Stihl 290 Piston

[bitzer]

I have an 039 that is in the exact condition (burned up piston and damaged cylinder). I will take a look at both carbs and find out how the now 310 will need to be adjusted for the change in displacement.

I've done the 290 to 310 switch and muffler modded and ported it and there is plenty of adjustment so no worries there. Good luck!



I don't see why they would need a different jet with such a small variance in displacement. It would be kind of counter-intuitive for production of that series of saw with all other interchangeable parts.

 

[nmurph]

the 290 uses a 0.56 jet and the 310/390 use a 0.58.

 

[joecool85]

I know but its only 2.5ccs away from the 310 and 7.5 from the 390.

That's what I was getting at. It's only a few ccs, shouldn't be a problem. I was just explaining why others were worried and why Stihl may have adjusted the jetting.

 

[nmurph]

It would be kind of counter-intuitive for production of that series of saw with all other interchangeable parts.

i am sure that Stihl found a reason for the different size jets, though it may only be to satisfy the EPA.

 

[joecool85]

i am sure that Stihl found a reason for the different size jets, though it may only be to satisfy the EPA.

It's just jets, otherwise the same, so it shouldn't be much cost to them. Also larger jets will allow them to set the carbs at a standard (say 1 turn out for L and 1.5 for H) on all saws regardless of displacement.

 

[Guarddog1]

Ok well back to the original question I have purchased a oem piston and jug for a 290 for 120. shipped to my house. They are available for that still just do some looking. All 390 stuff I had found was very pricey everyone wants to do the swap. Some on here sells the oe kits. For that price I was not going to try to clean the jug.

 

[bitzer]

the 290 uses a 0.56 jet and the 310/390 use a 0.58.

Good to know, thanks!







Good deal on the replacement Guarddog1! I tried looking for a 390 cylinder at the time too, couldn't find a decent price.

 

[EtzCutter]

This saw will be ran at high altitude and as I am overlooking the IPL, I will need a 0.54 jet rather than 0.58. The jet on the 290 is at 0.56...

 

[EtzCutter]

The same piston that I tried cleaning with acid and then sanding. After sanding it twice and feeling the inside of the cylinder I was convinced to get new cylinder and piston (thus I "scored" a new/used 310 for the 029). I was hoping it would clean up a little better than it did.

 

[joecool85]

The same piston that I tried cleaning with acid and then sanding. After sanding it twice and feeling the inside of the cylinder I was convinced to get new cylinder and piston (thus I "scored" a new/used 310 for the 029). I was hoping it would clean up a little better than it did.

I'd say you made a sound decision. While it may have run with the cleaned up piston and cylinder and new rings, it probably wouldn't have had full compression, and odds are it would have worn out quickly.

 

[EtzCutter]

For connecting the cylinder to the engine pan, would other red HT brand sealant work? I called my local auto store and they carry a "P" something brand red, HT sealant. What other brands have you used for connecting the engine pan to the cylinder?

 

[lwn9186]

I use Yamahabond 4 one tube will do several engines.

 

[EtzCutter]

I was able to acquire a MS 310 piston and cylinder and it was placed into the saw. On the sixth pull, the saw fired right up. This was my first piston/cylinder replacement as I was happy to see my efforts fire right up.

I am not sure as to why the original piston and cylinder burned up. I do have a Mityvac MV8500 on the way, will ya'll provide some insight and feedback as to what I should double check before running the saw full time?

I haven't torn the carb apart yet to clean it, which I plan to do. I checked all the fuel lines. I do plan to pressure/vaccum test the crankcase and engine.

 

[Saw Dr.]

I would not bother cleaning the carburetor if it is running properly. Did you trim the limiter caps on the carb needles yet?

 

[EtzCutter]

No the limiter caps are still on the carb. I ran the saw for about a minute after assembling it back together. I will have to fine tune the carb as it sounded like it was running "lean". Anyone have pictures and details of a muffler mod on the 290/310/390 saws?

 

[joecool85]

No the limiter caps are still on the carb. I ran the saw for about a minute after assembling it back together. I will have to fine tune the carb as it sounded like it was running "lean". Anyone have pictures and details of a muffler mod on the 290/310/390 saws?

Between running a little lean and maybe running old/crappy gas that's probably what killed it the first time. Run 91+ octane fuel, keep the moisture out of it (good container kept in a garage/shed etc) and run a quality oil mix at a reasonable ratio (somewhere between 50:1 and 32:1 depending on who you ask - although anywhere in there is fine) and you'll be good to go.

 

[isaaccarlson]

here is one pic of my muff mod on my 390

http://www.arboristsite.com/attachment.php?attachmentid=112898&d=1256398969
I also drilled the holes in the baffle tube a little larger
Good luck and take out your limiter caps

 

[EtzCutter]

This is one of the carb limiters. The part that sticks out is what I need to trim?

 

[nmurph]

yep, trim that little tab and you are all set.