Maintenance & Technical > KX500 Original

Newbie hello, and 1987 KX500C-1 top end.

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dean350b:
Hello, great web board!

Anyway, I bought a very nice 1987 KX500C-1. Unfortunately, it needed a top end done, no compression, would not start. Everything else on the bike is nice.

So I pull the cylinder off, and this is where the trouble begins:

1) Piston to cylinder clearance shot. Cylinder walls look nice, some wear, piston mic's out undersize, original 1-ring piston, "A", thown in the trash. Piston pin stepped, small-end roller bearing dead.

2) KIPS.....oh sweet Jesus pray for me. So, the two (1987) exhaust valves are frozen, completely frozen. Basically welded into the cylinder bores. The pinion gears on the valves are stripped. No teeth. After 1 whole day of working them with penetrating oil and prying them out, they are out. I need to hone the bores and buy new valves.

3) Bottom end: Nice, conrod lower bearing measures .014" (inches) sideplay, well within limits, no axial play. Thank god.

4) Cylinder: No cracks, Nikasil is getting worn, still usable, will do some ball-honing, minor porting and cleanup, and time the new KIPS valves to spec.

5) Piston: Ordered a new 1988+ Pro-X piston Part# 131038SB Piston Assembly  Bore Size: 85.95mm (+0.01) "B".  New roller bearing upper conrod, new gasket set. I bore mic'd the cylinder, this + 0.01 piston will give me back the needed loss of clearance in this cylinder.

Next time she is going to need re-plating of the Nikasil. Hopefully BikeBandit comes through with my two exhaust valves, as they were the only online source that shows them available. No Kawasaki sources had them, listed as obsolete.

Warning to any 1987-1988 owners, remove your KIPS actuator cover and try fully moving your actuator gear to verify your KIPS valves arent carbon siezed into the exhaust port like mine were. Better to clean them out now, then buy two $59.00 valves, or much worse.

Will report back on how she comes together and runs.


 

flyin9:
hey dean,
if your part place doesnt come through try www.worldofpowersports.com
53 bucks apeace and shipping looks like 18

dean350b:
THANK YOU!!

no sub for cubes:
hi

let me know if you can get the exhaust valves,i have an 88 which has the same valves but here in the uk it has proved an impossible mission to find them,they have been discontinued and nobody has new old stock  :-(


                                      thanks

dean350b:
Well, spent all day trying to find them. Nobody has them new. I tried everywhere.

Bought a used set on Ebay, thank goodness somebody had them.

Shouldn't these be reproduced by the aftermarket, or does welding them in at the wide-open position seem like the only recourse? Boysen or Wiesco could make them?
 
I know many "race (drag)" bikes just weld them wide open.

Sucks to have a system that gums itself up so easily.

BTW, spent most of the day cleaning the KIPS bores with a 20mm ball hone and easy-off oven cleaner.

The bores are nice now. Hopefully the 36:1 Castrol A727 will keep them working smooth for a year or two.

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