084 Cylinder kit FAIL

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Check your tank vent. If there's a grub screw in the hose, GET RID OF IT and install the little orange "umbrella" in the tank.

OK, did some searching here for "orange umbrella". Think I know what you are talking about now: part #1110 353 1600, right? Do I need anything else to retrofit this to an 084?
 
OK, did some searching here for "orange umbrella". Think I know what you are talking about now: part #1110 353 1600, right? Do I need anything else to retrofit this to an 084?
Still trying to figure this out. Do I need

1121 358 1800 (vent filter)
1121 358 2500 (tank vent cover)
 
OK, did some searching here for "orange umbrella". Think I know what you are talking about now: part #1110 353 1600, right? Do I need anything else to retrofit this to an 084?
Just check to see if you have the little hole in the tank that accepts that rubber valve. It has a tit that pulls through and snaps into place.
 
Just check to see if you have the little hole in the tank that accepts that rubber valve. It has a tit that pulls through and snaps into place.

Darn, if I understand it correctly, then I'm not sure that's going to work on this saw. It's more of a slit, although with a tiny round hole at the centre of the slit, and it's pretty close to the tank wall. Or is this umbrella much smaller diameter than I'm imagining?:

11_vent_assembly.JPG


12_vent_cap.JPG


13_vent_hole.JPG
 
OK, wait a minute. The IPL I have actually shows that part number for the 084AV. It must be smaller than I imagined. I'll try to order one from the dealer.
 
Ok: Checked all the bearings. Flushed out the crankcase with mixed fuel. New seals. Got another cylinder kit. Went over all edges to make sure they were properly chamfered. Set the squish to 0.027" using the soft solder method of measuring. Washed the cylinder and piston, lightly oiled with 2 stroke oil, installed the rings and assembled. Checked compression: 130 psi cold. Drained the fuel tank, installed the orange umbrella and removed the grub screw. Added another 100ml of oil to the fuel can. Mixed well, and refueled the saw.

Fired the saw up. Idles nice. Set the high speed for a strong 4-stroking when blipped. With the saw warmed up, took a slice out of a 2' diameter maple stump, moderate pressure, varying throttle from 1/2 to full -- still 4 stroking in the cut. Let the saw idle a bit, leaned out the high speed screw 1/8 turn. Still 4 stroking when blipped. Cut a second slice out of the stump. Checked the idle return in all positions and shut down the saw.

Started a hot compression check. 1st pull ~90 psi. Second pull, rising through 120. Suddenly pressure gauge dropped to about 5psi and the saw jammed. Removed the compression gauge and the piston was around TDC. Pushed back down quite easily, but jammed at TDC immediately on pulling the recoil again. WTF???

I removed the exhaust, looked inside, and found this little fellow sitting on top of my piston:

14_foreign_body.JPG


Brass coloured, non-magnetic, scores easily with a fine file, looks like brass. Where the heck did this come from and how the aitch-ee_double_hockey_sticks did it get inside my bloody engine???

I took this pic and stared at it scratching my head. Not a bearing, Doesn't look like a carb part, although it seems to be brass and vaguely looks like a float valve needle.

Wait a sec -- valve needle? Why would the pressure gauge drop before pushing the pressure release button? So I checked, and sure enough, the OTHER HALF OF THIS BUGGER IS STILL INSIDE MY CHEAP $#!+ HARBOR FREIGHT COMPRESSION TESTER HOSE!

Arrrggghhh.

So, what do all you guys use for a compression tester. 'Cause apparently I'm now in the market for a new one...
 
Could that be from a loose piston ring pin?

*edit*

Too late to the party! Unreal that a compression gauge check valve tried your engine!!
 
Too late to the party! Unreal that a compression gauge check valve tried your engine!!

I can't be certain that it was part of the compression tester that damaged the first cylinder kit. But it seems to be a strong possibility.

My old Canadian Tire automotive compression tester is reading 140psi (cold, without any additional oil). I don't trust the accuracy of that gauge, but it's a good sign. And I can pick the saw up with the recoil handle. Now I need to go find some big trees to cut and finish the break-in process.
 
Update: Ran 3-1/2 tanks of fuel through the saw over the last 2 days, starting with some 2' diameter birch and ending up finishing off the 4' maple stump that started this whole thing. It's pulling strong, very responsive, runs well in any position.The CTC compression gauge is showing just over 140psi.

One more question: What plug should I be running in this saw? I had a Bosch WSR6 in there, which is what the IPL I have calls for. The dealer looked it up in his system and gave me an SR10 -- a full 4 steps hotter. The plug is nice and clean, and I don't see any erosion of the electrodes yet (after only 2 tanks of fuel), but I am still at the rich end of the spectrum and running 40:1.
 
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