I've had a miss in the secondary ignition for awhile and didn't know which cylinder was missing. I haven't been too concerned about tracking it down since normally both the mag and the electronic ignition systems are on and the engine runs smooth as silk. I finally decided to address this mystery today and figured it would be easy with my laser thermometer to run the engine for a few minutes on just the secondary then see which header was the coolest. I gave that one try but the result was inconclusive, so I grabbed my Crayolas. After the engine had cooled, I put a few squiggles of orange crayon on each header next to the cylinder bracket. The unmelted orange crayon identified the problem cylinder immediately. Using the thermometer laser pointed at the header bracket where it meets the cylinders confirmed which cylinder was the culprit - have no idea why that didn?t work the first time, but anyway . . . why was that cylinder not firing? Was it the coil, the harness lead, or the plug? I took my Tiny Tach sensor wire off of its normal lead wire and wrapped it around the lead going to the problem cylinder and then ran the engine. I got an RPM reading on the Tiny Tach so that must mean the coil is firing and the juice is getting through the lead at least as far as the Tiny Tach sensor wire (but why is the Tiny Tach suddenly reading twice the RPM it should be?). So that left the plug as primary suspect in the case. I didn't want to pull the plug since they were so nicely indexed when I put them in . . . but worrying about that was pretty dumb I now see in retrospect. Maybe my days as a mechanic are numbered. Anyway, I pulled the plug and put in a spare and ran the engine and it still had a miss. So back to zero. I pulled the spare plug out and cleaned and re-gapped the original plug and put it back in and ran the engine and the miss was gone! These are Champion fine-wire 10mm racing plugs and when I re-gapped it I found the gap was quite a bit wider than it was when I put the plugs in 76 hours earlier. My assumption tonight is that it was the excessive gap caused by wearing away of the electrodes that was causing the miss. Tomorrow I'll pull the other three plugs that run off of the secondary ignition and clean and gap them and also take an accurate measure of just what the gaps are. Also need to look at that spare and see if it is also got too wide a gap. Are these green Great Plains coils that sensitive to gap? Are they wearing out and getting weak? I think they are motorcycle in origin and I've never noticed coils ever wearing out on my bikes . . . . I've put over 17K miles on my current bike without ever pulling a plug and it's got coils under the tank that work the same as the green coils on the 2180, so I'm not leaning towards the theory that the green coils are wearing out, but it looks like the miss was the result of too wide a spark plug gap and I would have thought electronic coils could jump just about any gap they're presented with.
I'm guessing the one I took out today was at least five thousandths over what the specs call for which, with these plugs, is .016 to .019. The electrodes have lost a significant amount of material for the gaps to have widened so much, but maybe that?s what fine-wire racing plugs do. Maybe they are designed to live short, hot lives on a track. This other issue that came up regarding the Tiny Tach readouts being twice normal is a mystery I feel I should know the answer to but just can't think of. Nobody will be in their office for a couple more days so I can't call Tiny Tach but maybe in the interim it will come to me. Or maybe I'll find the answer on the internet somewhere. Or somebody reading this will know exactly what's going on and tell me. This Tiny Tach has never done this before, but then until today I've never unwound it from the lead it's been on since I bought it about five years ago. I've put it back on it's original lead and also played with the number of times it's coiled around the lead, but nothing makes any difference. It continues to read twice as fast as it should. The change obviously has something to do with me fooling with the sensor wire. Any ideas anyone? Mike KSEE ____________________________________________________________ Old School Yearbook Pics View Class Yearbooks Online Free. Search by School & Year. Look Now! http://thirdpartyoffers.juno.com/TGL3141/5562b2806380532801fc1st01vuc
