440 finger ports

[Iggy]

Hey y'all, I have a farmertec 440bb that I'm going to build, before I got into that I wanted to practice on this standard bore, I ran this at Randys' this past October in class 2. Since Randys' I moved the lowers over and filled them quite a bit with jb weld, i also cut the finger ports, to open with the main transfers. I bought a right angle micro grinder to learn on this jug, I ended up a bit close to the intake and there's some Knicks all that aside what do you guys think of the design, and how it will perform? I have not run it yet, I'm hoping Saturday.

 

[Funky sawman]

It looks to me like it will catch a ring end on the intake side, unless you must run the piston backwards

 

[MustangMike]

Yea, I was under the impression that all the guys doing finger ports were running the Husky piston with the single ring. I think the ring gaps on a standard piston will catch on those (unless you reverse the piston).

 

[Funky sawman]

Ok that makes sense.

 

[Deets066]

Wondering what kind of porting tools your using?















Was it a rotohammer?

 

[Funky sawman]

OMG laugh of the day deets!

 

[MustangMike]

Easy Deets, he said he is just learning, and looking for advice. At least he seems to have the upper transfer lined up well with the fingers.

 

[Deets066]

Easy Deets, he said he is just learning, and looking for advice. At least he seems to have the upper transfer lined up well with the fingers.

I met Iggy at Randy’s place. So he’s fair game to razz a bit. Lol

 

[Deets066]

The design isn’t bad Iggy, widen your fingers a bit where the epoxy is. You need more room to feed them. Right now the top is widen than the bottom. Then work on smoothing things out

 

[drf256]

Better than my first fingers.

Honestly? They look awful.

The tunnels are too small to feed the uppers, but I see what you were thinking. The BB440 jugs tunnels are already too small to begin with.

You gotta try to stay between the intake and the upper. If you’ve already widened the intake, it makes it tougher. Need a strip of plating for ring support.

I do like your fingertips.

If you’ve already widened the exhaust you may not be able to flip the piston. You can’t run the ring pins over any port at any time.

Every one of those gouges in the plating needs to be beveled or they will ruin the piston skirt or catch a ring.

Get another jug and try again. I made the same intake port mistake you have my first time, I also used an AM jug.

Keep grindin’

 

[drf256]

 

[drf256]

Not that I’m that great at them, but I want to illustrate what I mean. Also, I open the “feed” area from the lower to the finger more than I used to now.

Kinda think of a funnel feeding it.

 

[drf256]

Here’s my newer way. More of a funnel feed.


MS460 jug.

 

[Stihlms]

Here’s my newer way. More of a funnel feed.


MS460 jug.

View attachment 161059 View attachment 161060

Wow that's extremely nice doc!

 

[Redfin]

Are you opened to the skirt on the primary side of the lowers?

 

[blsnelling]

I don't understand what this accomplishes that simply widening the factory transfers won't accomplish.

 

[John235]

Is that a 262xp cylinder in mixed in there

 

[MustangMike]

Brad, I think the goal is flow direction, the effect of which is debated. I like to install small bridge ports for the same reason. They seem to work well in the 440 Big Bores that I have done. Perhaps they help make up for transfer ports that are not optimal.

I keep them small, as I believe making them too big could hurt velocity, but I think providing an addl flow angle helps. They seem to run pretty well.

 

[00wyk]

Brad, I think the goal is flow direction, the effect of which is debated. I like to install small bridge ports for the same reason. They seem to work well in the 440 Big Bores that I have done. Perhaps they help make up for transfer ports that are not optimal.

I keep them small, as I believe making them too big could hurt velocity, but I think providing an addl flow angle helps. They seem to run pretty well.

I don't think the model crowd or the bike crowd bother to debate it. Boost ports are nearly always as standard or added. And a fair few older karts motors had them, if not all.

 

[MustangMike]

Some of the top chainsaw builders debate their necessity on a chainsaw motor, and while I like them and have seen strong performers with them, I have also seen some very strong performing saws that don't have them, so there is likely more than one way to skin the cat here.