Mercury XR2 150 stuggling to get on plane.

[jimmbo]

What do 3 and 4 share? The Center Carb, if it went lean from Fuel Starvation...
Plug looks awfully Dry.
I doubt the 'Oil Injection' is to blame as Mercury mixes the Oil in to the Gas, so all Cylinders would get the same Mix

 

[Faztbullet]

Preignition throw off from piston is what you see on plug

 

[Dukedog]

$$ wise?.. its 2.0 motor.. ya may be able ta jus have a boring done on those two holes.. probably tha cheapest wat out............ jmo

 

[llyons]

Hi, went ahead and pulled the heads to see a little more. Here are some pictures.

I am thinking that piston 3 melted from getting to hot. You can still see the rings attached so that part is good (maybe avoid more serious damage to cylinder walls. Number 4 looks like a ring gave out. I am no expert just guessing.

I think I read that a piston can melt like this and it doesnt do damage to the cylinder sleeves?

Overall im guessing that it can be rebuilt. Am I wrong on this?

Can you tell from these pictures if it was an oil issue or over heat issue? There is oil injection is still connected and the reservoir is full. I can also see oil in the transparent fuel filter (bluish tint).


In terms of the oil perhaps missing in the middle carbs, how could that happen if the oil mix is done before the fuel pump and that all the carbs get fuel/oil from the same source?
It was mentioned that I should move to a 2.5L engine instead. Will that motor mount on top of the lower unit that I already have? Is the 2.5 significantly heavier than the 2.0?


I have a mechanic that does pretty good work and so I will bounce these questions of of him as well but just trying to educate myself as well.

 

[jimmbo]

Interesting that the Piston itself went bye bye, but the Rings are still there

Doubt it was Overheating

The only way those Cylinders would be starved of Oil and the others not, would be lack of Fuel to them. Go through the Center Carb and Fuel Line suppling it, very thoroughly, you will find a Blockage or Improper assembly/parts. I guess the Reed Block could be a problem, but since it is 2 Cylinders...

Swapping Blocks of Different Displacement, even different HP, may need a bunch of other parts to be changed too, even if the replacement engine is complete and will fit the Midsection. Exhaust Tuner for One.

 

[Faztbullet]

Preignition failure

 

[Dukedog]

"Preignition failure", agree...
with prices of tha used stuff (power heads) on tha market and tha chances of someone pawnin' off junk (unless you actually know tha person with tha part/parts) now days you might be better off fixin' that one.. depends on what kinda shop ya have ta do tha machine work?
have those two bored least amount possible, new pistons/rings (maybe all 6), at least hone and new rings on other four.. your choice?
heads milled flat..
deck checked for flat?
rebuild carbs, up one size on main jetting in center carb (if cylinders bored more than .015)
all new 'lectrics trigger, stator, switch boxes, rectifier
this all depends on how good, how much faith you have in tha machine shop.. thats key to rebuild of any kind............. jmo.

jus a note if ya do this.... CLEAN, CLEAN, CLEAN then CLEAN some more..................................

 

[southkogs]

@llyons I merged both of your threads into one: i think you'll do better with all of the details in one place.

 

[Faztbullet]

That motor has been apart before...#2 has a Siezco piston, #4 looks to have a .030 piston(P3 casting) and had the new style head gaskets instead of original brown gasket. IMO I would just find a running motor and swap and use this one for parts.

 

[Dukedog]

That motor has been apart before...#2 has a Siezco piston, #4 looks to have a .030 piston(P3 casting) and had the new style head gaskets instead of original brown gasket. IMO I would just find a running motor and swap and use this one for parts.

damn, ya have awful good eyes for a 'ole man.. i can't see squat..........

 

[redneck joe]

For the boat, if the floor stringers and transom are solid in your opinion then repower.

 

[llyons]

That motor has been apart before...#2 has a Siezco piston, #4 looks to have a .030 piston(P3 casting) and had the new style head gaskets instead of original brown gasket. IMO I would just find a running motor and swap and use this one for parts.

I believe that is correct. We had somebody rebuild the motor back in late 1998/99. However, I dont think any of the pictures shows piston 2. I assuming you mean 1 and 3 (the melted piston).

 

[llyons]

"Preignition failure", agree...
with prices of tha used stuff (power heads) on tha market and tha chances of someone pawnin' off junk (unless you actually know tha person with tha part/parts) now days you might be better off fixin' that one.. depends on what kinda shop ya have ta do tha machine work?
have those two bored least amount possible, new pistons/rings (maybe all 6), at least hone and new rings on other four.. your choice?
heads milled flat..
deck checked for flat?
rebuild carbs, up one size on main jetting in center carb (if cylinders bored more than .015)
all new 'lectrics trigger, stator, switch boxes, rectifier
this all depends on how good, how much faith you have in tha machine shop.. thats key to rebuild of any kind............. jmo.

jus a note if ya do this.... CLEAN, CLEAN, CLEAN then CLEAN some more..................................

Thanks

what do you mean preignition failure? what might cause that? I know it was running well at WOT and just suddenly quit. I made sure not to try and start it back up or try to crank it to much after it failed

 

[llyons]

For the boat, if the floor stringers and transom are solid in your opinion then repower.

This is a really good question. Its certainly an older boat but i have never had an concerns about the structure of the transom and boat. We have always used a transom saver, only used the boat like 7-10 times a year


How might somebody size that up? Its a 1987 champion bass boat.

 

[Faztbullet]

See post #34 and 39