1973 Starcraft (fill in the blank)

[wannagetrdone]

I have a 1973 Starcraft aluminum semi v boat. Very wide and pretty deep. I had someone tell me it looked like a jupiter or juniper however it is called. My question is it came with a 1973 65hp Johnson the boat is rated for a 85hp. I have found an 1984 Mariner 115hp. Do you think it would be too much motor?

 

[jbcurt00]

Re: 1973 Starcraft (fill in the blank)

Pix? Length? Beam at the transom? Transom height?

Those will help confirm the Jupiter model. If the boat is USCG capacity tagged for an 85hp motor, it is likely correctly ID'd as a Jupiter as well.

The 115Mariner will weight substantially more then the 65hp current motor & quite a bit more then the 85max motor. Combined with an over a 1/3 jump in hp, combined with the added weight & torque, yeah, I'd think the 115 would be too much motor. Esp if the 1973 Jupiter has the flat hull at the transom similar to my Jet:

Not the concave V or V5 hull later designs, you can just tell that it's not flat across the bottom of the transom like it is on my Jet above:

or

BTW is the Jupiter you bought this boat?

Might get more traffic & help along the way if you'll take the advice & requests for more info and follow thru with those requests & advice. Particularly w/ regards to pix.....

Just the same, congrats on picking up a Jupiter, and a 65hp motor.

 

[wannagetrdone]

Re: 1973 Starcraft (fill in the blank)

Well I cant get pics as the boat is still at the shop. I know it is 16ft long and Im gonna say the transom height is 20in cause its a long shaft outboard. Im not sure about the width but I know its more than 5ft. I have problems with the 65hp thats on it but I have access to a 115hp mariner. The max my boat is rated for in 1973 was a 85hp. A 1978 Johnson 85hp weighs 285lbs and this 1984 115hp weighs 312lbs. Thats really not alot of weight difference. Im not sure bout the extra 30hp but if I put a different prop to take out some of the thrust you think I would be alright?

 

[jbcurt00]

Re: 1973 Starcraft (fill in the blank)

I won't say it can't be done, or that it can be done safely. And you'll probably have a hard time getting anyone to green light overpowering by a 3rd.

Something else to consider is when the power rating for OB's was changed. At some point, and I'm sorry but I don't know the date, the ratings system used to power (hp) rate OB's was changed. Under the old rating system, hp was rated at the flywheel and once transferred to the prop, there could be a 10-15% drop. Under the new ratings, OB's are hp rated at the prop. So your 85hp might 'only' be 77hp rating at the prop, maybe less. Then the jump to 115hp is greater.

Not seeing your boat up close & in-person, its condition in many areas not just the transom, or exactly how & where the boat is used, are just a few of the concerns beyond what I mentioned in the earlier post.

If you've already got it, or it's in great running order & a steal for the money, you might consider trading the 115 down for a smaller motor. There are ads on CL fairly often looking for smaller or larger displacement motors then the 1 the 'seller' is posting....

You could also start shopping for an 18ft'r now to put the 115 on Or keeping the 115 on standby for a year or 2, until the 2-footitis starts to kick in & you really want the 18' or 21'....

 

[wannagetrdone]

Re: 1973 Starcraft (fill in the blank)

Well Ive found the 115hp for $600 with power trim or a 50hp Johnson for $450. The transom, and the floor in my boat is less than two years old. The transom is 2pieces of marine grade 3/4 plywood laminated together with the brace in the center and the aluminum on the outside .

 

[Pugetsound]

Re: 1973 Starcraft (fill in the blank)

IMHO Do not put a 115 on the 16 ft boat. TO big and more power than you will ever need. Besides the local law or C G if caught will insist you remove it . An up to 85 would be nice ,but my 16 SS was very fast with a 55 HP on it . however I fish and boat alone. Whatever you buy be sure to get a Power tilt/trim if you can find one. Lifting the motor by hand gets old. As at 75 years is very dif. for me to raise the 55 on my present boat. Good luck have a great project the work will be rerwarded.

 

[jbcurt00]

Re: 1973 Starcraft (fill in the blank)

Well Ive found the 115hp for $600 with power trim or a 50hp Johnson for $450. The transom, and the floor in my boat is less than two years old. The transom is 2pieces of marine grade 3/4 plywood laminated together with the brace in the center and the aluminum on the outside .

Do you have pix of the deck & transom replacement, and how were they sealed prior to & after installation? How was the boat stored while not in use? Covered, indoors, bow high, drain plug removed? Was there flotation foam present when the deck was redone? It's condition? Was it replaced?

The 65hp Johnson that came on the boat is the 1 you posted in the engine forum? Carb thread & Won't run thread? It was suggested that low compression would cause some running problems, did you check the 120psi result you posted across the cylinders yourself? Compression check guage kit is available at car parts stores. Seafoam shot thru all spark plug holes, left to soak for a day or 2, may help, if low compression is stuck pistion rings. There were several models of 1973 Johnson 65hp offered for sale, as listed here, which model is it? Posting the model # in your engine threads will likely get you more traffic & replies. And follow up on suggestions, questions & requests for more info will too.

If I could spend a couple hundred (say up to $300, both the 115 & the 50 your considering, will likely need some attention, work too) & get the existing 65hp motor in good running order, I'd do that first. If not, then I'd buy the 50hp & put the $150 'savings' into a good donor boat for parts & pieces to sell & fund the rest of the rehab, possibly another motor &/or trailer. Or a 'good' pair of seats & pedestals, maybe even all 4 seats if you shop/wait for a deal.

Asking the same question, different ways or for different reasons, will get the same answer:

We wouldn't put the 115 on a 16ft'r....

 

[wannagetrdone]

Re: 1973 Starcraft (fill in the blank)

In my opinion it doesn't have low compression. With my Snap-on guages I read 135lbs for the top 2 cylinders and 123 or so for the bottom. I went to look at the motor yesterday and the bottom cylinder has minimal scarring that you can see but just barley feel. The concern the shop had was piston play. You can move each piston probobly 1/8in or more side to side and probably have 3/8-1/4in play overall. He says the reason it won't run in water is low compression not being able to push the exhaust thru the water. I ended up buying the 50hp Johnson instead just hoping it ll push the boat well enough with my family in it as well. I never actually got to take it out with the 65hp that was on it.

 

[jbcurt00]

Re: 1973 Starcraft (fill in the blank)

Less money upfront for the motor will get you back in the water, and for what it's worth, I think you made a good decision.

Can you run the boat w/ the 50 now, or do you need to rebuild it, some or completely?

When you can, post up some pix. Even if it's a wreck needing a total refurb

And for sure if you mount the 50 & drop it back in the water for a spin

 

[wannagetrdone]

Re: 1973 Starcraft (fill in the blank)

The shop is putting the 50hp on there this week and she ll be ready to go in the drink hopefully this weekend I'll get pics as soon as she is home.