Removing the wrist pins

[1967 R502]

Hello All-

I am trying to remove the pistons from my bike. After taking out the circlips I heated the piston with a propane torch. After about a half hour of waving the torch around the piston and getting it so hot that any remaining oil burned off, I still can't get the wrist pin out. Last time I did this was 22 years ago, and I remember it being about a 5 minute job. Am I missing something here? any particular technique about how to apply the flame? There is a very distinct ridge in the wrist pin channel behind where the circle fits. it stops the wrist pin from exitin. My memory being weak, I'm figuring the ridge is meant to be there and not a deformation in the piston.

[schrader7032]

Have you tried pushing the wrist pin in both directions? I seem to remember just using a hair dryer for heat...didn't need to get it that hot...and then used a socket that just fit inside the opening and with light taps from a hammer, the pins came out. Probably need to support the piston/rod so you're not hitting so hard out of plane. The Barrington manual doesn't really have any thing to help...just says to heat the wrist pin bosses (ie, not really the whole piston, just the area where the wrist pin resides) and the push the wrist pin clear.

I don't think there's supposed to be a ridge there...the circlips hold the pins in place.

[1967 R502]

Yes. Mainly I am heating the bosses. The piston is supported. But clearly there is a ridge.

[1967 R502]

Slight update. Being frustrated with one side, I went to the other. Came off in under a minute. No ridge in evidence,

[malmac]

I would suspect that the pin has worn into the piston thus creating the groove.

If the wear process has created a ridge rather than just a groove, you might need to reem out the hole so the pin is not jamming against anr ridge (if one is has formed).

I think if you go to a cheapie auto shop you may find a pin extraction puller/pusher that holds the piston and pushes the pin out without putting any side force onto the conrod.

All the best with the removal.


Mal

[1967 R502]

After a combination of Dremel, torch and wrist pin puller, I got the pin out. There is a a lot of wobble in the con-rod. My feeling is that this wobble pushed the wrist pin side to side against the circlips which built up the burrs on either side.

Piston and wrist pin are likely done.

Crankshaft will need to be reconditioned, I am sure.