New (to me) engine teething problems

[Smagu]

Thanks to the help on this forum got a 80hp 2 stroke late ‘80s I think, on the rib and seems to run well.

Few teething problems

1. Engine has a bit of a sneeze at idle and doesn’t like to idle as well as being hard to start. Going to clean carbs and reassemble anyone know what the stock mixture screw setting is roughly as a starting point

2. When in reverse engine likes to lift itself up out of the water (not much at low RPMs) but due to the issue with idling have to give it a bit of wellie to keep running so that may be the cause of this

3. The volts seem to get very high once today they were registering 15.2v!

4. At WOT after around 2 minutes it sends a constant alarm and goes into a sort of limp mode. This settles after turning it off for a few minutes. It pumps water well and doesn’t seem to be too hot.

It’s a premix version. 110psi top cylinder 107 middle 105 bottom. All spark plugs appear a healthy colour.

Any advice would be appreciated. Struggling to find any manuals either

[Tim M]

What model engine is this - you simply state 80hp 2-stroke. The idle issue sounds very much like carb / mixture related. The reverse issue sounds like something is broken or a catch isn't being engaged. I assume this engine doesn't have power trim? There won't be any sort of "limp mode" on a 1980s 2-stroke, so your alarm is likely to be overheating (you state its premix, but did it ever have auto mix / oil injection on it?). Again knowing at least what manufacturer this engine is would help point in the right direction.

[Smagu]

Tim you are correct sorry completely forgot all that information!

It’s a Yamaha 80hp serial number “L 350 123” 80 aet 6ho

Looks like it’s never been autolube from what I can see

It is power trim and tilt.

I think it must be overheating water only 4 degrees Celsius tho and good tell tale. Afraid to check thermostat as it’s an old engine and the last time I done that on an old engine a bolt broke causing a nightmare issue. Going to run a lot of salt away engine flush tablets through the cooling system.

[Tim M]

If it’s got power trim and it’s kicking up in reverse then it sounds like something has broken because it certainly shouldn’t be doing that. Does the PTT work properly up and down? Check the condition of the PTT assembly - try raising the engine up by hand (might be a two person job) then hold it in the raised position by wedging a piece of wood between the engine and the saddle bracket. In particular check the condition of the ram that’s in there - I wonder if the weld at the end of the ram has failed hence the engine is flailing around like that.

[Smagu]

Tilt and trim works great.
I’m wondering if the manual release isn’t properly tightened up. Must check this. The only other thing I can think of is the skeg has been broke off previously could this have damaged something?

Now I’m wondering about this over charging. Any way to narrow it down? Struggling to find a rectified for this old engine.

[GARYSHORT]

May also be water moisture in the fuel. Do you have an in-line water-fuel separator? Do you treat your fuel?

[Smagu]

So finishing up a few of the points above

1. Likely rectifier will report back when new one ordered
2. Engine jumping up in reverse due to manual tilt trim not being tight (Simple fix!!)
3. Rebuilding carb at moment will report back on how it runs
4. Overheating due to multiple blocked cooling ports (see new post, any gasket advice appreciated i.e OEM over after market)