KX Riders
Maintenance & Technical => KX500 Original => Topic started by: chrisorbics on January 28, 2007, 04:42:59 AM
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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
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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 :-D
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Same as Alan, did you clean the tank and blow into it with air upside down?
I'll find my book for compression.
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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
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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.
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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.
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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?
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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.
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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.
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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.
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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.
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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.
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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.
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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
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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
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Alright I am going to work on the carb again just so I know that it is clean. After that if it runs crapy I will tear it down. Thanks for al the help. Also if anybody has an extra rear wheel please contact me. I really need to find a replacement and can't afford to pay someone to build a new one for me.
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Are you sure you dont' want your 500.00 back?? :-D
Check e-bay daily and should find something. I got your 500.00 in cash waiting for you.
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Hey, If you really want it that bad maybe we can arange a trade.
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I paid $400 for my '86--I wish I had your problems.
I need a new piston, rod (and therefore crank work), chain, sprockets...
Best of luck to you--I do know it's frustrating to not get your bike to run right.
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Hey, If you really want it that bad maybe we can arange a trade.
No trade just your cash back :-D What state do you live in??
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Hey, don't give up on your bike yet.. I bought a 93' for 500 bucks. I have EXACTLY the same problems with the choke, with the bike running fine with the choke out, but it would die as soon as I pushed it in. I had some cracks in the reed valve boot, between the carb and intake. I bought a boyesen rad valve and replaced it. I completely dissasembled the carb, and cleaned everything. it didn't work. I believe that some of the passages in the carb body were partially rusted shut or something. So, I bought a new carb, and reassembled everything. It runs amazing now, except that it vibrates like crazy. The rings on your piston have nothing to do with your choke not working, but it wouldn't hurt to tear everything down to check it out.
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While on the subject of re-building very old and hardly used twostrokes I have to mention dried up old crank seals.
Better to replace em.
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hughes
No trade just your cash back What state do you live in??
I live in new jersey. I would never sell this bike for what I paid for it. If you saw this bike in person you would understand. This bike has never been betten on. Just by looking at it you can see it has barely been used.
SupermotoFan sounds like you have a lot of work to do. If you even need to know how something should look or be put together just message me because most of the bolts have never over been off of my bike. Good luck
dcollins4328 You are probably right. Where did you get a new carb and rad valve from? How much did everything cost you? I wonder if they make a rad valve for my year. I just but the reed box and carb back together and used high temp permatex between the reed block and the rubber intake and the reed block and the engine. It fired up as soon as I remembered to put the spark plug wire on the plug. Then it started up on the first kick. By the way nice deal. Do you have any pictures posted?
This is my new problem. When I start the bike up on full choke the choke goes down by itself or if I rev it up. Why does it do that? The bike dies every time. Is it supposed to do that? I wasn't able to keep it running because of the choke and it is so dam loud. I will fire it up on thursday.
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You can get a rad valve for it on denniskirk.com or rockymountainatv.com. It's about $170. I got the carb on ebay for $40. I don't know if they make them for that year or not? It sounds like you might need to replace your choke. All in all I have spent about $1000 on mine getting it into great shape again.
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Chris,
Thanks for the offer on the photos of your stock bike--I'm getting more familiar with what's right (and what's not) on my bike, but I may take you up on that sometime.
Now, with the choke: Did you say that the choke physically moves and shuts itself off while you're trying to warm the bike? Or is it that the bike stalls while still on the choke?
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Hi the choke physically goes down and makes the bike stall when I first start it up. I just don't get it. I have never had that problem. I just got a manuel off ebay so I am going to read that and see if it gets me anywhere.
dcollins4328 that carb you goto was used if it was only $40. I think a rebuild kit is around that much money.
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YEah it was used. My old carb had something wrong with the carb body, it was corroded or something, so a rebuild kit wouldn't have helped.
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Hi again I think mine has the same problem. I had it running today. I used a spray bottle to check the rubber intake boot for leaks while the bike was running. There is no leaks at all. It has to be the carb. I saw this bucket of carb cleaner at autozone. It says to soak the carb in it for about a half hour. I am either going to use that or bring it to my friends house and use his compressor on it. I can not wait to get this bike running right. It is all stock and has the greatest exhuast note.
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I was just ridding the bike and let me tell you that the power is adicting. I got a bucket of carb cleaner and let the carb sit in the cleaner over night. That stuff is great and worth the $20. So the bike fires right up and runs great. It does still need a little fine tuning but it is fine for now. So I rode it for about a half hour and the left side rear axle bearing fell apart and blroke a chunk of the hub and also cracked the center of the hub. So I really need a new rear wheel now.
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http://cgi.ebay.com/ebaymotors/KX500-KAWASAKI-1989-KX-500-89-REAR-WHEEL_W0QQcmdZViewItemQQcategoryZ35601QQihZ011QQitemZ320087456903QQrdZ1
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Right on, I bought a 97 500 last year and it was a basket-case. Let me give you a little of my experience. That gas would be the problem, especially if it is in the filter. Clean all fuel jets, tank, and line and now filter. Check your spark. If you lean the bike over gas should pour from the over-flow. Also check plug after kicking to see if it is wet. Pull out the reeds, check for cracked or missing petals. My 500 would start easy, but would die easy while missing two petals. Also a buddy of mine had a large mouse nest in his pipe which stumped us for awhile.
The powervalve is the rod in the little plastic cover on the side of the cylinder on the brake pedal side of the bike. They can be hard to cold start, even with a fresh re-build. It may get easier once you blow the cobs out. Is it hard to start when its warmed up?