Stihl 029 super to 039 conversion

[94BULLITT]

Here is a picture of piston my supposed to to be 390 p/c that turned out to be a 290.

 

[kkemp]

I remember reading that. I hope that doesn't happen to me.

 

[kkemp]

Well I tried a carb off my dad's 029 that runs good. My saw still didn't start . Took a compression test and it's only about 90 psi . So I'm pretty sure it ain't starting like that . What could cause that on a new cylinder?

 

[Czed]

Well I tried a carb off my dad's 029 that runs good. My saw still didn't start . Took a compression test and it's only about 90 psi . So I'm pretty sure it ain't starting like that . What could cause that on a new cylinder?

Broken ring possibly.

 

[kkemp]

I took it apart . Rings looked good.

 

[Dub11]

I have been told to use caber or oem rings

 

[Czed]

I used cabers but you should have got decent compression with the supplied ones unless they were really bad.

 

[kkemp]

I have some cabers to put in it now but I don't think the ones I had in it could've been that bad.

 

[Fruecrue]

P&C new, rings looked fine and only 90 lbs. compression? Something doesn't add up. Spark plug threads stripped?

 

[kkemp]

P&C new, rings looked fine and only 90 lbs. compression? Something doesn't add up. Spark plug threads stripped?

I checked everything on it . Wasn't leaking on the spark plug or decomp valve . Used the compression tester on other saws and it was right . .

 

[Fruecrue]

This was that closed port 49mm cylinder? I've never seen that before, done more than a few of these (oem and am), always had 150 lbs minimum. Normally I see squish between 30 to 40 thou. Did you measure yours?

 

[Fruecrue]

I keep looking back to the page 4 cylinder pics. Still blows my mind. Could be a port timing issue, but I doubt port height was changed when the engineer closed the ports. Was the cylinder dry?
On a side note I've always thought the rings would spread too far if I removed the support between the original style front and rear transfers, this new design says GFY to that school of thought.

 

[kkemp]

This was that closed port 49mm cylinder? I've never seen that before, done more than a few of these (oem and am), always had 150 lbs minimum. Normally I see squish between 30 to 40 thou. Did you measure yours?

Yep it's the closed port cylinder . But I completely forgot about measuring the squish . I put it back together now. I hope caber rings help . I'll measure the squish whenever I put the saw back together.

 

[kkemp]

I keep looking back to the page 4 cylinder pics. Still blows my mind. Could be a port timing issue, but I doubt port height was changed when the engineer closed the ports. Was the cylinder dry?
On a side note I've always thought the rings would spread too far if I removed the support between the original style front and rear transfers, this new design says GFY to that school of thought.

cylinder had a light coating of oil when I took it apart.

 

[Czed]

I've bought new comp testers that were bad do you have another to try.

 

[94BULLITT]

Did you check the compression with the throttle open?

Sent from my SPH-L710 using Tapatalk

 

[fearofpavement]

Did you check the compression with the throttle open?

Sent from my SPH-L710 using Tapatalk

That makes zero difference on a chainsaw.

 

[a. palmer jr.]

Many of the cylinders I buy have a hole in top for the de-comp valve, I usually just plug them, one more thing to not go bad.

 

[94BULLITT]

That makes zero difference on a chainsaw.

Yeah it does.

Sent from my GT-P3113 using Tapatalk

 

[dall]

you can take the carb completely off and get the same as if the carb is on the idle position