78 85 HP outboard is great. Can I get more HP from her?

[410Fortune]

Okay I have had this 2 stroke 4 banger for four years and I love it. It is a great little engine. Very reliable with just new fuel pump, plugs, coilpack, etc. My question is this:<br /><br />What can I do to the heads/intake/carb/reeds/etc to get some more HP? I have seen Evinride 4 bangers with the same block/dispplacement make 150 HP, correct? How do they do this? Different power head? <br /><br />Any advise would be greatly appricitated. Oh and I'm not afraid, I have good outboard knowledge and can do the machine work necessary....<br /><br />Remember this boat is in Denver and is a mile high. Not sure if it has ever been adjusted for high altitude but it runs better up here then it does at Powell or the Flaming Gorge......

 

[DJ]

Re: 78 85 HP outboard is great. Can I get more HP from her?

410,<br /><br />The 85 was a different engine than the engines that went to 140 hp.<br /><br />The 85 was a 96.9 cid. block while the others were a 99.6 cid.<br /><br />The 99.6 cid. block was used as: 88, 90, 100, 110, 112, 115, 125, 135 and 140. Even those 99.6 cid. blocks had differences between hp. ratings.

 

[410Fortune]

Re: 78 85 HP outboard is great. Can I get more HP from her?

OKay thanks for the quick reply. SO short or boring this baby out and doing all sorts of custom work to it (buy another boat first) are there any "tips and tricks" that apply to all 2 strokes I can try to squeeze a few more ponies from her?<br /><br />I mean with cars you add an intake, exhaust, bump up the timing a little, run a colder plug, bump up the fuel pressure, etc... <br /><br />Is there anything I can do like this to "maximize" my 85 HP. She just wont pull up on one ski, almost but not quite.....Of course I could lose 30#, then maybe.<br /><br />Up here in Denver we have a hrd enough time trying to get air to our engine's, is there anything I can do to help her breathe?<br /><br />Thanks!!!!!!!!

 

[410Fortune]

Re: 78 85 HP outboard is great. Can I get more HP from her?

OKay so now I have found some aftermarket REEDs to help a little. Any other idea's?

 

[DJ]

Re: 78 85 HP outboard is great. Can I get more HP from her?

410Fortune,<br /><br />You probably won't notice any change with the reeds. Plus you'll have to change them again in a couple of years.<br /><br />What is your maximum rpm when at wide open throttle? You may be able to prop. better for holeshot.

 

[ledgefinder]

Re: 78 85 HP outboard is great. Can I get more HP from her?

A chewed-up prop can make a big difference. Most of what the prop does happens in right at the edge - if it's chewed up, that's like trying to cut with a dull knife. If you've got a short enough pitched prop (say 17 inch pitch) & can't pop skiers right out of the water, I'd check the compression. All four cylinders should be within 5 psi of each other. Be careful not to strip those plugs putting them back in (I stay under 10 foot-pounds). Many feel the 90-115hp 99 cubic inch engines are better ski engines than the 135-140hps. The 90-115s have a good bit stronger mid-range.

 

[wilde1j]

Re: 78 85 HP outboard is great. Can I get more HP from her?

Your 85 HP at sea level is about 68 HP at 5000 and even less is the jets are sea level stock jets. Another, bigger, motor is usually the most cost effective solution if you're already propped right (~ 5500 RPM WOT) and have the right jets installed.