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Mercury v-150 black max pistons??? Stock or not?

Stevenlockamy

Stevenlockamy

Active member
I have a 86 mercury 150 black max. Just bought it 3 months ago I was pulling spark plugs and looking inside hole to just inspect pistons and noticed a raised casted number on upper top of piston it read 225! I have taken two of the same motors apart and have never saw this! Does anyone know or have any idea of what's goin on? Has someone put 225hp pistons in it? Power head is a mariner and has 135psi on all 6 so someone has been in it!

Just curiouse to know and trying to educate my self with this motor!
Any ideas what's going on Guys?
 
Is it a 2.4 liter or a 2 liter ? If its a 2.4 its just a standard cast flat top unless its been rebuilt with wiseco's . The 225's were chrome bore 2.4 liters but used the usual flat top piston.


Whats the serial number on the motor?
 
858-8346-c3 is block number. It a mariner power head. The number says its a 2.0 liter 150 the raised casting has me confused and they are flat top pistons like my other two 150's that I've blown up but neither one had the casting on top of piston like this new motor has!? The number on mounting bracket is A943061 which bracket and mid is mercury and I've had no luck with that number. No doubt it's a 2.0 but pistons have me baffled?
 
do you have the number off the welch plug ? That casting number is worthless

That number ... 0A943061 ... is for a 1986 2.0. It would not use the 225 pistons IF they are 225 pistons. . Never trust the mid tag. I have a 105 jet on mine according to the mid tag. Are you sure its the original powerhead? What number is stamped on the carb flanges? NOT the casting number. It will be a 14-1 or 22-1 or something like that on the top carb. 22-2 middle and 22-3 on the bottom. Something like that. Might not be 22 but you get the idea.
 
Last edited:
Serial Number identifies it as a 2.0L
ENG: 0A943061 1150766 MERCURY 150XR2 ELPTO
Manufactured 12/19/1985

But like you said, if the power head as been replaced with Mariner, that number probably wont tell you much
 
Power head was replaced with mariner,and what exactly is the welch plug? And top carb is wh-29-1..... So what does this mean?
 
Those are 85-86 XR-2 150 HP 2.0 liter carbs. Small venturi carbs that wouldnt run worth a flip on a 2.4 so its probably the right carbs for the powerhead. If they are original to the motor it's probably a vertical reed 85/86 2 liter 150. Could be the original powerhead on the mid. Why do you think its a mariner powerhead ? Nothing on a Mercury powerhead to distinguish it it from a Mariner. Its all exterior dressing and stickers that make a mariner a mariner. Without the block serial number why do you think its a mariner?

The welch plug is on the starboard side at the rear of the motor above the cylinder head. MOST V6 mercs/mariners have one there and it has the serial number stamped on it. You'll occasionally find it stamped on the flange where the front half and block meet. On rebuilds from Mercury its often missing.
 
The power head block number number is 858-8346-c3 I've looked it up and says its a mariner. It's also silver like a mariner...... So prob nothing special with internals was just curiouse about pistons? But motor will push my enticer 70mph so she runs great! So would changing carbs help if so what numbers of carbs? Looking to gain 1or 2 mph
 
Mariner poweheads are not silver. If its silver someone painted it that way or it was just never painted black from Mercury. That casting number is meaningless. All mercury and mariner powerheads in a multi year range have the same casting number. Then they are machined and have different specs for different motor builds. that casting number is going to be found on most all mariner and mercury 2.0 liter outboards from the early 80's when they went to heead bolts that didnt go into the cylinder walls up through '89 or so until they went to the fat block. Its the numbers stamped on the welch plug or hand stamped into the block itself that tell you what the motor actually is. In other words stop looking at the cast in casting number / block part number. It means nothing and certainly does not mean it is a mariner powerhead. Its probably the original powerhead to the motor given the carbs are correct for an 85/86 mercury and you have an '86 mercury mid section. In short you have a vertical reed XR2. Theres not a LOT you can do to it. Changing carbs wont do anything. Raising compression will. Get some 28 CC heads on there and run premium gas. Pick up some Chris Carson reeds. Run the jetting up 2 numbers.Simple stuff makes a big difference. Switching to a horizontal reed front will help top end at the expense of the bottom end. Same with the tuner.
 
Thanks Wired I will deffinately look into what u mentioned! I know the 2.0 motor is not a power plant but would like for it to out perform most 150's! Haha, or I may just keep saving for a 225 pro max. That's what I really want and I'm sure with right set up boat should run high 70's easy maybe 80's
 
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