Mcculloch PM610 Piston Rebuild Questions / Help

[Khalil1090]

Hello Everyone! This is my first day as a member here. I look forward to providing any help I can in Restoration and rebuild projects. I also look forward to any help that anyone can provide! It's always appreciated.

Lost my Grandpa to cancer a few years back and his chainsaw was handed down to me. I remember the days as a kid going to cut firewood and this saw TORE it up! Well 20 some years later and the saw started on my 5th or 6th pull. Of course it did not stay running and didn't run much after that. The saw is a Mcculloch PM610. I plan on restoring the saw completely and getting it back to perfect. I understand it might now be worth it, however it is to me with the sentimental value this holds.

The saw has been completely disassembled and cleaned. I replaced the carb gaskets, spark plug, fuel filter, throttle spring, pull rope, exhaust gaskets, spark arrestor, etc. She still wont start up...

Took it to a small engine shop, and sure enough the piston was scored and shot. No problem. Ordered a brand new aftermarket piston from Chainsawr.com which is "claimed" to be better than OEM since it has the one thick ring instead of 2 small rings. Also ordered the Piston Bearings and new engine gaskets.

Disassembled saw and now I just have the piston connected to the rod. My questions are below. Thank you in advance for Any help! I hope to get this saw screaming again. I can also provide some pics if needed.

1. How do I press the old bearings out and disconnect the piston from the rod?

2. I plan to use Yamabond to seal everything when I'm done. Any tips or tricks here? Is it safe to use a very thin layer of yamabond underneath the new gaskets I'm going to be putting in for extra protection or is this not a good idea?

3. Has anyone ever honed a chainsaw Cylinder? Mine does not look to bad, but would like to clean it up if possible. Any ideas?

Thanks all!

 

[Yukon Stihl]

Hi And welcome
Use the search function and do a bunch of reading.
Post some pic's of your cylinder.
There are lots of those saws around so parts are easy to come by.

 

[a. palmer jr.]

Not a good idea to hone a chainsaw cylinder because of the chrome plating. I sometimes clean em up a little with automotive sandpaper in a fine grit but don't get carried away with it. As for removing the piston, this appears to not have the circlips so the piston pin will need to be pressed out. If it was me, I would try to rig up some kind of a press maybe using a "C" clamp. When you put the new piston in you might need to put the wrist pin in the freezer for awhile to make it easier to press in. I would put the ring on the piston after it is on the engine to keep from breaking it..

 

[Khalil1090]

Not a good idea to hone a chainsaw cylinder because of the chrome plating. I sometimes clean em up a little with automotive sandpaper in a fine grit but don't get carried away with it. As for removing the piston, this appears to not have the circlips so the piston pin will need to be pressed out. If it was me, I would try to rig up some kind of a press maybe using a "C" clamp. When you put the new piston in you might need to put the wrist pin in the freezer for awhile to make it easier to press in. I would put the ring on the piston after it is on the engine to keep from breaking it..

Palmer Jr. thanks for the information! Yes you are correct the piston does not have any circlips. I have a large c clamp and will try to press out the bearings and press to install them as well. Thanks for the tip on the piston ring. I will not put it on until the piston is on. I have some automotive sandpaper and will o my best to clean it up. I’ll lost some pictures soon. I plan to tackle some of this project tomorrow. Thanks again!

Khalil

 

[Brian Thacker]

Your PM610 is a great saw. I have one and it will start anytime I ask and cuts like a tractor. Many call them a McCinderblock and they seam to get a bad rap.

Take a heat gun and heat the piston up. I have two different ways I get the wrist pin out of and back into a piston. I took a block of wood and cut a half moon in it that a piston will fit into and will cradle the piston. I also drill a hole where the wrist pin is so it can be driven threw. You must be very gentle with this method. I also use a big C clamp as A.palmer mentioned. This is my preferred method. When you install the piston onto the rod I usually take a heat lamp and put it over the end of the rod to heat it up. I put the pin itself in the freezer and doing this makes it much easier to install.

A lot of good helpful people on this site that can explain almost anything and help you threw almost any problem.

Brian

 

[Khalil1090]

Your PM610 is a great saw. I have one and it will start anytime I ask and cuts like a tractor. Many call them a McCinderblock and they seam to get a bad rap.

Take a heat gun and heat the piston up. I have two different ways I get the wrist pin out of and back into a piston. I took a block of wood and cut a half moon in it that a piston will fit into and will cradle the piston. I also drill a hole where the wrist pin is so it can be driven threw. You must be very gentle with this method. I also use a big C clamp as A.palmer mentioned. This is my preferred method. When you install the piston onto the rod I usually take a heat lamp and put it over the end of the rod to heat it up. I put the pin itself in the freezer and doing this makes it much easier to install.

A lot of good helpful people on this site that can explain almost anything and help you threw almost any problem.

Brian

Brain, thanks so much for the help. Yeah I know these saws are good. I can’t wait to get it running. I will try this method out that you speak off. Sounds like I understand how to get the piston off and how to press it out. When installing, is it just reverse? Basically press it in with the c clamp? I got new bearings for the new piston as well. Should I put those on the piston before I install the piston? Sorry if these are obvious questions. This is my first time replacing an actual 2 stroke piston. I’ve seen others done, but these Mcculloch pistons and bearings are different. Also I’m mostly under cars and working on trucks so this little bit is new too me. Thanks again!

 

[Brian Thacker]

Yes, just in reverse. Put the bearings in first. I am un shure about the piston on a 610 but most pistons have a arrow that points to the exhaust port.

Brian

 

[Khalil1090]

Hey Guys, Wondering if I need to purchase some sort of sealant for the Gaskets. I got a whole new Engine gasket Kit along with the Oil Gaskets. Seems like on the old gaskets there was some sort of thin layer of sealant that went on the bottom before they were seated? The old ones were hard to get off and when they came off I could see the residue from what was underneath them. Almost looks like a thin layer of glue or something? Any ideas before I put these new ones on? Thanks for the help!

 

[a. palmer jr.]

If you want to you can use a thin layer of Motoseal but I think it requires you to coat both surfaces, kinda like contact cement.

 

[Khalil1090]

If you want to you can use a thin layer of Motoseal but I think it requires you to coat both surfaces, kinda like contact cement.

Thank you!

 

[Khalil1090]

Hey guys! I know it has been some time since I last posted about this! The saw has been in storage until I can find time to complete. Which I’m just getting around to it now! I have purchased a brand new piston + piston ring “thick ring that replaces the 2 thin rings” new bearings etc.

I had the new piston installed to the rod with new bearings. The cylinder is completely cleaned up and does not have any scoring. Everything is ready to be put together now.

I’m confused on how this new thick piston ring goes onto the piston. The piston actually has a little metal ball that sits in the grove. At each of the piston ring ends, it curves. So the only way this piston ring fits is to line up those curves with that little ball on the piston. It can either cup the ball, or if you turn the ring upside down it covers the top of the ball.

Anybody of you guys know how this piston ring is suppose to be installed? Or am I even making any sense? I’ve never seen this before.

Also I need to remove flywheel so I can install the final bearing and seal that sit on the inside of the flywheel. Any suggestions or tips before intake it off?

Thank you!!