Correct spark plug for J 140 TLATF Outboard

[Rbeaulieu]

I know that having the precise spark plug for your specific motor is important. I find a number of plugs listed (I think)when searching for the correct plug for my 1993 Johnson J 140 TLATF 2 stroke Outboard Motor. I have found Champion QL78YC , NGK BPZ8HS-10 and others but the motor was sold to me with NGK BP R 7HS Plugs.
The motor was running fine until recently. I can rev it perfectly in neutral but when in gear and under load and wide open the motor push me about 10 miles per hour at best. Almost as if the gas is too rich (which its not) or it was running on 1 cyclinder.
First thing I wanted to confirm is that it has the correct plugs before moving on.
Thanks for any help you can provide.
Regards,
R Beaulieu

[Joe Reeves]

The standard recommended spark plug is the Champion spark plug QL77JC4, gaped at .030.

The alternative spark plug is the surface gap plug QL16V.

The engine model number you state of J140TLATF, I believe to be incorrect. It should be J140TLETF. There is no "A" in the model number!

Do not rev the engine over 1800 rpm when it is in neutral or on a flushette. You run the risk of encountering a runaway engine!

With all s/plugs removed... check the compression and spark. The compression should be around 100 psi and even on all cylinders.... the spark should jump a 7/16" gap with a strong blue lightning like flame... a real SNAP.

Let us know what you find.

[Rbeaulieu]

Spark Plug and compression

Hello Joe and thank you for your response.
After I got your reply I went out to the motor Model and Serial Number Plate and Model Number is actually what I had stated,with an A.
Model J140 TLATF Serial Number G 0331315 787
I'm a rookie boat and motor owner so my questions may appear a bit juvenile.
I was actually able to access that Johnson Model number when pulling up Spark Plug Charts but didn't trust myself.
Thanks for the advice on revving in neutral. Much appreciated. I didn't wrap it way out by any means .
I will need to go the you tube route to learn how to check the compression as you recommended.
I'm hoping that you might be able to access a Model number as I listed it with the A not an E. Sure would make me feel better

Thank You again for your reply!
Regards,

Randy Beaulieu