Merc 650xs

[Popa Sam]

I ran across this in some old papers and thought it may answer some questions that I've heard about these motors. Mainly when they were introduced.

[peterse90]

The 650XS was legal for FE and SE classes here in Canada right from the start.
A few showed up in 1975 and by 1977 there were quite a few.
I had mine in 1978 and 1979 on a Seebold SE hull.
They were still being used and still very competitive right into the mid/late 80's against the OMC's. That's why FE/SE were such great classes to race in here in Canada because we had Merc VS. OMC racing.
I believe the 650XS was a legal engine everywhere but the US.
The Merc 650X (the MOD 50 version) I think started in 1976.

[Mark75H]

I thought the XS was approved by APBA as a regular FE/SE motor ... 250 per year, sold thru regular dealers and advertised in the regular catalog.

[peterse90]

Quite a few American drivers use to compete in our CBF races here in Canada, not one had a 650 XS.
I remember the SE class in St. Louis in 1980, about 20 boats and not one Merc.
I think by 1975 Merc had pretty much handed FE/SE to OMC in the US.

If I remember correctly any joint sanctioned CBF / APBA races that were held in the US we were not allowed with our 650 XS

[Mark75H]

Yeah, if the 650XS was sold in 75 and was not in the 75 catalog, APBA might not have approved it until 76 when it was in the main catalog. That would explain it both ways.

The XS had more success in Europe than North America, even that ended as the OMC Mod 50 motors evolved. In the kneel down modified division, one of our bench marks is the power head had to have once been approved as an OPC stock motor. The 650XS is legal under that definition in mod. The X motors were run under APBA OPC mod rules and OE rules and didn't have to be approved, so the 650X and 700X are definitely out ... even if enough of them had been made.

[peterse90]

The XS had more success in Europe than North America, .

The XS had GREAT success here in Canada, and was very competitive for many years.

[stinger]

There were a good number of 650xs running here in australia from 1976 on.Also 650x and 700x.These motors were basically a twister 11X cut in half. The 650xs was used on both v bottom and tunnel boats.Rated flywheel hp was approx 90hp.The 650xs in competition here, was performance wise ,about equal to omc 75 stinger and hustler short shaft models,maximum flywheel rated at 80hp. The omc model FT19s came here in 1977 with a flywheel rating of 110hp, these competition models were allowed to run in stock class?The omc FT19s was far superior to the 650xs. The 1500xs and 85xs models here were basically stock although slightly tuned,the 1500 at 155hp and the 85 at 90hp.

[Mark75H]

In the US we were never told the 850XS was anything other than 85 hp and OMC never revealed the hp of their race motors.

Do you know what would be different to make an 850XS 90 hp instead of the regular 85 hp?