Help...50hp 4stroke 2003

[Cup420]

Had a little stutter at WOT and found a loose plug. Changed the plugs and made sure all were tight. Now motor is bogging down, struggling to get from 4500 to 5000 rpm's. Acts like it WANTS to go but takes a good minute or two of surging to get to 5000 and full speed. It was running fine except for the stutter.The last time I took it out.

Just did a compression test and the numbers are not good 1...90, 2...90, 3...60, 4...60. I feel like I did something wrong because there's no way the boat would even run with these numbers. And it ran yesterday.

 

[boscoe99]

When doing the compression test, was the motor fully warmed up, throttle wide open, battery fully charged and the gauge known to be accurate?

 

[Cup420]

When doing the compression test, was the motor fully warmed up, throttle wide open, battery fully charged and the gauge known to be accurate?

No on all but the battery. I'll do that and try again.Thank you. I have a pretty decent gauge.

 

[Cup420]

When doing the compression test, was the motor fully warmed up, throttle wide open, battery fully charged and the gauge known to be accurate?

Question... How am I supposed to heat the engine up and to pull the spark plugs? Doesn't that make the spark plugs easier to break? I'm also going to check today to see if maybe my carbs are out of sync. I'll go ahead and check spark too.

 

[Cup420]

When doing the compression test, was the motor fully warmed up, throttle wide open, battery fully charged and the gauge known to be accurate?

Doing a compression test and something isn't right. When I have the throttle closed, or off just on the one cylinder, i'm testing right now.I'm getting 90. When I have the throttle wide open, i'm getting heading up towards two hundred!! That's definitely not right! What am I doing wrong??

 

[Cup420]

Truthfully, I don't think that compression is my problem. That's just one of the first things you check. So that's my idea behind it. I really feel like it's an air or fuel problem. February of last year...fuel pump, coil packs and fuel system all replaced and carbs were completely rebuilt. I've got a stutter now

 

[racerone]

Well---200 PSI for a 4 stroke ( throttle open ) sounds correct !