Hi I need help with my 1986 kawasaki kx500.

[chrisorbics]

I bought a 1986 kawasaki kx500 b2 works replica for $500. This bike is in very good shape. I was told that the bike has about 50 original hours on it. The guy was selling the bike because it was his first dirtbike and he flipped it and has a scare on his back from it.

When I got the bike it had water in the gas. I drained everything and cleaned the carb. There was jelled gas in there. I installed an inline fuel filter to prevent more junk from getting in the there. I put fresh gas in and finally got the bike fired. I seemed to run good at the house and then I had big problems when I got it to the woods. When I got it warmed up and put the choke down the bike would run like crap and die out. It I rev the bike up with the choke up sometimes the choke goes down and the bike dies. The idle screw has to be set very far out in order for the bike to run. It is not even touching the piston inside the carb like it should be. Once the engine is warmed up and you put the choke down the bike either dies or it idles at half throtle.

After all this I thought that the rubber peice between the carb and the reed block had to have a crack through it letting air in. After looking at it it does have cracks in it but not all of the way through. Now that I have it all apart I can see some scratch marks going up and down the piston. I am going to try and find a compression guage today. The compression feels very strong. How low is too low for compression. Some people say 100 but I think that is too low.

I was also considering that the head gasket is leaking. Maybee even the base gasket but visually the engine is clean enough to eat off of. I would think if something was leaking that I would see something. I am going to try and think of some way to figure out if I have a leak.

Also the bike sometimes misfires one or two kicks before it starts. I have a b9es gapped at .025 in the bike right now.

As you can see I need some help. Any help would be great. This forum has so much info. I am glad to be a member and hopefully I can contribute to some other peoples problems.

Chris

[alan]

You may have more than one problem! I would take the carb off first and make sure that there is nothing in the float bowl and make sure the pilot jet is not clogged up! Compression should be greater than 135, sorry I can't find my book at the moment! If you installed a fuel filter on it may already be clogged up from the crud in the tank!

I sure the other members will have lots more suggestions!

Alan

[Danger4u2]

Same as Alan, did you clean the tank and blow into it with air upside down?
I'll find my book for compression.

[Danger4u2]

My book is a factory Kawasaki service manual for 1988 Kx 500.
Cylinder compression (usable range)
735-1150 kPa
7.35- 11.5 kg/cm2
105- 164 psi

Good luck,
Danger

[chrisorbics]

Hi the carb is just sitting off to the side right now. I have taken all the jets out several times and cleaned them with carb cleaner.

This bike really has me confused. Does anybody know where the power valve cover is on this bike. I just want to make sure it is clean.

[chrisorbics]

Ok i think 106 is a bit low but that is good that I know now. Thanks.

Do you think i should take the top end apart since is can see scratches on the piston? I have a new piston and ring.

[chrisorbics]

I just got back from shoping around for a compression tester. I could only find one of the crapy ones that you have to hold on by hand with a rubber peice on the end. I don't think I could even fit the on top of my engine. There isn't much room. So I will have to wait on that. Thanks for all the help so far. I am still just stumped with this bike. Has anybody ever had or heard of a bike running so irratic?

[hughes]

Hate to bring up the carb again but I just want to make sure you cleaned it. With jelled fuel in the carb it can be very hard to clean. The entire carb needs to be disassembled, all jets cleaned and all drilled passages in the carb body needs to be cleaned, float and needle removed. If the bike only runs or idles with the choke on that's a good indication that carb can't provide fuel through it's normal jets and passages. Does the fuel shut off valve work correctly?? report back on your compression readings.

[gowen]

50 hours on a 21 year old bike isn't good. Mainly if the fuel has jelled.. Take the top-end apart, your rings could be frozen.. Your reeds could be cracked, your carb boot MIGHT be leaking. It's hard to say, but I'd pull the top-end apart just to double check.. I'm going to guess frozen or stuck rings.

But all this together, taking the topend apart is a good start.

[c-152]

I agree with the others on this website that jelled fuel is  a pain.  I buy the carb cleaner in the gallon container so you can soak all the pieces for a while.  Just be sure not to have any rubber pieces in there.  I had a similar trouble with my RMX and I fussed with the carb for weeks until I tore it down, rebuilt the topend, cleaned it and put it back together.  If the guy who owned it before you didn't premix correctly or used the cheap stuff, then it could be completely gummed up.  I wouldn't change mains yet becaue if it used to run fine and now it doesn't, then that is an indication of something else wrong.  Fine tune it later.

[chrisorbics]

Hi ok I am going to look at the carb again and try to bring it over to someone with a compressor to blow it out. I have completely disassembled it and used the carb cleaner with the tube one the jets and all of the passages. Maybe there is still something in there somewhere.

The bike was running less than a year ago but the previous owner couldn't handle the power and it sat till I bought it. The origninal owner who he bought it off of had the carb drained and supposedly put gas in it and fired it right up. What do you mean when you say the rings or actually ring is frozen? It has the original piston and single ring in it. Do you mean that the ring is pushed into the piston and froze on the piston? The engine is obviously not seized because I have had it running many times.

I will have to look for a big thing of carb clean. I know I have seen wd40 and other oils in a gallon container but I will have to look to see it they have carb clean.

I just got a compression tester today but I had no time to do anything with the bike. I will do it tomorrow definately. I think I am going to take it apart anyway because there is definately something wrong. I will check the compression first though. Thanks for all the help so far. I will report back soon.

[chrisorbics]

Hi I just did a compression test and got 180 psi. Wow is that too much. I guess the guy I bought the bike from was not lying about the low hours. Is that too much compression? My friends 1999 honda cr125 has about the same compression but he has a wiseco piston with two piston rings. My bike is all stock and original as I have said with one ring. I guess this means that it is the carb that is giving me the problem. I foregot to get the gallon container of carb cleaner. Hopefully I will get to the store tomorrow. Does anybody think it could be something else that is causing my problem? Is there still a posibility that the ring is stuck? Should I still take apart the top end? I am thinking the top end is ok. I will let you know what happens after I get the carb apart.

[gowen]

Your ring doesn't sieze but, the carbon buildup from running rich or the like can crystalize or harden causing the ring to stick in the piston giving crappy performance, but 180lbs sounds a fair amount. I'd consider that normal.

Your next bet is to get that carb streightened out.

[hughes]

Your ring doesn't sieze but, the carbon buildup from running rich or the like can crystalize or harden causing the ring to stick in the piston giving crappy performance, but 180lbs sounds a fair amount. I'd consider that normal.

Your next bet is to get that carb streightened out.

Gowen is telling you that the ring must float(move in and out) in the ring groove as it runs over ports in the cylinder, The rings expand as it compresses the gases in the cylinders

[c-152]

On a bike that is that old, I would rebuild it.  The compression is fine and it doesnt need rebuilt but by tearing it down, you will probably find the culprit.  To me it sure sounds like something is gummed up in there.  A good cleaning should clear things up.  A teardown only takes a couple of hours.  Thats what I would do