140 hp mercury rpms

[twigass]

i bought a 91 bass tracker 18ft and put on a 79 140 mercury with a 19 k prop it runs between 5500 and 6500 rpm and only reaches 48 mph that is gps readings not odometer is that standard or am i pushing too many rpms and is that as fast as it will go, and if not what should i do to get the max out of it

 

[OldMercsRule]

Re: 140 hp mercury rpms

My Seloc shows 5300 to 5800. I doubt an occaisional burst to 6000 would hurt much, but 6500 seems like yer turning too much. JR

 

[Clams Canino]

Re: 140 hp mercury rpms

You Seloc is showing you the RPM range to PROP it for. This is to set the correct loading (gearing) for the overall package of boat and outboard.

It's not telling you to actually *run* it like that on a regular basis.
PROP IT FOR 5500 - CRUISE IT AT 4200

-W

 

[twigass]

Re: 140 hp mercury rpms

thanks for the help. but still a little confused i am new at this so bear with me, people say it should go about 60 is that right or are they blowing smoke up my butt, and can that motor handle premium or no and 50-1 is that good for an older motor. also what brand of plugs do u rec for that i have champs in it now flat bottom style. the props also the 1 is a 2 phase pitch and the other is just a big pitch, i dont get rpms out of it like the other about 5000 for big pitch and 6200 for 2 phase also 2 phase gets 48 and other only 42. tach is off a little around 500 so they r a little off.any help is good help

 

[Clams Canino]

Re: 140 hp mercury rpms

60 is not right. Champion or NGK are good- yes they are flat bottom - that's correct for the inlines. You need a 5500 RPM prop (something between the 2 you have) and then *run* normally it at 4200. If you just want speed, buy a new motor and blow it up under warrantee. the old inlines are all a worn a few thousanths and WILL blow up under extended WOT use. I live on a 3 acre, lakefront home because people run them at WOT.

-W

 

[Scaaty]

Re: 140 hp mercury rpms

WILL blow up under extended WOT use. I live on a 3 acre, lakefront home because people run them at WOT

HA!

 

[OldMercsRule]

Re: 140 hp mercury rpms

WILL blow up under extended WOT use. I live on a 3 acre, lakefront home because people run them at WOT

HA!

Me thinks Wayne has a rather large n' very valid point that he put in a very profound way: Scaaty!! I only have enough faith in one of my inlines to hot rod very much, (n' I don't do it cause it's 38 years old and I would hate to have to get another one). You strike me as an ol' rodder who would understand the very valid corncept he states here. You're fresh 1350 should be good fer some serious roddin' once broken in!! JR

 

[twigass]

Re: 140 hp mercury rpms

thanks for the help guys didn't really want the speed but everyone telling u something diff is what confused me so i appreciate itvery much and will go back to original prop and have fun

 

[Clams Canino]

Re: 140 hp mercury rpms

Yes... you PROP it for 5500 or so WOT - the speed you get is what you get.

Daily cruise outta be at 4000-4200 - the speed you get is what you get.

-W