Finger ports POWER GAINS ?

[Dingie 2]

I have read everything that I can get my hands on about 2 stroke exhaust ports. If a wider exhaust port should give mid and upper RPM gains without loosing bottom end. But could shorten ring life. If raising exhaust ports should help upper RPMs and hurt lower RPMs . What gains would someone get if they drilled a 1/4 '' hole on each side of the exhaust port 4mm to the side with the top of the 1/4 '' hole being 2mm above the stock port ? The power head that I am thinking about trying this on is a 2003 V-4 Yamaha.I have been told that some of the 200 V Pro Yamahas had finger ports Does anyone have a pic of them ? Thanks for ant help Joe R

[RUDERIOT]

Fingerports are extra intake ports that are normally installed on either side of the boost port. Thay are said to increase low end power & are usually about the same height as the transfers. I'm becoming convinced that they are unnecessary in a well thought out very stout motor.
As far as the two extra higher exhaust "ports" I can see no advantage & have the thought that it would just confuse the motor. Put the exhaust where you want & be done with it.

[David - WI]

Triple exhaust ports are very common in snowmobile engines... they are a great way to get more exhaust port time-area without a long, narrow bridge to worry about.

Usually it's not quite as simple as "drilling" them in, though... in order to make them work they need to flow well and not disrupt the main exhaust flow too much.

In the picture, you can see from the mold of the port how they flow together:

[Dingie 2]

:confused: :confused: David , They have small ports next to the main exhaust ports on go cart and motor cross motors as well, I was wondering about the location of the additional ports.. I thought that one small port on the side and a little higher than the stock port would give the same power increases as a wider taller exhaust port. I would think that a outboard that isnt on a ultra light hull would need a wider power band . I am looking for more power across the power band and raising the RPM some on the upper RPM band. Does anyone have any Pics of the E Tec or Yamahas before and after port work. Joe R:confused:

[jphii]

You're not gonna find an etec that's been cut, but here's a pic of OMC fingerports that have been cut.

[props4u2]

That's a Cummins motor isn't it! LOL

Lee

[H2OPERF]

Engines with the extra exaust ports generally have transfer ports with flat roofs that are aimed at the back of the cylinder,outboards ported for lower rpm have canted roofs aimed more at the center,with the two exhaust ports right above the transfers alot of your intake charge would mostlikely end up in the exhaust.More exhaust timing helps but most people neglect the intake,you dont need a 2 exit doors if u only have one entrance. Jphii lets see the exhaust side too.Dave

[jphii]

You're killin me Dave, you wanna see all my secrets:D:D:D

[racer]

You have to be very careful adding extra ports, done wrong you will ruin its power output.