Getting more power from a 50hp yamaha 2 stroke

[nousername]

i have a 1999 yamaha 50hp autolube 3 cylinder engine.
I am considering selling it for something up to 70hp but the weight of the yamaha is making me think it is maybe a base for a more powerful engine setup in the same range...hence the question ?
Maybe someone with a bit more knowledge on the subject could confirm my thought process or insanity ?

Any and all advice welcomed , ta !

[69cmw]

Search for Rolfhat’s post on the same subject

[nousername]

Originally Posted by 69cmw

Search for Rolfhat’s post on the same subject

Could ou post a link, i'm not good at finding results through searching, thanks !

[spartacus]

Link here: https://www.rib.net/forum/f50/my-thundercat-61912.html

My understanding is the 40/50hp 3 cylinder shared the same block. I used to have a Yamaha 40V after waiting for a 50hp to come on the market, which never did show up. The was on the back of a Pro 7-man.

By the time you’ve finished with tweaking it, which won’t be cheap, it still won’t put down the horses of a 70hp.

Rolfhat started with a Tohatsu 50 D2 then took a Yamaha 70hp and basically pimped the hell out of it.

This any use? https://www.boatsandoutboards.co.uk/...l-now-8103546/

[nousername]

Thanks for the info and help folks !!

[Davie]

If you have a 50g it’s the same 850cc block as the 70 so it would be a case of finding parts but you will need to sort out your own exhaust. All the other yamaha 50hp models use the smaller 6h4 derived block which you won’t find bolt on parts to up the power.

[boater]

Originally Posted by nousername

i have a 1999 yamaha 50hp autolube 3 cylinder engine.
I am considering selling it for something up to 70hp but the weight of the yamaha is making me think it is maybe a base for a more powerful engine setup in the same range...hence the question ?
Maybe someone with a bit more knowledge on the subject could confirm my thought process or insanity ?

Any and all advice welcomed , ta !

Hi , I may be selling a mint condition Yamaha pro 50 hp , I’ve heard from a good source that they put out nearly 70 hp , it’s on the back of a small cat at the moment that is also for sale , will post pics later 👍

[Davie]

Originally Posted by boater

Hi , I may be selling a mint condition Yamaha pro 50 hp , I’ve heard from a good source that they put out nearly 70 hp , it’s on the back of a small cat at the moment that is also for sale , will post pics later 👍

That's because the pro 50 / 50G uses the 849 cc block which is common with the 60F and 70B blocks. Your engine will have the torque of the 70 but not the rpm as you will need the bigger carbs and an exhaust which is available in usa from a company that will come back to me. The other thing that is different is the 50G runs the g series gearbox house which is very narrow in relation to the K series house.

[Roflhat]

Definitely possible to get more power from the 50hp, but as a general rule it's always best to start with the biggest engine you can safely put on your boat. Will net a lot more reliability and longevity from the engine, even after a handful of modifications it usually takes a long time get the engine running as sweet as it did from the manufacturer.

For a Yamaha a good start is hydrotec in the states, they make a fairly bolt on package for more hp. But the 50hp is a pretty tried and tested setup for thundercats, they're stronger than the Tohatsu in standard form, better engine mounts, crankshaft etc. Carbon reeds, skimmed cylinder head and some fettling on the engine tuner can net a decent improvement in performance

[Roflhat]

Another cool thread on here - https://www.rib.net/forum/f36/yamaha...ing-77960.html

[spartacus]

Cheapest Yammie 60hp I've seen for a while. Nothing a full service, and paint couldn't fix.
https://www.andyseedhouseboats.co.uk...tedPTToutboard