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Kz650 compression after rebuild
- baldy110
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When I assemble an engine I will manually rotate it during the build process just to make sure everything is turning smoothly. For instance when I finish installing the crank I will rotate the engine by hand if that is smooth I will go to the next step. After installing the pistons and cylinder I will rotate the engine if it is smooth then I move onto the head, and so on. If something is not smooth I will stop and figure out why, fix it then move on.
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- vict182
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Everything was moving smoothly step by step
Everything turns smoothly also now everytime the engine is cold
The problem occurs only when the engine is hot
I am reclutant to take things off like cams, head and cylinders when the engine is hot
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- baldy110
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- vict182
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When the engine is cold everything was smooth during rebuild and everything is still smooth now when the engine is cold
I think at this point i should speak with people who worked on my cylinder block to fit the wiseco pistons
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- baldy110
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- Nessism
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You might want to remove the spark plugs and turn the engine over with a wrench on the end of the crank. It should turn reasonably easily. Do it both hot and cold to tell if you can notice a difference.
If the piston to cylinder clearance is too tight the engine will stick. I'll be surprised if this is the issue.
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- vict182
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Will keep you posted
Thank you
Vic
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- missionkz
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Don't be pulling anything apart yet.
Assuming you aren't trying to start it in gear, just remove the spark plugs and crank the engine around by the kick starter using your foot then do it by hand.
You should be able to do it with very little effort by foot and only a little harder by hand.
Put one spark plug in at a time and see how the actual compression effects the effort.
Bruce
1977 KZ1000A1
2016 Triumph T120 Bonneville
Far North East Metro Denver Colorado
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- Nebr_Rex
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baldy110 wrote: I didn't mean take it apart while it is hot I was simply telling you how I do things. If everything went together smoothly and you have this problem now when it gets warm your left with one choice at this point. Taking the top end apart one piece at a time until you find the problem. Now I am assuming this problem was not present before putting in the piston kit. If not then it is something that was introduced when adding it. Most aftermarket piston kits need a larger piston to cylinder wall clearance since the pistons are forged, not cast, they have different expansion rates. If the machine shop set the clearance to the stock piston specs then problems will come up, I have had shops do that.
+1
Air cooled engines need air flow over them while running.
Use a fan in front of the bike if you are 'tuning while stationary.
.
2002 ZRX1200R
81 GPz1100
79 KZ1000st daily ride
79 KZ1000mk2 prodject
78 KZ650sr
78 KZ650b
81 KZ750e
80 KZ750ltd
77 KZ400/440 cafe project
76 KZ400/440 Fuel Injected
www.dotheton.com/forum/index.php?topic=39120.0
.
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- vict182
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I take a ride
Then i stop
Make some changes with air screws
Then turn the engine on and ride again
Always reading oil temperature on a display i installed
Temperature when i stop is always around 80° celsius. When i start the engine to ride again temperature is never more than 90° celsius
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- KZB2 650
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1978 KZ650 b-2
700cc Wiseco kit 10 to 1.
1980 KZ750 cam, ape springs, stock clutch/ Barnett springs.
Vance and Hines Header w/ comp baffle and Ape pods, Dyna S and green coils, copper wires.
29MM smooth bores W/ 17.5 pilots, 0-6s and 117.5 main
16/42 gearing X ring chain and alum rear JT sprocket.
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- 650mod
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Hopefully it's nothing too severe for you.
78 kz 650 custom
Wiseco 720cc big bore
Dynajet stage 3 carb kit with pods
2002 Kawasaki Z750 exhaust
2001 Buell lightning front end
1999 Ninja 600 swingarm with 1999 Ninja 900 rear rim
converted to monoshock rear
Too many goodies to list fully
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