need advice on motor build up.

[smallfry1227]

i have a briggs 5hp flat head that i am wanting to modify for my mini bike project. i am needing to know what all after market parts will fit in it and where to get them. also i plan on porting and polishing the heads and changing the carb from the gas tank/carb to just a carb. i know how to port them but how do you polish them and what do i use. thanks any help would be appreciated. also i removed the governor.

 

[OzFab]

For starters, you won't be porting the "heads" as it only has one & there's no ports in it, they're in the block.

Port & polishing is the process where the rough casting marks are removed form the port channels to create a smooth surface &, therefore, increase flow.

Porting is achieved using varying grades of gringing stones then the polishing is done using varying grades of sandpaper, finishing with about 2000 grit on the inlet & around 1000 - 1500 for the exhaust

 

[smallfry1227]

i meant to say the block. thanks though.

 

[r_chez_08]

There is loads of info here
http://www.diygokarts.com/vb/showthread.php?t=1583

I am lead to believe that raptor parts fit in these blocks but not a Briggs expert.

Fabroman, the inlet port is generally rougher than the exhaust port so that the air 'tumbles' and fuel particles become atomised. The exhaust wants to be smoother so that the gases can exit as quickly as possible.

You can diy port with some cheap dremel sanding and polishing drums, which can be used in a drill or dremel.

 

[smallfry1227]

ok thanks for the link.

 

[OzFab]

Fabroman, the inlet port is generally rougher than the exhaust port so that the air 'tumbles' and fuel particles become atomised. The exhaust wants to be smoother so that the gases can exit as quickly as possible.

Ok, not that I've ever done it but, I thought I read it the other way around. Makes sense though