6 of us went on a ride the other day. I let a freind ride my 750 while I rode my mean streak. We went 75 miles when my 750 started acting up. The tach had quit working and sounded like it was only running on the back cylinder. We checked everything we could think of and after about 10 minutes the bike started right up and ran fine. We went another 20 miles and it started all over again. There was white smoke coming out of the front cylinder exhaust and the tach again wasn't working. The throttle had to be wide open to keep the engine running. We limped it the rest of the way home and after sitting for 20 minutes or so, it fired right up and I rode it around the neighborhood with no problem. What could have happened? Is the tach connected to the front cylinder coil? Any suggestions will be a great help.