Ok here's the scenario. I have a Kawasaki Kx500 and the piston just blew up not too long ago. I'm working on the bike myself as much as I can. If anybody has any advice or anything throw your in. I'm going to keep you guys posted on what I'm doing each day on the bike and if anyone has any advice or tips that would be great.
This is going to be a project so work along with me here through the computer. If you guys want pictures or anything to help me out here just ask and I'll put em up. Also if you have any parts for my bike let me know and I'll take em off your hands.:YEAH

 

Monday 4/14/08 - Took the plastics and took the head off the top end to look at the piston. The head seems to be ok but the piston has a small part blown out and there are small fragments of metal everywhere. You can see the piston rings where the piston blew out. The piston also has a small hairline crack down the top middle, not sure how far down it goes.
Took the exhaust off and it had fragments of metal inside everywhere. That leads me to think that the bottom end probably has pieces of metal inside of it as well which means I'll have to take it apart, ****.
The jug does hold the anti-freeze so the top isn't cracked or anything but I'll see tomorrow if it has any gouges in it.

What's bothering me is the tire and the piston don't move. What's the chance the the crank or something in the bottom end is messed up, which means this will become a very expensive project.

 

Ok well I just bought a top end jug and the 500cc piston off ebay so I have everything I need for the top half. Let's hope the bottom end isn't messed up.

I would like to have this bike running by the end of the week considering all goes well so do any of you guys know any secrets on how to clean the bottom end of the engine without actually splitting the engine in half and cleaning it like that?

 

4/15/08 - Today was a pain in the ***. Had to unbolt the engine... which took me about 2 hours to get everything unhooked... the raidiator was taken off, unhooked the clutch, took ignition wires off, and small things like that. Installed new front brakes for the hell of it and got them working as well. Took the chain off, looks like I might need a new one or at least a new connecting piece for a few riding sessions. The o-rings on the chain look a little work out and dryrotted, I'm going to use it until it goes though.

Inspected the bottom end of the engine and there was barely any debris of the blown piston there. Most of the large pieces went out into the exhaust. The connecting rod is in perfect condition, the piston rings look fine but I'm going to install a whole new top end and fresh piston kit to be safe. My biggest worry was that the connecting rod broke or that something in the bottom end seized up like the crank but everything is fine, actually perfect :YEAH .

So all I'm waiting for is the top end and the piston kit to come in, which should be friday. Got that for a steal on ebay...$220 including shipping ...thanks to PowerSportsNation. Talked to them today and they said it is in the box waiting for pickup and should be to me by friday or earlier. Considering all goes well the bike should be up and running by early next week.

Still have the major concern of how to clean the bottom end out without cracking the case in half. I talked to my friend who just graduated from UTI and he said to use Kerosine or parts cleaner and flush it out really good. Still need some advice there.


First Picture - Piston is blown only on one side and you can see from the top down to the first piston ring.
Second Picture - The cylinder got a few knicks in it and there is alot of metal debris sitting in the exhaust lip.
Third Picture - The crank is in perfect condition and turns very smoothly. Haven't taked the bottom end apart and I don't think I am going to. Some very very small metal debris is on either side of the crank. I have to somehow clean that out without cracking the bottom end in half.

 

4/16/08 - Can't do much today without the new top end and a piston kit. I'll probably just flush the bottom end out with oil. I'm going to use 30 weight oil because it is so heavy that it should pick up all of the tiny metal fragments and carry them out through the drain hole. I'm going to flush the engine once a day until the new parts come in.
Got a mechanic buddy of mine to jump in on the project and I'll tell ya, he knows his ****. He is also taking the top end that I have now to his shop and honing it out. Can't wait for a nice ride when the bike is fixed!

 

Good luck with the bottom end. All it takes it 1 flake of metal to ruin the bearings

 

Yea, just going to take it easy the first few sessions and hope for the best. Had my buddy look at it and from what we saw it doesn't look like much made it to the bottom. The piston blew and most of the small pieces fusion welded to the exhaust port.

 

Ok, I've been working alot of 13 hour shifts this past week so I haven't had much time for the bike. The new top end and piston came in the mail and they were both in great shape. I put the top end and the piston on and bolted the engine back on the frame, connected the clutch and the electrical components as well as installed the exhaust and carbeurator.


The chain that I have now has dryrotted o-rings and is a bit rusty so I talked to my buddy and he is on his way over with a new chain and a throttle cable. The throttle cable that I havge now has a kink in it and it wont return after you hit the throttle.

The bike fell over on it's right side and the new front brake lever that I just put on broke. I ordered a new front brake lever, new chain, and a new throttle cable off ebay and the last part should arive somewhere around thursday or friday latest. I will be able to give the bike a try when my mechanic gets here so hopefully I'll be riding today! I'll get back to you guys and let you know what the outcome is... wish me luck.

 

Just tried to start the bike and I have no compression, great. I don't think the top end was bored out and even if it was I don't think it would matter because the piston that came with the top end was used in the bike before mine. I think I might have put the piston in backwards, with the arrow not facing the exhaust port. Does anyone know if putting the piston in the wrong way would be the cause for no compression?

 

Ok well took the engine back off this morning, once again, and I saw that the piston was facing the right way, arrow towards the exhaust port. With a closer inspection I saw that the cylinder had been bored and re-sleeved and for some reason the piston that came with it doesn't fit.

Called up the company that I bought it from, Power Sports Nation, and spoke to the owner. He said that he would have no problem resolving this and that I should just measure the piston and the cylinder and he would get a piston that fits for me. What a great guy, I didn't even have to make a fuss about it. You don't find many people like that now.
For that reason I am telling everyone what a great place that is to do buisnedd with. I have bought many parts from them and this is the first time I have had a problem, as small as it is, and they gladly are willing to help me out. Check out ebay if you need any used parts and look for powersports nation, very reliable and pleasnt company to deal with.

 

did you figure out why the tire/crank werent spinning?

if you are that concerned with stuff being in the crank case..... you better get a manual off ebay and crack it open!!! the only way to be sure that the bearings are clean is to spin then by hand to feel if there is any grit in them. you may be able to salvage them by spraying something like wd40 or brake cleaner in them and blowing them out really well with compressed air.

you dont mess with stuff like that, those bearings are probably $30 each if they have **** in them or even if they are worn out.... if they break, it will cost you more to fix the motor and have to take it apart again... chances are the whole motor would be destroyed. and replace the crank seals!!!!!!!!!


what year is it? I dont remember when they started using nikasyl cylinders... had to be early 80's if that has been resleeved with an iron sleeve its been blown up at least 1 other time. did that guy clean it out?

 

Well the last time I had it cleaned out it had a whole new bottom end, all new seals, new top end minus the head. My buddy and I are figuring that it is one of the gears.

Here's what it does:
If you give it a kick it has compression, and plenty of it, in the top end. The gears kick into place through all of them but. Now when you push the bike when in gear generally it should have the back tire lock up on you however, when you put the bike in gear now and you push the bike there is only a small amount of resistance.

It is definatley something in the bottom end but I really don't want to crack it in case I mess something up and then I have a bigger repair on my hands. My buddy and I think that it might be the gear that runs through the engine to connect the kickstart to the gears. I'm just hoping that there aren't fragments of a broken gear down bottom waiting for me. I might just part the bike out and put it on ebay, I really don't want to but who knows.

 

those bikes are fairly easy to work on... the biggest problem you will run into is that you probably dont have the tools..... you need a puller for the flywheel..... a lot of people try to pry them off with a screw driver and end up cracking the cases..... SOMETIMES you can work them off with a deadblow.... tap the sides and around the top.... sometimes it will come off easy... then you will need a special puller for the cases... most of the internal parts are assemblies that come out..... its not like parts are gonna come flying out...... having a shop manual is always a big help!

you can do it! focus little grass hopper!!!

 

Haha good encouragment but I'd rather not have to crack the case myself. Like you said the biggest problem I would come across is not having the tools for it. And if by chance I ended up cracking the case I would more than double the cost to have a shop fix it. I think I'm just going to take the top end off of the engine and bring the engine to a small shop and have them work on it. Couple hundred bucks could save me alot of money. I have an old 2-stroke RM125 engine that I am going to take apart and tinker around with so I can learn the parts before I start working on my riding bike.

 

if you have a kawasaki shop manual its EASY! i would trust myself before i let some retard making $10/hr working out of a shed touch my motor.

 

Good point, and I just figured out... with some help I might add, that it isn't my gears or anything. Just needs a new clutch that's it. So another $156 out of pocket and I'm good to go. Whenever the clutch assembly gets here I'll put that on and slap the engine back on the bike. I hope to god that's it for a while. I still have the task of finding a kickstarter for this beast though, I'm getting pretty tired of run-starting it. They don't come along often on ebay and that's where I'm looking, trying to save myself some money where I can.

 

how much are the kick start parts that you need? I'll compare with what I can get them for.

make sure you get the torque spec for the clutch bolts, they are usually between 8-12 ft/lbs make sure you torque these with a torque wrench, if you over tighten them THEY WILL SNAP OFF!

and when you call for the spec, dont let the ***** sucker at the service desk say... "yeah, I think its XXXXX ft/lbs." tell the homo to get off his lazy *** and look it up!!!

my dealer is like that, i'm sure they do that because they have an attitude about you doing it yourself, they want to charge you $85.00 to do it for you!

******!

 

Yea I hear you on that one. Well I will have to get the manual for this bike for future occasions. I work at Englishtown Raceway park so I have been talking to a few people who are familiar with the 2-stroke Kx 125's and 250's and I've been picking up a few tips here and there.

I really haven't looked at any of my local dealerships or shops for the kickstarter only because I am looking on ebay. I have a bid on a kickstarter for around $70-80 as we speak but that still has 4 days left on the auction.

At last weekends race I was talking with Micky Kessler from KPS and he is helping me out with ordering the clutch kit and he is putting it on for no charge, great guy. Honestly if it weren't for him looking at my engine today I probably would have split the case to inspect it and had a heck of a lot more time wasted. Best news I've heard about my bike in a while. Only bad thing is that I have to wait about 2 weeks max for the part to come in.