07 obv with 5.7 indmar assault 325.
prop is a 13.7x17.5 mvc hc oj prop which i understand is stock diameter and pitch so iiuc the low rpm is not a prop pitch issue and ‘correcting’ the low wot rpm issue by lowering prop would mask a potentially real and serious issue.
Top speed is about ~39 and top rpm is ~4510-4560 (alone or loaded).
spec for my engine is 4600-5200.
per engine manual wot should be on higher end, and others with same boat say they get top end rpm and closer to 45mph.
My concern is not with the speed or performance.

My question is if it’s symptomatic of a real issue, then i do want to track it down. it sounds serious per manual and others to be below minimum and so far from upper range of wot. my concern is the underlying cause - if the engine isn’t performing as it should due to other issues and consequently could cause (long term and or catastrophic) damage.

my speed matches gps (pp stargazer) so it’s not off by 5 mph. i also have tach and pp rpm so i think it takes gauge error out of the mix bc they both get the same signal and give me same rpm.

I revvd in neutral and it would cut out past high 2s/3s so it was like up and cut out, rev up and cut out. was weird.

Any inouts/suggestions?
i realize to track down everything - i could eother go diagnostic first or throw parts first. basically i would prolly start with parts replacement, i would clean flame arrestor, change out fuel filter (is ther just one or low and high pressure?), spark plugs, rotor and cap and wires, and for diagnostics i could check fuel pressure and compression test. before i go down the path of chasing that or paying a fortune to do it - is there any chance nothing is wrong or not serious enough to bother? and any other obvious/easy things to check or replace? really just looking to enjoy our boat every season and get it baselined in a good spot, don’t want to overthink it but getting concerned based on everything i’ve read on the topic since i’m off by hundreds of rpm seems like something is off maybe a single cylinder not firing or all not firing at full potential…


Sent from my iPhone using Tapatalk