Somethings off????

[lakertaker]

I just recently bought a new boat 1990 20' seapro walk around. It has a recently rebuilt evinrude 200 v6 aluminum propped at 15x16 with a light load I'm only running at 4000 rpms and 30 mph gps (wot), had 5 people in the boat today and could only pull 3000 rpms at 19 mph. Shouldn't it be doing better than this? Checked compression 90 psi on all Cylinders and spark jumps 3/8" gap. No signs of waterlogging although haven't had a chance to weigh it yet. Any ideas? Any help is greatly appreciated.

 

[hwsiii]

Re: Somethings off????

Laker,welcome to Iboats prop forum and we will try to help you as much as we can, but there is certain information that is needed in order to help you. The following form has all of the information that is needed to help you with your problems in finding the right prop. If you do not know all of the information that is asked for on the form please give us the most information you have available as I have a program I designed to find the right prop for any planing hull boat that needs this information, and most other people who are trying to help you will need the same information. It requires time to find all this information when we have to look for it and in my defense I expect you to be willing to expend as much effort in finding the right prop as I do. We hope to be able to help you get the exact prop you need for your particular uses, and this information is required to do that.
It is not as simple to pick the right prop as most people coming to this forum think it is, that is why we ask so many questions, it is for your benefit we ask all these questions. And if you have a stainless steel prop or are changing to one the blade geometry of the prop can make a lot of difference in speed and RPM.

Iboats Boat and Motor Info

1. Year, make and model of boat
2. Length, width and base weight of boat, look for boat decal on back of boat
3. Number of people and gallons of gas normally on boat
4. What do you use the boat for
5. Is it a Deep Vee and if so how many degrees of deadrise
6. Year, make and model of motor
7. HP and gear ratio of motor IMPORTANT
8. Manufacturer?s recommended WOT range
9. Anti-ventilation Plate height above keel of boat if it is an outboard in inches
10. Is it a bass boat or does it have a pad bottom
11. Does it have a hydrafoil or trim tabs
12. Make, model, diameter, pitch and whether SS or aluminum prop
13. WOT RPM and speed from prop, how much gas and how many people in boat for test data

REMEMBER, The numbers I give you will be NO better than the information you give me

The only thing I ask of you is to come back and give me a report of WOT RPM and speed for my database.

H

 

[steelespike]

Re: Somethings off????

hwsiii Can really help with the right numbers.But until then your Compression is low. 100 psi is considered the ideal minimum.Is compression even all cylinders. Was the engine warm with all plugs out?Throttle opened. These won't make much difference but every little bit helps.You may want to try another compression gauge.Check the simple things Throttle opening all the way?All plug wires in good shape?PDouble check spark.All plugs burning evenly all look about the same? Link and Snyc carefully done timing right on.Something is screwy running a 17 you should
at ABOUT 5,500 rpm and ABOUT 45mph.

 

[hwsiii]

Re: Somethings off????

Steele, as always you ask the questions that really matter, I just try to figure out which prop SHOULD be right, IF everything else is right. And that means nothing if the motor isn't running right in the first place. You do a great job.
My knowledge is certainly NOT in the motor area.


H