Murph, a couple of winters ago my neighbour couldn't get his snowmobile started, which had been in storage for the summer in his garage. He had mentioned that his fuel mileage had dropped off somewhat the year before as well. Anyway, after several minutes of attempts, I told him to check the gap on the plugs...he was reluctant, thinking that it had run the previous year and he hadn't changed the gap. Well, we tried and tried to start it, figuring that maybe it just needed to burn off the fogging oil, but it just wouldn't catch. We took out the plugs finally and checked the gap...If I recall(couple of years ago) it had measured somewhere around .030" so I checked his engine (700 cc Skidoo) online and I believe the required gap was around .024". We tried cranking the motor with the plugs out to check for a spark at .030 to no avail, so I suggested we gap both plugs down at .002" increments to see where the motor would start. At .028" nothing, wouldn't catch, at .026" it was catching but only just...hard to start, but started non-the-less with a rough idle. So we took it down to the recommended .024" and it started much easier and ran better, although there was still a touch of roughness in the idle so we actually took it down to a gap of .022-.023 and it ran/started easily and smoothly. That could have easily explained why he was using so much fuel before and also would have made his sled run rough with much less power. I know this is a TWO stroke motor and may well be more succeptable to gap changes but I was amazed that such a small adjustment was the difference between not starting and running well(literally a few thous)...after that, it started on the first crank, every time.
