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FOUND SOME INTERESTING UIM SD CLASS HISTORY..1980's

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 PostPosted: September 30th, 2018, 10:26 am   
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Matt your'e got to like this!
SD was the S750 class......T750 motors on small tunnels.
OMC is tops in our T750 here.
In the 1980's overseas the top runner was a yamaha/mariner 60 hp

https://www.screamandfly.com/attachment ... 1500306975

Originally Posted by lars strom
We tried the new stock Evinrude 60 2 cyl. 1980 when it was released from OMC in the UIM SD class but the Mariner 60 was much faster. (Also 2 cyl).
Bertil Wik was racing the Mariner 60 in the UIM SD class and he won every SD class race for years. He got the nick name "Super Bertil" from that era.

Now the bad news.
In the USA they were able to get 70HP out of the mid 1980's OMC motor.

ANTHONY McCULLOCH
On a modified 45 powerhead we were running #63 mains after:
1- porting reed blocks & using carbon reeds w/o stops
2-adding velocity stacks to carbies
3- mill head more than 45 specs
4-matching ports block w/sleeves
5-dry out and coat 45ss exhaust tuner

Some of the other things can not mention a public forum but things above were considered fundamental to get a 45ss to go from 6,200 on the test wheel to turn 7,000 or an increase of about 8 hp = 70hp on 93 octane gas.

Did you ever get your critch going?...what kind of performance did you get out it?
We are running high 60's @ 7200 rpm with great acceleration.
same rpms with other props means we are up against pipe
Fixing to go to 1.87 gearcase with lowater pick-up and some other things.
Will test on sst60 test wheel.


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 PostPosted: September 30th, 2018, 1:18 pm   
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Don,
cool to hear stories like this but stop giving the OMC guys ideas!

:)

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 PostPosted: September 30th, 2018, 5:31 pm   
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Ha Ha! I'm on it!

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 PostPosted: October 1st, 2018, 11:52 pm   
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The interesting fact about the T750 twin cylinder motors is the good models were made in the early 1980's. After that the outboard manufacturers change those models to 3 cylinders.
The twin cylinder models were built very well and many twin models became their COMMERCIAL model.
The horsepower rating was crankshaft rating in the early 1980's. When the motors became prop shaft rated their hp rating was normally 5 hp less. So the 60 hp models are 55 hp at the prop.
There is only ONE motor T750 twin that had a crankshaft rating over 60 hp in the early 1880's
The 1982 SUZUKI DT65ESZ was 65 hp at the crank. So it would be 60 hp at the prop.
https://www.brownspoint.com/store/pc/suzuki/dt65.asp
PDF is on the link
https://www.youtube.com/watch?v=x47rk4cYQNk
The video shows this motor has very big carbs, and the parts book shows very large reed cage with 4 four pedal reeds and a small tuner.
Got to like the reeds....http://www.boyesen.com/power-reeds-257.html
With the same mods as the OMC listed above.....it should be a plus 70 hp motor in race prep..
Maybe we can get people interested in building some T750 motors this winter.


Last edited by Hounddog on October 3rd, 2018, 12:13 am, edited 3 times in total.

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 PostPosted: October 2nd, 2018, 11:05 am   
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T750 guys are gonna be in trouble next year!


Attachments:
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chrysler.jpg [ 23.94 KiB | Viewed 5858 times ]

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 PostPosted: October 2nd, 2018, 12:45 pm   
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Paul does this mean you want to sell your existing t750 motor? lol

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 PostPosted: October 2nd, 2018, 5:04 pm   
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craig737 wrote:
Paul does this mean you want to sell your existing t750 motor? lol


Jes doesn’t have that much confidence in my mechanical abilities with a chizler :?

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 PostPosted: October 2nd, 2018, 8:33 pm   
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LittleCharger wrote:
T750 guys are gonna be in trouble next year!

https://www.screamandfly.com/showthread ... -outboards


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