Another Yamaha 90 2 Stroke non-auto oil dispense Knocking

[flyin4delta]

This is a 2000 90HP without the auto oil dispense.
I bought this boat last week and the previous owner picked me up at a different ramp than which he launched and so I was not exposed to how good the boat starts.
I drove the boat and she sounded great shifted strong fwd and rev.
Day before yesterday I took it out and was a little hard to get to stay running when I put it in gear. But finally got it to stay running after 20 min of running it up and trying to put in gear. Once started ran great!
Next day I took it out but on the way to the lake i put in 6gals of mid grade fuel, 16 oz of pennzoil 2 stroke oil which is 50:1 mix according to the bottle. Got to the lake and was again hard to get to stay running. But finally again after 20 min she ran. So I go to take off across the lake got it up to about 40mph and after about 10 seconds at that speed she starts knocking and then dies. I just fired it up and idled back to the ramp. No reduction in power but the knocking became louder the more power I gave so I just idled back and then hand loaded the boat took it to the shop and it could be daysssss before they get to my boat. Does anyone have ANY idea of what it might be?

 

[robert graham]

Re: Another Yamaha 90 2 Stroke non-auto oil dispense Knocking

May be a plugged carb, lean fuel mixture, fried piston. May need carbs cleaning, new piston, but hopefully not. The knocking is not a good sign! Good luck and let us know what happened.

 

[flyin4delta]

Re: Another Yamaha 90 2 Stroke non-auto oil dispense Knocking

May be a plugged carb, lean fuel mixture, fried piston. May need carbs cleaning, new piston, but hopefully not. The knocking is not a good sign! Good luck and let us know what happened.

OK BAD news... Turns out something maybe a needle bearing got into the piston and totally ate up the top of the piston head. Look like someone took a flat head screwdriver and pounded the crap out of it. Ate the head up too... I was told I might be able to save the head.
Where would a needle bearing come from that could get into the cylinder?

I had 1/125# 2/125# 3/40#. No bueno... Guess its time to change out the sleeve, piston, and maybe a head. Any suggestions on the process of getting the new sleeve in or where that needle bearing might have come from. I have never done this big of a job on a outboard before is there anything I should know or keep in mind? Also where is a good place to get a sleeve for that engine? C90TLRZ
I am having a hard time finding one.

Thank you for anything anyone can give.

 

[robert graham]

Re: Another Yamaha 90 2 Stroke non-auto oil dispense Knocking

Same exact motor as mine. Maybe a piece of broken piston ring that got hung in the port and broke off. Ring may have been stuck in groove by carbon deposits. Not knowing the condition, maintenance(or lack of maintenance), of the motor, then hard to say about repairs. You could replace piston, sleeve,head,etc., and still have a motor with issues, especially if it's a saltwater motor or has heavy carbon deposits. Maybe check some Yamaha shops for an inspection and ballpark figure on repairs, also price of another similar motor in good running condition. Your motor could be sold for parts. Sorry for your troubles, but the C90Yamaha motors are generally very good!
Keep us posted on what you decide to do. Good Luck!

 

[flyin4delta]

Re: Another Yamaha 90 2 Stroke non-auto oil dispense Knocking

Got the powerhead off and now talking to a shop that is offering to re-sleeve, new piston, and needle bearings for 1000-1500.
I can buy a remanufactured for 1800. Comes with all new pistons and everything! Talk to me guys let me know what in the world these mechanics are doing that cost 1000-1500?! I have already pulled the power head and everything.... And the remanufactured one comes with a year warranty....

 

[robert graham]

Re: Another Yamaha 90 2 Stroke non-auto oil dispense Knocking

Seems to me for the $1800 that the remanufactured powerhead might be the best way to go. Is that price include labor and installation of remanufactured powerhead? May just want to bite the bullet and get it fixed right, even if it costs $2500. Do your pistons, cylinder and head have much carbon on them? If you go with the remanufactured powerhead, start using the Yamaha Ringfree in the motor all the time. Good luck and keep us posted with what you decide to do.

 

[jeffersondodson561]

Re: Another Yamaha 90 2 Stroke non-auto oil dispense Knocking

Reman from a good, reputable always the way to go, which manufacturer did you go with?

 

[flyin4delta]

Re: Another Yamaha 90 2 Stroke non-auto oil dispense Knocking

Reman from a good, reputable always the way to go, which manufacturer did you go with?

I was looking at the ones from here on iboats.com
who would you recommend?

 

[flyin4delta]

Re: Another Yamaha 90 2 Stroke non-auto oil dispense Knocking

O well... I just dropped 2100 and bought one from iBoat.com... Not real happy but I think it will be the best decision.

Now the question is should I keep the old powerhead or send it back for 250?
There are a lot of parts that I would have by keeping it....

 

[robert graham]

Re: Another Yamaha 90 2 Stroke non-auto oil dispense Knocking

For the core price of $250, I'd just keep it for all those spare parts, many of which could run you more than $250. You can pop that remanufactured powerhead on there and it'll be mostly like a new motor, have to break it in, use double oil for 1st tankful, run slow 1st 10 hours, etc. Install a fuel/water separator, use Stabil and Ringfree all the time, install a new water pump impellar, change oil in foot, you'll be ready to go! My 90C is a 1999 model and never had a problem with it, just clean, fresh gas and it runs clean and strong all the time. Never had carbs off or cleaned! I hope those rebuilt carbs on that powerhead have been linqed and synched properly...probably have. Good Luck and let us know your progress!

 

[flyin4delta]

Re: Another Yamaha 90 2 Stroke non-auto oil dispense Knocking

How much is "low power" for 10 hours? like 1/4 power? I don't think the new powerhead will come with carbs. Should I rebuild my carbs or just clean them good... The report I paid for in the VERY beginning of this process said "found #3 cylinder leaned out due to varnished carbs" So I assume that means the needle valve was varnished? And how would you know if any one cylinder is being leaned out? I understand no fuel=no oil=damage but other than a change in power. how would one know? Because I really don't want to go through all of this again....
Thank you

 

[robert graham]

Re: Another Yamaha 90 2 Stroke non-auto oil dispense Knocking

When carb jets get plugged with varnish, debris, water, whatever, it cuts fuel flow to that cylinder, creating a very lean fuel condition and high temperatures in that cylinder. You need to start fresh with clean/rebuilt carbs, then install a fuel/water separator, use Stabil and Ringfree all the time, check and clean fuel filters regularly. If one carb is plugged you would have some indication by the rough running of the motor, which it did at the get-go. Those carbs have 10MM brass hex-head drain screws on the bottom/sides where you can drain them now and then to be sure there's no trash in them. Once you get this motor set up right and keep clean, fresh gas in it, it'll run great! Check: Yamaha Outboard Owner's Book for 10 hour break-in procedure. It's not complicated, just mostly run in lower RPM's, double normal oil for about the first 10 hours of operation. Good Luck!

 

[jeffersondodson561]

Re: Another Yamaha 90 2 Stroke non-auto oil dispense Knocking

O well... I just dropped 2100 and bought one from iBoat.com... Not real happy but I think it will be the best decision.

Now the question is should I keep the old powerhead or send it back for 250?
There are a lot of parts that I would have by keeping it....

Not really sure what components you would want from the old PH. I would get your 250 back from the core. You have stripped all of the "stuff" off the PH right?: Flywheel, wiring harness, coils, carbs/choke/fuel hoses/ignition components...? You are just going to send back the block.

 

[flyin4delta]

Re: Another Yamaha 90 2 Stroke non-auto oil dispense Knocking

Thats what I am going to do.