Advice for 90HP Yamaha Lying Dormant For 25yrs

[SouthCarolina1]

Background: Been looking for a good cheap 90HP Yamaha but until now the ones I have seen for sale were either busted or expensive. My patience was rewarded! I bought a 1989 Glasstream with a 1989 Yamaha 90 ETLF on a galvanized trailer for $600!!! The seller was the original and only owner, still had the paperwork from the dealership! He said he bought it new off the lot in 1990, used it until '93 and then put it in storage because of traveling for his new job. The hour gauge on the boat was sitting at 80hrs! He also had a receipt for having the motor winterized by the dealership in '93. While it was in storage unit rats had ate the wires, carpet, even the rubber off the anchor, and then defecated all over the boat. There is not a solid section of floor. The rats were about 2ft away from eating at the gauges but thankfully never got to them. The rats also did NOT get into the motor! Woohoo! He told me that his wife had been "busting his balls" about getting rid of the boat and had enough so he was selling it cheap to get rid of it ASAP, which I was happy to oblige! The motor will be a solid upgrade on my 1860 Polar Craft.

My Questions:
1) I slightly movd the flywheel by hand to verify it was not locked up but I have not turned the motor over. I am sure the cylinders and o-rings are dry. I am planning on pulling the spark plugs and filling the cylinders with marvel mystery oil. After sitting for two days turn the motor over by hand several times and then attempt to start the motor to perform a compression check. Is this sufficient or should I do something else?

2) If the compression check is satisfactory I plan on rebuilding the carbs, replacing the fuel lines, fuel pump, fuel filter, oil lines, spark plugs, new water pump, the gear oil, clean out the oil tank and strainer, and verifying the electrical components are functioning. What else could I do or replace to prevent motor failure? Should I replace the reed valves? Oil pump? Oil check valves?

 

[SouthCarolina1]

[No message]

 

[99yam40]

good luck with a motor that was put up for that many years without lub to protect the shiny internal parts.
oil might help it move after all of those years, but it cannot make the rust pits go away magically
rings, cylinder walls, crank shaft , bearings, etc

 

[robert graham]

Maybe/hopefully when motor was "winterized" for storage they fogged it to protect crank/rod/wrist pin bearings....if not they may have pitting/corrosion after laying up so long....

 

[robert graham]

Maybe/hopefully when motor was "winterized" for storage they fogged it to protect crank/rod/wrist pin bearings....if not they may have pitting/corrosion after laying up so long....

 

[SouthCarolina1]

The winterization receipt from the dealer lists fogging as one of the tasks performed. Also the first thing I did when I brought the boat back was pull the spark plugs and using my borescope, I inspected the cylinder walls. I did not see any pitting or corrosion. If I had I would be breaking the motor down right now for a rebuild and not asking the questions I asked which by the way none of y'all addressed.

 

[robert graham]

If they drained the carb float chambers also, you should be good to go. New water pump, change lower unit oil, she might be ready to go without cleaning carbs....if they're plugged up at all, you'll know right away in starting, idle, mid-range and wide-open throttle......I bought my 1999 C90 new and never any problems....carbs never been cleaned or screwed with...really bullet-proof motors!...

 

[fmt2bx]

Hey Carolina, Good for you. These are great motors! I think you are on the right track here, pour a little bit of oil in each cylinder and turn flywheel over by hand a few times.
I think that you will probably want to remove the carbs and clean them up eventually, check if you have O rings , gaskets etc in there and replace if needed.
Fuel lines is a good idea but check them first, might not be needed. Primer bulb same thing.
Water impeller definitively .
Reeds , when you remove the carbs you can inspect them , use your boroscope that might be handy. They usually are in pretty good check.

Also, the first time you start, how about running from a 50:1 ratio gas tank? That would eliminate any possibility of damage should the oil system not working right (very rare also). At least you ll have piece of mind.

Water muff on and fire up that puppy, I bet you you are gonna be just fine.

Good luck and congrats again! 1

 

[SouthCarolina1]

I let the oil sit in the cylinders for a couple of days, turning the flywheel by hand and adding more oil each day. Replaced the water pump. Compression check showed 118, 118, and 119. I have a bunch of parts on the way but after doing the compression check I had to hear it run. Needed a little throttle to stay running but she started right up. I thought the 50:1 gas ratio was a good idea so that's what I did. Ran it for just a minute. I still have a lot of maintenance to do but I feel pretty good about the motor. Thanks for everyones advice.

 

[Doh]

My Dad, bought a 90 Yamaha New in 1984, we still have it. It does get stored for long periods since his passing (2-3 years) but fires up easily. (we do drain the carbs on lay up).

Makes me want to drag it out and try it, it has been 5-6 years now.

No worries, they are a Bullet Proof motor.

 

[thatone123]

Depends on the climate and where stored. I have seen many 20-30 years out boards in perfect condition inside. Some start after a few revolutions of the engine. Northern climates that are dry are not a problem usually. Hoses may be hard, Waterpump impellers usually take a set but even some work after many years, but best to replace. Florida is hard on outboard internals. Old gas did not have the problems that new high tech fuel does.