Loss Of Power

[yubi]

I am getting so frustrated and need help.
I recently pulled my carbs on my EXS1200 boat because of a hard starting problem and found them to be messed up from the previous owner.
I then overhauled them back to standard, except for upping the main jet to 140 (up from standard 135) and changed the Pop-off arm spring to 95 grams.
I put her in the water and she started easy and ran well at 6500rpm for around 15 minutes , she then started to miss a bit and dropped to 5000rpm and would not return to full throttle.
I docked up and rested for two hours , took her back out and she ran full WOT for another 20 mins until I slowed to make a full turn and she then would not go back over 5000rpm again.
I am baffled . Could the lighter spring tension cause her to flood out when declerating or could the main jet be too large (I increased it because I have Riva / K&N Flame arrestors on it and thought the jet size would have to increase ? ) or is it the coil overheating after awhile and causing it ?

PLEASE I NEED ADVICE & HELP .... THANKS :emotredf

[mikey20]

Re: Loss Of Power

Have you taken a compression test sounds like you may be siezing the engine also if it has the 1200 power valve motor you may want to check the cat's to make sure they are still in one peice.they come apart over time.Riva should be able to tell you what carb adjustments you should make for their flame arrestors.Also have you changed the fuel filter or done any other maintenance to the fuel system .

[David3aces]

Re: Loss Of Power

are the small oil lines still attached?

[yubi]

Re: Loss Of Power

No . I am running premix 50:1
I am going to check the compression tomorrow, but I believe it is ok.
If the engine was seizing why would it run well afterwards and then act up again ?