Outboard Questions

[Jarvis Raynor]

Greetings all,



I have a question concerning the performance of my 04 Tracker Avalanche w/Mercury 150 XR6 outboard. Back in January 13, I had to have the powerhead rebuilt as a result of overheating. Prior to overheating, my top speed was between 58-61 mph gps. After the rebuild, I can barely reach 45 mph. What reason could possibly cause this? Nothing has changed except the rebuilt powerhead. The prop is a 14 1/2 x 23 tempest. I followed the break-in procedure as recommended by Mercury as well as have the mechanic who performed the rebuild to look it over. Not sure if I'm omitting any more necessary information, but I just wanted to give a brief description of my problem. Any assistance is greatly appreciated..

 

[Mini]

I woul dmake sure that you are obtaining true wide open throttle (WOT)



What RPM before and what are they now?

 

[Jarvis Raynor]

Thanks.. WOT before rebuild was between 5600-5800 rpms. After rebuild, between 5000-5200 rpms.

 

[Jim clear]

I have a "05" 150 XR6 on a 882, Max RPM according to merc is 5600.

 

[Kirby Wilson]

Have your mechanic check the compression on the cylinders. Should be around 115PSI . All cylinders should be within 2 to 4 PSI of each other.

Rebuilt or new should have a warranty.

 

[Scott Hammer TOXIC]

If you are not reaching full RPM's you will not reach full speed WOT. Your quest is to find out why. You can eliminate most of the set-up issues (engine placement/prop to pad, etc.) and prop because none of that changed and you were running peak before the re-build. I would check throttle/linkage and compression and plugs. Motor should perform as good if not better than before.

 

[Mini]

Once it "loosens up" the motor should perform as good or better than before.

 

[Jarvis Raynor]

mini,



What exactly does "loosen up" mean when referring to the engine? Are you saying when it fully breaks in or something? And also, what actually happens to an engine after the initial break-in process? Thanks..

 

[Mini]

Yes. Once the "break-in" is over the rings on pistons should be seated properly. Then the wear lessens on the walls of the cyliners. This will allow the engine to spin easier (same happens to all moveing parts too).

 

[Jarvis Raynor]

Got it.. Thanks..

 

[Jarvis Raynor]

Okay, so I talked to a mechanic who tells me that when doing rebuilds with new/remanufactored power heads, it's is very common to not fully adjust the timing on the outboard until after the initial break in process., which could cause a decline in performance. Once break in is complete, the timing is re-adjusted, and in most cases, full power and performance is restored. Just checking with this forum for more opinions/comments to see if this sounds right? Thanks.