Trimming up a small engine

[Rusty Bluck]

Can you pick up some speed by trimming up a 9.9<br />I have a 17.5 gruman and its slow. Do you think you could pick up any speed with a homemade jack plat?????

 

[Beaux]

Re: Trimming up a small engine

You would get a lot more results out of lightening your load (weight) in the boat than by a jackplate. The word speed and 17' w/9.9 are kind of like oil and water. Also, Is you motor running at its normal rpm at wide open throttle? BTW, what exactly are you considering slow?

 

[Rusty Bluck]

Re: Trimming up a small engine

Its running at about 9 mph. I dont think the motor is turning out the rpm that it should. A friend of mine has the same boat and he has a 15hp kit on his boat and its not any faster than my boat. <br />I want to get a bigger engine but there are allot of 9.9 lakes around here.

 

[steelespike]

Re: Trimming up a small engine

R B, See if you can find a load prop for your motor.Carry as little weight as possible and<br />be careful to distribute it evenly.<br /> I have a barebones 18ft utility that I know would plane with your 9.9. Not sure how much load it would plane but I bet 3 light guys carefully placed would plane.<br /> If your boat is glass it is eating up most of your power.If its full dress that is a lot of wasted weight as well.Keep the weight to a minimum.

 

[Beaux]

Re: Trimming up a small engine

I would say a prop change would make a difference but you need specifics to make sure you dont over-rev your O/b. If you can find a shop tach to borrow from a buddy and see what RPM you are turning at WOT, then you can see whether or not you need less pitch or different prop to allow for higher rpms at WOT. If you are in rec. range, you should not do anything to motor/setup except play with weight and distribution of weight to allow for easier plane. Of course, this is just my opinion. Sounds like you are setup okay anyway. If you give specific weight of rig,model # of motor,rpms at WOT,type and size of prop you have now; then one of these prop gurus like Dhadley could help you determine what would be best for top speed. Good Luck

 

[OBJ]

Re: Trimming up a small engine

Performance of your rig could be improved by raising the motor so that the anti-ventilation plate (that's the plate right over the prop) is even with the keel of the boat. No more than an inch above. This is taking into consideration that you have the right shaft length for the boat which I am assuming you do. If you raise the motor, keep the clamps at least 3/4 inch from the top of the transom and use bolts to secure the engine to the transom. A wood block under the transom clamps will help hold things in place. This with the right prop pitch (there is an 8 pitch available) may help. But as Beaux said, a tach or some means of checking rpms is highly recommended.<br /><br />OBJim

 

[SpinnerBait_Nut]

Re: Trimming up a small engine

You can get you a bigger motor and mount the one you have now beside it to use on your 9.9 lakes and have the bigger one to use elsewhere.

 

[OBJ]

Re: Trimming up a small engine

Guys around here do that a lot spinner_bait nut. We gots lots of 10hp restricted lakes. <br /><br />OBJim

 

[brent suzkui wyble j16]

Re: Trimming up a small engine

Outboard Jim, get a Suzkui 15 4 stroke and take the decal off the back! 23mph on a 16' glass skiff! w/9 pitch 3 blade. works in north FL.

 

[OBJ]

Re: Trimming up a small engine

Hey brent....<br />That's what a lot of guys do up around here. Or they get their 9.9's beefed up. Always funny some guy comes in and say's "Soandso passes me up like a freight train passin up a bum and we got near identical rigs. Fix it!" And what's wilder, 95% of them don't give a hoot what it cost. Ya'd think they wuz fishin' the Bass Masters every time they went out. Lord ya gotta luv this buisness!!<br /><br />OBJim

 

[brent suzkui wyble j16]

Re: Trimming up a small engine

outboard jim, what can be done to beef up the 15?

 

[OBJ]

Re: Trimming up a small engine

Hi brent...that's a good question. Never give it any thought as most everyone around here is only interested in getting their 9.9's beefed up to 15's. (restricted lakes and all) I don't think there is much you can do as far as bolt on stuff is concerned. You may be able to bore it out to the max (book says .030 over) go a jet size over (maybe) and install power reeds for smoother pick up and acceleration. If you go all out, there's a guy over in Jersey that can get these to turn 9grand. He was also an instructor for OMC. I'll have to take a closer look at it though. I got a couple 9.9/15's setting at the shop I been tinkering with. <br /><br />Anybody else got any input?<br /><br />OBJim