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Old 04-09-2008, 09:22 AM   #1
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Unhappy Help, is my engine ok?

New bee question ... help.

I just got a new OS TZ12 5 port and before breaking in, I notice when I turn the crankshaft, the cylinder liner is hitting against the head/heatsink.

Is this normal? I was rotating the crankshaft and it seems to be stuck every 180 degree, then I told off the head to find out that the piston is pushing up the liner above the square position and hitting the head.

Help ..
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Old 04-09-2008, 10:37 AM   #2
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the engine should not be easily turned by hand that is the pinch of the sleeve on the piston there is nothing wrong with that.
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Old 04-09-2008, 10:44 AM   #3
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you are on the money for a brand new motor, its when you roll the flywheel over and little or new resistance...then is time for some help
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Old 04-09-2008, 11:17 AM   #4
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So just so I am clear, if I take off the heat sink, the gold color liner moves up (above the engine and into the original heat sink space) when the piston comes up, so this is normal?

This just seems strange to me that the gold liner hits the heat sink every cycle...

Thanks for your help!
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Old 04-09-2008, 11:52 AM   #5
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the sleeve doesn't move when the engine head is screwed on. So the top of the sleeve doesn't hit the head.
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Old 04-09-2008, 12:31 PM   #6
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all your feeling when the motor is intact, is the piston hitting the taper point of the sleeve(compression) which is right on the mark. and yes with it apart, when the motor has good pich it will lift the sleeve out when you rotate the flywheel.....

also are you using the right PLUG for the motor???????

just making sure you really arent hitting something on the top side...(any marks or dings on top of the piston?)
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Old 04-09-2008, 03:41 PM   #7
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With the heat sink off, the piston being pushed up is hitting the pinch on the sleeve and getting stuck. Once stuck it moves the sleeve up in the crankcase since the heat sink is not there to hold it in position. This pinch on the sleeve at top dead center (TDC) is where the compression comes from. This is normal. Once the heat sink or head is bolted back on the engine the sleeve will stay in position. It does not move.

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Old 04-09-2008, 08:25 PM   #8
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Quote:
Originally Posted by bboy View Post
New bee question ... help.

I just got a new OS TZ12 5 port and before breaking in, I notice when I turn the crankshaft, the cylinder liner is hitting against the head/heatsink.

Is this normal? I was rotating the crankshaft and it seems to be stuck every 180 degree, then I told off the head to find out that the piston is pushing up the liner above the square position and hitting the head.

Help ..
Just put everything back to original condition.

The piston is not hitting the top ( underhead ).

It's the pinch that creates the feeling of stuckness.

Smear some after run oil at the pinch area. Two drops of oil in conrod / crankshaft. Three drops in rear bearing, and you can start the break in process.

I believe OS also give you 1 more shim in the box, use that for break in process. Additional shim helps to reduce the work load for conrod, get more stable idle, and reduce engine compression.

OS engines usually takes very long time to break in. Even after 1 race, sometimes the pinch stuckness is still there. Don't worry.... it's good thing.
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Old 04-10-2008, 06:42 AM   #9
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I see, thanks everyone for your help. This is so helpful.

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