CMB 28.5 Evo

[Steven Kinney]

Anyone know how to get the crank pin out of a 28.5 Evo motor? There isn’t a way to push it out the back so I am not sure how to get it out. Thanks

 

[Stuart Barr]

Pull the wrist pin clip out through the exhaust port. Use a head bolt to snag a thread in the wrist pin to pull the pin out through the exhaust port.

 

[Steven Kinney]

Do I need to remove the piston to get to the bottom what’s called in the paperwork a crank pin?
I am trying to get the pin that goes through the bottom of the connecting rod out so I can pull the rod and piston all in one.
Thanks

 

[bermudadude]

sorry no thats not how any of that works .

like was said u have to remove the piston clip and pull the piston pin . then u rotate the rod into the "position" and the crank will come out . ii cant say the position as ive only done the nitros .

yea an engine with a hand removable crank pin makes for a bad engine

takes patience - good luck

 

[Steven Kinney]

Thanks you Stu appreciate the help.

 

[Wasted wages]

The crank pin is a press fit, it holds the rod in place as well as the two halves of the crankshaft together. As stated above, remove the wrist pin circlip thru the exhaust port, and the thread a head bolt into the wrist pin and pull it out of the piston and rod. The piston will come out of the top of the case.

Then you can rotate the crank into a downstroke position that will allow the crank and rod to tip out of the case.

sometimes you will need to rotate and wiggle the crank to find just the right spot for it to come out.

Reinstallation is just the opposite of removal..

Be careful with the circlip, they are known to be forcefully ejected, never to be seen again. I use a set of dental picks and a hemostat ground to keep a grip on the clip during removal and installation.
Wear safety glasses ! It would be a good idea to purchase a few clips to keep in your parts box.

 

[Steven Kinney]

Thank you I finally got it figured out. Once Stu told me that I pull the piston then everything came out. The wrist pin clip is a fun one lol. Thanks again!

 

[David Bryant]

I hate wrist pin clips

 

[rhomodel]

I changed to Seger clips and they are much easier to work with, especially in difficult engines such as the CMB. These work on Zenoah and the likes engines.

Stop piston clips seger (10 pz) x piston ø34

 

[bermudadude]

that seger is the worst type of clip ever. use at ur own risk

 

[David Bryant]

interesting, never seen Seger clips

 

[Daniel's Racing]

that seger is the worst type of clip ever. use at ur own risk

Exactly. Never use any clip with either end rolled. Same thing with the e clips.

I would never use them. Without the sharp end at the ends it can rotate and that is a bad thing.
You never install the gap in clip with any access slot. Gap straight up or down and as long as ends are away from access slot in piston. Those type can rotate. If gap gets to the sides the speed at which piston changes directions is enough to collapse and dislodge the clip.

The sharp ends must be catching and holding in the groove so it doesn't move.

 

[Daniel's Racing]