trappermike
ArboristSite Guru
Did you try a smaller plug gap(.015") ? If the miss seems to go away it means your ignition is a little weak.(this doesn't mean there's anything wrong with your ignition,it just may not be strng enough for higher rpm and cyl. pressures) However if your saw is not mis-firing at maximum cutting speed I don't see it as a real problem,but it would be nice to eliminate the miss. It is quite possible that when you redesigned the pipe that your new design was much more effective,raising cylinder pressure enough to require a stronger spark! I have run into this before,on an 088 hot saw I built,it would rev free to 15,500 cleanly,but under load in the cut the motor would misfire badly from about 10,000 and above.I realised it was the ignition breaking down under load,tightening up the plug gap helped,but I still could not get anywhere near the revs I needed under load. I regretfully reduced my compression from 220 psi to 190 and the the engine runs perfect and the problem is gone.
Unfortunately with most saw ignitions there is no way to modify them for stronger spark. With a highly modified engine creating much higher cylinder pressures(Not compression) a stock ignition that was satisfatory in a stock motor may prove a little weak. All you can do is get the most from your stock ignition- make sure the coil has a clean ground,the spark plug cap "spring contact" is actually contacting the inner mtal plug wire,see that the coil/flywheel air gap is as close as possible,and try to find a race type spark plug with a "fine-wire type center electrode,of platinumor iridium types,and plug gap is .015" to .020",a wider gap is preferred.
Check the things I mentioned and let us know if closing the plug gap helped...
Unfortunately with most saw ignitions there is no way to modify them for stronger spark. With a highly modified engine creating much higher cylinder pressures(Not compression) a stock ignition that was satisfatory in a stock motor may prove a little weak. All you can do is get the most from your stock ignition- make sure the coil has a clean ground,the spark plug cap "spring contact" is actually contacting the inner mtal plug wire,see that the coil/flywheel air gap is as close as possible,and try to find a race type spark plug with a "fine-wire type center electrode,of platinumor iridium types,and plug gap is .015" to .020",a wider gap is preferred.
Check the things I mentioned and let us know if closing the plug gap helped...
