Opti Overhaul

eyexer

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Been super busy so haven’t worked on the motor for awhile. Finally got back to business last night. Got the crank back in and buttoned up. Need to get it in road gear now lol. I’ll post some pics

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eyexer

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Got more of the tedious work done tonight after work. Every piston pin has little needle bearings to install in the connecting rod head. Couple hours of pissin around and I got em all on the rods and rings installed. Next step to install in the cylinders. The Optis are a strange motor in that there are different pistons for the left and right sides. They have a convex dish in the head unlike any other two stroke piston I’ve seen. And there are differences in years. Some years have a round indent some have an oval one. There is also a difference in main bearings. Some years have a singe row of needle bearings some have a double row. This motor has a double row and round indents. It’s something you have to know before you order your overhaul kit. It’s been interesting anyway. 2DEAC925-1C1E-4285-813F-C6B912957717.jpg
 

Davey Crockett

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It looks like it has been interesting for sure. I wonder what the story/theory/idea is behind no roller cage for the bearings ? What a pain in the ass that must be. Strong magnet when putting them in ? I suppose using any type of grease to hold them in place would be a giant No No .

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Thanks for posting , I like anything mechanical and after seeing your project it makes mine seem like a piece of cake.
 

westwolfone

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Some of that engineering (needle bearings? why? ) is why they don't last like car engines.
 


eyexer

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They have cages on the rod caps. Most of these designs are due the rpm’s they run. Cars and pickups can get away with less engineering because they don’t run 6k rpm. Everybody thinks they don’t last like car engines but they actually do when you figure the number of revolutions they make compared to cars. For example this motor had at least 1200 hours on it. That would be equivalent to probably 3600 hours or more on a car engine. We’ve had six dodge 5.7 hemp motors at work that have had to have the cams/lifters/push rods/rockers replaced at anywhere from 36000 to 70000 miles. They don’t hold up. Wearing cam lobes way down causing push rods to fall out of rockers. And what’s worse is you can’t change the cam bearings on em because they’re cast into the block lol. It’s a throw away motor. Honda actually uses the same blocks they have in they’re Cars from what I’ve read. And the load these outboards see vs what a car sees is quite higher. Takes a lot of torque to push a 21’ boat verses a car down the road. By the looks of the inside of this motor, had it not had broken reeds twice it would make 5k easily.
 

SDMF

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They have cages on the rod caps. Most of these designs are due the rpm’s they run. Cars and pickups can get away with less engineering because they don’t run 6k rpm. Everybody thinks they don’t last like car engines but they actually do when you figure the number of revolutions they make compared to cars.

Figure 2:1-3:1 RPM outboard motors vs. car/pickup motors.

Car/truck cruising down Interstate @ 75 is going to turn 1800-2200RPM in most cases. Let's say that 75MPH is 65%-75% of what a passenger vehicle is allowed to go. Now boat cruising @ 3/4 throttle is going to be running 3500-4500 RPM depending on what motor you're running.
 

westwolfone

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You are right about the rpms they run and the difference in the load of a boat vs. a car.

I've had a few 350 chevys that would run 6000 all day and they weren't very expensive to build.

I just don't get how a 350 HP outboard costs 5 times as much as a 350 HP crate motor for a car.
 

Allen

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In talking with guides down in Florida, they were running mostly Yamaha and Suzuki motors. Although, the guys that took us out on the deep water were running Mercs. The 200 hp, 2015 Suzuki had over 1800 hours on it already, and the twin 2015 Merc 150s (all 4-S) had around 1200. They universally disliked the Evinrudes, which I thought was interesting. In their opinion, ETECs are made for the recreational crowd, not for daily work where you get lots of hours in a short amount of time.

Makes the 150-250 hours I put on my outboards a year seem trivial.
 

eyexer

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You are right about the rpms they run and the difference in the load of a boat vs. a car.

I've had a few 350 chevys that would run 6000 all day and they weren't very expensive to build.

I just don't get how a 350 HP outboard costs 5 times as much as a 350 HP crate motor for a car.
they cost so much more because your paying more per unit for R&D etc. Chevy probably sells more motors in a week than merc in ten years. But merc has the same R&D costs spread out on 1/100th the number of units. At first glance it makes no sense I agree. But when you realize they have so few units to spread that cost out it makes sense.
 


westwolfone

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You're right and thanks for posting this thread.

I am always interested in mechanical things.
 

SDMF

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Makes the 150-250 hours I put on my outboards a year seem trivial.

150-250hrs in the boat/season maybe but I'd bet you don't put more than 50-60 "running" hours on your motors.

My main motor hours averaged 30hrs over the last 3 seasons. I don't do any tubing, waterskiing, wakeboarding, etc just fishing. However, I do make some fairly long runs and fairly often and get 35-40 days/summer on the boat. For the little bit that I pull cranks I have a kicker but most of my fishing is with the bow-mount electric. I'd be really interested to see sometime how many running hours that bugger's got on it.
 

Allen

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I put 150 hours on my pontoon last summer, AFTER I blew the motor (equipped with an hour meter). The Lund gets used more in the spring and fall, but a 6-7 hour day of pulling cranks on the big motor (no kicker) is not unusual. I had to sit down and actually look at a calendar a while back to fill out a fishing survey for NDGF and while I tend to not like doing long runs on either the river or the big lakes, I handily found over 70 days my floaters were on the water. That's the beauty of living where you can boat during any given month of the year.

On either boat, a long run for me would be from Beulah Bay over to Indian Hills on Sak. As neither rig are speed demons, I tend to be near full throttle as I motor from one place to another if the water allows it. That being said, your point is well taken. Of all those hours, even with the tubing and stuff, I would guess 70 percent of the time they are at less than 1100 rpm (about my max rpm setting on the Yamaha/Lund combo when pulling cranks in current). The Toon with the newer Merc probably has a much higher percentage of running time since it's either drifting with the electric, or running/pulling.

The total hours on my Yamaha has been something that I've been curious about the past couple of years. Problem is...it never needs to go into the shop so I never get a printout on how many hours she has. Ok, she's had a water pump done and a stator a couple years ago, but I forgot to ask then.




150-250hrs in the boat/season maybe but I'd bet you don't put more than 50-60 "running" hours on your motors.

My main motor hours averaged 30hrs over the last 3 seasons. I don't do any tubing, waterskiing, wakeboarding, etc just fishing. However, I do make some fairly long runs and fairly often and get 35-40 days/summer on the boat. For the little bit that I pull cranks I have a kicker but most of my fishing is with the bow-mount electric. I'd be really interested to see sometime how many running hours that bugger's got on it.

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p.s. I know there were years where the Lund didn't get a lot of hours. That's back when I fished the Misty Waters and Hoge Island area frequently. At Hoge I was able to motor to the fishing areas using the electric, there were many days where I only started the big motor to trailer the boat. It kinda felt like I was cheating.
 

eyexer

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got all the pistons installed last night. Nice to have that finished lol. 27873F3A-7774-4851-AC1E-2812B7419BFF.jpgD7C7F969-54B9-4C70-A9C7-03DD3F7545AA.jpg066D7DDE-7BB5-4BF6-A516-077F5A15A9CC.jpg
 




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