What is safe rpm for 1989 88 spl?

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pennyanman1

Seaman Apprentice
Joined
Sep 8, 2005
Messages
30
Hey all,
Now that the weather is cooling off I'm seeing about 5800 rpm with a light load and the motor is SCREAMING but seems ok. I'm a bit nervous about running that high. Normally I get about 5450 to 5550 with average (4 people and 20 gals gas). I don't want to blow it up, but I've read a few places that 5800 for a cross-flow isn't harmful. Any thoughts?
 
Sea Rider

Sea Rider

Supreme Mariner
Joined
Sep 20, 2008
Messages
12,345
Re: What is safe rpm for 1989 88 spl?

If 5800 is the max rpm at wot stated for your given engine, you are at the max top, just don't go over if you still have throttle, use your tach to slow down a bit if passing. Definitelry more people and weight will slow top rpm.

Happy Boating
 
C

Cricket Too

Lieutenant Commander
Joined
May 14, 2003
Messages
1,732
Re: What is safe rpm for 1989 88 spl?

5800 is fine, in fact you should be shooting for that with a "normal" load. The experts on here will tell you to prop it to get as close to 6K as you can with a normal load, but 5800 is good. The only thing you'll do running it at that RPM is burn more gas. Remember it's a 2 stroke, not a whole lot of moving parts, and they love WOT if they are propped right.
 
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pennyanman1

Seaman Apprentice
Joined
Sep 8, 2005
Messages
30
Re: What is safe rpm for 1989 88 spl?

I don't plan on running there regularly as the boat isn't all that comfortable going that fast, but I try to cruise at about 4500 and it seems like I'm burning about 5 gph, so I wasn't necessarily looking to prop down. The hole shot is good too, the motor winds right up, no bogging. I am just supprised that these old cross flow motors can live turning that fast. I figured I'd be hurting it.
 
Sea Rider

Sea Rider

Supreme Mariner
Joined
Sep 20, 2008
Messages
12,345
Re: What is safe rpm for 1989 88 spl?

Will be wasteful changing for a lower pitch prop to gain those top 200 extra missing rpm, gas is expensive, buy more beer instead. Plainly in agreement, preffer to prop my engine/boat light loaded as possible to achieve max rpm stated for that engine, that way you can run at constant wot knowing you will not be over reving the engine.

Happy Boating
 
V153

V153

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Joined
Apr 16, 2011
Messages
1,764
Re: What is safe rpm for 1989 88 spl?

5800 is no problem. I routinely wind my 90 in excess of 6K. Heard tell from old racers they'd run 'em much higher than that? Just keep good oil & gas in it and y'oughta be fine. They are extremely thirsty at higher rpm.

Don't know what kind of boat you have. But for 'cruising' try to find a prop that'll run 30mph @ 3000-3500rpm. Kinda a magic # for those motors. You'll get about twice the fuel mileage vs wot.
 
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pennyanman1

Seaman Apprentice
Joined
Sep 8, 2005
Messages
30
Re: What is safe rpm for 1989 88 spl?

19 foot Penn Yan Lapstrake Deep V. I feel like the rig was a bit piggy at 3K, it seems much happier at 4K. My old 1976 115 was happier at 3500 with a 17" SST, but the 88 seems happiest at about 4 to 4.5K trimmed out with a 16" SST (the old 17 repitched and balanced with a little more agressive cup). These things love gas that's for sure, but running up Lake George (northern NY) on a 38 mile round trip I burned about 9 gallons running at 4.2K and 28 mph trimmed out. I think the motor is actually a little small since the hull is rated for 150, but I never really find it under powered. It pulls skiers and watertoys all summer long without protest.
 
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