1976 Mercury Racing 650XS outboard intake and carbs

[Fast Fred]

1976 Mercury Racing 650XS outboard intake and carbs
NO RESERVE, NO RESERVE, NO RESERVE !!!!!!!! Item number: 270143161798

like 4 hrs left, it's at under 300bucks, for yous cross flow guys, see if it will fit a 59cuber, i 've seen the factory Dyno slips on the 650merc did make 100hp at the crank.:cool:

[RogerH]

The intake assembly is in great shape and came with an additional manifold and two complete reed blocks. Anyone got a 3-cylinder 650 I can start with? I've got two rebuilt 4-cyl. 650 power heads if you want to swap. What was special about the midsection, and what gearcase did they run under these? How about exhaust. Sorry, lots of questions. Could use some help putting a motor around this intake.
Thanks,
Roger

[Mark75H]

They used the smaller 50 hp sized lower unit

The mid section had solid motor mounts.

I think some years/versions of the regular motor were basically the same from the crank down with the exception of the motor mounts.

[mercmack]

There Is A Merc 700 3cyl Block In E-bay...this Will Get You Started
Its A Complete Block And Crank Assy..good Price Too.
E-bay No....290142145244
The Same Guy Is Selling The Gearcase/lowerunit Also..
Its The Short Shaft Tower Thats Going To Be Hard To Fine..
I Do Have A Set Of Solid Mounts If Your Interested..

[mercguy]

The intake assembly is in great shape and came with an additional manifold and two complete reed blocks. Anyone got a 3-cylinder 650 I can start with? I've got two rebuilt 4-cyl. 650 power heads if you want to swap. What was special about the midsection, and what gearcase did they run under these? How about exhaust. Sorry, lots of questions. Could use some help putting a motor around this intake.
Thanks,
Roger

too bad you did not live closer to me Rogar, as I have a couple 650's I would give you!!! Both need repair (like they all do or will shortly). I also have short midsections and lower units.............all from 50hp's......

[crankbearing]

Roger,

The 650 3 cylinder and 700 triple stock motors use bigger pinion gear then the 50HP, an moreso if you are going to put that powerhead on top of it. They also used a D2 gearcase, the length of the lower end of the driveshaft is longer then the 2nd gen 50hp motors.

You are going to want to get a 650xs,700x or the like block to copy the porting from.

Regards

[RogerH]

Dave, Thanks for the pointers in your reply. I need all the input I can get. I must admit that I'm getting confused between the 650XS and the 650X / 700X. It is apparent that the "X" motors were strictly race with SSM LU's and ported blocks etc... Can you confirm whether the "stock" 650XS motor was in fact just a stock 3-cylinder 650 or was if a modified block in some way?

Right now I just have a complete crankcase/carbs and a stock 70hp 3-cylinder motor. I lost the 700X block on eBay (tried hard - not hard enough), so am not sure what I'll build. The foot is still very confusing to me (50hp ?? D2? low H2O puck-up?? etc???). Daren and others are right that finding a 15" LU is difficult. Anyone have one?

Take care,
Roger

[crankbearing]

Roger,

The 650XS in my estimation is the exact same port wise as a 650X or 700X. They are very radically ported and were a Sand Cast / Die Cast combination one of the two can never remember which casting method went with what engine. So to answer the question no a 650XS was not a fishing block (service block) in that terminology. They were an as cast full race model.

The 650XS DID not have low water pick-ups that I know of it used a stock 650/700 Fishing lower unit. I have tons of these lying around and could rebuild one for you. I think they used the stock gear ratio as well. The D2 I am referring is a casting number located down in the housing that we used in the field to distinguish a 650 3 cylinder lower unit from a 50HP 4 cylinder lower unit and again the driveshafts are a little different. Sam is correct a stock fishing housing 500, 650, 700 etc will work and you can add the solid motor mounts to it. I thing I have tuner plate and housing in any form. I even have a bunch of short shaft 50 housings with shocks as well if you wanted to build a short shaft version. The 650Xs were all Long Shaft motors if I recall.

Now one thing I WAS NOT aware off is that the blocks were mated as a casting finish instead of the machined finish we know of most blocks. If this is in fact the case you are going to need to machine the faces (mating Surfaces) and Align Bore that block combination to be sure that you match up 100%. This was mentioned in a post on another board from Jerry Wienandt.

[Mark75H]

The 650xs blocks were sandcast and use the 3 carb type front. They came with the 50 hp sized foot that was used on some years of the regular Merc triple. One difference in the mid was use of solid motor mounts instead of isolation

650x and 700x used a diecast block, 3 carb front and sat over an adapter that mated them to the T2X mid. Because there was less horsepower than normally used with a Superspeedmaster, the rear gear set was not used and the gear ratio had more reduction ... 13:16 I think.

Merc claimed 90 hp for the 650XS, speeds & lap times from the 650x & 700x suggest about the same power.

The Tillotson TC3 carbs are virtually impossible to make run consistantly right. There is a little variation in the carbs between the XS and X motors, some use a single fuel nozzle and others a dual nozzle.

Merc made a prototype looper triple based on another crank, so it's not the same motor at all. Fred Hauenstein was involved with it and posted some of the details here on BRF. None of these looper triples were ever sold and were not raced in the US.

[Trident]

Don't mean to quibble, but the 650XS block is NOT sandcast. The Crankcase cover and intake manifold is sandcast. The block is diecast.

I'm looking at two of them, here. Perhaps some of the misunderstanding is because the die casting is unpainted and has a slightly rough texture, kinda like the 44XS race block (on painted service blocks you don't see that texture) Older blocks, like '60's M500's are smoother, even under the paint. The sand cast case and manifold are much rougher, cruder castings and are a slightly different color. This is also true of the 650X and 700X.

No, the porting is NOT the same on a 650XS/650X and a 700X. The 700X has the more radical porting. Too radical, in my mind... I felt the 700X was a better dyno motor, the 650 variants, with some modification, got around the course better. (The age old trap: if some is good, more is better, then way too much must be just right)

Yes, on the X versions, preferred ratio was 13:16, single pinion. The gearcase was the smaller, painted die cast speedmaster. There was also a 1:1 ratio for that. If memory serves, these were reverse rotation from the later SSM-6. Props were a problem.

Hope this helps.

Jerry Wienandt
Trident Racing

[MN1]

650x and 700x used a diecast block, 3 carb front and sat over an adapter that mated them to the T2X mid.


Here is a photo I took at Miami Marine Stadium 1979. Doesn't look like a T2X mid.
Mark

[Hounddog]

Having had these motors for years, here is some additional infro.
-the carb set shown is 650X or 700X ..650XS has lower carb with flat bottom
because of the mid-section and cowll.
- 700X has finger ports and thin ring pistons its stronger
-tuner on 650X and 700X is shorter and wider.. 650 XS tuner is special
-650XS has a 164 ratio foot..15 inch only
- motors like av gas and lots of oil
-carbs drip and are messy
-tough to tune and difficult to start when warm
-great motor to race..very smooth.. little torgue
-not alot of low end power..like 6700 to 7300 rpm range

[Mark75H]

I don't know what possessed me to say that the 650x used the T2X mid. I think the only thing it used from the T2X was the swivel and a bracket or 2.


Jerry, if you saw a SSM that was smaller than a regular SSM, it must have been the V SSM that Fred said he used on the other motor. The 650/700X SSM is the same size as the inline 6 SSM.

[largecar91]

$2200.00 new. I'll take 2!!:D

[Trident]

Picture is the right tower and gearcase. I forgot about the 14:15 ratio option for these. I remembered the 13:16 and 1:1 (what was that for?)
This is NOT the same gearcase as my SST140 and SST120 #6 (mercury lists it in the parts list as 'VI SSM') Some parts interchange, but its a different housing...

Guys around here ran those cases in SST70, as they were cheap, plentiful and fast. Cheap 'cuz they were obsolete. Fast 'cuz they were smaller. But they rotated wrong way to use the latest props.

[RogerH]

Bill & Dave,
Please check your PM's that I sent concerning the parts.
Thanks,
Roger

[mbd29]

All right you techno guys what is wrong with the picture of the 650X in the Race Catalog.

Jerry this should be no problem for you.

[Trident]

Yup, I'm with Bill...

Race motors had the usual plastic 'bucket' top, held down to a 'pan' with 4 bungees, two on a side. The pan had a sheet steel center piece which sandwiched in between the powerhead and tower. I use that setup on my 650XS based FEH. Same cowls 650X or 700X. Mine originally said 700X. Closer inspection, I could see it was a little decal (sticker, actually) over the big sticker. Carefully peeling off the 700X, under it was 650X... OK, they recycled leftover cowls, apparently.

This cowl might be a 650XS. I don't have one to look at for comparo... but those were a clamshell with a bump on the front to clear the carbs. Or. sometimes catalog photos are preproduction mock ups... dunno.

I was studying the tower and gearcase in the pic... those look right to me. I recall, in the day, first looking at those towers on OPC tunnels, thinking they looked kinda tall and skinny, wimpy looking things, compared to the V-6 stuff. But they worked fine...

[guy hanson]

Hi there all outboard wizards, I have been watching this thread and just had to make a comment! yes I cant help it. Sam I think there is not much you dont know about any racing outboard, your knowledge is amazing, so when I see you stuff up on a technical reply I have to giggle, only because it doesnt happen!!! and some of the other guys on this motor are pretty sketchy too! I am in Australia and we had a handfull of these little motors here, 650 and 700 variants , and I raced one back in the mid 80s and my boss raced one in the late 70s. some of these motors and remains reside in my garage today. I am fascinated that no outboard motor manufacturer has bulit a mid range HP motor like this for ??? how long I am not sure, but why didnt these things take off?? why did Mercury only build a V6 race motor after about 1990? and getting to my other point, are there not many of these things around any more??? I get that feeling with the sketchiness on their specs and general knowledge, it seems we all know plenty about Twisters and Stranglers but not these? :)

[Skoontz]

was a buddy of dad's who worked at OMC. He got let go for taking some X-115, GT115 "scrap" and got cuaght. Ended up moving from Waukeegan to somewhere in Connecticut. Dad would tell me these stories as you jsut described Bill, and in my youth I would cry.

[Mark75H]

Bill, Guy didn't say Merc didn't build a V-6 until 1990, he asked why did the V-6 was the only racing motor they made after 1990 ...

The answer to that question and Guy's main question is the same ... the most amount of excitement and free press always comes from the biggest and fastest class running. For the most part factory based racing is about showcasing the biggest fastest newest product.

The 49ci/850cc motors became an exception to this during the 70's and 80's due to some races in Europe, BIG RACES, 850 was the largest class - and a lot of racers ran it, maybe 1/4 or 1/3 of all racers in Europe at one time. Again, this was the biggest show running, so the factories dueled it out with them. US and AU racers got lucky that racing motors were being built other than the most expensive and fastest and I'm sure selling a few more motors helped defray the cost.

I'm sure you are right about the difference between a 650xs and 700x porting is mostly in the finger ports ... did you really mean to say that there was a difference in the porting between the racing department 650x and 700x?

I'm iffy on the CCC looper ... seems like it is easy to misidentify the earlier V-6 prototype looper as a CCC, which it is not ... just like the "Merc looper 650xs/700x racer" which turned out to be a prototype project Fred Hauenstein was involved with and not a variant of the existing motor.

There are some threads on Screamandfly that easily explain the reasons for the porting variations on the Merc T2's & T2X's ... there is no reason to put a part number on a motor that has been custom built with experimental porting.

[RogerH]

I've especially enjoyed the last couple of posts as it points out how important it is to document information like this. For me, this 650XS endeavor has been one huge learning experience. I haven't even received the 650XS motor (from eBay) and I've learned a ton already. Thanks to everyone! I'm so engineering oriented, that knowing / learning the details is a huge part of why I've decided to restore vintage outboards and boats. I also like that I can build some projects to suit my own tastes and challenges. I found out early that sanctioned racing the equipment I built wasn't what I enjoyed the most. I remember being surprised how many owner / driver teams there were, and I see there are still a lot of team arrangements like that.

I enjoyed this thread and will try and remember to post some shots of the finished motor whenever that happens.
Off to NY for our first grandchild's arrival - back Oct 1st.
Regards,
Roger

[Mark75H]

That Bill is exactly right! If it were not for the internet and discussion forums ... I would not know 10% of what I've uncovered about outboard racing. Much of what I thought I knew in the beginning turned out to be dead wrong. I really have to give credit where it is due ... to the hundreds of contributors of many different boards across the years who have enlightened us all