems, you won't feel any compression (can usually push the kicker down with a finger) good luck bud, hope this helps!! :cheers:

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I can push the kicker down with my hand, not quite with my finger but it is possible to push down with my hand.

 

Do you have any links to what I should be buying for a top end rebuild? Is it something I can do myself or should I look into sending it to a garage?

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I can push the kicker down with my hand, not quite with my finger but it is possible to push down with my hand.

Do you have any links to what I should be buying for a top end rebuild? Is it something I can do myself or should I look into sending it to a garage?

You can and should do. It yourself. It'll be fun. I'd say piston kit should do it.

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I finally got the head off after having trouble with a nut and unfortunately the crank has a lot of play when I push up and down, video is below. I also checked the bore and thankfully it's all nice and smooth.

The piston rings were also stuck into the piston towards the back of the piston to the point I couldn't get them out even when I tried with tools.

My guess is that I need to replace the crank which requires me to split the cases which then requires special tools. I'm going to call a garage tomorrow and get a rough quote and if it's a cheap enough price I'm going to have them do it if not I'm not really sure what to do next.

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I finally got the head off after having trouble with a nut and unfortunately the crank has a lot of play when I push up and down, video is below. I also checked the bore and thankfully it's all nice and smooth.

The piston rings were also stuck into the piston towards the back of the piston to the point I couldn't get them out even when I tried with tools.

My guess is that I need to replace the crank which requires me to split the cases which then requires special tools. I'm going to call a garage tomorrow and get a rough quote and if it's a cheap enough price I'm going to have them do it if not I'm not really sure what to do next.

Side to side play is alright. Up and down play is very bad. Thats a no go.

Big ol gouge in the piston too, look at the cylinder walls. Make sure it isnt extremely gouged, and that the plating is okay.

Hope that "car mechanic" doesnt make it to my car any time soon.

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