Force 50 Low rpm Problems

[jwall116]

Hello iboats!

New to the forums and as a boat owner. I recently purchased a 1986 Bayliner Capri with a Force 50.

I have ordered the manual for the engine, and just waiting on it to arrive. So I would like to ask these questions prior to tearing into the engine.

The problem I have is two parts,

1) In neutral, if i blip the throttle it revs up as normal but during the decel will buck and shake as if it's only running on 1 cylnder/ When it is doing this, it will not return to normal idle for some time.

2) While in no wake zones, rpms are just above idle it will be fine at low rpms and high but at a certain rpm.. lets call it 1500-2000 range it blurbles by means of dipping in rpm. A slight raise or lowering of rpms puts me in the <1500 rpm or +2000rpm.

Does this sound like a timing issue? I have replaced the plug, they were black, and full of oil (previous owner ran it at 40:1.... YES he was an old man stuck in his ways)

Fuel is marina 87 gas, Oil is Penz semi Synthetic @ 50:1

I am not new to 2 strokes, but brand new to marine 2 strokes.

Also the boat is only getting 25mph via gps. The engine sounds good at full throttle, however I was expecting around 28mph with just me in the boat.

Any insight would be highly appreciated!!

 

[jerryjerry05]

#1: The throttle cable might need to have a bit of back pressure to make it come down when slowing down.
UNhook the throttle cable.
Put it in N
Then see where the cable meets the ball.
It should slip over the ball with a bit of resistance making it tight.

First do a compression and spark test.
The 40-1 might have add a bit of carbon to the rings.

Is the motor running on the right pin on the transom?
There are 4-5 holes where the pin can go and it can put the motor at a better tilt.

How much of a load ?
The 50 wasn't meant to go real fast.

How many RPM's at wide open?
They didn't put a tach on the small Bayliners, get a Tiny Tach it's easy to use.

 

[jwall116]

I have ran sea foam through two tanks of gas back to back. I mixed 1 can to 5 gallons and ran it wide open

The surging problem has gone away, the low speed adjustment was about 1/4 turn too lean. Enriched that needle and sped up the idle and she runs great.

I have checked and messed with engine trim, There are 4 usable slots. Counting #1 from the transom, I have tried slot #2 and #3. #2 kept the bow down in the water and left me with lots of sea spray and -4 mph top speed. Slot 3 is where i was when I bought the boat, and I havent tried the highest slot.

The engine has planing foils on it so I may adjust and move up to the top slot. I do not get any bow surging on slot #3 and am getting 25 mph.

Waiting on my compression tester to come in.

Plugs are great, engine runs great. Just want a little more speed!

Tach has also been ordered!

 

[jerryjerry05]

More speed? Try running with the fins/foils off.
The farthest hole will probably be too much. The bow will be up too high on take off.
The PO probably had it in the right place.

Load: too much of anything? Leave it at the dock.

The 50 did have a T/T system.
Not that hard to install if you can find one from a fresh water motor.