half power at start up

Hi, I just bought an used 9.9hp. It runs good. The only thing is that the motor only output half of the power when it is first started. It can reach the full power about 10 minutes later. The boat is only at about 6.5 miles at start up, then it can reach about 11 miles about 10 minutes later.


My first impression was that only one of those two cylinder was working. So I removed both spark plugs, and found that one is dry while the other is "wet". Attached is the picture of the the plugs. Does this mean the "wet" one does not work? What caused the the half power issue at the start up? Should I replace the plugs? thanks for your help

Checked the reed valves ??-------Checked compression ?

Thanks, that's a good idea. I'll try that.

kimcrwbr1 said:

did you try swapping the plugs and see if the problem follows the plug?

Click to expand...

Looks like that I need to replace the spark plug. Now, I got a new problem. I can not find the model number and the serial number. I found a tag. But it was totally worn out. Can not tell anything about it. I did some research. And found a number on a "seal plug". It is G4188991. Any idea what year it is? The previous owner said it is a 90's.

The current plug is BR7HS. But I did not find any Evinrude outboard using BR7HS at http://shop.evinrude.com/products/553609/2-Stroke

needs some help on this.

thx

Are rockpeng and eaglepeng one of the same ????