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Join Date: Mar 2006
Location: Kyle, Texas
I agree Mitch. We need to verify if there's spark. VulcanJoe, I don't see what year your bike is, so this statement might not apply: This sounds like the hot start problem a lot of us have dealt with. I'm sure you have an MF battery in the bike, right? Of course you've been a member here longer than I so it is possible that you have an old MF battery that needs to be replaced. Again, I'm just thinking out loud... I'd check the battery voltage with the key OFF. If it is 12.5v then I'd check the coil wiring to see if you're getting a rather large drop off when the key is turned to ON. Check the red coil power wire with the key ON with each coil. If it is quite a bit lower, like 11v or so, then you have some weakened wiring going to your coils. You're probably doing these tests on a cold bike. Imagine when things get heated up good that the voltage would probably drop some. I'm not saying that this is your problem, but from what you described, it sure could be. Check out the coil wire mod in my sig. It's worth at least testing for, whether you decide to mod the wiring or not.
Either thing, weak spark, or too much fuel, gives you a rich condition, and can give you the "wake the dead" backfiring on trying to start the bike when its hot. The fact that you said after you waited 15 minutes or so, the bike started up, again sounds like it needed to cool a bit. Some claim that the r/r gets too hot and puts out lower voltage, which is why lots of us moved it out to the left passenger foot peg area. I did this and the coil wiring mod the same night and one or both of them solved my hot start/backfiring problem. It never did it again. Of course the coil wiring mod bypasses the r/r for coil power, and uses heavier gauge wire straight from the battery to the coil, via a relay, so more than likely, the coil wire mod did the trick. Just saying... something worth checking on.