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Discussion Starter #1
i need help with my 1987 kdx 80 it has no compression and i want to know if its the piston or the seals or the needle bearings or what
 

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Discussion Starter #2
[i need help with my 1987 kdx 80 it has no compression and i want to know if its the piston or the seals or the needle bearings or what and i cant figure out how to get the exaust off it
 

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OK

Pull the spark plug out and see if it has a shiny glitter on it...if it does then you can bet that you burnt a hole in the top of the piston...if you can get the piston to the top of the head does it move from side to side? Is ther lots of oil on the plug usually if you break a ring you will get lots of smoke the plug is really oily. I f you burn a hole in the piston then the spark plug is a silverish/whitish..in color...if it isn't the piston...you have some real problems. Pulling the head off will reveal the problem. If you take it into the shop tehy can cross hatch hone it for you get you a new pistoon and rings and you have to break it in gently,,,in fact adding a litle oil to the fuel tank is customary for a great break in, but don't over rev it and make sure you break it in slowly. or you will have to start all over again...YOu will be surprised at how fast one of these bikes can be rebuilt...I had an old Kawi 175 and we rebuilt it at the shop in less than an hour. New rings, piston, wristpin clips, gaskets, honed the cylinder, new spark plug, even adjusted the carb. Although it had an oil injection pump on it we added some 2 stroke oil to the gastank for the break in. I rode it pretty easy for a couple of weeks, then gradually started putting more throttle on...
 

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Discussion Starter #4
i pulled off the exaust and the top of the motor. now i can see the piston and all that good stuff. the thing is that i cant figure out how to get the piston off the wrist pin
 

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skyhunt

I could lead you through part of it..but having the Kawasaki Service manual is important because all of the bolts will have to be torqued back on within special limits. The wrist pin through the cylinder has a retaining clip if youlook real close at the end of it and the cylinder itself. So what did you find? inside?
 

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Discussion Starter #6
on the side of the piston i noticed a rather large chunk missing from it and that is probaly the culprit all the bearings seem fine and everything spins fine.
 

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CHUNK

Where did you find the chunk? You need to find it an get out, or eventually it will find its way ito something spinning when you take a bump, then you may be looking at repairing the bottom end... Happy to hear that you are doing the teardown and work yourself...just havethe shop do the cylinderbore cross-hatch honing and measure it to make sure youhave the right size piston and rings...they can hone it to perfection an dthen get you the Exact size piston/ring setup for what they just did in honing. Don't forget to add a couple ounces of 2 stroke oil to your gas for break-in.
 

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Discussion Starter #8
Do i need to take the whole bike in or jus the top end of the motor in order to get it cross-hatched?...and do i have to take the old piston as well?
 

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Discussion Starter #10
the local shop said the cylider head thing was in to bad of shape and said to get a new one anybody know were to get one for cheap new or used
 

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Questions/answers

IF I had to replace the head, I would try to get a new one, only because I would wnat to know EXACTLY what I was getting. Removing the jug/cylinder for honing is not difficult. Once you get it to the shop they use a very precise machine to make sure tha tyou have a perfect round, and not eliptical bore for the pistons and rings. The crosss hatch that they leave you with is so the the clyinder and rings seat properly, thus giving you maximum compression. They will sell you rings for your piston or they may want to sell you another piston and new rings depending upon how much metal/material that they have to remove to give you a perfectly round bore. Wiseco pistons are widely used because they contain more silicone in them and are surperior to most pistons that are delivered from the factory. wrist pin may be necessary, but the wristpin clips are a must. You DO NOT want one coming loose, and for what they cost, you can't complain as they are very inexpensive. Just remember, once again, when breaking in the engine to add some extra oil into your gastank as an aid in giving the top end a better job of seating in your new piston/rings. Just osage of your injection system or usual mix of fuel/oil mixture that you run.
 

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Motorswap

I don't know if you can do that. Isn't one water cooled...and isn't the frame different? I'd much rather have a 2 stroke dirt-bike or dualsport than a 4 stroke. I'm 51 so maybe I'm wrong, but I think that there is a lot less that can go wrong on a 2 stroke, and you will get more revs and power from a 2 stroke of equal size cc motor. Besides the weight difference after the coolant..etc... You could call the shop or a salvage yard they advertize all over the place...Besides the 2 stroke has a lot less moving parts in it...
 

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MOTOR SWAP...

you could even call Beartooth Kawasaki for free and ask them...
 

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Discussion Starter #15
the klx 250 motor is on ebay for like 5.00$ so i thought if it wasnt to hard then id give it a try
 

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Motor

You could bid on it even if it didn't fit you could most likely clean it up a bit and get your money back on it in just parts alone ...if you didn't just outright sell it for someone in the area that needed a spare...
 

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Motor

Save all our paperwork on it from ebay, print out the pages if you win it nd then take pictures of the serial no...etc. the if you keep looking you may find one with a blown motor...then it's just a matter of going therough your motor first and then buying another bike...then you will have two...just incase you happen to ned to swap/change bikes or want to sell one later for a street bike...
 
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