What am i doing wrong??

[doc874]

I have stripped and clean a McCulloch 1-51 saw my problem is when i put the piston and crank back into the cylinder i spin it counter clockwise and all is fine but, when i spin it counter clockwise it seems the rings are catching on the port or something else. I removed the crank and the piston slides nicely-no problems not sure whats-up with this. I took pics to better visualize the parts. I also took a pic of one of the bearing pins along side the piston connecting rod, the rod is fine not bent etc...Thanks for any help.

 

[BostonBull]

Just a thought........try putting some mix in there then do everyhting all over again. Maybe it just needs some lube?

I am just speaking out of my arse here

 

[PES+]

You had the piston backwards. The ring ends were catching in the ports

Did you take the piston off the rod? I would think probably not so just turn the rod around and it should be fine.

 

[RiverRat2]

piston should have an arrow or index mark on the top!!!!

It always goes toward the Exhaust port!!!!!!:monkey: :monkey: :monkey:

 

[doc874]

Thanks for the replys. I figured out the problem. The way the lower half of the connecting rod is machined is/was the problem. Since i have two of these saws stripped, the parts got mixed and you can only use the 1/2 moon piece at the bottom of the connecting rod on the one its machined for, the other one created a small gap that the bearing pin was getting caught in. The setup on this saw is much like the piston/cylinder set-up on a lawnboy mower, no ring pins on the piston so as long as the ring gaps are not overlaping each other its ok.once i got it figured out it is fine, although, odd that it would turn freely one way and not the other, i would have thought that if the rings were catching on a port it wouldn't matter which way it was traveling, up or down is this right?. Thanks all.

 

[PES+]

Yes...I was forgetting the bridged ports in the saw engines and was thinking kart motors no pins in the 51s
The kart motors will act like that with the piston reversed due to the shape of the transfer port tops

 

[Al Smith]

Well,this must be a learning curve day for an old turner of wrenchs,McCulloch at that.I never knew a 1-51 had a removable head let alone a 9 port transfer,wow.

To the question at hand,no reason for the "snag" in rotation that I can think of.

 

[PES+]

Ummmmm

AL?
Three of those nine holes are the exhaust ports
the nine ports have three more holes

 

[PES+]

I hope that didn't sound punkish AL I did not mean to

I too am interested in the removable head with that style connecting rod.

I can't help but think that Mac Canada must have had different standards