1999 Honda BF40 Losing power- will not exceed 4K RPM

I have a 40 4 stroke and it was having a major loss of power. I pulled the carbs and cleaned them, however did not pull the jets(likely a mistake). I reinstalled the carbs and boat ran excellent for about 35 minutes and got a solid 5500-6000+ rpm; and then I experienced a rapid loss of power, down to about 3500. I got the boat back to the dock and ended up replacing the internal fuel filter(larger spin on filled only had a few hours on it). I am still unable to get it above 4K, even with the throttle all the way on the pins. I'm pretty mechanically inclined, but I'm just not sure what the problem could be. I'm going to replace the spin on filter tomorrow. Not that it much matters, but the boat is a 13 Whaler GLS.
Any advice would certainly be welcome.
Thanks in advance!

First. Make sure that the linkage on the carburetors is actually going to full throttle. Purhaps the linkage came off of one of the carburetors. A spark plug wire came off? Just look for all the obvious things.

If all ok......Do a cylinder drop test.

With the engine idling, remove the spark plug wires one at a time and note if there is a decrease in rpm for the motor. Most likely, there will be one cylinder that does not decrease.

It is not uncommon for some dirt to be dislodged in the system, after a carb cleaning, then get caught in the main jet. Usually, it is very small, and only gets caught in the jet set.

Mike

Mike, thanks for the advice. I started the motor and began to remove the spark plugs lines. The two lower ones had loss of RPM, but top had zero loss of RPM. However, there was spark coming from that line. So, not to sound dumb, but should I assume a clogged jet and/or replace the plug? Any advice would be awesome!

Most likely it's a clogged jet. But to eliminate the possibility of spark plug.....awitch it with one of the others and retest

Mike

Mike, thank you very much- you were 100% correct. Pulled the carbs and gave a good cleaning, popped them back on and got a full blown RPM and the little boat got her legs back. Had to adjust the linkage a bit, and I think the butterfly valves need a little tuning, but I will get to that ASAP. Are the vacuum gauges from Harbor Freight worth a crap? I don't see the need to spend a bunch on a super nice carb guage kit.
For those who don't know, pull the entire manifold instead of just the carbs, makes it way easier.

Glad you got it going. I am not familiar with the Harbor Freight gauges. Others on the forum have recommended some fairly inexpensive ones....I do not remember what they were.

Hopefully, others will jump in and recommend.

Mike