Is this a closed port 55.......Now repaired Piston cut and photos added

[Uzi]

Picked this 55 up cheap on eBay and I've cut a lot of firewood with it this season. Unfortunately it went lean and scored the piston. It didn't completely seize and actually started back up but would not run well or idle. I've torn it down and the ring was melted into the piston around the exhaust port. The cylinder clean up fine but now I'm trying to find a piston for it and the one in it measures 45mm but everything I find searching for it says 46mm. I'll include a couple pictures if the cylinder and piston. Any input appreciated .

 

[struggle]

the closed port cylinders are 45mm and are open across the piston.

The closed port cylinder is very different from the open one.

post a picture of the cylinder.

Parts are not easy to find for the closed port version which is more desirable due to it have higher rpm performance range.

I recently rebuilt one and had to use aftermarket open port cylinder as the closed port cylinder the plating was chipping off from it being scored.

Also best to replace the impulse port nipple grommet and pressure test/vac test with carb base installed as they are prone to leak in that area.

 

[Uzi]

 

[Uzi]

Piston

 

[Saw Dr.]

Your saw is closed port

 

[fearofpavement]

any chance you can save the piston or is it smeared pretty badly?

 

[Icehouse]

Uzi, blsnelling just did a build on a closed port 55, check out that thread, should answer some questions. It's about a air induction 55. Best wishes

 

[Uzi]

I'm not sure on the piston it's got one semi-deep gouge but the ring land isn't in that bad of shape dont know if it would be worth trying to sand it up and re-ring it.

 

[Uzi]

Uzi, blsnelling just did a build on a closed port 55, check out that thread, should answer some questions. It's about a air induction 55. Best wishes

Thanks I already pmed him when I saw that thread. Hoping I could get a piston with the skirt cut from him that might work in my cylinder.

 

[firefighterwolf]

That piston is fried.... not salvageable IMO.

 

[crane]

Did you find the cause of why it "went lean"? New piston/rings or cylinder won't last if that problem persists.

 

[diggers_dad]

Also best to replace the impulse port nipple grommet and pressure test/vac test with carb base installed as they are prone to leak in that area.

+1

 

[Uzi]

Did you find the cause of why it "went lean"? New piston/rings or cylinder won't last if that problem persists.

I am not sure the exact cause of it going lean but it will be pressure checked when I get the parts to re-assemble it.

 

[Uzi]

I thought I'd come back and update this now that I've got the saw back together. I bought a piston from a open port 51 to get the 45mm size that I needed. I did a little bit of porting to the cylinder and a whole lot of grinding on the piston with a dremel to get the windows cut in it. I widened the transfer ports and opened up exhaust and intake ports. I also removed the base gasket and gutted the muffler. Put the thing back together with some permatex gasket maker on the base and sealed up the intake grommet....no air leaks at all. Fired it up and cut with it this weekend and it absolutely screams.

Here's a few pictures of the piston and cylinder for those curious how it looked.

 

[stihlbro]

Nice work you've done there. It's evident the replacement piston you used will work. How would you rate the saws performance since replacing the piston?


Joey

 

[Uzi]

I'm really impressed although I've only run 2-3 tanks of fuel since putting it back together. I never checked compression before the rebuild it was $100 eBay saw that had a missing clutch cover. I just bought the cover put it together and ran it. It made it about 6 months of use before the meltdown. And it was pretty hard use I'd run gallons and gallons of fuel through it in those 6 months.

I need to get the compression tester back on it and see what it reads now that it's been run. My completely stock (except fuel screw limiters removed) 455 rancher used to out run it no problem. Now it's the other way around granted the 455 is running a 20 and the 55 is an 18 I think this thing would be faster even if they had equal bar lengths. It has tons of torque for a small saw and jumps the bar tip and saw frame pretty good when you stab the throttle. It never felt that way before the rebuild. It's sure cutting a lot faster than it ever did so I'm happy with that.

 

[Ozhoo]

Nice job. I'd expect compression to be around 160ish. I'd also expect you're piston to come apart in a blaze of glory one day, but until then run her like you bought her on eBay for 100 bucks. What rpm have you got it tuned for?

 

[Uzi]

I'd also expect you're piston to come apart in a blaze of glory one day, but until then run her like you bought her on eBay for 100 bucks. What rpm have you got it tuned for?

I did a lot of reading about closed port stuff and read about other people who've cut pistons to fit and then had them crack or blow apart. This was a cheap no name piston and the casting on it is super thick. The wrist pin area on it was about 2 times as thick as the husky piston. It made the piston pin c clips an absolute &*(#% to get in. I left the area above the piston pin thicker than stock and the area below on the skirt is much thicker than stock too. I'm going to run it hard like the $100 saw that it is and see what happens if it blows I'll try to figure out why. I still don't have a $150 into this thing so it's not going to be a huge loss if dies.

 

[Uzi]

What rpm have you got it tuned for?

I've got no tach and so no idea what its turning.

 

[Ozhoo]

The best thing about being able to do this sort of stuff is that if/when you blow one up that you get to fix it