91 Mercury 115 Powerhead Swap With 97 125?

[justchecking]

How do I cross reference power heads to see which power head I could swap? In particular, could I swap a 1997 125 power head for my 1991 115 power head? Would my 115 carbs work if I rejetted them? (My 91 115 has a bad cylinder).

 

[79Merc80]

Re: 91 Mercury 115 Powerhead Swap With 97 125?

I'm no expert, but I think that the 100, 115, and 125 used the same block, so should bolt right on. Not sure about the carbs though.

Craig

 

[Faztbullet]

Re: 91 Mercury 115 Powerhead Swap With 97 125?

It will fit but the 1991 is a "small bore"(105cid) and the 125 is a "big bore"(113 cid). Everything should fit except carbs as the 91 uses 21 series carbs and the 125 uses 34,52 or 81 series. Your carbs may not feed the engine as emulsion tubes and passages are different. If you can get the 125 carbs get them with block.....

 

[justchecking]

Re: 91 Mercury 115 Powerhead Swap With 97 125?

Thanks for the responses. I didn't think about the emulsion tubes or the fixed idle jets in the lower two carbs.

How do those 2+2 engines work? In the lower two cylinders do the carbs let in just enough fuel for lube, but not enough to fire (or backfire) occasionally?

This may be a moot point, since I've been checking shipping and it looks like around $500!