need help with 200 merc black max

[steven]

i have a 200 merc black max it started as a 1983 but slung rod thruogh block was put back togeather with 1985 block and a 150 crank but ever sense then it keep blowing #2 cyl the carbs were spotless timing is correct and all cylenders are firing at the right time. any one know why this is doing this im going to build it one more time this makes 6 times and i really want it to stay togeather this time.

 

[Chris]

A common cause is a lean condition.

What does the cylinder and piston look like when you pull it apart?

-Chris

 

[steven]

the piston starts scaring and chipping at exhaust port, thats wat i thought too but i was running more than enough oil and the car was jetted out and spotless i was thinking maby the choke solonoid/valve sticking open might couse it is it possible?

 

[Chris]

The other things that come to mind are reed valve issues or a blocked exhaust port.

I gather there are no signs of a overheat condition?

-Chris

 

[steven]

no no over heat nothing else getting hot has 5 psi water pressure at idle and 10 to 15 psi or higher when running above idl and thermousstats have been removed and exhaust port is completly clear. and it has a new set of performance reeds made from plastic or wat ever thay are made from but not metel.

 

[Chris]

Hi Steven,

If you've checked out all that stuff, then you've got me brother.

Chris E, one of our other members is pretty good with this stuff, perhaps he'll be around and add to my ideas.

-Chris