slow overhauling

[amahaork]

all winter ahead of me, so no rush to fix it right away. are yamaha oem piston rings has some kind of coating, like moly or something?

[rodbolt17]

depends on what Yamaha outboard is being discussed.

[amahaork]

would love to get some education on all Yamahas and 1995 saltwater 2 stroke 200 hp specifically, please.

[amahaork]

If this forum claimed to be Yamaha forum to assist maintain Yamaha engines and selling Genuine Yamaha parts, so I would be able to find info here what and how Yamaha cylinders have to be reconditioned, what cylinders walls finish required to accept new Yamaha OEM rings. Appreciate your Professional Expertise .

[boscoe99]

If this forum claimed to be Yamaha forum to assist maintain Yamaha engines and selling Genuine Yamaha parts, so I would be able to find info here what and how Yamaha cylinders have to be reconditioned, what cylinders walls finish required to accept new Yamaha OEM rings. Appreciate your Professional Expertise .

I don't know what this website claims to be, but this website can provide you with a service manual for your particular model of motor. Within that service manual is all of the information that is available from Yamaha Japan with respect to the overhaul of that model motor.

Keep in mind this is not a Yamaha forum. It is a Yamaha dealer forum. They do a damn fine job. But, they are not Yamaha and they are not the Yamaha training department.

If you were to actually talk to Yamaha themselves they would recommend that you not do an overhaul yourself but rather take it to a Yamaha dealer for the overhaul.

The Yamaha modus operandi with respect to service manuals is that they are intended for a mechanic who has a basic background in rebuilding motors. They are not a tutorial that will tell someone with no knowledge of motors all that needs to be known about an overhaul.

[amahaork]

You got it right, I am "someone ..." who happens to have a boat and in current situation I am facing difficult dilemma: due to high cost of fuel and service, either to quit boating or try to fix it myself. This site sell parts and advise how to repair Yamaha engine, so I am here. If I cannot fix it, I quit boating altogether. cui bono? What would you recommend me to do, Mr. Boscoe99 ? Thank you.

[boscoe99]

First get a genuine Yamaha service manual for your motor.

If it specifies the surface finish for the cylinder walls, then hone to that finish.

If the service manual does not specify the cylinder wall surface finish, which I suspect will be the case, you are on your own. You might then want to use the internet to try and find a generic hone finish for a two stroke motor. Something similar to the following:

Technical information on using engine hones, flex-hones, ball hones

If you are not happy with what you find in the SM and the internet then you might want to consult with a two stroke engine rebuild shop. It might be more cost effective to let them refinish the block for you than it would be to find and buy all of the tools that you need. Honing, while not rocket science, does require a small amount of technical expertise. This is the sort of thing that we here in the states would normally let an engine shop do for us.

If it were my motor, and I had little money to spend on it, I would just get a 240 or 320 grit hone and hone the hell out of the motor, trying to get a good cross hatch on the cylinder walls. Then, fit the pistons to the cylinders verifying that all clearances are to specifications. Cleanliness is everything. Wash the block down several times to remove all swarf and swill. Who knows, you might get another 10 good years out of the motor.

[amahaork]

Thank you for your encouragement. I will show block to one more reputable machine shop seeking their opinion. what amazed me, that not damaged cylinders in a block shows no wear whatsoever, not in ring area, not in a piston area. Cylinders mirror - like, rings has no scratch on them, piston clean, just slightly discolored from blow-by. Even in a small area where piston newer touched cylinder wall, surface of cylinder same as in piston and rings area, pristine. I can see 45 deg cross hatch, but it's finished, probably, with 800 grid? I think it is one of the Japanese trade secrets. Looks like Yamaha worked cylinders the way to bypass break-in. It's beyond my comprehension and against my instincts. I visit all machine shops I found in my area: (marine, auto, food, air planes, hydraulic) and every shop told me this surface is bad and required honing for break-in rings. I understand they need business but, what is the point to install OEM Yamaha rings on a cylinder walls honed with 240-280 grid stones. I feel that they will not last two years, not alone another 12 years. Thank you.

[99yam40]

I do not know about your Yamaha motor, but there were some outboard motors with special linings/coatings on cylinder walls.
So, I would be looking for info for your motor exactly, not just in general Yamaha.

Rodbolt17 is a Yamaha master tech, So give the motor info and maybe he could answer with some helpful info.

I believe he has said in the past he sends the blocks and new pistons to machine shop to have the cylinders bored and honed to fit the pistons and then rework the ports properly

[boscoe99]

Jasper Engines overhauls both four stroke and two stroke Yamaha motors. Give them a call and see if they will give you the grit size for the hones that they use.

Contact Jasper Engines and Transmissions