35 HP Force seems weak

[SEGAangler]

I have a 1987 35 HP Force on a 1982 LamPro 14' tri-hull (I'm not sure of the boat's actual weight; it's rated up to a 70 HP). The engine seems to run well however it barely moves my boat. While I know I won't set any speed records with this combo I expected more than it's giving me. I can only get up to about 7.5 mph while going WITH a strong current. Does this seem right or possibly a weak or troubled motor? I have checked the shear pin in the prop and it is still good. (It has a 10x13 prop).

 

[wickware]

Re: 35 HP Force seems weak

Post some pics of your boat and motor from the rear and side showing the props location to the boat. Something might not be setup correct and causing a conflict that Pros can help with. I get 30 + MPH with me and fishing gear in a 15 ft fiberglass Raycraft with a 1970 35 HP Chrysler. Most of all I can get on top of the water with two of us and gear.

Any history of the boat being water logged from going under water will help.

 

[SEGAangler]

Re: 35 HP Force seems weak

Unfortunately I bought the boat used not too long ago and don't know it's entire history. It hasn't been sunk that I'm aware of. The boat seems light (I move it around on trailer by hand). I will take it out of garage and get better pictures and side view after work. The basics that I've read appear to be correct--cav plate basically even with keel...motor sits perpendicular to water surface.

 

[jerryjerry05]

Re: 35 HP Force seems weak

Do a compression/spark test.
Check plugs for proper burn?
Motor looks like it's setup right.
Is the throttle linkage working correct.
Take the cover off and check it out.
Does it rev up when it's moving?
Check for water in the fuel,check the fuel pump diaphram for rips/tears?

 

[wickware]

Re: 35 HP Force seems weak

Back to Basics! JerryJerry covers them well, Good ?Fire, Fuel, Compression.

1 .Do you have a way to check the RPM, Compression, Fire and pic of plugs close?
2. Can you riv it up on a youtub or will a voice mode pic work (I tried to att one and it was not allowed)?
3. I am getting a feel that you are not getting good rpm to get good power.
4. Going back to are you getting a good full throttle range on the motor?s linkage, carb and rpm?
5. In a barrel I?m not sure how high you can take it above idle for a second to show it will go up. ?HELP Pros?!
6. I might have hit 500 rpm above and I knew I had a lot to go but would not in a barrel vs a lake "trailered".

 

[SEGAangler]

Re: 35 HP Force seems weak

I am going to borrow a gauge and check compression. I'll post results. RPMs...I haven't got a tach. I will rev and post it on YouTube. (I'll post link to it). The linkage APPEARS to have full range but I am going to ensure it truly does while in gear also. I will also put up pics of plugs for you

 

[SEGAangler]

Re: 35 HP Force seems weak

Quick update and one problem found (hopefully the only one). I am NOT getting full throttle travel when in gear. I get WOT in nuetral but when in gear I'm only getting about half-throttle when "wide open". The following pics are 1-WOT in nuetral; 2-WOT in Fwd gear; 3-Shift linkage; 4-shift plate. Is there anything that stands out as wrong in the pictures or where should I begin looking to see what the conflict is between the shift cable and throttle cable?

 

[jerryjerry05]

Re: 35 HP Force seems weak

Put it in the water.See if it really isin't going all the way.
Go for a ride with the lid off and someone else driving.
Basics,Any one working on anything needs to start there.

 

[Frank Acampora]

Re: 35 HP Force seems weak

Took me a couple of minutes to figure it out:

Check on the shift linkage going up toward the flywheel. There is a plastic "clip" that prevents full throttle operation in neutral. It moves up to clear the magneto advance plate when in one gear and down to clear the plate in the other gear, allowing full throttle operation. Yours is obviously not adjusted correctly since it is allowing full throttle operation in neutral and limiting travel in forward.

You will need to adjust the plastic piece on the threaded rod and there MIGHT be something else you need to adjust too.

 

[SEGAangler]

Re: 35 HP Force seems weak

Thank you to EVERYONE who has helped with all the wonderful advice. Frank...you nailed it. That little plastic clip/pivot point on linkage was hitting the little safety tab keeping it from throttling. All appears correct at this time and (weather permitting) a trial run is scheduled for after work tomorrow. I will update on the outcome.

 

[SEGAangler]

Re: 35 HP Force seems weak

Trial run was an absolute success! Thank you again for all the help & advice