Mercury 650 4 cyl.

[reelfishin]

I have the chance to upgrade from a Merc 500 50hp to a Merc 650 65HP. The 500 is too small for my boat and I think the added 15 HP would be just what it needs. The 50HP is a 1976, and the 65 HP is a 1971 model.
Does this sound like a logical swap? The 65HP has excellent compression, looks nearly new and came off a similar boat.
What concerns me is that the 650 uses the earlier style distributor ignition, is this still a viable motor to run these days or are they just too hard to find parts for?
I won't miss the underpowered 50HP, and would welcome a simpler ignition system, but don't want something that can't be fixed if it breaks.
The 65 HP is in good running shape as it is, needing maybe only a prop change to make it work.

Any input?

 

[WillyBWright]

Re: Mercury 650 4 cyl.

Make sure the boat is rated to handle it. Make sure it has spark. Neither ignition system is cheap to fix, but the 650's is about double the price on components. Never try to get the rotor off the shaft. It's a permanent part of it and they are no longer available. That's killed many a 650 inline-4 by do-it-yourselfers.

 

[reelfishin]

Re: Mercury 650 4 cyl.

The boat can take up to a 120 with no problem, but it's lived all these years with a 50HP. The 500 was in good shape mechanically but lacked power and was in need of some serious rewiring. The harness had just about fallen apart. It was also too short for this boat, it was a 15" shaft set on a bracket to make it work.
The 650 is a 20" and was originally of a fire/rescue boat in a nearby town which had no water in which to ever use it, they sold the boat at auction after they decided they had no use for the boat. The guy who bought it sold the boat with intentions of using the motor on his bass boat, but it was too long, so a mutual friend had arranged an even trade. The 650 looks near new and fires up with ease. I was told however that it spend about 20 years just sitting in storage awaiting use, the guy that originally bought it at auction had it serviced at a local shop or dealer, but that was a few years ago, it's been sitting in a garage for the last few years since. I hooked it up today on my boat and it fired right up with no problems.
I got the original manuals with it and noticed that there's a timing belt that drives the distributor and was concerned about that needing replacement?
Did these ever break?
Were these motors prone to any particular problems?
Its about 60lbs or so heavier than the 500, but its still light enough to handle by myself and with eliminating the transom bracket, there with be even less transom stress. I do want to add a large aluminum mounting plate, just to keep the motor from being in direct contact with the transom.