Mercury 250xs ADVICE

**drwarz** · 01-31-2023, 11:24 AM

Is there Any difference between a Gold Block motor and a Black Block motor besides color , are the internals and porting the same. Thank You

**XstreamVking** · 01-31-2023, 11:37 AM

I think the gold blocks were hand built by merc racing. Had about 280 hp Black was reg. production with less hp.

**Dd24skater** · 01-31-2023, 12:16 PM

The gold block engines are amazing, most of the took premium fuel and p-plus oil.

**aj06bolt12r** · 01-31-2023, 02:57 PM

Here for the details.. What is actually different? Port timing? Compression? Ignition timing? Rev limiter? Fuel curve? How and why do they make more power than a black block 250XS?

**Chaz** · 02-01-2023, 11:09 AM

Originally Posted by drwarz

Is there Any difference between a Gold Block motor and a Black Block motor besides color , are the internals and porting the same. Thank You

Nope , yep , and your welcome ...

If you had a Alodine block .. and scattered while under wty. chance's are good it would be replaced with a black powerhead. It would run the same.

At some point, the 300xs blocks all came thru, black .. no better, no worse .. and if you scraped a small bit of black off of the surface, you would see that they are all Alodine underneath ...

**cameronj** · 02-03-2023, 04:18 PM

Originally Posted by aj06bolt12r

Here for the details.. What is actually different? Port timing? Compression? Ignition timing? Rev limiter? Fuel curve? How and why do they make more power than a black block 250XS?

I have experience with two 2003 250XS gold blocks and here is what i found/was told.

1- Higher compression
2- 03,04s have a lower rev limiter 5850 vs. 6300
3- Need to run premium on the XS pre 06 or 07(don't remember.) I always ran 93 or 94 octane.
4- On both rebuilds i had the ports blended/cleaned up a little but the XS blocks I was told were the best blocks picked and than hand built by Mercury Racing.
5- With the higher compression they have a different tune vs. the Pro XS
6- To my understanding different oils(XS = mercury racing and Pro XS = optimax oil. I always ran mercury racing in mine and never had an issue) - Make to mix the cocktail in with each tank IMO

Both I ran for one year each and loved each. Had one issue and it was the fuel pump relay which left me close to stranded but figured it out and swapped the trim relay over and made it home. After that i always carried a spare relay but never needed it. Fuel mileage was amazing VS. my 2.5. On both i upgraded the compressor to the newer black one and that would be the first thing i would do if i was you IMO. One had a DBR tuner/tune but no noticeable difference IMO except the rev limiter increase. I ran a 28.5 scorpion with extra PVS's drilled or a 27P trophy with solid plugs in all 3 PVS vents and was on plane with either motor either prop quicker than my 300X on the same boat with the same set up.