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Post by redsqwrl on Mar 29, 2009 10:11:17 GMT -5
Timing of the magnets is set by the KEy in the Flywheel.
Timing of the point(s) breaking open is set by a cam that is usually either ground into the Crank or a cam lobe.
These two items need to happen together to make spark at the right time.
If the key is missing or partially sheered the magnets will get there to early or to late relative to when the points open or close.
Point gap is next. it matters in the form of Dwell angle. dwell is a term used to understand the period of time or (degree of rotation) the points stay open or closed.
I have seen bad spark plug wires act like this. I have also had wires make contact off and on with the back of the flywheel. Frustrating.
Mike
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Post by chesterwin on Mar 29, 2009 11:16:29 GMT -5
Old Zip, thanks. Great news!! I had to go home to walk the dog and couldn't resist giving a few pulls and she fired up!! Ran it 10 or 15 seconds before shutting her down. The compression feels much better. I intend to get some premium fuel and oil it a bit heavy before running her anymore. After a couple of tanks of fuel I'll report back with compressin from the new piston and cylinder. Thanks for all the great advice from everyone!! I've learned a lot! Once this one is "tuned", I've got anther that needs TLC. I'm contemplating buying an xl 925 next. I think that would be about 25 cc's more power.
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Post by MCS on Mar 29, 2009 11:20:50 GMT -5
Arm slipping on the shaft There is no arm to slip on the shaft. The crank is one piece. If you have the piston locked with rope nothing should be turning when you remove parts from either side of the engine. What was the fix?
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Post by chesterwin on Mar 29, 2009 12:46:41 GMT -5
I guess it was the socket wrench that was slipping after all. I checked the fire with the muffler off to make sure it was hitting at the top of the stroke. Gave it a few pulls with choke on and it sputtered, choke off, a few more pulls and she fired. Shut her down after a few seconds till I mix some premium fuel with extra oil for break-in. I'll post back with compression results after a few tanks of fuel. Thanks again with all the help. This is the first cylinder I've had off.
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Post by MCS on Mar 30, 2009 17:10:06 GMT -5
The original ratio for the SXL was 16:1 of 30wt oil. It certainly won't hurt to run a tank of 16:1 of good 2 cycle oil. TCW-3 is really not the ideal oil for air cooled 2 cycles but so much of the 2 cycle oil in the stores is TCW (Two Cycle Water). OldZip: Why the comment about hi test gas (premium)?
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Post by chesterwin on Apr 5, 2009 14:16:27 GMT -5
Still having trouble. Got her started a few times with great difficulty. She runs great at high rpms but once it idles down she dies out and will not restart. Could this be a fuel issue? The carb is a new Zama that I've had on the shelf for about 10 years. I've checked the reed valves and they look good. I'm temped to pull a carb off one of my other sxl saws but they're running so good I hate to fool with them. Does Oldzip or anyone have a carb kit for the original SDC carb that I took out? The Zama replacement was made in China and I just don't feel good about it. Thanks.
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Post by MCS on Apr 5, 2009 16:40:49 GMT -5
You can get the diaphragm and gasket kit for the SDC at: www.mfgsupply.com/m/c/38-4184.html?id=yjCBxdLVComplete rebuild: www.mfgsupply.com/m/c/38-8340.html?id=yjCBxdLVBut, check with those forum members that have parts and try to support their businesses. I've never been into the Zama carbs so I can't offer any help, but if the saw runs at high speed that pretty much rules out the ignition. You can't do much harm in swapping a known good carb into the saw for a test run. About the worst thing that could happen is spitting the fuel line or tearing a gasket.
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Post by OBR on Apr 5, 2009 18:58:08 GMT -5
My sxl has a zama....no problems with it at all. Very straightforward I thought. If you've got any questions lemme know.
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Post by chesterwin on Apr 7, 2009 15:31:22 GMT -5
I traded the ZAMA carb with an SDC from another saw. Slight tweak on the idol screw and the other saw purrs with the ZAMA. This one is still acting the same....great at high speed but it dies at low rpm and is very hard to start. Anyone have a suggestion before I tear it completely down again? Thanks.
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Post by MCS on Apr 7, 2009 20:42:24 GMT -5
I keep a pump oil can with two cycle mix in it. It really is handy when you need a shot of gas for troubleshooting. When the saw is in its "I don't want to start" mood, pull the spark plug and give it a shot of gas. Putting some gas straight into the combustion chamber eliminates the carburetor, the reeds, and the crank seals from the picture momentarily. If the saw sputters and runs for a second or two, you may have to crank it a few time as it might be flooded, then you will know that it is a fuel delivery problem of some sort.
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Post by aviatur on Apr 16, 2009 19:39:55 GMT -5
I have been away for some time, but have just gotten back online, and have been reading this thread. I have to add my 2 cents worth, and at the same time admit my stupidity. I got a HL 2000 auto awhile back and was trying to get it to run. I took the cylinder off and checked everything out. Next I filed the points and regapped them. I then took off the carb and reed valves and freshened everything up. New kit in the carb, new fuel line and filter. Had everything ready to fire, and pulled my arm off trying to get a pop out of it. Everytime I took the plug out, it would fire, sometimes being wet and other times dry. Shot fuel in intake and could not get a pop out of it. This went on for 3 days. After my right arm started dragging on the ground, I found the problem. The plug wire had rubbed into the insulation where it ran over the cylinder cover, and when I took the plug out and gounded it against the cylinder, it would move the wire to where it wouldn't ground out, ahowing a good spark. Once I found this, I slipped a peice of fuel line over the wire, put it back on, and HOLY COW!!!! It started on the first pull, and man, does it run!!! I feel so much better now, for getting that offf my chest....lol
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