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T750 2Cyl Short OMC (1980/1982) Kit with 60hp Carbs, more..

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 PostPosted: October 12th, 2018, 6:40 pm   
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Jan 2019: NO LONGER FOR SALE

Lots of items here but overall, I believe this is what most of the T750 guys are running, basically.

The main item is a complete short shaft 1980 Johnson 50hp 2cyl, "100" block. Compression is good (140/145 - photos below) and it runs.
I just started it on the stand in my driveway (short video available). Cosmetic condition is a faded cowl and corrosion below the waterline but it is all there including controls with a key. Lower unit seems fine - no leaks, it shifts, I haven't checked the gear oil yet.

Also have a nearly complete 1982 Johnson 2Cyl 60hp long shaft in parts with the main goodies being the 60hp 1.25" venturi carbs, intake, all electronics, also a "100" block. Missing from this 1982 60hp is the maybe just the starter. It is in pieces because it "blew" a piston. The crank and rods have a bit of rust on them from previous owner storage but the block itself looks rebuild-able with oversized pistons if you want a fresh block and want no downtime (cyl walls look good, no compression relief hole).

Also have potential Power Trim for this motor: Approx 1991 Johnson 2Cyl 40hp bracket and power trim for a long shaft. This bit needs a new trim motor, and I believe the tilt bracket needs to be cut/shaved to length to fit the short shaft motor, and that is I think.. (other racers can provide guidance, I hope). I believe one of the fastest T750 teams runs this lightweight power trim setup.

I had a plan to get this running mint with the 60hp carbs rebuilt, new paint, and customized power trim, but I don't think I'll be able to find the time to do this. I believe just based on my first run on the stand it will need the fuel pump and carbs rebuilt, probably some new engine mounts. ..and then if you care about looks some paint and sweet decnals..

Asking $1200 for all of the above. Located in Guelph. Would love to see this go to a future racer. I might be willing to do the work to assemble this for racing (carbs, fuel pump, custom power trim, mounts) if the buyer is willing to pay for parts and some of my time. Otherwise this would be a great project for the DIY'er.

Message me if you have any questions or want to chat.

Edit:
-The 1982 60hp includes the long shaft 2cyl Nitro lower gearcase complete. The casing is in better cosmetic shape than the short one. I'd be willing to keep this to adjust the deal.

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Jan 2019: NO LONGER FOR SALE

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Critchfield T850 OMC 56ci
Delta T750 Yamaha 55
1989 Voodoo Yamaha 70
1980 Thundercraft v142 Restored


Last edited by mattmak on January 7th, 2019, 7:51 pm, edited 1 time in total.

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 PostPosted: November 9th, 2018, 7:10 pm   
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I've cleaned up the 1982 60hp carbs. They are getting all new parts from the carb kits. Interestingly the main jet for the top is slightly different than the bottom, but the parts catalog reflects this (56D and a 55D). The 1982 60hp carbs have 3 jets each - might be nice for fine tuning all Load/RPM ranges. Photos coming soon. When the 60hp carbs go on I'll check the jets on the 50s to see what's in there.. The 50hp carbs also have a 1.25" venturi.

Fuel pump is getting completely cleaned and rebuilt.

Fuel line will be replaced.

Now have 3 cowls for this motor - 1980 Johnson 50, 1982 Johnson 60 (prev owner painted), 1984/1985 Evinrude 60hp VRO.

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Delta T750 Yamaha 55
1989 Voodoo Yamaha 70
1980 Thundercraft v142 Restored


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 PostPosted: November 9th, 2018, 7:45 pm   
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1989 Voodoo Yamaha 70
1980 Thundercraft v142 Restored


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 PostPosted: November 10th, 2018, 5:37 pm   
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I found a trim motor for the 1990-ish trim, so the hydraulics are working. But I need a tilt tube and ram pin for that swivel/tilt bracket, plus other misc hardware off that bracket (stainless lock nuts for the lower hydraulics pin, the stainless cross bar that connects to the two side brackets at the bottom, ground straps, misc bolts).

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Delta T750 Yamaha 55
1989 Voodoo Yamaha 70
1980 Thundercraft v142 Restored


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 PostPosted: November 11th, 2018, 11:08 pm   
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Found this. Not sure how this can happen.. I raced with a block this summer that had previously consumed a whole steel reed petal. Shredded it to chips, some of which I found in the spark plug. Inspected the cyls with the head off and amazingly found little damage to cyl walls. Only piston top and combustion chamber got pitted in a small area. Cleaned it out and replaced the reeds, compression was good one so hopefully this OMC block is similarly unaffected.. The reed cages and reeds from the 1982 60hp (pictured in above post) will be going in..
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Crank and rods look pretty good!
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Pulled the long shaft midsection apart. Got the engine mounts off it to use on the short shaft. Photos of the long shaft adapter and tuner. Any tips for how much to chop off? :)
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Critchfield T850 OMC 56ci
Delta T750 Yamaha 55
1989 Voodoo Yamaha 70
1980 Thundercraft v142 Restored


Last edited by mattmak on November 12th, 2018, 11:11 am, edited 1 time in total.

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 PostPosted: November 12th, 2018, 12:30 am   
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Just shows you never know what you will find and the advantage of parts motors. The aluminum went thru the motor so there has to be some damage. A buyer would be concerned. You should take the powerhead apart and check it out. If it is OK best to blue print it or sell it disassembled. An T750 racer would want to SST 45 blue print anyway.
As for cutting the tuner....I would......measure the distance between the top and bottom exhaust ports.....you want to have the pipes equal length from their respective exhaust port, one side of the tuner will be longer than the other.... You can always make the tuner shorter so for starters make the long side bottom cylinder end just above the cavatation plate where the exhaust holes would exit in the mid. Cut the other pipe for the top cylinder shorter equal to the distance between the top and bottom exhaust ports.


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 PostPosted: November 12th, 2018, 7:24 pm   
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Scoped the cylinders. Here is a video one take:

http://mattmak.com/boat/omc_2cyl_resto/scope/scope.mp4

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Critchfield T850 OMC 56ci
Delta T750 Yamaha 55
1989 Voodoo Yamaha 70
1980 Thundercraft v142 Restored


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 PostPosted: November 16th, 2018, 8:52 pm   
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Measured the 1982 60hp head combustion chamber pocket depth. Came out to approx 0.525 in which is pretty close to the 0.515 APBA SST-45 spec. So I will just clean this up and sand it on a granite surface.

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Critchfield T850 OMC 56ci
Delta T750 Yamaha 55
1989 Voodoo Yamaha 70
1980 Thundercraft v142 Restored


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 PostPosted: December 9th, 2018, 3:08 pm   
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Delta T750 Yamaha 55
1989 Voodoo Yamaha 70
1980 Thundercraft v142 Restored


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 PostPosted: December 9th, 2018, 5:58 pm   
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The engine is apart. Came apart a lot easier than I thought it would. The paint looks bad but no bolts were difficult to get out - no powdered aluminum in the lower or mid.

The lower mount bracket was loose on the Steering Shaft splines. Amazing. But apparently this is not uncommon..? This is the only location so far where the Yamahas have been more difficult to deal with (getting the lower bracket off the steering shaft splines).

The 1982 60hp lower mount bracket fits tight to the steering shaft splines of this short shaft, and also the lower rubber mounts from that motor are in better shape, so will be using those. If anyone has tips for stiffening the lower rubber mounts, but not having them be solid, let me know.


Jan 2019: NO LONGER FOR SALE

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Critchfield T850 OMC 56ci
Delta T750 Yamaha 55
1989 Voodoo Yamaha 70
1980 Thundercraft v142 Restored


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