I have heard of and visited this site on a few occasions and there is obviously a lot of knowledge here. I am wondering if anyone might have an answer on this for me.
I have a Yamaha 40 horse jet which has been modified to a 50 horse. This supposedly can be done as there is very little difference in the actual head other than a few modifications to jetting etc. The problem is after a few years of running fine with no hiccups it is now starting to act a bit strange. It will not rev past about 5180 rpm and if I am cruising along at full throttle accross a lake for example, it will slowly loose rpm and speed down to as low as 4100 rpm. If I back off the throttle and hit it again it will usually get back up to the higher rpm but will not get past the 5180 mark. If I remember it should be topped out at around 5500? Any ideas would be greatly appreciated as I would like to get it fixed up over winter. Thanks in advance.
Bill
I have a Yamaha 40 horse jet which has been modified to a 50 horse. This supposedly can be done as there is very little difference in the actual head other than a few modifications to jetting etc. The problem is after a few years of running fine with no hiccups it is now starting to act a bit strange. It will not rev past about 5180 rpm and if I am cruising along at full throttle accross a lake for example, it will slowly loose rpm and speed down to as low as 4100 rpm. If I back off the throttle and hit it again it will usually get back up to the higher rpm but will not get past the 5180 mark. If I remember it should be topped out at around 5500? Any ideas would be greatly appreciated as I would like to get it fixed up over winter. Thanks in advance.
Bill