[NSRCA-discussion] 140DZ wristpin removal...help!

[Bob Kane]

Removing the wrist pin is a necessary part of disassembling a YS four stroke. There is a screw on the front of the engine in the center of the cam follower housing part of the block. Remove that screw, and you can insert a piece of wire to push the wrist pin out. It usually pushes out with little effort, but sometimes it is stubborn and you have to tap it out.  The wrist pin has to go back in the same orientation, the end that goes in first when reassembling the engine has a solid face, the other end has a hole in it.  Also, that little screw has a clear plastic washer, don't loose it.

When reassembling the engine, put the conrod on the crankshaft. Start the piston and ring in the liner from the bottom, and push it in a little so the wrist pin hole is exposed. Put the front teflon retainer in the piston, then slide the whole assembly into the block.  Position it so you can see the opening in the piston and conrod, then slide the wristpin in. Don't push too hard or you will push the teflon retainer out, and the liner will not push any further into the block. It might take a couple of tries, but it can be done.

I assume you mean the piston ring. There is a second ring on crank shaft. If our plans include removing the crank to replace the main bearing, be careful, the crank ring is easy to break.  I know  ;)

 Bob Kane
getterflash at yahoo.com



----- Original Message ----
From: Bob Wilson <wilsorc at gmail.com>
To: General pattern discussion <nsrca-discussion at lists.nsrca.org>
Sent: Sunday, July 27, 2008 7:54:57 AM
Subject: [NSRCA-discussion] 140DZ wristpin removal...help!


I'm trying to replace the ring on my YS 140DZ.
No problem removing the head and back plate apparatus.
I was hoping that the piston and connecting rod could be removed without removing the wristpin...but that doesn't seem possible.
I carefully removed the piston liner and removed the Teflon wristpin retainer through the (rubber stoppered) rear access hole.
Now, how do I remove the wristpin?  
 
It seems that it should just slide out through the rear access hole.  
 
There is a front access hole through the cam gear housing that I assume is for using a punch to push the wristpin out the rear access hole...but I don't want to start banging around if this is incorrect.
 
I know a lot of you guys have done this and would appreciate any help you could give me.
 
Thanks,
Bob Wilson


      
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