Identify this case work

[hoppedupandcutdown]

I changed the trans in my 421 Serval 4mm 115 rod and noticed these marks in the crank area.

What's it from/for?

I was under the impression a 4mm didn't need trenching. and I've not seen trenching like that.

 

[#1JUANstunna]

My guess it is someones porting package. They are roughing up that area for atomization I think is the theory. I really don't know but that's what I've heard. May be BS

[sstaton1983]

My cases look exactly the same, mine is cut deep with epoxy on the bottom...

[locogato11283]

I don't see any trenching there. I see case porting.

[Surfrjag]

I have seen a set like that FAST did

[sstaton1983]

The crank case area is shaved down with a rough texture....

[trickedcarbine]

Wow, this is coming up quite a bit lately. It is definitely surfaced and done to promote turbulence in the case. I've seen lots of snowmobile stuff like that. Kinda the same thought when guys "turbo" the crank webs. How bout a shot of the upper case half on the under side?

[Nightmare]

My 350 is the same way.

 

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[RadarRacing]

Dune trash racing used to do that. A buds old school 350 from DTR is like that. It runs good but I dont know if the cases help any.

[registered user]

were turbo cranks just snake oil ? seen people do similar stuff on the head. prettty sure it amounted to a waste of time. probly reduced power actually

[trickedcarbine]

were turbo cranks just snake oil ? seen people do similar stuff on the head. prettty sure it amounted to a waste of time. probly reduced power actually

I know a few of the older designs definitely benefit from it. (Old GPX 670)No clue if any of the common Atv cylinders would benefit.

[sleeper06]

I do that with case porting , fast does it also , if its an older bottom end I put together the crank webs will have cuts in it like a sand paddle to throw the fuel,

[WINDYCITYJOHN400]

Case texturizing is an old builders trick that is now getting more publicity thanks to the internet.

All my motors are texturized. It isn't a big HP thing. But it keeps everything in suspension better. Tear down a stock motor.....you find a puddle of oil/fuel in the bottom.

Tear down a texturized motor......you don't.

[locogato11283]

Yea, FAST has been doing it for as long as I can remember. It's pretty old news really.

[hoppedupandcutdown]

Thanks, guys.

Looking closer at the F.A.S.T. invoice on my motor that I got from the guy I bought the bike from, it does say  "Banshee case porting for Cubs"