Hi -
I am new at this posting stuff and not so good with computers. So, hopefully I won't mess this up. Apologies in advance.
A few weeks ago my 2 young grandsons combined their savings and bought an 1968 Starcraft with a 1977 Merc 500 (50 hp). The motor ran well in the test drive. When we got it home we changed the oil in the lower unit and added fresh regular gas using a 50:1 mix. to the mounted aluminum tank.
Boat ran great. They used the boat over a period of a few weeks and probably put about 3-4 hours on the motor during that time. All was well.
Yesterday my younger grandson put the boat in the water and started it up. It was idling at a much lower RPM than in the past. When he gave it gas it seemed to plow. He was not able to get the boat on plane and came back in.
We pulled the plugs. Based on a quick look on the internet they are the correct NGK center electrode plugs. They seemed a little wet to me, so we cleaned them with carb cleaner and put them back in (should the plugs be 100% dry like in a 4 stroke?). Back in the water it went. But, same problem. We pulled the boat and I ran it with the muffs for a while. It seems to have an inconsistent miss at a variety of RPMs (did not put in gear, just used the neutral throttle).
I'm pretty good with a wrench but haven't has a 2 stroke Merc in 35 years. Generally, before I dig in too deep, I like to try, and rule out the easy stuff first. So, my next steps in diagnosis are to change the plugs and put in new high test gas mixed 50:1. Let me know if you think this is a good place to start or if you have any other simple diagnosis steps. For example, I wanted to try to see if one of the plugs/cylinders was the culprit but really did not know how to test for that.
Thanks in advance for your suggestions. I'll let you know how it goes.
I am new at this posting stuff and not so good with computers. So, hopefully I won't mess this up. Apologies in advance.
A few weeks ago my 2 young grandsons combined their savings and bought an 1968 Starcraft with a 1977 Merc 500 (50 hp). The motor ran well in the test drive. When we got it home we changed the oil in the lower unit and added fresh regular gas using a 50:1 mix. to the mounted aluminum tank.
Boat ran great. They used the boat over a period of a few weeks and probably put about 3-4 hours on the motor during that time. All was well.
Yesterday my younger grandson put the boat in the water and started it up. It was idling at a much lower RPM than in the past. When he gave it gas it seemed to plow. He was not able to get the boat on plane and came back in.
We pulled the plugs. Based on a quick look on the internet they are the correct NGK center electrode plugs. They seemed a little wet to me, so we cleaned them with carb cleaner and put them back in (should the plugs be 100% dry like in a 4 stroke?). Back in the water it went. But, same problem. We pulled the boat and I ran it with the muffs for a while. It seems to have an inconsistent miss at a variety of RPMs (did not put in gear, just used the neutral throttle).
I'm pretty good with a wrench but haven't has a 2 stroke Merc in 35 years. Generally, before I dig in too deep, I like to try, and rule out the easy stuff first. So, my next steps in diagnosis are to change the plugs and put in new high test gas mixed 50:1. Let me know if you think this is a good place to start or if you have any other simple diagnosis steps. For example, I wanted to try to see if one of the plugs/cylinders was the culprit but really did not know how to test for that.
Thanks in advance for your suggestions. I'll let you know how it goes.