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Post by marcmacd on Sept 2, 2021 7:44:34 GMT -5
Recently acquired up this beauty from a gentleman who said it worked until it started having a "high compression" issue. Pulls fine with spark plug out (i know pully system is fine) but feels like tight (high) compression when system is closed. From my research, the consensus seems to be high carbon content in the piston so I will remove the spark plug and soak it in seafoam for a day I guess, clean the muffler/port, replace the spark plug, and replace fuel line and filter(as the current line is like putty). Gonna hold off on rebuilding the carb until I do all this first and try it and there's no decompression valve on this saw. Besides all that, is there anything else I may be missing (besides maybe a coil issue)? Thanks in advance. Attachments:
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Post by xl130 on Sept 2, 2021 7:55:08 GMT -5
Those saws can have very high compression when they are healthy. If it’s bucking and kicking like crazy and ripping the pull cord out of your hand when you try to start it then possibly the flywheel key had been sheared off and the timing is off?
That’s not overly common but possible. I would pull the muffler and inspect the piston exhaust port as you mentioned though.
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Post by marcmacd on Sept 2, 2021 8:14:23 GMT -5
Ok will do Thanks man. It pulls out but has about 3 points where it just wants to stop and would interrupt what should be a smooth pull. Feels internal in the combustion chamber but will definitely pull the fly wheel. I'm out of province till next Thursday so just trying to get a good plan of attack when I get home.
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Post by edju1958 on Sept 2, 2021 9:30:35 GMT -5
I'm wondering if there may be as ring issue?XL-130 has a valid point with the flywheel key possibly being sheared.That's an obviously easy fix.I've had 2 or 3 saws within the last 6 months that had broken rings.One saw was pulling over by hand beautifully when I was cleaning the points.I always pull the points out when I clean them,makes it much easier to see them & the condition they're in.I went to turn the crankshaft & it wouldn't turn.The ring had broken when I was turning it over by hand! I was pretty lucky there because if the ring had broken when the saw was running it might've severely damaged the cylinder.Another saw I disassembeled recently pulled over fine,but had low compression.When I pulled it apart I found one of the rings was broken in 3 places. Just wondering if the ring(s) could be getting caught on something?But,then again you say it pulls over fine when the plug is taken out.There'd have to be an awful lot of carbon in that engine to cause such high compression.
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Post by blythkd on Sept 2, 2021 11:34:19 GMT -5
I'm still hung up on the turning stiff in 3 different places. Excess carbon on top of the piston would get tough at top dead center. Bore damage doesn't seem very likely since it has such good compression. Have you checked for a loose screw behind the flywheel? Kinda reaching here and I don't even know what the screws behind a 76 flywheel look like but most similar saws have screws behind the flywheel that can come loose and cause problems. Usually it will lock them up though.
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Post by xl130 on Sept 2, 2021 12:58:58 GMT -5
I had a 76 not long ago that a was doing something similar. I decided to pull the cylinder and sure enough the wrist pin retaining ring had come out and was binding up the piston ever now and then.
Lol just something else to worry about😉
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Post by stillsawing on Sept 2, 2021 17:14:00 GMT -5
Broken clutch shoe? Like Ed mentioned, pull flywheel, strip the clutch to the crankshaft, check the auto oil pump. If still giving the same symptoms, may be an internal glitch.
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Post by lesorubcheek on Sept 2, 2021 20:10:12 GMT -5
Just a hunch, but something easy enough to try... Have you taken off the starter and tried turning over by hand? You can kinda feel if it wants to bind anywhere doing this. And, while the starter is off, pull it a few times and look at the rope as it pulls out and rewinds as it goes back. 350/360s are notorious for being hard to pull over if the starter rope stretches and doesn't wind properly. The torque a starter exerts is all a function of the distance the rope is from the center, and if the cord has stretched and is a little small, it can pull in between the previous winding rather than stack on top, so the pull is starting with a shorter moment arm as well as friction pulling around and binding. I realize this isn't a 350/360, but it's the same for all saws, and any with a smaller starter winding diameter are more likely to feel difficult. Again, just a thought, but it's good to make sure the starter cord is winding properly on the pulley. Best of luck.
Dan
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Post by marcmacd on Sept 3, 2021 8:22:37 GMT -5
Sounds good guys Thanks. Lots to check.
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Post by Clasec on Sept 3, 2021 9:26:56 GMT -5
Had a SuperXL that turned hard in a few spots off and on. The rod cap had loosened and the needle bearings were binding.
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Post by marcmacd on Sept 10, 2021 17:12:16 GMT -5
One of the keys was lodged up in the fly wheel. I have NO idea how that didnt snap with me reffing on it. Deep clean new fuel line and...ITS ALIVE! MOHAHAHAHA
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Post by sparky on Sept 13, 2021 15:42:23 GMT -5
Cool!and it wasn't a torched jug or piston.
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Post by edju1958 on Sept 13, 2021 16:52:22 GMT -5
Glad to hear you got it running & it was a fairly easy fix.
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