[scorpionryder]

Will a 69 85hp powerhead bolt up to a 115hp lower unit of the same year? I've got a scored piston in the 115 and a good 85hp powerhead. Will there be any major performance issues?

[ledgefinder]

99% bolt-on swap. Everything will bolt up. There's a minor difference in the wiring harness, due to the ignition & the method of driving a tach; more on that later.They are virtually the same motor, just tuned for power at different rpm ranges. The 85 is 94 cubic inches, the 115 is 97. The 85 has a stouter low & midrange (ie, pops up skiers better). The 85 has a nice top end, & you'd never know it was missing anything unless you ran it top-end versus top-end against a 115. I've run both in the water & on a test prop, and the 115 definitely has an animal scream on the top end that the 85 doesn't have - they'll turn typically 5400 on the test prop, versus the 85's 4800 rpm. The 85 is a little better on fuel, which you may appreciate as you've run a 115 for a while. In sum, you won't notice any difference except on the very top end. If the 85 powerhead is bare, you'll be using the 115's ignition & harness, so there won't be ANY differences between the motors. If the 85 has it's ignition, complete with the powerpack, I'd recommend sticking with it as I think as times go by the points-based ones have held up better, and idle better.The 85 runs a points-triggered ignition, while the 115 runs a sensor coil-triggered ignition. Both powerpacks are powered by 12V from the motor. If you do need to mix up the ignition parts, post back & we/I can guide you through it. If you do have a couple ignitions, don't toss the leftover one - keep it for spares or sell it on eBay. Worth $40-$100.

[jimmbo]

What about the exhaust tuning? any diff? ledge?

[scorpionryder]

Thanks! The good 85 is bare and the blown 115 has a powerpack.Is it a straight forward job to do the switch? I have worked on motorcycles and cars before but never on outboards.I plan on getting the seloc manual and I already have the clymer one. Is it pretty much all bolt-on? I also found a good 69 115 fully dressed powerhead ready to go but it's more $$. Would that be easier in the end? Both have good compression but are still used motors.

[ledgefinder]

The 1969 85 & 115 are both 'flatbacks', and I think have the same piping down in the midsection - so I think the exhaust tuning is same.The one thing I'm unsure about on the swap is using the 115 carbs. Everything will bolt up fine, but the bigger 115 carbs may not work optimally with the milder 85 tuning (or they may work great!).If you use the sensor-based ignition off the 115, note the two little metal dowels holding the rotor to the crank. Those will go in holes in the 85 crank, which will be there even though they're not used on the 85's points-style ignition. Otherwise, everything should be identical to the setup on the 115.The dressed 115 would be easier, but the bare 85 is still 100% bolt on. I don't think you'll notice the power difference in real everyday use, if that's any help. The 85 was clearly underrated, and I suspect a good bit of the difference was just marketing.