Nissan/Tohatsu 25 hp to 30 hp upgrade should be done but there is no difference??????

[Doubles]

I've read on several forums how to do this up grade. I have installed the 30 hp gasket and the timing appears to be set at 25. The last timing mark is lined up with the mark where the two cases meet, both butterfly valves are horizontal and there is no increase in power. Does anybody know why I am not getting anymore power? The air/fuel mixture and idle seem to be ok too.

 

[pvanv]

Re: Nissan/Tohatsu 25 hp to 30 hp upgrade should be done but there is no difference??

If you aren't getting the 20% increase you expect, perhaps you need to review the rig itself to verify correct trim, jack height, etc.

 

[Sea Rider]

Re: Nissan/Tohatsu 25 hp to 30 hp upgrade should be done but there is no difference??

Yep, verify what Paul recommends, to get the max out of those horses, engine must be trimed so to sit perpendicular to water level when boat is floating alone, boat must ride well ballanced paralell to water level, anticav plate included. Water flow must pass under small upper deflector plate to get the max rpm with minumum tail drag. Check related issues. http://forums.iboats.com/honda-tohatsu-nissan-outboards/leg-height-myths-609265.html

How do you know there's no difference, have you checked both wot rpm and max speed included with a GPS on flat, glassy, no wind waters to compare them. Depending on your boat model application, probably will need a prop pitch optimization, only possible to check with an induction tach...

Happy Boating

 

[JB]

Re: Nissan/Tohatsu 25 hp to 30 hp upgrade should be done but there is no difference??

I suspect that the best prop for the 25 is not the best prop for 30. The expected 20% increase in rated HP usually requires more rpm because it probably doesn't increase torque at what is peak rpm for the 25.

Modifications to one link in the chain usually requires modification in other links to be even measurable, much less felt in the seat of your britches.

 

[TOHATSU GURU]

Re: Nissan/Tohatsu 25 hp to 30 hp upgrade should be done but there is no difference??

It's a few hundred RPM increase...The difference would be at WOT by 1 or 2 mph.

 

[nissan18hpstolen]

Re: Nissan/Tohatsu 25 hp to 30 hp upgrade should be done but there is no difference??

It's a few hundred RPM increase...The difference would be at WOT by 1 or 2 mph.

Where do could i purchase this upgraded gasket? Also, is there a youtube video of how to install it? I just purchased another motor (last one was stolen-hence my name) and when i'm supposed to be WOT the throttle valve in the carb it at 40% open. Not sure if the guy that i purchased the motor from didn't "refurb" it correctly or if there is something i need to change - i.e. the gasket, to get full WOT.

Thanks and i'm new to the forum so if this has already been answered, point me to the post and i'll do my homework! Thanks!

 

[GA_Boater]

nissan18hpstolen Please start new threads with you questions. Look at the Help Tip on top of the page. Thanks.

Closed.