Yamaha 8hp 2 stroke help

[guitarguy15]

I am looking to get more out of my engine. I am familiar with cars and car engines and I do have some limited boat specific knowledge.

What I would like to do is get about 20mph out of it. The motor is on a fairly light boat, a crestliner 13ft, and I'd say hits about 12-15 as of now. The motor has no problems, starts first pull and runs till I shut it off. One thing I noticed was that my fuel filter is pretty nasty and has things floating in it so I will replace that obviously, I don't know if this will help performance. I guess it really just depends on how dirty it is. But what can I do to this thing to get more out of it? I'm not afraid to spend some bucks on it. I've read about removing the governor but I seem to brain fart every time I go to do it and not be able to locate it. Any help is appricated, thanks

 

[JB]

Re: Yamaha 8hp 2 stroke help

Ahoy, guitarguy.

Welcome to iboats.

Don't mess with your engine except to be sure that she has correct plugs, gapped correctly and that Link 'n' Synch is right on.

Improvements in performance are much more available in tuning the rigging and propping.

By trial and error find the perfect height on the transom, then the perfect trim angle.

Get a tachometer and find the perfect pitch SS prop.

Experiment with weight distribution in the boat.

Those measures usually count for at least 50% increase in HP.

Good luck.

 

[guitarguy15]

Re: Yamaha 8hp 2 stroke help

Alright, thanks boss. I'll tool around with that today

 

[guitarguy15]

Re: Yamaha 8hp 2 stroke help

Can you describe a link n synch for me? I think someone has been in there and messed around before me, which is why I'm not so afraid to mess with it thanks

 

[robert graham]

Re: Yamaha 8hp 2 stroke help

8HP on a 13' boat may not run 20MPH, but like JB mentioned, the set-up and weight distribution of your boat/motor could help some....maybe add some weight in front of boat? Good Luck!

 

[guitarguy15]

Re: Yamaha 8hp 2 stroke help

So I think a found something that might have been a problem, my prop is like a 7.5x8.5 or something stupid like that. I have an old 9x10 around that I found. But what hub kit do I get for it? I have been all over the internet searching and can't quite find it. It is an older, I'd say 90's, motor so if anyone can find what I need that would be great

 

[JB]

Re: Yamaha 8hp 2 stroke help

Can you describe a link n synch for me? I think someone has been in there and messed around before me, which is why I'm not so afraid to mess with it thanks

The L&S gets the throttle correctly connected to the carb and the carb and ignition timing exactly synchronized, GG. It is different for almost every outboard. You will need the Service Manual to do it right.

 

[guitarguy15]

Re: Yamaha 8hp 2 stroke help

bump for help with the hub kit! lol

 

[JB]

Re: Yamaha 8hp 2 stroke help

bump for help with the hub kit! lol

That is a prop issue, GG. Try the Prop Forum.