finally got my ship running here are the numbers looking for your input

[flatstick]

Guys, finally got my bug running and took it out for a spin. 98 ZX 195C. load was me alone and 25 gallons of gas. air temp was 65, water 68 degrees. water had one foot chop, wind 15mph. do not have speed as I do not have GPS. rpms seems a little low to me at WOT 5200. motor is a Yammie 3.1 200 ox66. prop is a Tempest 25, jackplate is 12inch. measured the motor and looked to be 5-5 1/2 inches below the pad. trailer made it tough to get a perfect reading. water pressure seemed great as it was 22 average and did see 24 at times. to me it seems like the motor can come up a tad. the hole shot is fantastic from a dead stand still. what do you guys think ? pics may be available if there are enough responses

[TMATTE]

Sounds like your motor is a little low, which would account for your low RPM's.

Raising the motor on the jackplate will give you more RPM's and more speed. Just keep an eye on the water pressure.

[ChrisH]

i would raise to about 4 inches and run it. you can come up about a 1/4" at a time from there. you should be able to turn that tempest pretty fast

[flatstick]

Kind of figured what you guys are suggesting, just wanted to see what height everybody else is running. the road is not very level by my house. tried the best I could to get good measurements but just be eyeballing you can see the jackplate is mounted low on the transom and the plate is only raised like a 1/2 of in inch. figure I can get better measurement at the ramp. I know it is hard to say but if it works out where I raise my motor another 3/4- 1 inch ( moving in 1/4 inch increments and watching the water pressure) what should I expect to gain in rpms in similar conditions , your best guess. the Yamaha manual says rpm max is 5,500, is that what you guys would be shooting for on this setup at this time of year ? like everybody else looking to squeeze a few mphs out of my rig. was thinking about getting the prop redone yet it seems like I am close to be maxed out, would you agree ? here is a pic of the rear look close and you can see the motor is not raised very high on the jackplate.


http://i62.photobucket.com/alb...4.jpg

[Franklin]

Just jack it up a 1/4 inch at a time while paying attention to your water pressure and noting the speed rpms and driving characteristics....I say 5500 is BS....I say look for 5800-5900......

Franklin

[flatstick]

I tend to agree with you on the 5500 being a little low as people keep saying that Yamaha has been conservative on that top rpms. 5800-5900 hmmm may need some prop work to get there . hard to figure I would gain another 600 or 700 rpms just from going higher. considering the water and air temps are in the high 60's, I will surely not get these rpms in the dead of summer. well keep the suggestions and opinions coming guys.

[ChrisH]

i have mine propped to run 5800 in the winter. i run around 5500 in the summer with the same setup. if i could afford a winter prop and a summer prop id do it but for now thats what i do

[flatstick]

What you are saying makes sense. I too can not afford two props. now I need to get around that 5800 mark for the cool weather. this way I should be similar to you, maybe around 5500 fro the summer.

[Bass Junkie]

First I would get a good measure on how far below the pad that propshaft is sitting. Then jack it up to 3" or 3.5" under and start doing the fine tuning from there. If you are 5" or 5.5" under you are way too low.

[flatstick]

Agreed , going to get to the boat ramp this week and find a nice level spot. curious to see how many rpms I will pick up. by going up an inch or so can I expect to see a nice increase in rpms ? did not trust the measurement but as stated you can see the motor is only raised about 1/2 an inch on the plate. also the fact that the water pressure did not change much stayed a lot higher than I expected

[Y2SAYS]

I'm new to this bassboat thing. How do you measure where your motor is sitting? Where should I measure how many inches my motor is below the pad?

[flatstick]

Here is a great post with pics to show you an easy way to do it. when I did it I was parked on an uneven spot, so I want to get everything level and take it from there. hope this helps.

http://www.bbcboards.net/zerothread?id=65514

[flatstick]

Well here is my update. took the motor up 1/2 an inch then measured it at the boat ramp. looks like I am currently at 4 3/4 inches below the pad. air temp was 62, water was 64. ran 30 gallons of gas, me and a 240 pound friend. picked up 2 mph on the speedo and ran fairly steady at 5400 rpm. by myself did see 5500 rpm. water pressure dropped to 20psi. will take it up another half an inch and see what readings I get. holeshot was still great


Modified by flatstick at 7:47 AM 9/30/2006