50 Yamaha 6H4

[88workcar]

Either way, thier tacho's must be setup wrong if they are reading 8000rpms..

By the way, the yamaha's run out of thier port timing above 6000rpm soon so youll actually lose power if you run it above that.. let alone 8000rpm lol

Apparently you have many winning boat racing trophys in the den at home hu fella. 8000 is common place. I turned a 40 7000 22 years ago, what do you do. I yes I did direct my answer to someone YOU!

[88workcar]

Matter fact Mr Pete, put us up some pictures with rpms, speeds, ect... Tell us all about you. !st thing we do know is that you have never owned anything that tures 8000rpm. I have a mustang that I shift at 7500rpm, I guess I am waisting time there too.

[Mark75H]

Depends on the porting ... with stock porting I am certain 8,000 rpm is making less horsepower and will be passed by better set up.


7,500 in the Mustang depends on the cam ... cammed for regular street driving ... 7,500 might be possible, but its beyond both the torque and hp peaks.

With an alternate cam ... could be good ... very good

[88workcar]

Have mid 90's Yamaha 50hp 6H4.

Anyone know what RPM I should be chasing with this motor and what RPM is too high?

Rev limiter is disconnected (came that way when I bought it).

I'm using it on an Aquarius inflatable Thundercat/SLT mostly for recreational fun and some racing. But I'd like the motor to last some

Thanks!

Andrew

OK Mr. Mark75 and Mr. Ballistic. Who said stock? Not Ace and NOT me. So why is my answer to the original question being questioned. This motor at 8000 set up right will fly, who is going to argue with that? And my mustang, is set up for it and does it every time I crank it. Ran a 10.76 on BFG drag radials, drove it to the track and home, and to the grocery store the next day. But were talking outboards.

The last 90 Yammi I had ran 87gas and turned 7500 every day, 78mph and I even held it wide open for about 7miles one time, with no breakdown. I don't run junk, I run very well built engines. Balanced, blue printed, ported, timed, jetted, and drive them hard. I think that I stayed well within the guidelines of the original question with my original answer. And don't take it well when someone with 12 post in say's my answer is BS. Want me to build a motor for you Mr Balistic? Any time buddy, buisness is buisness.

As I said before in 1987 I was turning a 40 yammi 7000 rpm, and for years I may add. This is not new to me. Hell yall should see the banshee motors that come out of my shop.

[YAMAHAFASTCRAFT]

for a stock 40/50 yamaha 7500 -8000 is very realistic.but there are some of us that twist them alot harder and make hp at that range.and by the way i got one i fish with and 7400- 7700 depending on the load and been doing that since new in 1991.i do agree it will being stock stop making hp about 6800.now if you port them and let them breathe there are no rpm limits we turn our race engine 8600 and will prove it if you want to see it.

[YAMAHAFASTCRAFT]

quess you haven't been to sabine river,or conway,south carolina.. out

that is right come to sc and see and tell us our tachs are wrong.

[proprider01us]

Ran mine at 8300rpm yesterday and got me a 2nd place finish with it running against 3cyl Johnrudes. Just starting to tune the thing, so hoping for more.

[Ballistic]

This topic is awesome

Topic starter has a stock block and asks what kinda RPM he may swing it.
Then everyone starts telling him 8000rpm (which will kill his block fast and he wants it to last)
Then someone agree's 8000 might not be the best
Then all of a sudden someone says " Who said stock?"
And to top it off.. we are making the switch to modified car motors... on a boating forum....

Ofcourse i stand by my case.. I told the topic starter 1 time that 8k is not a good idea and that was that. All my other reply's was major trolling
I couldn't believe how badly you wanted to prove you where right (which your not in the case of a stock block)

[Mark75H]

This topic is awesome

Topic starter has a stock block and asks what kinda RPM he may swing it.
Then everyone starts telling him 8000rpm (which will kill his block fast and he wants it to last)
Then someone agree's 8000 might not be the best
Then all of a sudden someone says " Who said stock?"
And to top it off.. we are making the switch to modified car motors... on a boating forum....

Ofcourse i stand by my case.. I told the topic starter 1 time that 8k is not a good idea and that was that. All my other reply's was major trolling
I couldn't believe how badly you wanted to prove you where right (which your not in the case of a stock block)

WARNING: replies other than apologies will be deleted by BRF administration. Just do not reply if you disagree or just want to vent.

[Ballistic]

can someone start a thread, where we can discuss modifing a 50 yamaha, i know there's some knowledgable racers on here, lot's of back yard racers wants to know the in and outs of making more power.. i've tried lots of things people have said. this is a great race site... enjoy......................out

Sounds like a plan. Who is stopping you? Go for it!