# 2004 90 HP Yamaha 2 Stroke



## RunningOnEmpty (Jun 20, 2015)

Double oil for sure. Opinions on break in very so I would follow what yamaha recommends to be safe. Page 45 http://www.yamaha-motor.com/assets/service/manuals/2004/lit-18626-05-50_899.pdf


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## MaverickMikeT (Dec 14, 2016)

RunningOnEmpty said:


> Double oil for sure. Opinions on break in very so I would follow what yamaha recommends to be safe. Page 45 http://www.yamaha-motor.com/assets/service/manuals/2004/lit-18626-05-50_899.pdf


Awesome! Thank you! I'm going to do the double oil, just wanted a little more guidance from there


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## RunningOnEmpty (Jun 20, 2015)

MaverickMikeT said:


> Awesome! Thank you! I'm going to do the double oil, just wanted a little more guidance from there


No problem.


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## DuckNut (Apr 3, 2009)

MaverickMikeT said:


> recommendations on how to break in a freshly overhauled 2004 90 hp 2 stroke ?


Ask the guy who rebuilt it and is issuing the warranty, don't rely on the Internet. Because the rebuilder may have specific instructions and you may void his warranty.


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## Smackdaddy53 (Dec 31, 2012)

DuckNut said:


> Ask the guy who rebuilt it and is issuing the warranty, don't rely on the Internet. Because the rebuilder may have specific instructions and you may void his warranty.


No computer, run it under 3500rpm and do a lot of hole shots and throttle changes for 10 hours then run the piss out of it. If it's going to fail, better sooner than later.
The key is letting the motor get to full operating temperature before running WOT.


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## No Bait / Lures Only (Apr 10, 2011)

Call Jon Wolfe @ Hydrotec for suggestions...Hydrotec was Yamaha's rebuild center for 2 stroke engines


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## RunningOnEmpty (Jun 20, 2015)

Smackdaddy53 said:


> No computer, run it under 3500rpm and do a lot of hole shots and throttle changes for 10 hours then run the piss out of it. If it's going to fail, better sooner than later.
> The key is letting the motor get to full operating temperature before running WOT.


The hole shots really help to seat the rings. I pretty much do exactly as you described, but without waiting 10 hrs to give it hell. 10 hrs of running is a long time!


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## Smackdaddy53 (Dec 31, 2012)

Just waiting for the powerhead to warm up helps a lot to keep from screwing up your motor at any point from break in to 1000 hours.


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## MaverickMikeT (Dec 14, 2016)

DuckNut said:


> Ask the guy who rebuilt it and is issuing the warranty, don't rely on the Internet. Because the rebuilder may have specific instructions and you may void his warranty.


Good point, he told me to do something very similar to what's listed in the manual, that's also in line with most everyone's suggestions on here... just wanted to make sure. Thank you, this site is awesome


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## Smackdaddy53 (Dec 31, 2012)

How did it go? I have a freshly rebuilt 1998 Mercury 90ELPTO on my other boat and it's about time to break it in.


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## MaverickMikeT (Dec 14, 2016)

Smackdaddy53 said:


> How did it go? I have a freshly rebuilt 1998 Mercury 90ELPTO on my other boat and it's about time to break it in.


All is good with the engine, got a fuel venting issue in the tank now, but I think I cleared it out ...


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## Smackdaddy53 (Dec 31, 2012)

I had an issue that I thought was a fuel vent but it was my primer bulb not holding prime due to being horizontal and sucking flat. This particular bulb has to be at a 45 degree angle to vertical to work.


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