Brought my 70 hp Yamaha 2-stroke motor into Kettle Marine in Feb. because the motor was running rough and cut out a couple times. Last outing of the fall it ran really rough, and overheat alarm went off, and seemed to have white smoke (tough to tell, as that was Dec. 10th and air temp was 25).
1st visit they went through the motor found a broken fin on the impeller, and a couple of small items. They replaced the impeller. They ran it and alarm did not go off.
I took it out, overheat alarm went off after 10 minutes.
2nd visit they went in deeper and found the broken fin in the water line, and found missing O-rings on the line attachments for the water line, and found low water pressure. They made the fixes, did a compression test (110 on all cylinders), and ran it for 30 minutes on idle and did a temp check on the motor (130F) after 30 min. Replaced the water pump, replaced the O-rings.
I took it out, no issues with idle, but after 3-5 minutes on plane overheat went off and it shut down. Started back up, ok on idle, shut down on plane again. Actually ran smooth until shut down.
3rd time in for service - So, it looks like a blew out at least 1 piston ring. Compression test was 110 4 weeks ago, 100 a week ago. Tests showed a 40% leak.
I was quoted a rebuild of up to $4500.
Motor is likely somewhere over 1000 hrs.
If the rebuild was under $2000, I would go that route, but for some reason the 70 Yamaha is tough to rebuild. I checked online and found the shops I could ship it to only do 90hp Yamaha and up.
I am deciding whether to fix or repower. Kettle Marine quoted a price of $7300 for a 2021 Merc 75 hp. That may be the only 75/90 motor left in Wisconsin. No one else had one in stock. They dropped the cost of the earlier visits off the price of the 2021.
After I added throttle controls, Itroll/with Hunt mode, and a Bluetooth connection module (I can get all the readouts on my phone instead of getting smart gauges), with installation, cost is $9300.
I was hoping to repower with a 90, but I will have to sit out the summer, no Mercs are available until Sept or later, no Yamaha until 2022.