68 sportwin9.5- no top speed

[mike vaughan]

I am having the same problem as Mike Ku Aug 30. Motor run good to about half throttle than races. Have drained lube and it looks clean(no chunks). Shear pin is ok. I think there is suposed to be a washer behind the shear pin- if not could this be the problem? Thank for any help.<br /><br />Mike

 

[JB]

Re: 68 sportwin9.5- no top speed

Your prop may be cavitating (or ventilating), Mike. Is the plate just above the prop (called the cavitation plate most often) even with the bottom of the boat? If you have a short shaft (15") motor on a long shaft (20") transom, that will happen.<br /><br />Let us know.<br />Red sky at night. . .<br />JB

 

[mike vaughan]

Re: 68 sportwin9.5- no top speed

I had a suspision that that might be the problem. Probably the only thing I can do is to use a shallow boat, correct?

 

[BayStLouis]

Re: 68 sportwin9.5- no top speed

You might be able to find a long-shaft kit or entire lower unit to replace the short one, if that is indeed the problem. Probable cheaper than getting a different boat - and wiser than cutting the transom.<br /><br />OMC built those engines from '64 through '73 - there are parts out there. If I can find an old e-mail printout around here somewhere, I'll give you contact info on a guy who claims to be parting-out a number of those 9.5s.

 

[mike vaughan]

Re: 68 sportwin9.5- no top speed

will this be a difficult change? or hard to find parts? or will it be easier to get a longer lower end?<br /><br />Mike

 

[BayStLouis]

Re: 68 sportwin9.5- no top speed

Here's a post I spotted on the sailors.com "SailBoard":<br /><br />Subject: 9.5 lower unit<br /><br />--------------------------------------<br /><br />[ Follow Ups ] [ Post Followup ] [ SailBoard Message Center ] [ FAQ ] <br /><br />--------------------------------------<br /><br />Posted by Tim Braun on Monday February 26th, 2001 at 7:05:44 AM PST:<br /><br />In Reply to: old part posted by david on Wednesday June 21st, 2000 at 2:16:41 PM PDT:<br /><br />David, I have over 20 of these outboards for parts. I get 100 dollars for the lower unit. Let me know if you need a long or short shaft leg for your motor. I also have the orig. service manual for that year.<br /><br /><br />Here's the URL for that message, perhaps Tim Braun can help:<br /> http://www.sailors.com/SailBoard/messages/875.html <br /><br /><br />Definitely pick up a parts manual and service manual off of eBay, too.<br /><br />-BSL

 

[nbru21]

Re: 68 sportwin9.5- no top speed

I JUST DISCOVERD THE SAME PROBLEM WITH MY BOAT. I CALLED WHERE I BOUGHT THE BOAT (GRUMMAN 16') AND THEY TOLD ME I COULD NOTCH MY TRANSOM UP TO THE HEIGHT OF THE BRACE, IF THIS GAVE ME THE CORRECT DEPTH FOR MY CAV PLATE. IF NOT MY FREE MOTOR NEEDS A LOWER UNIT TO MAY IT WORK RIGHT.<br />THEN ITS A $2OO.OO MOTOR.

 

[mike vaughan]

Re: 68 sportwin9.5- no top speed

BSL, I have someone looking for a lower unit or extension kit for me. Having trouble getting e-mail address from Tim Braun for your earlier post.<br /><br />Thanks for the help,<br />Mike

 

[BayStLouis]

Re: 68 sportwin9.5- no top speed

Mike:<br /><br /> My Microsoft Explorer pulls up the e-mail address: "cheapstuds75@hotmail.com" when I click on Tim Braun's name at that message board.<br /><br /> Good luck finding the parts that you need.<br /><br />- BSL

 

[mike vaughan]

Re: 68 sportwin9.5- no top speed

Tried motor on shorter transom boat- same problem, but can only get about quarter throttle before it starts to race. Went to local parts shop, they say it is probably the rubber hub inside of the prop that is spinning. This is probably the problem because when I was running the motor for a while and it would slip the slipping would get worse as it would warm up from slipping. Hopefully will get to try out the new prop this weekend.<br /><br />No luck in finding an extension kit for this motor.<br /><br />Thanks for the help. It is greatly appreciated.<br /><br />Mike Vaughan

 

[mike vaughan]

Re: 68 sportwin9.5- no top speed

Just to let everyone know, it was the rubber hub inside the prop. Put a new prop on and took it out for a spin. Went like a bat out of hell. <br /><br />Thanks for the guidance.<br /><br />Mike

 

[Fouled Plug]

Re: 68 sportwin9.5- no top speed

This motor has a shear pin and a hubbed prop?

 

[mike vaughan]

Re: 68 sportwin9.5- no top speed

Yes there is both the shear pin and the rubber hub. After I inquired at the local shop about an extension kit, he told me that more than likely it was the rubber hub that had rotted or gone bad from years of non-use. This is one to remember for future use.<br /><br />Mike

 

[jack avery]

Re: 68 sportwin9.5- no top speed

Hey Fouled Plug<br />I have a 1964 short shaft 9.5 sporttwin that has a shear pin and a rubber hub too. I changed to a new prop a while back for the same reason. Right now it is not running, but at least it still has the shear pin and rubber hub.

 

[12Footer]

Re: 68 sportwin9.5- no top speed

Fouled Plug, on the Forces and Chryslers, they used a pinned hub spline, pinned thru the prop shaft. But it is still a standard rubber hub in the prop. I know, it's kinda<br />silly to have a splined shaft with a pin thru it,(kinda overkill) but then, it is a Force. <br />I guess it's not the only maker who did that.

 

[Fouled Plug]

Re: 68 sportwin9.5- no top speed

Yhat's the great thing about this board. Ya learn something every day! I have not personally owned an outboard with the hub/pin setup, but it's good info for future use. It was my first thought in m vaughn's original post, but when he said the shear pin was fine I assumed it was cavitation. D'oh! Glad you got it fixed, at any rate.