bayliner problems from last year,

[fortunate son fishing]

hey, sorry its been awhile since i have visited the forum. not sure if im supposed to comment on an old one or start a new one so im just starting a new one.

ok so i have the 1985 bayliner trophy, aq125a/270 and recently got her out of storage. cleaned up test run and getting ready for this summers fun. i was talking about a re power.(not going to anymore) i went out yesterday and played around a bit. hit a lil over 5,000 rpms by myself going around 23mph. from last year almost every trip out had a least 4 people on board every time. hit the 4,500-4,800 rpm range and maxed out at 17-19mpg depending on waves. i would like to get to the 23-25 mph range but am not sure what to do. i know my prop is a 15x15, and my spare is a 14x15. with 4 people the 14x15 seems to work better but not by much. i have two books for maintenance but doesnt give me a prop spec. does anyone have a suggestion on what i should run. im thiinking of trying a 14x17 hopefully don s can answer this for me.

side note. im thinking about switching to electronic ignition still and possibly a new carb, or new head with the 2 carb set up. but would like to see if a prop can get me where i wanna be before doing this. thanks guys John, Fortunate Son

 

[Mullin]

Re: bayliner problems from last year,

I think if you go up to a bigger pitch on the prop then your rpms will dip too low. From what I've heard 'lugging' the motor can be very bad.

5000, 4500-4800rpms...that's a huge range. If you where running at 4500 rpms I'd say drop a pitch to raise the rpms, but 4800-5000 is right on.

I boat at high altitude (6750ft high) and needed to drop pitch to raise the rpms. The boat came with a 19 and a 17 degree prop, I bought a 15 degree prop and it now revs a little too high if I'm the only one on it, to 5100rpm. It is better though and more responsive too. When towing a tube now I can punch it in a turn and really whip the tube around. And It didn't loose any speed, still hitting about 28mph IIRC.

I just put in the Hot-spark electric ignition kit. Works great and is easy to do, and only like 50 bucks.

EDIT-
I was thinking that since you have the heavy 'trophy' version of this bayliner, perhaps trim tabs would be a worthy investment. I hear they can really do amazing things for getting up on plane and picking up the back of the boat.

 

[Don S]

Re: bayliner problems from last year,

You can install a new carb, and a new ignition system, but you need HP to go faster, about 10hp per 1 mph in speed. You must keep your WOT (Wide Open Throttle) in the specified range for your engine which is 4800-5000 rpm at normal load.
You do not want a prop that lugs your engine, or it won't last long.. It's only a 117 hp motor.

Will move this to the Prop forum for more info on your props.

 

[steelespike]

Re: bayliner problems from last year,

The Trophy series goes from 14ft to 28 ft..You'll need to help us what Trophy?Apparently a big one.
We need the gear ratio usually on the leg somewhere perhaps a tag on the upper gearcase.
You can figure the ratio by removing the plugs and in gear count the revolutions of the flywheel for the prop to rotate once.
As usual Volvo numbers are beyond me. Seems AQ 125 would be a 125 hp near as I can tell soimetimes it is,270 apparently is the drive which I can almost never find in the right combination.Long story short what ever you can help with??
If we get enough info we may be able to tell if a little prop tweak might help.

 

[Don S]

Re: bayliner problems from last year,

Steelspike

Maybe this Volvo site will help you find the engines. http://www.volvopenta.com/volvopent...lication_search/pages/publication_search.aspx Type in aq125 and you will find all kinds of info.

Finding drives of the 270 and 280 vintage has to be looked up under engine model, not drive number.

One of those weird Volvo things. Took me years to figure them out, and I was a Volvo Penta certified tech.

 

[steelespike]

Re: bayliner problems from last year,

Thanks Don.I get the feeling from my limited explorations that Volvo makes many drive system combinations for
very specific applications thus the many confusing numbers.
Is that a reasonable assumption?

 

[fortunate son fishing]

Re: bayliner problems from last year,

ok thank you don.
i have trim tabs but they took a crap early last summer. gettin those fixed next week. i can get all the info off the boat tomorrow,

mullin- can you send me a link to the ignition kit you used. or specify which particular one you used?

im going to get a new fuel filter monday. not sure how often you replace them but im guessing its been a few years. I think im going to look at a new carb and plugs and all that to.

 

[rkcarguy]

Re: bayliner problems from last year,

Tabs make a big difference.
My prior boat would barely get up on step when we got 3 people and gear in it.
Installed a simple set of those plastic smart tabs SX and I was up on step in ~100ft with the same prop.
4800-5000 is the correct rpm range for this engine, if you are falling short of the 4800 minimum then you need to look at ways to get it up there. Less weight or move it forward, tabs, smaller prop, maybe a 14x15 4-blade Solas amita...around $120.