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I am repowering my 1988 Montauk with a used 2005 Yamaha 90hp two stroke, I currently have a 1988 Yamaha 70 two stroke on the boat with the older Yamaha multifunction gauge, does anybody know if it will be a simple plug n play install, or if the harness, key switch, tach and control will work? Thanks-Jack

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Hello jaxmyth, your 2005 Yamaha 90 as my 2007 do not have much in the way of digital sensors that will benefit from Yamahas latest and greatest diagnostic gauge displays.

I do not recall, does your previous 1988 Yamaha 70 have the Precision Blend 2 stroke oil tank mounted on the power head as our newer models do? I ask because there is a "Low Oil" sender in the tank that couples to the latemodel harnesses. You may want to research this.

Does your current Yamaha gauge employ the "trim-bar", "Over-heat", and "Low-Oil" displays? The 2005 will most likely have these functions as mine does unless they have been purposely disabled. Have you compared the motor to harness plugs and visible wire color codes with pin connector count.

If you like contact www.simyamaha.com and inquire with them, they are very pleasant to deal with.

Best,
Angel M.

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Dauntless- yes the 1988 70 hp does have the precision blend. the current gauge that I have is the old version of the multifunction display which has the trim bar, overheat and low oil displays.. I just want to know if the harness from the 2005 motor will work with the one currently on my boat. Im not talking about the command link new stuff. I should have been more thorough with my description. sorry bout' that.

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Hello jaxmyth, do you have access to the 2005 Yamaha 90? There is a 17 year design gap between the two harnesses to be absolutely sure on compatibility without physically inspecting the pin count and wire color code positions at plugs.

Do an inquiry regarding harness compatibilty with the site I suggested, they are very knowledgeable www.simyamaha.com. Is the 2005 Yamaha 90 a private sale or through a boat yard/marine service? If the outboard is very clean and it appears from your information that a harness is not included I would seriously consider purchasing a new harness for it just for the sake of safety and reliability.

The re-rigging will add time and labor perhaps additional cost but at least you will be assured of no electrical gremlins (crossing our fingers and knocking on wood) going forward. These are just my thoughts jaxmyth.

Best,
Angel M.

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Yeah I already have the engine, and if necessary I will purchase a new harness, I just wanted to ask here first in case there was somebody with experience that could tell me. I will be installing myself so the labor cost depends on how many beers I drink while doing it . I'm just trying to save some time and money by reusing the old stuff.. Thanks again

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Yeah I hear you on the cost versus boating fun. I guess I'm just weary of older wiring, it may look intact until "Murphy's Law" kicks in. You never had an electrical concern with the Yamaha 70 and now you mount the "New to you" 90 and the older Yamaha puts a jinx on you for retiring it...it happens...LoL.

One other item to check...amperage draw between the Yamaha 90 and the 70??? Will the older harness comply? I would think so but better to verify. If your current Tach is trouble free I would certainly use it and forgo the expense of the newer digital brother...there somewhere between $250.00 thru $350.00 pending sale source...ouch!

Best,
Angel M.