what is stock compression for na 1991 fF/I 200hp 2.5?

[coffeeguy]

What compression numbers should I see on a stock 1991 2.5 fuel injection motor?
What would be a bare minimum lower number?

[TEXAS20225]

any merc small block compression falls below 100 yer done:eek: me i just rebuilt my pmax after breakin its 145//148 on all six

[jeff dunn]

What compression numbers should I see on a stock 1991 2.5 fuel injection motor?
What would be a bare minimum lower number?
Stock should be 120 to 125 , factor in gauges vary, but should be with in 5 lbs.
if you start seeing 10 lbs less diff , might wanna take a look.

[Riptide]

I have an original bone stock fishing motor 2.5 200 that has 130-135 on all 6.
Normal?
Not normal?

[1nebel0]

That is somewhat higher than stock...were the heads shaved? Need to do a Seafoam treatment to see if carbon is raising the compression if you have done a decarb procedure...

[Riptide]

It's completely stock w/ approx. 161 original hours.
I've put 61 hr.'s on it and it had around 100 original hr.'s on it when I purchased from original owner.
Block nor heads have even been touched.
Funny thing is, somebody mentioned a block stamping of 175 on a 225PM in another thread and this motor has the same 175 stamp on the block.
Hmmmm
I know it scoots like a scalded ape with his ass on fire.
I run rec 90 and sentry through it religiously.

Apologies Coffeeguy, didn't mean to hijack your thread.

Personally, I wouldn't even think about purchasing a used fishing motor under 125#'s unless I was getting it at a good price.

[tlwjkw]

Its all in tha "gauge".......They can be like "Chin's" ina Hong Kong phone book.

[coffeeguy]

I figured 125 + but have no ides if injected ones ran less. Thanks

[wired247]

It's completely stock w/ approx. 161 original hours.
I've put 61 hr.'s on it and it had around 100 original hr.'s on it when I purchased from original owner.
Block nor heads have even been touched.
Funny thing is, somebody mentioned a block stamping of 175 on a 225PM in another thread and this motor has the same 175 stamp on the block.
Hmmmm
I know it scoots like a scalded ape with his ass on fire.
I run rec 90 and sentry through it religiously.

Apologies Coffeeguy, didn't mean to hijack your thread.

Personally, I wouldn't even think about purchasing a used fishing motor under 125#'s unless I was getting it at a good price.


The difference between a 225 pro max block and a 200 is block the 7 petal front end. On an assembled engine there are other differences but none that affect the compression. My old bone stock 225 promax with new old stock block built from scratch with pro max parts ran 128-130 PSI on 3 good gauges. Current 1999 .015" over 225 pro max block has 134 PSI across the board with stock 38 CC heads .

Injected or non injected doesnt matter.