1996 Larson 194 Not accelerating hard and Low top speed

[BrodyO]

Hello,

I've recently purchased a 1996 Larson SEI 194. The boat has the 5.7 Volvo Penta, 550 hours. Engine runs great, super quiet and all stock as far as I can tell. I took it out last weekend with about 6 people. Boat ran and performed well but didn't seem to have the get up and go or the top end speed I expected from.that engine. Top speed was 34mph at 3900 rpm. I'm afraid if I add pitch for the top end and getting it to the right rpm range that it'll make my get up and go and time to plane even worse. Prop seems to be a 14.8" diameter and 19° pitch 3 blade. Any tips to a different prop that will improve both? Is there anything relatively easy to squeeze a few more ponies out of these engines, I'm mechanically inclined but I don't want to tear and engine that runs so good all the way down. Thanks in advance!

 

[Grub54891]

First, Welcome to the forums. I don't have any info for you at the moment, but others will chime in when they get back from boating/fishing. Going up in pitch I'd think would make it worse. But I'm not a prop expert.

 

[Sprig]

There’s a lot of unknowns here so with little information I’d suspect 3 things. First possibly water in the foam in the hull making the boat quite heavy. Second possibly incorrectly propped. Third the engine. Seems like you should be getting higher rpm at wot and any of the three could cause the low rpms and lack of power.

 

[Sprig]

Actually as I think about it 6 passengers may be a lot of weight depending on the weight of the occupants. That weight could be affecting the performance. Weight in a boat kills performance. Take the boat for a short ride by yourself and see how it performs.

 

[89retta]

Your rpms are about 1000 to low. You should be up around 5000 at wot. Check and make sure you have spark to all cylinders

 

[Old Ironmaker]

The first thing I thought was 6 people is a heavy load. But that doesn't explain not getting up to at least 4800 RPM even with waterlogged foam. If I have learned anything about propping from the boat folks here is you either get better top end speed or a better hole shot and get on plane quickly but not both.

Good advice so far and welcome to iboats. If a problem can't be solved by the folks here it can't be solved by anyone.

 

[JimS123]

My little 3.0 liter (that everybody calls crap on these forums) will easily handle 8 people onboard my 19 footer with only a few hundred rpm loss. Your prop size sounds about right.

Sounds like you're not running on all cylinders, your gas is crap, or you have some other engine problem.

 

[89retta]

One other thing to check . Make sure your carb is opening all the way. Remove the flame arrestor push the throttle to wide open and look into the carb and check that the butterfly is wide open. Do this without the boat running.

 

[JASinIL2006]

That is not right. My Larson 186 with a 350 Mag will do 50+ mph with 6 people aboard. Something is noy right.

 

[BrodyO]

Thanks for the replys. Engine only has about 500 miles. I'll make sure the carb is opening all the way and check spark on all cylinders, probably just replace all the plugs while I'm at it if you guys have suggestions for that. It was 6 big guys but I agree the rpm seems way too low but like I said the engine runs smooth as silk. I'll let you know if I get anything figured out.

 

[roffey]

comparing apples to apples, my boat is 20 feet and has a 4.3 TKS (carbed motor). With 5 adults and three kids we run about 4500 RPM and 45 MPH (just me I run 55 MPH on the GPS), I have 24 inch SS prop and it will get on plane. My feeling is your motor needs attention, maybe a tune?

 

[mr 88]

What rpms does she run at WOT with just you aboard ? After that report back, otherwise everyone is just throwing paint at the wall hopping something will stick. ^ 6 big guys with who knows what they brought with them vs a family with a couple of women and kids in a boat that I believe weighs a lot less than a Stingray is no apples to apples. A 19" prop is one of the most common setups for a boat your size with that engine and drive configuration

 

[mr 88]

Meant to write that it weighs a lot more than a Stingray, not less.

 

[frantically relaxing]

as others have noted, might not be firing on all 8- one dead cylinder would account for your speed & rpm...

Other possibilities based on past experience:
If it's carbed, and it's a Holley, the powervalve may be dumping too much fuel. Evidence of this will be soot on the transom...

Could be in the distributor- in my old Sun Runner the distributor bushings were worn enough that the shaft play was causing the ignition trigger wheel to run out too far as the engine sped up, causing too large a gap for the trigger wheel to trip the hall effect switch consistently. (New Mallory fixed that problem)

Check plugs & wires & ignition timing-

And finally, and this is a bit of a long, sad story- We bought our Regal from a broker, and 10% being a fair price to avoid the hassle of selling our beloved Chap 260ssi, we had the same broker sell it for us. It sold in less than an week.. A couple of months later, I spied our Chap being trailered- I had the piece of hose I'd removed from the water tank to the pump so I thought I'd give it to the new owners, and asked them how they like the boat. "Oh, we love it!! But-- we thought it would be faster!" That puzzled me a bit; it should be hitting 48-50-ish-- "Best we've gotten is 41mph at about 3900 rpm..." (sound familiar?)

Well, I'm not sure what the problem is, yada yada, and then as I make my way around the back of the boat, my heart sunk- the outdrive is covered in white milkshake...

Oh crap, I think I know why the slowdown-- and as I got closer, I noticed the dipstick was missing... Did you change the outdrive lube? "No, but [the broker] did, they changed the oil too.."

Whoever the dumass was at [the broker] that changed the lube forgot to put the dipstick back in! How many times you taken her out? "this is our 3rd trip". - Oh gawd-- get it back to them...

SO, I told you that story just to say: Check the outdrive too, whether or not it was okay the last time you checked...

 

[roffey]

Meant to write that it weighs a lot more than a Stingray, not less.

I guess my point was to say the boat does not seem to be running correctly and they should investigate.

 

[BrodyO]

Ok so here's what I have verified and found out since I last posted. Yesterday I verified that the choke was working and was allowing me to go full throttle and it was. Next I took the rotor off to make sure it looked good and wasn't full of moisture and it was good. Next I changed all of the plugs, all of the old ones looked golden brown and didn't appear to be misfiring, checked all of the wires and boots at the same time and nothing was cracked. I then made sure that the firing order was correct and it was. I got out on the water yesterday and tried it with me(200lbs) a buddy (275lbs) and my girlfriend(130lbs) and at first it was same deal, 35 mph but after that I felt kind of stupid. My trim sensor on the boat doesn't work so I'd always have it all the way down once we were in deep water, yesterday at WOT I slowly started to trim up and ended up getting the boat up to 45mph at 4400-4500RPM. It won't take off out of the whole with that pitch but still, it's much better. I still expected a little more out of it but that's much better.

 

[roffey]

I think you should be 4600 -5000 RPM at WOT and 4600 would be low. I think you mentioned you had a 19 inch prop? If so my feeling would be make sure the prop is not the problem, maybe bent or cupped. The RPM des seem low. Is your tach and speedo correct?

My lake mate has a 19 foot Larson with a 4.3 and his top speed is 48 mph with just him and weight is a big factor as is the trim. I can get an extra 10 mph by trimming up the motor.

 

[BrodyO]

The exact lettering on the Solas prop is 3x14.8x19R which means 3 blade, 14.8" diameter and 19 pitch right?

 

[roffey]

yup... 3 blade, 14.8 diameter, 19 inch pitch or 19 inches for every rotation.

if the prop is bent from digging in mud or cupped it will not have the right pitch and performance will suffer. Maybe some one will have the magic pill for your boat. To me the motor seems like you did all the right things but I do agree something seems out of line, not sure what, sorry.

 

[briangcc]

When starting from a dead stop, I trim all the way down (in) and punch the throttle. As the boat gets out of the hole and onto plane I start trimming out (up) until the boat porpoises and then I tuck it in a tad to stop that condition.

Something still seems off as to me, that speed at WOT doesn't seem quite right. You're pushing what...300HP? Provided everything is in top notch form I would think you'd be doing better. I'd do some more digging as that 22yr old boat is probably hiding a secret or two.