Greetings:
I have a 2000 YZ125 with a very recent bottom end AND top end rebuild. Before the engine was rebuilt, the plug hardly ever fouled. Now that it is rebuilt, the plug fouls easily. If it is ridden hard, i.e., "on the pipe" and the revs kept up while idling, then the plug seems to do ok. The first time I let the engine idle normally or don't keep revving it on a jump, etc., the plug fouls and the engine bogs badly and then it won't start unless the plug is replaced. (interestingly, if I clean the plug and put it in my RM250 it runs fine while it won't work in the YZ after cleaning) I have had the carb apart twice and cleaned it and then took the bike to a local Yamaha dealer 3 times - they tweaked the carb adjustments and told me to keep it "on the pipe" while riding. I think it may be a weak magneto but the dealer doesn't think so. (I don't know if they checked the mag or not). Why would the bike NOT foul plugs so badly before the rebuild and now fouls so easily?? I use a 38 to 1 mix, have tried fresh gas 3 times, and the rebuild was to factory specs. ANY IDEAS???? THANKS!!
I have a 2000 YZ125 with a very recent bottom end AND top end rebuild. Before the engine was rebuilt, the plug hardly ever fouled. Now that it is rebuilt, the plug fouls easily. If it is ridden hard, i.e., "on the pipe" and the revs kept up while idling, then the plug seems to do ok. The first time I let the engine idle normally or don't keep revving it on a jump, etc., the plug fouls and the engine bogs badly and then it won't start unless the plug is replaced. (interestingly, if I clean the plug and put it in my RM250 it runs fine while it won't work in the YZ after cleaning) I have had the carb apart twice and cleaned it and then took the bike to a local Yamaha dealer 3 times - they tweaked the carb adjustments and told me to keep it "on the pipe" while riding. I think it may be a weak magneto but the dealer doesn't think so. (I don't know if they checked the mag or not). Why would the bike NOT foul plugs so badly before the rebuild and now fouls so easily?? I use a 38 to 1 mix, have tried fresh gas 3 times, and the rebuild was to factory specs. ANY IDEAS???? THANKS!!
