One thing to look at on these HP500efi's will be the number of hours @ 4500 rpms and above. This will be generally a critical factor in how weak the valve springs and valve train in general. Another factor will be what type of issues if any the engines had during that 350 or so hours, ie., overheats, overspeeds, loss of oil pressures, etc. if known or divulged as well as records of oil changes and services. Lastly, obviously generally fresh water use with good maintenance will generally deliver engines in better shape than their salt water brethren. Head gaskets seem to be a problem area because of raw water and it sure would have been nice if Mercury Racing had used the Cometic type MLS stainless head gaskets , better valve spring materials and high volume oil pumps in those engines also.
My opinion is that when making offers or buying boats with these engines that have 250-300 plus hours without top end refreshening the pricing should reflect the need for this and you need to be very careful going to the 350-400hour uses with untouched engines you don't know all these exact factors and a dropped valve or serious head gasket failure in any engine can be catistrophic and expensive.
Sincerly hope everything works out well and safe for you, they are in general very good engines as time has proven.

Best Regards,
Ray @ Raylar

i did use it to my advantage. he was asking 62k for it....i dont think i did too bad.

i had the boat surveyed on friday and the guy that did it told me it ran 80 on gps during the sea tryel so i gess thats good

Looks like this is your boat?...nice!

http://www.powerboatlistings.com/view/15464

yup.......:D:D:D:D

Yes, these boats should run low 80's, depending on the elevation & water type. I think the factory's spec was 83-84 MPH in saltwater. My dad has a 2000 w/500's & regular B1's and it easily hits 80 in TN.

I have 300 hours on my 5000 EFI's and I'm have the Top End done prior to the start of the season, rather be safe than sorry. I'll know in a week or so how everything looked.

ok cool.

douse any one know if all donzi zx's are set up to spin in wards or is that more geared to the motor and drive setup? also if it is set up like that douse that make docking harder at first? im going from a 26 single to a 33 twin.

My dad's props were put on wrong, spinning outwards, and docking was pretty easy. We switched them to spinning innwards but have yet to run the boat again. It'll be interesting to see how it behaves around the dock. As far as I know all the boats were set up to spin innwards.