1973 25' Seacraft Seafari
 

I finally have the boat running consistently after a lot of little road bumps.
Here is a video I took today. Ran great!

https://m.youtube.com/watch?v=V-W7AI9Tp_w

Very nice, 49,000 @ 40 mph not too shabby!! A humble suggestion, use only top of the line two stroke oil. If you do those OX66s will go forever!! The really good oil, full synthetic, will keep the rings from sticking and burn much cleaner. To some it's overkill, to me it's cheap insurance (unlike my health insurance)

looking good

Thanks DonV, I'll do that.

Nate - Looks good . . . Which prop are you running? You might want to consider propping it so the engine turns 5500rpm.

Bigshrimpin-thanks. I know it's a Mirage thst was custom tuned but that all I know. What would you recommend to get to 5500?

1.81 ratio lower
4900 WOT @ 40mph probably means you are running a 17p mirage?

I would probably drop down to a Mirage 15p or an Enertia 15p that should give you the extra 400 to 500rpm. Stay away from the Rev4 if you need the extra rpms.

Good suggestion! Don't know if Yamaha sells a full synthetic 2 stroke oil, but Evinrude's XD-100 full synthetic oil, made for oil injected motors, burns very clean and has very high detergent content.

BRP claims that if you run XD-100 in an E-TEC with the computer set for reduced oiling (for XD-100 only!), the motor will not only use less oil, you'll never have to decarb the motor! However some HO models don't have the reduced oil setting, and some guys that run their motor hard leave them on the factory default TCW-3 setting but still use XD-100 for extra protection. Mine is set on the leaner XD-100 setting, and I used about 1.5 gallons of oil and 155 gallons of gas on a 700 mile trip I made circumnavigating S. Fl. a few years ago. BRP advertises 1 gallon jugs of XD-100 for $45, but my local dealer buys it in bulk and sells it for $35/gallon if you bring your own jug.

Also agree with Big on propping . . . with all needle bearings, 2 stroke motors love to rev (or "yodel" as Terry E. says!), but if you lug 'em down as you're doing with too much pitch, it increases pressure and temperature in the cylinder, which increases ring, piston, wrist pin and bearing loads, and reduces exhaust scavenging, which means more carbon deposits and ring/cylinder wear! For example, although my motor hits peak HP at 5250, and the WOT "Operating Range" is 4650-5850, BRP says the OPTIMUM rpm is 5300-5500, so I'm propped to turn about 5450 with the maximum load I ever run. Don't know if Yamaha specifies the narrower optimum rpm range, but if not, I would guess that you'd be pretty close if you propped it for at about 5500 @ WOT with the heaviest load you normally carry, or at least the top half of the recommended operating range.

Excellent price on the XD-100 in bulk, which is pretty much as top of the line as you can get for two stroke oil!! I'm a very big fan of Amsoil HP synthetic oil. I buy the "preferred customer" package each year for $25, you get a very nice discount on their products, Their HP oil is the only oil that compares equally with the XD-100 and will work on the "lean setting" on eTecs. I buy it by the case of four gallons, with shipping to my front door and tax it's $120. Now as far as automotive oil I like the Amsoil "signature series", my car requires full synthetic, I change it every 15,000 miles.

Can`t remember who did the testing, but they had every one I can think of and Amsoil was just a tiny tic below xd 100 in two or three categories

Leads me to think Amsoil makes xd 100.

Hummm....good point Sandy, I don't think BRP has their own refinery! Someone has to make it for them to their specs. See below link, lots of mumbo jumbo for XD-100 and Amsoil HP, for folks like Denny :)

http://www.amsoil.com/performancetests/g2968.pdf

Fairly well controlled test they ran by using twins on the same boat, and very thorough evaluation they conducted! It's good to see it was based on ASTM standards! I used to do similar distress trending work on jet engine hot sections after endurance tests, but nobody had done that before, so there were no standards . . . we had to just make up our own as we went along! We got good results but it was harder to convince our USN and USAF customers that the tests were valid since both the tests and evaluation procedures were all new! They finally agreed with us, but it took awhile!

The reported distress differences are so small that they're probably due to minor within-tolerance differences between engines. Interesting that it did confirm that XD-100 burns so clean that a decarb process is not needed to prevent ring sticking! I tend to agree that it's probably the same oil, although E-TECs have been run for thousands of hours in commercial applications like Sea-TOW, so a longer test might have been more definitive. Don, do you know if Amsoil has their own refinery?

Building and operating a refinery is an enormous capital-intensive operation that's way beyond what the engine builders could afford, so their oils are simply made to their specifications by one of the major oil companies. Don't know if that logic also applies to Amsoil or not. Although the Amsoil stuff is probably close enough to safely use in an E-TEC that's off warranty, BRP has a good record of often covering parts costs of some failures well beyond the warranty period, so I think I'll keep using XD-100 since I really don't use that much anyway and it's cheap insurance as Don says. However the Amsoil stuff appears to work great, so using it in any oil-injected motor seems to be a good idea!

Now that we've really got this thread off on it's own tangent.....I don't think there's a refinery involved. From the Amsoil web site.


What's the difference between conventional and synthetic motor oils?

Answer: Motor oil, whether synthetic or petroleum-based, consists of molecular chains of hydrogen and carbon atoms, referred to as hydrocarbons. Petroleum crude oil is a thick, highly flammable dark-brown or greenish liquid with high energy density. Many contaminating elements exist in this complex mixture of hydrocarbons, including sulfur, nitrogen, oxygen and metal components such as nickel or vanadium. Petroleum crude oil is the raw material used for a wide variety of petrochemicals, including solvents, fertilizers, plastics and lubricants.

The oil refining process separates the various types of molecules in the oil by weight, resulting in a concentrated batch suitable for manufacturing products such as gasoline, LPG, kerosene or lubricant base oils. The chemical composition of conventional motor oil can vary substantially depending on the raw crude oil refining process.

While petroleum base oils are refined, synthetic base oils are manufactured and can achieve a higher performance level. Synthetic oil is chemically engineered for a certain molecular composition with a tailored and uniform structure. Such fine-tuned control over the final molecular composition of synthetic oils is the key to their superior performance properties. Designing molecular structures in a planned and orderly fashion results in molecules, and end-products, that are far more stable than their refined petroleum counterparts.

Bracket pontoon filling with water
 

So, we took the boat out yesterday. Everything ran great, except the oil reserve pump which I knew was out, so had to manually add oil to motor reservoir. No biggie. After we got back I noticed a lot of water running from under the bracket. I pulled the plug on the bracket pontoon and it ran for about 10 minutes. Looking back at this picture I can tell the boat is sitting stern heavy. I tested it again by putting water into the pontoon through the maintenance hatch and found its slowly leaking between the bracket pontoon and the boat itself, not through the plug. I need to seal the pontoon properly and hopefully prevent it from taking in water, perhaps seal bracket bolts again? This was supposed to be done by the service in SC, but seems it wasn't done properly. Any suggestions on product? There is bottom paint around the bottom portion of the pontoon, the bracket is a Stainless.

Ouch!

leak through the bolt holes? or through a crack in the pontoon? A crack should be fixable with 5200 or epoxy. Bolt holes could be sealed inside the pontoon with good caulk, but what about where the bolt goes through the transom? That has got to be sealed to keep water out of the transom core. Doing bolt holes right probably requires pulling the whole thing off the transom.

It might be leaking through the bolt holes since its not through the plug. I didn't see any seepage on the inside of the transom bolts but that doesn't mean it won't happen. Is it possible to take out one bolt at a time and properly seal without taking off the entire bracket and motor? That's something I could do otherwise I have to pay someone to do it. I was thinking I would seal the entire pontoon properly which would, in theory, protect the bolt holes within the pontoon from any seepage. I can easily take out the 4-6 bolts running the length of the platform and properly seal those because they are easily accessible inside and outside of transom. Then, maybe seal the length of the platform also? Good thing is it's only been out for a few short rides but it's apparent that after sitting in the water for a while it gives it enough time to fill that pontoon.

Thanks for the help!

Do you have access to inside of transom? If so, I'd pull the bolts, drill the holes oversize (like 3/4"), fill with thickened epoxy then redrill. That'll keep the water out of the transom core, but if they didn't put plenty of 5200 between flange and transom, you could still have water leaking into flotation tank. Don Herman uses lot's of 5200 on that flange and swears that after it cures, you don't even need the bolts! But you'll need lots of debond, a knife and some wedges to get the bracket off!

There's a very small inline oil filter on the discharge line near the tank. When clogged won't allow transfer. I used 5200 to seal my bracket.

Sounds like "PAY to PLAY" type customer to me :p

Thanks gents. I will do all the above. Going to seal entire platform and float first and then seal bolts.

I know the best way to do it would be to take the entire platform/bracket off but im confident the exposed bolts are sealed properly so if I seal the float correctly the leaking should cease. If not, i'll have a bigger job ahead of me.

Being a cheap bastard, it's more like pay to save!!! :)