300xs break in questions - 2hrs run so far and she's using more oil than opec!

**Pachanga_rick** · 07-15-2017, 03:41 PM

Well the 1st hour I ran between 4200 & 5150 rpm never leaving the engine at one rpm for more than 1 min.

Hour 2 says I can run full throttle, but never more than 10 minutes at a time.. but I basically ran it around 5500 rpm with a few wide open pulls.

I have 1.5 hours left on the Smartcraft before it's finishef with its break in cycle.. but I noticed it's using an obseen amount of oil.. from looking at the tank I'm guessing around 1 gallon per 25 gallons of fuel.. is that normal?

Also when I push the throttle to get on plan the engine almost feels governed and does not feel like she wants to go past 2500rpm. I need to tilt the engine and allow the motor to break free and spin up to get past 3000 rpm..than she jumps up and goes.

Not sure if it's just oil soaked plugs from the break in or another issue.

**RSWORDS** · 07-15-2017, 03:58 PM

Once out of break in oil usage will go down some.

Also though, oil usage is not dependent on fuel usage. All other things being equal, it doesn't matter if it takes you 10 gallons of gas or 100 gallons of gas to get somewhere. If The motor ran for the same amount of time at the same RPM it's going to use the same amount of oil to keep everything lubricated properly. This is why I lot of people see a decrease in fuel consumption with the new optimax motors but not as much a decrease in oil usage.

**mjw930** · 07-15-2017, 04:32 PM

During break in the computer runs the equivalent of 20:1 mixture. It will flip to 40:1 once it's past break in. BTW, mine has 4.6 hrs and still shows it's in break in mode. I've gotten two responses on how long the computer keeps it there, 5 and 10 hrs. I'm hoping it's 5.

I also noticed it pulls well to 5500 then falls flat and am told that's due to the break in fuel/oil curve and that will change as well as how it pulls from idle (similar flat spot you noticed) once it's past the break in programming.

**Hot Shot Merc** · 07-15-2017, 07:11 PM

If its anything like the 280 computer break in time you have to keep it under load. It will click off minute for minute that way. Run your biggest prop like a 32 and keep the engine trimmed under and the rpm over 3500. Anything under 3500 wont click off for break in time and higher rpm with the motor trimmed up isnt enough load either. I had clocked over11 hours of break in time on a stop watch and it still wasnt out of the (i think it was 8 hr break in)so we looked at the computer with a DDT and it said I had said I had 15 minutes left to go out of 8hrs normal break in time for the 280. I was then told that it has to be under peak load to count the time away. I was running around normal with a smaller prop and engine trimmed up on the Lightning stv and it wasn't under enough load. I then put on my 32 cleaver and ran around the lake at 5000 rpms with the engine trimmed all the down under super load and it came out of break in 15 minutes. So that clicked the time off minute for minute.

**WILDMAN** · 07-15-2017, 07:15 PM

Supposed to run double oil during break and for the first four hours. And then it goes variable depending on how much throttle is applied. Also needs to be under load to be applied to the four hours. Idle does not count. I have run them almost to the rev limiter after the first hour for short bursts

**WILDMAN** · 07-15-2017, 07:22 PM

Originally Posted by Hot Shot Merc

If its anything like the 280 computer break in time you have to keep it under load. It will click off minute for minute that way. Run your biggest prop like a 32 and keep the engine trimmed under and the rpm over 3500. Anything under 3500 wont click off for break in time and higher rpm with the motor trimmed up isnt enough load either. I had clocked over11 hours of break in time on a stop watch and it still wasnt out of the (i think it was 8 hr break in)so we looked at the computer with a DDT and it said I had said I had 15 minutes left to go out of 8hrs normal break in time for the 280. I was then told that it has to be under peak load to count the time away. I was running around normal with a smaller prop and engine trimmed up on the Lightning stv and it wasn't under enough load. I then put on my 32 cleaver and ran around the lake at 5000 rpms with the engine trimmed all the down under super load and it came out of break in 15 minutes. So that clicked the time off minute for minute.

The 280s always sucked during break-in I thought. Some of them would take 10 hours to get off break-in before that would go over 6000 RPM. The 300xs seems to go to the Rev limit right away. Mercury tells you to keep it 4000 to 5400 for the first hour. They also run them for about two hours before they are put together

**Hot Shot Merc** · 07-15-2017, 07:29 PM

Originally Posted by WILDMAN

The 280s always sucked during break-in I thought. Some of them would take 10 hours to get off break-in before that would go over 6000 RPM. The 300xs seems to go to the Rev limit right away. Mercury tells you to keep it 4000 to 5400 for the first hour. They also run them for about two hours before they are put together

Yep. They limit them to 6000 and you fowl the plugs too if you idle around too long and the bitcch wont start. I know several people that had the same time issue and putting them under that load works minute for minute but seems like forever running around plowing water trimmed all the way under to load it up. Wish I knew that before wasting almost 12 hours breaking mine in. I think it says that in the manual actually but who reads those rite?

**Euroski** · 07-15-2017, 07:57 PM

Which prop you using? On my Cougar I needed to have larger vent hole because the Bravo 1xs-30 was holding the RPM down.

**WILDMAN** · 07-15-2017, 11:54 PM

Bravos have never worked that good for me. I use Drag 4 props

**Hot Shot Merc** · 07-16-2017, 06:47 AM

Damn Euroski!!! I just noticed you have 3 300 xs motors ona 22' boat? Holy crap!! Thats badass. How does it run?

**vnemous** · 07-16-2017, 06:49 AM

Originally Posted by Hot Shot Merc

Damn Euroski!!! I just noticed you have 3 300 xs motors ona 22' boat? Holy crap!! Thats badass. How does it run?

Thats gotta be one wide Cougar or a typo

**Davidlake** · 07-16-2017, 11:41 AM

Keep idle to a minimum. Too much idle time is the fastest way to window an SX. Believe me, I know first hand!

**mjw930** · 07-16-2017, 11:44 AM

Originally Posted by Davidlake

Keep idle to a minimum. Too much idle time is the fastest way to window an SX. Believe me, I know first hand!

Window? That's a new one on me, what's it mean?

**Pachanga_rick** · 07-16-2017, 11:54 AM

Originally Posted by mjw930

Window? That's a new one on me, what's it mean?

Put a hole in the block with a piston, rod or both..

My ramp is close to the open water, i only idle for a few minutesat best before I get going.

**mjw930** · 07-16-2017, 12:32 PM

Originally Posted by Pachanga_rick

Put a hole in the block with a piston, rod or both..

My ramp is close to the open water, i only idle for a few minutesat best before I get going.

Thats what I thought but I wasn't sure having not heard the term.

I just checked and I have 4:53 on the motor and it's still reporting it's in break in mode. Of that roughly 20 minutes is at idle. Most of the running time is between 3500 and 5500 RPM with the bulk of that between 4000 and 5000. I think I saw 6000 RPM on one run but I backed out due to boat wakes.