help 89 z25

[chewey]

just bought my first donzi and it needs a little work and i need a little help. the boat will not plain out and i think it needs to be re proped but i dont know what the max rpm should be. the boat has a 14.5x24 raker prop 460 cobra omc out drive.it is a 1989 z25 the seller claims it will plain out at around 8 seconds and run 60 mph but when i am out running it it will not plain out under 60 seconds and runs max 4000 rpm at 40 mph. and cavitates everytime i turn sharply also there seems to be no difference in throttle from mid to high untill i do plain out.and one more thing he has changed out the carb to a 750 insted of a 650 i am lost and could use some direction I am at 2300 ft. elevation and i am told that the prop i need should be a 20 or 21" i am also told that that is real small for this boat

[jdsdls]

First thing to due is check out the basics.

1) Is the drive all the way down and tucked in when you start out.
2) Does the baot have trim tabs. Make sure they are down also.
3) Can you borrow a prop form somewhere if so try a 22" pitch and see if you have any changes.

Good Luck

[wytmike]

The prop probably is to big for the boat. 21" or 22" would probably be better at 2300'. You might want to check the secondaries on the carb. Are they opening? You said there was no noticable difference between half and full throttle. Your secondaries may not be opening causing a lot of your problem.

Mike

[Andy McCarty]

Chewy I to have a Z25. If you would like to give me call tonight i can give you any information you would like. I am In Kentucky which is on the Eastern Time Zone. My home number is 859-224-8190.