Expert: Marc Mielhausen - 9/1/2004

Question
Marc-
I have a nice old Poulan 71A chain saw, 1961, and it has always been such a great saw - simple, powerful, loud, and heavy.  The ignition system is very simple - a cam actuated contact point, a coil, a condensor, the magneto (flywheel), and the spark plug/wire.  My problem is that I have no spark.  The other problem is that the parts are very hard to find.  I bought the only condensor I could find several months ago, and have about 1 or 2 hours run time since.  My question is this :  what EXACTLY is the function of the condensor, and if I suspect it can I test it?  If I can't test it to confirm its functioning, can I replace it with a similar-but-not-exactly-the-same condensor?  How are they rated/spec'ed?
Simlar question for the coil - how do I test it?  I'd like to confirm it's integrity also.  With my meter, what should I see and where?
ANy help will be very appreciated.  Hurricane Frances looms and I need my saw!
Kindly -
Scott Carter

Answer
The condensor is just a capacitor that stores primary ignition current while the points are open to prevent arcing across the points.  To test it, you need to have the equipment to charge it and do a leak-down test (let it sit for a few minutes and ground the lead to the body of the condensor and there should be a spark if it has properly stored the current).  The coil can be tested by a shop also.  It is tested by simulating the action of the primary ignition circuit and verifying spark output.  You should be able to get ignition parts for that saw....check with aftermarket suppliers.  Hope this helps.