Thread: OX66 Powerhead swap, 225Vmax to a 250 Saltwater Series

[otfin843]

Ill start by introducing myself, as this is my first post. My "name" is Bug and I am located in Charleston. I run a small boat shop, when not at my daily job. I have heard this is a great website for 2 stroke questions. I currently own three Yamaha 2 strokes, and want to piece two of them together. The first one, a V225TLRX, has a blown powerhead. The other motor, a SX250TXR, has a good powerhead, but unfortunately has a 25" midsection. I Have removed the old powerhead(Vmax) and lower unit and plan on mounting the good one tomorrow. I figured i would start with replacing the gasket that the powerhead sits on. Other than that, what do you guys recommend to get this motor started? The motor has been sitting in a garage for a long time and needs a full prep and tune up before it can be turned on.

My main concern is that. I am not sure of what i need to do to get it ready. Ive heard everything from fogging the motor with oil, replacing gaskets, tilt trim seals, and lower unit seals. Anything else? Anything you guys recommend i do while the motor is in pieces? Any upgrades that you guys recommend? I want this motor to be bulletproof and most importantly, fast.

Can my 20" lower unit that came off of the 225 Vmax work on the 250 saltwater series? I also have another 20" lower unit that came off of a 2004 200 vmax. Any ideas if this will work as well?

It is going on a 1998 21' Maverick Master Angler.

[formula29]

What kind of boat shop do you run??? there are a lot of variables in your questions, and some are very elementary. start with cleaning the carbs and spraying some lube in the cylinders and rotating it to get some oil on the walls.

[cpostis]

I'll put my two cents (not sense) in!

First off, buy a service manual for the SX250 and follow procedures outlined in the manual. Second, don't worry about cleaning the carbs, there are none on this motor. The motor is fuel injected. You will want to clean the VST. What is the condition of the cooling passages? You should check and clean all passages including the exhaust plate. If you want the motor to be "bulletproof", you should tear the motor down, check all components/systems for satisfactory tolerances, and replace if not.
If you feel comfortable with the internal condition of the motor, you should at least manually lube all bearings by hand that you can reach. You may have to pull the intake and reed valve assembly to reach mains and connecting rod bearings. You must prime all the oil injection lines. When you first start it, you want to run on 50:1 fuel/oil ratio along with the oil injection system.

Again, follow the procedures in the manual. If you take short cuts, more than likely you will NOT have a "bulletproof" motor, or even a running motor if you vary.

[formula29]

I got his swapping mixed up and which motor was blown, since you are using the ox66 don't forget about the basket filters in the injectors, I would replace them as well, basically clean the fuel system and lube the internals before cranking,

[otfin843]

What kind of boat shop do you run??? there are a lot of variables in your questions, and some are very elementary.

The only thing we don't do is outboards. Outboards are about the only thing i am not lessoned in. Thus the reason of my elementary questions. I have swapped out the powerheads, and plan to start cleaning the fuel system. Should i be worried about any of the other gaskets? Should i take the cylinder heads off and inspect cylinder walls? I have heard of people running "double oil" for a short period of time. Is this necessary? Is this the time to swap up to carbon fiber reeds?

Other than these vague questions, my main concern is to make sure the motor is tuned and lubed up, prior to me turning it on.

[formula29]

I guess I would start with the base gasket for the ox66 and see if it matches the manifold of the upper case you want to use, there is too much going on with what you are asking, you are working with an almost 20 yr old powerhead that you want bullet proofed? not going to happen, the closest you will get is if you tear it down, and reseal the block, but that's not worth the time or money, you may as well rebuild it, again not worth the money, so with what you are trying to do just clean the fuel system lube it up and roll the dice.

[otfin843]

Ok, i am sorry for asking so many questions in one post. Ill try to work through this a bit more organized.

I took off the cylinder heads last night to inspect the inside. The cylinder walls look great but there is some carbon build up on the pistons. What do you guys recommend for cleaning this? While i have the heads off, is there anything else i could do?


The water passages and sleeves do have some build up as well. Whats the best route to clean these?

Thank you again for the help, this site is about the only help i have. Headed to break down the VST

[cpostis]

First off, I'm not a "Certified Yamaha Outboard Mechanic". However a couple of months ago I did disassemble my SX 150 TXRZ. My motor had 20 times more mineral deposits than this. Carbon deposits on the pistons were slightly worse than yours. I did replace heads, clean what I could the mineral deposits by soaking/brushing in heated vinegar. The carbon on the pistons I cleaned with mineral spirits, plastic scraper, and stiff nylon brush. I also cleaned carbon from the exhaust/intake ports and the mid section exhaust. For this I fabricated a long handle with a stiff brush slightly larger than a finger nail brush.

Looks like I can still see original hone marks on the cylinder walls. (good thing).

All in all, I think this motor is in pretty good shape. I'll defer to others as to what they think.