Mercury XS motors

[2us70]

Can any of the Mercury insiders explain the differences between the XS motors and the standard production motors? I raced the 500, the 650 and the 850 quite a lot but I stopped before the XS versions came out.

[WaterZebra]

Can any of the Mercury insiders explain the differences between the XS motors and the standard production motors? I raced the 500, the 650 and the 850 quite a lot but I stopped before the XS versions came out.

The 1500XS was ported for top end and had a low water pick up gear case. Louvered cowl too.

[2us70]

Can I assume the 650 and 850 also had the low water pick up units also?

[WaterZebra]

Can I assume the 650 and 850 also had the low water pick up units also?

Important point: All XS models were built with short mid sections. OMC never did except the 3 cylinder models. The 850 had a low water pick up but I can't speak for the 650. I would loved to have run the 850 in Sport G but there was no class in my region at the time. I don't think the 850 had a louvered cowl either.

The 1500XS was the engine of choice for Sport J racing. I never bothered to attend any divisionals or nationals because it was dominated by the likes of Doug Pearl, David Lee and Ken Hoffman.

[2us70]

I recall the guys running the standard 1500s having problems with overheating the top 2 cylinders when running high on the transom. The 3 and 4 cyl motors didn't seem as prone to this problem. I also remember a few folks getting caught running the speedo pitot hose to the motor instead of the speedo head. I would have liked to have been able to run those low water pickups to avoid having to limit engine position based on water pressure.

[WaterZebra]

I recall the guys running the standard 1500s having problems with overheating the top 2 cylinders when running high on the transom. The 3 and 4 cyl motors didn't seem as prone to this problem. I also remember a few folks getting caught running the speedo pitot hose to the motor instead of the speedo head. I would have liked to have been able to run those low water pickups to avoid having to limit engine position based on water pressure.

I think the F (family class) guys didn't have the cooling problems like the Sport (tunnel) guys did. The Vee bottoms would form a "hump" of water behind the transom which would catch the gearcase. I never liked the OEM stock classes because the concept of "stock / OEM" was taken to ridiculous limits. Best way to provide cooling water is to scavenge prop blast water (which Mercury actually did in the mid 60s). The OMC world speed record (176 mph) actually found another 4 mph by plugging the gearcase low water pick ups and using prop blast instead (RC K&B outboard style).

[2us70]

The Production (Family) class boats could also have water pickup problems since you could jack the motors up as high as you wanted. Once notch back transoms became popular the water pickup problems kind of went away. The one class that never had the issue was FS. The Family Ski class boats were just J production boats with seats for a crew of 2, a much higher weight limit and a motor height limit. This height limit caused a different problem. Shoving that big clubfoot lower unit through the water caused sudden and unpredictable prop blowouts. Not fun in a pack of boats to suddenly have one turn hard right or left.

[WaterZebra]

The Production (Family) class boats could also have water pickup problems since you could jack the motors up as high as you wanted. Once notch back transoms became popular the water pickup problems kind of went away. The one class that never had the issue was FS. The Family Ski class boats were just J production boats with seats for a crew of 2, a much higher weight limit and a motor height limit. This height limit caused a different problem. Shoving that big clubfoot lower unit through the water caused sudden and unpredictable prop blowouts. Not fun in a pack of boats to suddenly have one turn hard right or left.

Was the FS class an ancestor to Mod VP?

[2us70]

I don't think so. Mod VP came after I had stopped boat racing so I am not familiar with those boats. As I recall FS was an attempt to get more regular boaters into racing. There was an Evinrude dealer who even rigged a Hydrostream with complete dual controls. His plan was to introduce and train new drivers in it. He named the boat "Drivers Ed". The guys name was Ed Mead so the name was pretty clever. The boat did not do well and he sold it to Tommy Chandler who put a Mercury on it. I think Tommy may have run it in J Production. At Action Marine we had built an FS boat for Tommy and his buddy. That boat suffered a big prop blowout at the start of a heat at Nationals in 1973. Scared his buddy so bad he never got in a race boat again.

[largecar91]

The 650XS did not come with a low water gearcase. the 650X/700 came with a Speedmaster gearcase. These were 1/2 of a T2/T2X powerhead. I don't know exact HP but I was always told around 90.

[WaterZebra]

The 650XS did not come with a low water gearcase. the 650X/700 came with a Speedmaster gearcase. These were 1/2 of a T2/T2X powerhead. I don't know exact HP but I was always told around 90.

I think the 650XS was expected to beat OMC's SE engine but the results were dismal. I vaguely remember Mike Seebold running a 650X before stepping up to the bigger engine classes? Does anybody remember Mike Seebold running a T2? I think the 850XS only made one model year appearance in Merc 's catalog?

[2us70]

In 1970 and71 I managed to hold off the OMC 49in motors in SE with a 44in Merc 500. My 1970 Nationals win was the last for a 44in motor in SE. In 1972 I started running a 13' Action with a 49 in 650 in E Production. In the heavier Production boats The OMCs loop charged motors already had the advantage in spite of an inferior lower unit. In 1973 we figured the only chance for a Mercury was maybe in the much lighter SE boats. We took the motor from my E Production boat and stuck it on a little tunnel boat we had in the shop. We took this boat to Eufala Alabama for Nationals. In the first heat of the finals we broke the 5 mile record only to have the record broken again in the second heat by Bobby Drewery. We wound up second to Bobby. Both boats were Mercury powered. This was the last time Mercury won Nationals in SE class. Same motor different results. Also note how high we had the motor on the tunnel. We used tunnel strakes to direct water to the water pickups on the strut.

[peterse90]

The 650XS did not come with a low water gearcase. the 650X/700 came with a Speedmaster gearcase. These were 1/2 of a T2/T2X powerhead. I don't know exact HP but I was always told around 90.

This picture is old and maybe a little too small, but for SURE the 650XS did NOT have low water pick-ups.

Been over this many times before, in Canada in the late 70's and early 80's we had great OMC vs. Merc racing in both our FE and SE class racing. Merc 650XS was VERY competitive against the 49 ci OMC's;

Attachment 540677

[2us70]

I think the 650XS was expected to beat OMC's SE engine but the results were dismal. I vaguely remember Mike Seebold running a 650X before stepping up to the bigger engine classes? Does anybody remember Mike Seebold running a T2? I think the 850XS only made one model year appearance in Merc 's catalog?

At the 1973 Nationals Mike Seebold ran in SG. I ran one of Action Marines boats in an elimination heat against him.