Hey Guys........I've only been making incremental progress because of work, so I have been absent. I was the one with the really ugly comp numbers on one motor. The boat is finally back on the water and doing well. Here is some info that may be of interest to someone.
It turned out the valves and valve seats on the low-comp motor were heavily pitted, no doubt due to low mounting on the previous boat and water intrusion. The cylinders weren't pitted. I had the heads reconditioned. One seat had to be replaced. I haven't compressed it again yet to see the difference, so I don't know anything about the rings at this time. While apart, I tilted the motor up and let Seafoam soak in the cylinders repeatedly. And then of course changed the oil.
When I fired up the motor for the first time, the shimmy at idle was gone. Nice.
I was still dissatisfied with mid-range performance, so I had the props tweaked. They are Merc Mirage Plus, 15.5 x 15P. The shop reduced diameter to 14.75 and increased pitch to 17. I went from 27mph @ 4200rpm to 31mph @ 4200rpm. Fantastic! The top end changed a lot also. I went from 41mph @ 5900rpm to 41mph @ 5300rpm.
It is always said that these motors should be propped to run at approx 6000rpm, so I called the shop and told him the numbers. He felt 5300 was too low and suggested reducing the amount of cupping. But I never run above 4300rpm, so I don't care about top end. I like the current mid-range numbers.
So I went to the Honda website and looked at the specs. Honda says max operating range is 5000-6000rpm. This surprised me because I'd always heard 6000. Clearly Honda is saying that max rpm operating range depends on the prop, and what I get out of it is that anywhere between 5000-6000 is OK. So I might just tell the shop to leave them alone. I'll take the 5300 because I don't care about it. I DO care about 31mph @ 4200rpm. That's huge!
Anyway, after a lot of upgrades and some gelcoat repairs, the boat is just about ready to make it's first trip out to the Shelf, 80 miles off Freeport, Texas for some wahoo, tuna, mahi or whatever is there. Overnighting in the deep blue is a spiritual experience.
I will officially welcome myself back......!
It turned out the valves and valve seats on the low-comp motor were heavily pitted, no doubt due to low mounting on the previous boat and water intrusion. The cylinders weren't pitted. I had the heads reconditioned. One seat had to be replaced. I haven't compressed it again yet to see the difference, so I don't know anything about the rings at this time. While apart, I tilted the motor up and let Seafoam soak in the cylinders repeatedly. And then of course changed the oil.
When I fired up the motor for the first time, the shimmy at idle was gone. Nice.
I was still dissatisfied with mid-range performance, so I had the props tweaked. They are Merc Mirage Plus, 15.5 x 15P. The shop reduced diameter to 14.75 and increased pitch to 17. I went from 27mph @ 4200rpm to 31mph @ 4200rpm. Fantastic! The top end changed a lot also. I went from 41mph @ 5900rpm to 41mph @ 5300rpm.
It is always said that these motors should be propped to run at approx 6000rpm, so I called the shop and told him the numbers. He felt 5300 was too low and suggested reducing the amount of cupping. But I never run above 4300rpm, so I don't care about top end. I like the current mid-range numbers.
So I went to the Honda website and looked at the specs. Honda says max operating range is 5000-6000rpm. This surprised me because I'd always heard 6000. Clearly Honda is saying that max rpm operating range depends on the prop, and what I get out of it is that anywhere between 5000-6000 is OK. So I might just tell the shop to leave them alone. I'll take the 5300 because I don't care about it. I DO care about 31mph @ 4200rpm. That's huge!
Anyway, after a lot of upgrades and some gelcoat repairs, the boat is just about ready to make it's first trip out to the Shelf, 80 miles off Freeport, Texas for some wahoo, tuna, mahi or whatever is there. Overnighting in the deep blue is a spiritual experience.
I will officially welcome myself back......!