Post up your ported cylinder Artwork

[HYPERSAWS]

I will give it a shot

 

[huskihl]

Stay tuned.....

 

[cus_deluxe]

Stay tuned.....


View attachment 171879

WOooooooooooot

 

[AlfA01]

They'd feed beside the piston for anything but a full circle piston.

Yes, of course. But, the same volume of fuel/air is converging on the same port as factory.

I'm thinking to find a gain here there would need to be an increased volume on the fingers and the upper enlarged?

 

[drf256]

I will give it a shot

The problem is that the ring pack area will close off the bottom of your feeds before or just after the uppers open. Also, air will take the path of least resistance. If you extend them down the jug more or poke through a hole into the transfer tunnels, you’ll likely gain. I wouldn’t tell you to do that if you hadn’t already ground in the cylinder. Watch out for your ring ends, you’re likely better off poking holes through where the two red circles are. My gut tells me that nothing will change how the changes you made affect performance.

We add bridges ports, boost ports and/or fingers to increase flow. On a dual port saw I can see the merit, though some real seasoned builders say they add little or nothing to a saw if your uppers are correct. @tree monkey

On a quad, the factory already added the extra ports for you with elegant angles that are difficult to recreate. You get both speed and flow because they gave you more transfer area with more small ports. Generally in a worksaw, no one adds anything to a quad. In race saws, where all out speed over any reliability issues prevails, people do add boost ports and all other crazy stuff.

My bet is that an OEM cylinder will increase your performance over any port work you do to that meteor. And you’ll save money on burrs.

 

[Deets066]

The problem is that the ring pack area will close off the bottom of your feeds before or just after the uppers open. Also, air will take the path of least resistance. If you extend them down the jug more or poke through a hole into the transfer tunnels, you’ll likely gain. I wouldn’t tell you to do that if you hadn’t already ground in the cylinder. Watch out for your ring ends, you’re likely better off poking holes through where the two red circles are. My gut tells me that nothing will change how the changes you made affect performance.

We add bridges ports, boost ports and/or fingers to increase flow. On a dual port saw I can see the merit, though some real seasoned builders say they add little or nothing to a saw if your uppers are correct. @tree monkey

On a quad, the factory already added the extra ports for you with elegant angles that are difficult to recreate. You get both speed and flow because they gave you more transfer area with more small ports. Generally in a worksaw, no one adds anything to a quad. In race saws, where all out speed over any reliability issues prevails, people do add boost ports and all other crazy stuff.

My bet is that an OEM cylinder will increase your performance over any port work you do to that meteor. And you’ll save money on burrs.

Well said Doc

 

[Moparmyway]

The problem is that the ring pack area will close off the bottom of your feeds before or just after the uppers open. Also, air will take the path of least resistance. If you extend them down the jug more or poke through a hole into the transfer tunnels, you’ll likely gain. I wouldn’t tell you to do that if you hadn’t already ground in the cylinder. Watch out for your ring ends, you’re likely better off poking holes through where the two red circles are. My gut tells me that nothing will change how the changes you made affect performance.

We add bridges ports, boost ports and/or fingers to increase flow. On a dual port saw I can see the merit, though some real seasoned builders say they add little or nothing to a saw if your uppers are correct. @tree monkey

On a quad, the factory already added the extra ports for you with elegant angles that are difficult to recreate. You get both speed and flow because they gave you more transfer area with more small ports. Generally in a worksaw, no one adds anything to a quad. In race saws, where all out speed over any reliability issues prevails, people do add boost ports and all other crazy stuff.

My bet is that an OEM cylinder will increase your performance over any port work you do to that meteor. And you’ll save money on burrs.

EVERYTHING

And I mean EVERYTHING he just said

X2

 

[srcarr52]

Yes, of course. But, the same volume of fuel/air is converging on the same port as factory.

I'm thinking to find a gain here there would need to be an increased volume on the fingers and the upper enlarged?

IMO feeder/bridge ports such as those are not for adding a large amount volumetric flow. They are to add a small air jet that that reaches the cylinder quicker due to the shorter port length and causes the incoming charge to fan up the cylinder. This is why they are normally done on the intake side only, where you want the fresh charge to climb the intake side of the cylinder, loop around the chamber all while pushing the exhaust out (loop scavenging).

Feeder, boost or finger ports are normally kept pretty small in comparison to the actual transfer ports, with entrance angle much steeper. They are there to start the loop scavenging cycle without having to rely on the traditional puddling and then rising on the intake side, which at higher RPM there is not time for. Once the piston has opened the transfers port enough the flow through these extra ports becomes choked and their directional effects are lost to the now much stronger main transfer flow.

With that said, I don't think the porting shown that started this discussion would run well. Feeder ports on both primary and secondary ports of a quad port design would not be beneficial, especially in conjunction with the cat-eye port entrances. This is likely to trap a large amount of exhaust gas in with the fresh charge during port opening and I suspect it may also cause a lot of tumbling which would mix even more exhaust throughout the rest of the transfer cycle. It may be ok if a large amount of charge is wasted out the exhaust, which would hopefully include the majority of the trapped exhaust from the start of the cycle.

 

[HYPERSAWS]

I appreciate all the input helps a lot thanks

 

[Deets066]

Nice write up Shawn

 

[srcarr52]

Nice write up Shawn

Thanks. It is only theory, so I could be completely wrong.

 

[huskihl]

 

[Deets066]

View attachment 172133

Thumb is almost as big as the bore.....

Must be about 52mm huh??

 

[huskihl]

Thumb is almost as big as the bore.....

Must be about 52mm huh??

They say the camera adds 10 lb, so...

 

[Stump Shot]

They say the camera adds 10 lb, so...

 

[redlight066]

Did a little work to this makita 6421. Is there somewhere you can buy a non-cat muffler instead of breaking into these childproof mufflers. Sure would be a hell of a lot easier. Didn’t use enough heat peeling the muffler in half (cracked the flap) and had to have Sam weld one side back together. Haven’t done any stainless yet.

 

[mettee]

SLEequipment.com has the non cat muffler for sale, they drop ship from makita. $62 plus shipping I believe

038174200

 

[Deets066]

SLEequipment.com has the non cat muffler for sale, they drop ship from makita. $62 plus shipping I believe

038174200

Do they still have the baffle?

 

[huskyboy]

SLEequipment.com has the non cat muffler for sale, they drop ship from makita. $62 plus shipping I believe

038174200

Those still have a restrictive baffle inside that I remove. 7900 muffler.

 

[mettee]

Do they still have the baffle?

Still have the baffle yes. But you can cut the end off from the port.

Then it's pretty free flowing