Carter Flowing -- Epoxy Questions!

[Areomyst]

I'm seeing a lot of matched&flowed carters that have the passage that goes behind the main bearings filled with epoxy and filed flat.

Why is this done? I can see it will improve direct flow to the transfers, but it would seem like you would want at least a little flow behind the bearing so that it is lubricated better.

On the Minarelli engine, it seems to me like one would want to actually put another bore that goes from the bearing bore/seal and points to the transfers, and keep the one (work out sharp edges, etc) that goes from "reed cage" area to the bearing. I have done this, and will post a photo of the unfinished piece. (It is not matched to any cylinder, it is just a practice one)

[ir]http://www.scooterinvasion.net/pics/p1010012.jpg[/ir]

What kind of epoxy is usually used? I need to fill the part where I cut through the carter. > Please keep in mind, that this is a broken carter that I've been grinding on for fun and practice. Suggestions are beyond welcome!

Does the duration of the reeds being open factor in much when working the carters?

 

[Big B NRG]

In holland we use some 5 eur. epoxy. That works really well.

Devcon is also good, but $$

 

[narx]

From what I've read, JB weld is very popular in the US.

 

[StepVino]

I used JB to fix a broken cold start feed tube, in the bowl.
Days later when I had the carb apart, the JB did not set.
It's been months now, and it's still a bit soft. I don't
think it likes gasoline.

Same with some Devcon I tried, but there seems to be
many types of that, so maybe I used the wrong one.

Maybe in both cases I didn't let them fully cure before
exposing them to gas fumes .

 

[tiba_karotsu]

i use local manufactured "steel" epoxy, Cord Steel Epoxy, quick dry, hardens like rock, much better than popular imported brands.

 

[Mr.Aerox]

i used 'nural 21' epoxy but came off after a few hours and made my cylinder seize... now i use quicksteel, its very good, similar to loctite mp20 but its a bit expensive. did u sand your carter? or u used a special tool for dremel? looks very shiny

 

[Areomyst]

i used 'nural 21' epoxy but came off after a few hours and made my cylinder seize... now i use quicksteel, its very good, similar to loctite mp20 but its a bit expensive. did u sand your carter? or u used a special tool for dremel? looks very shiny

I used an attachment on my dremel to "shine it up" a bit... I am getting the rubber abrasives, mandrels with sandpaper, and polishing wheels for my Foredom handpiece though. The dremel things aren't too bad, you just have to go real slow so you don't tear up the abrasive pad. They are also more expensive, and not as efficient. I posted a photo of it in my other thread "Post Photos of your Porting Tools", but I will show it again here. When I get my mandrels and polishing bits, I will post them under that thread.

[ir]http://www.scooterinvasion.net/pics/P1010011.jpg[/ir]

The photo of the carter is very rough. There are a lot of hard edges and cut marks, but when I'm done it will be perfectly smooth, and mirror polished. Then, after I'm satisfied, I'll carry the same work out on one of my engines.

So does anyone have any insight about the extra bore? Is my theory sound, or should direct flow to the transfers be improved by sealing the bores up? If it's more a matter of 'personal preference and/or theory' then I think I'll do all of mine like that.

 

[Big B NRG]

I once tried this to my engine;

V-force membrane:

 

[Areomyst]

I once tried this to my engine;

Very nice photos! How did it work out? The way you molded the epoxy, it looks to direct all the charge straight to the transfers. Did the crank hold up well enough?

 

[Big B NRG]

Very nice photos! How did it work out? The way you molded the epoxy, it looks to direct all the charge straight to the transfers. Did the crank hold up well enough?

Well, to be hounest, I don't know. Because when I was dynojetting it, it had all kind of problems to bad.
The crank holded up just like normal, like you can see, the big end is clear, so oil can flow.

It was for flowing it straight to the cylinder instead of keeping it in the crankhouse space.. Maybe I will try it some other time, but it will be glued in.

 

[narx]

Very interesting Big B but hmm wouldn't a fresh charge be sucked underneath the piston in the upstroke anyway so I don't actualy see a benefit in shaping the carters that way.
Also there must be some turbulence around spinning crank and I don't have a damn clue what's happening in there at 13k rpm

Here's another pic with the same layout, I don't know what engine is that.

 

[StepVino]

All this work is amazing. It reminds me of Italian fountains.
Not that there's any similarity, just the workmanship.

The other day I was wondering what would happen if you
put reed petals at the entrance of each transfer port. Forget
how impractical it would be, just how much more efficient
the pumping might be.

 

[Big B NRG]

Very interesting Big B but hmm wouldn't a fresh charge be sucked underneath the piston in the upstroke anyway so I don't actualy see a benefit in shaping the carters that way.
Also there must be some turbulence around spinning crank and I don't have a damn clue what's happening in there at 13k rpm

Here's another pic with the same layout, I don't know what engine is that.

Well, when tuning blocks etc, think at what happends at 14k rpm. In theory step-by-step this happends, piston goes up, membrane opens, fuel is filling the engine all around, piston goes down, membrane closes, fuel goes thru the ports, piston goes up, exhaust blows the fuel back in, ignition, start all over again.

Now at 14k rpm, there issn't much time the piston moves up and down 233.33 times a second!! So the thought was to get all the fuel right to the transfers, to get more fuel in thru the transfers at the same time, thereby increasing cylinderfilling, gaining HP.

Right now I don't have it in, but maybe someday again.