DF25 Rev Limiter

[gogittum]

My recently purchased 2008 DF25 V-twin runs great and I'm almost pleased with it, but there's a problem. (another one)

When I put it into F and give it power, there's a smooth surge of power and it lifts onto plane quicklly and easily. Love it - sounds more like a diesel than an outboard; it's very quiet, and it has a nice, soft growl to it. This is a carbureted, tiller steer motor.

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My boat is a 16 ft Starcraft Seafarer - the one with the high freeboard and weighs 286#, hull only. The old 15 hp Johnson 2 smoke drove it to 22.2 mph on the GPS with just me (170#) and my dog (48#) and minimal gear on board - camera, soda pop, 10# of tools, CG equipment.

When I hit full power with the DF25, it accelerates smoothly and quickly to 26 mph and goes flat. Still throttle left in the twist grip but it doesn't do anything - doesn't even sound like it's trying, as in bogging or such. Prop is a 10 x 14, so doubt if it's over-propped. With the 10 x 13 spare prop I only got 23 mph, so again, I think it's hitting a max rpm and stopping there - no way is it hitting 5,000 rpm. I put a cheap induction tach on it, but it's erratic and no telling what real rpm's are but seat-of-the-pants feels like around 3500 rpm or so. I cleaned the carb jets and picked up a bit but it's still dead on top end.

I stumbled across a mention of low oil level causing a rev limiter to engage, but checked the oil and it's fine and looks new. What else should I look for ??

I had expected this motor on that light hull to give me an easy 30+ mph full throttle and it's not even close. I'd be real happy with a cruise speed of 25 mph. (the boat will hold a smooth, sustained plane right down to under 8 mph) Help.

[Moonlighter]

The great American professor of management and father of the quality movement, W Edwards Deming, said

“Without data, you're just another person with an opinion.”

Until you KNOW what rpm your engine is able to achieve, you are just speculating and shooting in the dark.

[Murray]

Might want to consider getting a genuine Suzuki service manual. It will have all the settings and specifications that you need to check/verify. Do you know the history of the maintenance done or not?

[cprice11]

My 50 lb lighter boat only went 28 with a 25 hp Mariner.

[gogittum]

Might want to consider getting a genuine Suzuki service manual. It will have all the settings and specifications that you need to check/verify. Do you know the history of the maintenance done or not?

Far as I know, it Is a Suzuki service manual, purchased and downloaded online. Thanks.

[gogittum]

My 50 lb lighter boat only went 28 with a 25 hp Mariner.

Seems like it should do better than that. Have you tried different props ?? What rpm range can it achieve ??

[gogittum]

The great American professor of management and father of the quality movement, W Edwards Deming, said

“Without data, you're just another person with an opinion.”

Until you KNOW what rpm your engine is able to achieve, you are just speculating and shooting in the dark.

Let's assume that the seat of my pants isn't too far off. I do have a huge amount of experience with boats in general and with engines of all types in many applications. Closest to this would be the Suzuki V-Strom 650cc V-twin motorcycle that I rode for a couple of years - I sold it just a year ago. That one did have a tach and I'm very familiar with how it felt and sounded at various rpm's.

My big question is: Is there a rev limiter on the motor and if so, how do I re-set it or by-pass it or eliminate it ?? I've given up on this junk induction tach and am going to order a Tiny Tach - that has a good reputation.

[gogittum]

Come on, guys. Is there or is there not a rev limiter on my 2008 DF25 ?? If there is, what triggers it ??

[Murray]

Come on, guys. Is there or is there not a rev limiter on my 2008 DF25 ?? If there is, what triggers it ??

Your service manual will tell you what triggers the rev limiter.

https://www.suzukioutboardforum.com/...fetch?id=44612

I see oil pressure isn’t listed in the above link(from the Sticky section). Low oil pressure will activate the fail safe system.