Need help!

[Andyshine77]

The saw had contamination, my guess is a clip was still in the case, or a bearing came loose. The second pic is tells me the clip came loose, are you sure both clips are intact? If the bearings are fine flush the case and make sure everything is very clean before reassembly.

 

[Chainsaw Jim]

No kidding. Well, I'll have to give it a whirl. I worry about hang up on my piston rings.....something to be concerned about or no?

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Leave the top edges tapered nicely and you should be fine.

 

[SEAM]

Sounds like you may have damaged one of the rings when inserting the piston - it does happen.
Bearing debris from the bottom would be drawn up only with the engine running...

 

[drf255]

The bottom of your intake port is a bit mangled as well.

That can be filled with Devcon aluminum putty or JB weld and sanded, or you can grind it lower, but that will affect intake timing and case pressure.

Just make sure you go around the edges of all the ports with a small diamond or carbide ball bit when you're done. Every area that the piston crosses, and every area you modify, needs the plating chamfered into the casting. Do that to the transfer bridge areas as well. Then hand sand all the edges and run your fingers over them many times.

A very easy place to make an error. It will groove a new piston and rings in a heartbeat. I learned this the hard way.

When you say that the original piston had "bad grooving", was it similar to what you're showing? I agree that there's some foreign body in there.

One last thing, what was the piston ring end gap on assembly?

Good luck.

 

[a. palmer jr.]

In my opinion you're asking for trouble by re-using the cylinder and piston. What I would do is flush out the engine and put in another p/c kit after making sure the bearings and seals are okay. You did state this was another person's saw, not yours. I would take the loss and try to make it up later like most shops do and consider it a lesson learned about what can go wrong. This kinda stuff happens to almost everybody who works on this stuff for other people including me..

 

[mortalitool]

The bottom of your intake port is a bit mangled as well.

That can be filled with Devcon aluminum putty or JB weld and sanded, or you can grind it lower, but that will affect intake timing and case pressure.

Just make sure you go around the edges of all the ports with a small diamond or carbide ball bit when you're done. Every area that the piston crosses, and every area you modify, needs the plating chamfered into the casting. Do that to the transfer bridge areas as well. Then hand sand all the edges and run your fingers over them many times.

A very easy place to make an error. It will groove a new piston and rings in a heartbeat. I learned this the hard way.

When you say that the original piston had "bad grooving", was it similar to what you're showing? I agree that there's some foreign body in there.

One last thing, what was the piston ring end gap on assembly?

Good luck.

The cylinder and piston that was on it had almost identical grooving on it. This makes me wonder.....

I have replacement cylinder and piston kit on order as we speak. New crank case gasket. New bearings on the way with new crank seals. Gonna split the case and really look and inspect the bearings.

In my opinion you're asking for trouble by re-using the cylinder and piston. What I would do is flush out the engine and put in another p/c kit after making sure the bearings and seals are okay. You did state this was another person's saw, not yours. I would take the loss and try to make it up later like most shops do and consider it a lesson learned about what can go wrong. This kinda stuff happens to almost everybody who works on this stuff for other people including me..

I won't be using this cylinder for this saw. I'll keep it and use It at some point in my life. I hear ya when you say this stuff happens to almost every body who works in this stuff for other people. Doesn't seem to happen if I own it but I do it for someone else.....and the problems start. Geez. I assembled it the way I would assemble my own stuff. Sometimes that's just the way she goes eh. But I'll end up eating this screw up and making it up later on in different saws and such.

Thanks for the feedback. Was pretty bummed when this happened but after letting it sit and just thinking and reading your responses I don't feel all that bad for making this mistake. 1 more lesson learned and I'll keep on keeping on.

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[Chainsaw Jim]

If you decide to never use the scrap cylinder then send it to me. I'll gladly pay you for it.
I've seen port jobs intentionally done to saws that look way worse than the damage on this cylinder, with damn good gains from the work too.
And the rings can't catch on a part of the cylinder they never touch, so the damage to the intake floor can be ignored as long as it is smooth with the bore.

 

[mortalitool]

chainsawjim, Im thinking about grinding away the bridge area from this cylinder and slapping it on my 660.
When i do though, would i have to advance the timing?
I would assume while in there grinding the bridge away, i might as well open up the intake and exhaust....right? Match the muffler to the exhaust port and such.
This kind of turned into a fun project/experiment. Either have to find another 660 or modify mine.
With this kind of port work being done, would this cylinder be a "work saw" or just a racer? Curious on this.

Thanks!

 

[mortalitool]

If you decide to never use the scrap cylinder then send it to me. I'll gladly pay you for it.
I've seen port jobs intentionally done to saws that look way worse than the damage on this cylinder, with damn good gains from the work too.
And the rings can't catch on a part of the cylinder they never touch, so the damage to the intake floor can be ignored as long as it is smooth with the bore.

ARE YOU "THE CHAINSAW GUY" ON THE YOUTUBE CHANNELS?

 

[Chainsaw Jim]

I'd call it a project since it has been done successfully in other shops. You literally don't need to change anything unless you decide to go with a max flow air filter to let more flow. No timing change needed. You can do it, but you'll already have good gains without. There are many threads around here on what to do properly with intake and exhaust. Don't worry so much about the outer exhaust flange as it is usually matched to the muffler pretty well.

 

[Chainsaw Jim]

ARE YOU "THE CHAINSAW GUY" ON THE YOUTUBE CHANNELS?

No I am not. He's not very far away from me though. Only like 80 miles down the road.
I do have a channel if you look for my name.

 

[mortalitool]

No I am not. He's not very far away from me though. Only like 80 miles down the road.
I do have a channel if you look for my name.

Cool! i appreciate all the tips and the help. I thought i was out of luck with this cylinder. From what you are telling me thats not the case.
I will post up pics of the process ill put the cylinder through. But im afraid i have no time and wont for a few months. I have 4 other saws to re-build and 3 HT131 shafts to swap out.
while all this is taking place i have a regular day job and i also sell firewood on the side. and the wood pile has been calling my name all summer. Having my wood splitter being worked on for a few months by the help of a great neighbor isnt helping me out in my splitting wood game. But i do look forward to messing with this 66 cylinder.

So in the meantime ill be lurking for a 066/660 junker for this cylinder to call a home. I would use my 66 but i like the way it runs right now.

 

[mortalitool]

No I am not. He's not very far away from me though. Only like 80 miles down the road.
I do have a channel if you look for my name.

i forgot to ask,

what do i lookup on the youtube to find your vids?

 

[Chainsaw Jim]

i forgot to ask,

what do i lookup on the youtube to find your vids?

My username.

 

[mortalitool]

My username.

Awesome. Thanks!

 

[mortalitool]

so i have a question,

by removing the bridge port, am i making this cylinder an "open" port cylinder?

I know some husky saws have open and closed port cylinders ... i always thought that was the way the bottom part of the cylinder was made...open and not open....( straight into the lower end if you will )