blew up my 90

[mattdd]

I have only had my boat for about 1 1/2 years, and don’t know a lot about boat maintenance. I have a 1986 aluminum Lowe w/ an '86 Yamaha 90. the other weekend it died on me while I was on the water. I cranked it till the battery was dead. I had the battery tested and it was bad so I replaced it. I use my boat to get to my hunting spots, and the Friday b4 opening morning it wasn’t running right when we put it in. I took it to some places and they said it might be some electrical things, but it would be ok to run it a short time. So we took it out. The way back in Saturday evening it died as a storm front was moving in. After about 20 min. it started back up and we made it back. Took it to a diff place Monday and they took it apart to look into it…………"number 2 cylinder is gone, head is warped badly". The hot horn was unplugged and I didn’t realize it was overheating. The cooling water pump wasn’t working and that is what caused it to overheat. Anyway this couldn’t come at a worse time. Hunting seasons are just starting and with the holidays and all I don’t have much $$ for repairs. Is this thing totaled? The boat is decked like a bass boat and has all fishing accessories. So the boat has some value. But being so old I don’t want to drop over 1000$ on a used motor, do you think I could find one cheaper then 1000$. What would be involved in an overhaul. I haven't even looked at it myself. But assuming it isn't totally destroyed, could the cylinder be overbored and maybe get a new head, or have it milled. Am I screwed or is there something that can be done with in a reasonable budget.

 

[rodbolt]

Re: blew up my 90

depends on how much you can do yourself. sounds like that motor was neglected by the previous owner as well. if its a salt or brackish water motor it may or may not come apart. if the crank is not damaged then its not to bad to put 3 new pistons in new bores and have the head surfaced, odds of actually finding a well maintained used yamaha are slim.<br /> hate to see them die like that but testing the alarm system is a monthly test. what area of the world are you in ?

 

[mattdd]

Re: blew up my 90

missouri. no salt or brackish water. i think it will come apart pretty easy. the shop only charged me 40$ to pull the head and figure out what was wrong, so i dont imagine they spent to much time getting it apart. i rebuilt a chevy 350 engine once. i was helped alot by a chiltons manual. is there a good manual that covers overhauls fora yamaha.

 

[rodbolt]

Re: blew up my 90

the factorey manual is about the best. once the poer head is apart you need to have the block and crank inspected professionally. bore all 3 holes as all 3 got hot. rebuild the carbs,replce the water pump,t-stat and pressure control valve grommet. replace the fuel pump. clean the oil tank and check all plastic lines for flexibility. if the crank and rods are ok, bore 3 holes then buy the pistons for them as well as the correct rings,circlips and pin bearings. its easy to swap the pistons as the pins are a push fit not a press fit. takes about 20 hours or so. I would also remove the exhaust cover to replace the gaskets. and fix the alarm system .<br /> with a good crank assy the job can be done for 6-9 hundred and give many more years of service.<br /> the big thing is cleanliness on reassembly and attention to details as some of the tolerances are tight.

 

[mattdd]

Re: blew up my 90

thanks for the info. is the powerhead the block? my father in law helps build custom bikes, and said he knows machine shop people and he seemed willing to help, so i might just be able to keep this thing. know where to get rebuild kits, or have a favorite place to shop online?

 

[rodbolt]

Re: blew up my 90

no "kits" really. ya tear it down make a list check it twice and order what ya need. you also ned to determine why a piston failed or it will fail again.<br /> make sure the machine shop persons have experience with two stroke bores.