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Old 07 April 2008, 03:51   #1
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Country: USA
Town: Athens, GA
Make: Legend Craft
Length: 5m +
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Suzuki 25 hp

Ive got a 1999 Suzuki 25 hp 3 cylinder, was wondering if anyone knew of any modifications I can make to increase hp? I have changed out the throttle linkage and removed the throttle linkage stop on the middle carb (basically to turn it into a 30hp), but was wondering if anybody had any more ideas to amp it up a touch.
Thanks
J
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Old 07 April 2008, 10:31   #2
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Country: UK - Scotland
Boat name: Wildheart
Make: Humber/Delta Seasafe
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Engine: Merc 60 Clamshell
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Have you tried it yet? I'll bet you get about 30 seconds at WOT, followed by a hesitation then into "limp home mode" at T+50 seconds....

You may need a replacement CDI so it doesn't think it's "over revving".
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Old 07 April 2008, 14:10   #3
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Im not having any issues, just trying to get more hp out of my suzuki. It's not hitting the rev limiter, I just tinkering trying to get some more power.
Thanks
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Old 07 April 2008, 16:45   #4
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Country: Other
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Boat name: Nautile
Make: Sea Rider 450 Rib
Length: 4m +
Engine: Tohatsu 5/18/30 HP
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Quote:
Originally Posted by Greenhead1984 View Post
Im not having any issues, just trying to get more hp out of my suzuki. It's not hitting the rev limiter, I just tinkering trying to get some more power.
Thanks
Check if there is a same 30 HP model, if so, replace your carb 25 HP jets and change for the 30 HP jets, remove the air restrictor if your 25 is currently using one located between the carb body and engine head, basically a plate with holes. (get a spare parts manual to check both head parts to see if both are the same head) Some brands needs to change the whole reed valve assembly & carburator because the gas passages are thiner/wider comparing both models, a change of just jets will not update the next engine model.

Lost 6 months experimenting to change a Evinrude 10 to 15 HP, both same 250 cc head, changing a 15 jet didn't better the performance, was worst. Finally knew that you needed to change complete 15 reed valve assembly (larger intakes) + complete 15 carb and the cost was near $ 200. Sometines is better and cheaper to buy a larger standard model instead of converting after purchase. Examples 4 to 5 / 10 to15 / 25 to 30 etc.

This modification will work fine as long as both engines 25 & 30 have the same cubic centimeters, example 450 cc for both, the difference is that 25 is fuel and air restricted compared to 30. Maybe will need to change the pitch propeller, make a wot rpm run to match the best wot maximum rev engines for that model, example 5500-6000. If the change is possible to gain the extra 5 HP, move your linkage back to the position factory adjusted.

Happy Boating
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